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The Advanced Technology Large-Aperture Space Telescope _ATLAST_ by dandanhuanghuang

VIEWS: 24 PAGES: 139

									                       Response to the Second RFI from the Astro2010 Committee
     The Advanced Technology Large-Aperture Space Telescope (ATLAST)

                                        Submitted by:
               Marc Postman, STScI on behalf of the ATLAST Concept Study Team
                                       August 3, 2009

                                     ATLAST Co-Investigators:
Vic Argabright1, Bill Arnold2, David Aronstein3, Paul Atcheson1, Morley Blouke1, Matt Bolcar3, Tom
Brown4, Daniela Calzetti5, Webster Cash6, Mark Clampin3, Dave Content3, Dean Dailey7, Rolf Danner7,
Rodger Doxsey4, Dennis Ebbets1, Peter Eisenhardt8, Lee Feinberg3, Ed Freymiller1, Andrew Fruchter4,
Mauro Giavalisco5, Tiffany Glassman7, Qian Gong3, James Green6, John Grunsfeld9, Ted Gull3, Greg
Hickey8, Randall Hopkins2, John Hraba2, Tupper Hyde3, Ian Jordan4, Jeremy Kasdin10, Steve Kendrick1,
Steve Kilston1, Anton Koekemoer4, Bob Korechoff8, John Krist8, John Mather3, Chuck Lillie7, Amy Lo7,
Rick Lyon3, Scot McArthur1, Peter McCullough4, Gary Mosier3, Matt Mountain4, Bill Oegerle3, Bert
Pasquale3, Lloyd Purves3, Cecelia Penera7, Ron Polidan7, Dave Redding8, Kailash Sahu4, Babak Saif4,
Ken Sembach4, Mike Shull6, Scott Smith2, George Sonneborn3, David Spergel10, Phil Stahl2, Karl
Stapelfeldt8, Harley Thronson3, Gary Thronton2, Jackie Townsend3, Wesley Traub8, Steve Unwin8, Jeff
Valenti4, Robert Vanderbei10, Penny Warren1, Michael Werner8, Richard Wesenberg3, Jennifer Wiseman3,
Bruce Woodgate3

                                                Co-I AFFILIATION CODES:
           1 = Ball Aerospace & Technologies Corp.              2 = Marshall Space Flight Center
           3 = Goddard Space Flight Center                      4 = Space Telescope Science Institute
           5 = Univ. Massachusetts, Amherst                     6 = University of Colorado, Boulder
           7 = Northrop Grumman Aerospace Systems               8 = Jet Propulsion Laboratory / Cal Tech
           9 = Johnson Space Flight Center                     10 = Princeton University

                                                       Table of Contents
Executive Summary....................................................................................................................3
1. Scientific Overview for ATLAST-8m and ATLAST-9.2m......................................................3
     Table 1.1: ATLAST Science Requirements Flow Down......................................................8
2. Technical Implementation.......................................................................................................9
   2.1 Payload Instrumentation: ATLAST-9.2m Optical Telescope Assembly.............................9
     Instrument Table 2.3: ATLAST-9.2m OTA.......................................................................14
   2.2 Payload Instrumentation: ATLAST-8m Optical Telescope Assembly..............................15
     Instrument Table 2.4: ATLAST-8m OTA..........................................................................20
   2.3 Mission Design: ATLAST-9.2m Observatory..................................................................21
     Table 2.5: ATLAST 9.2m Mission Design Table...............................................................24
   2.4 Technical Implementation: ATLAST-9.2m Spacecraft Implementation...........................25
     Table 2.6: ATLAST-9.2m Spacecraft Mass and Power......................................................31
     Table 2.7: ATLAST-9.2m Spacecraft Characteristics ........................................................32
   2.5 Mission Design: ATLAST-8m Observatory....................................................................33
     Table 2.8: ATLAST-8m Mission Design Table .................................................................36
   2.6 Technical Implementation: ATLAST-8m Spacecraft Implementation.............................37
     Table 2.9: ATLAST-8m Spacecraft Mass and Power.........................................................41
     Table 2.10: ATLAST-8m Spacecraft Characteristics .........................................................42
   2.7 Payload Instrumentation: ATLAST-9.2m Hybrid Instrument for Fine Guidance and
   Wavefront Sensing................................................................................................................44
     Instrument Table 2.11: ATLAST-9.2m Hybrid Instrument (FGS/WFS&C) .......................46
   2.8 Payload Instrumentation: ATLAST-8m Fine Guidance Sensor ........................................47
     Instrument Table 2.12: ATLAST-8m Fine Guidance Sensor Facility.................................49
   2.9 Payload Implementation: ATLAST-8m Wavefront Sensor & Control System .................50
     Instrument Table 2.13: ATLAST-8m Wavefront Sensor Facility .......................................52
   2.10 Payload Instrumentation: Exoplanet Imager (ExoCam) [8m and 9.2m].........................53
     Instrument Table 2.14: ExoCam (Imaging Mode of Exoplanet Instrument) .......................55
   2.11 Payload Instrumentation: Exoplanet Spectrometer (ExoSpec) [8m and 9.2m]...............56
     Instrument Table 2.15: ExoSpec (Spectroscopic Mode of Exoplanet Instrument)...............58
   2.12 Payload Instrumentation: Visible Nulling Coronagraph (VNC) [8m and 9.2m].............59
     Instrument Table 2.18: Visible Nulling Coronagraph.........................................................62
   2.13 Payload Instrumentation: UV Integral Field Spectrograph (UV IFS) [8m and 9.2m]......63
     Instrument Table 2.19: Ultraviolet IFS ..............................................................................65
   2.14 Payload Instrumentation: WFOV Camera [8m and 9.2m] .............................................66
     Instrument Table 2.22: WFOV Camera .............................................................................69
   2.15 Payload Instrumentation: VIS/NIR Multi-Object Spectrograph (MOS) [8m and 9.2m] .70
     Instrument Table 2.23: VIS/NIR Multi-Object Spectrograph .............................................72
   2.16 Total Payload Mass Tables............................................................................................73
     Table 2.24: ATLAST-8m Payload Mass Table (kg)...........................................................73
     Table 2.25: ATLAST-9.2m Payload Mass Table (kg)........................................................74
3. Enabling Technology ............................................................................................................75
     Table 3.1: ATLAST-8m and ATLAST-9.2m Technology Development Summary............75
   3.1 Schedule and Cost for the ATLAST Technology Development Plan ...............................78
     Table 3.2: Technology Development Cost Estimates (FY09 $M, No Reserves).................79
4. Mission Operations Development [8m and 9.2m]..................................................................81
     Table 4.1: Mission Operations and Ground Data Systems..................................................83
5. Programmatics & Schedule ...................................................................................................84
     Table 5.1: Top 8 Programmatic Risks for ATLAST..........................................................85
     Table 5.2: ATLAST Key Phase Durations.........................................................................90
     Table 5.3: ATLAST Key Event Dates ...............................................................................90
6. Cost Section for ATLAST-9.2m............................................................................................91
7. Cost Section for ATLAST-8m...............................................................................................97
Appendix A: Master Equipment Lists .....................................................................................104
     ATLAST-9.2m OTA Master Equipment List...................................................................104
     ATLAST 9.2 m Hybrid WFS&C/FGS Master Equipment List ........................................115
     ATLAST-9.2m IC&DH Master Equipment List..............................................................121
     ATLAST-8m OTA Master Equipment List .....................................................................122
     ATLAST-8m Fine Guidance Sensor Facility Master Equipment List...............................125
     ATLAST-8m Wavefront Sensor Facility Master Equipment List.....................................126
     ATLAST Wide-Field Imager Master Equipment List ......................................................127
Appendix B: Off-Axis 8 m Telescope Design ........................................................................132
Appendix C: ATLAST-8m Spider Options.............................................................................133
Appendix D: List of Questions Addressed in this RFI ............................................................134
Appendix E: Acronym Definitions..........................................................................................138




                                                                 2
Executive Summary
    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a mission concept for
the next generation flagship UVOIR space observatory (wavelength coverage: 110 nm – 2400 nm),
designed to answer some of the most compelling astronomical questions, including “Is there life
elsewhere in the Galaxy?” This RFI presents, in more detail, two different observatory architectures that
tackle the same set of scientific goals. The two observatories have similar optical designs that span the
range in viable technologies (e.g., monolithic vs. segmented aperture, Ares V LV vs. EELV, passive vs.
active wavefront control) and that, with the right technology development and launch capability, could
enter phase A in the 2017 – 2020 timeframe. The architectures are an 8 m telescope with a monolithic
primary mirror and a 9.2 m telescope with a segmented primary mirror. This approach provides several
pathways to realizing the mission that will be narrowed to one as our technology development progresses
and the availability of launch vehicles is clarified.
    Although ATLAST requires some technology development, both observatory concepts take full
advantage of heritage from previous NASA missions, as well as technology developments currently
underway for missions in development. The 8 m monolith architecture is similar to the Hubble Space
Telescope (HST), although the optical design is different. The 8 m mirror has an areal density exceeding
that of the HST mirror, providing superb stiffness and thermal inertia. The use of such a massive mirror
is made possible by the availability of the Ares V launch vehicle. The 9.2 m segmented mirror concept
relies heavily on design heritage from the James Webb Space Telescope (JWST), both in development of
lightweight segmented optics and wavefront sensing and control, and also in the development of Near-IR
detectors. The 9.2 m segmented concept can be launched on a Delta IV Heavy launch vehicle with a
modified 6.5 m fairing. The non-cryogenic nature of ATLAST makes the construction and testing of the
observatory much simpler than for JWST. We have also identified departures from existing NASA
mission designs to capitalize on newer technologies, minimize complexity, and enable the required
improvements in performance.

1. Scientific Overview for ATLAST-8m and ATLAST-9.2m
     The scientific case for ATLAST was outlined in our initial RFI to the Astro2010 committee,
submitted at the end of March 2009. Here the specific questions posed in the second RFI are addressed.
By virtue of its ~15 milli-arcsec (mas) angular resolution at ~500 nm coupled with its ultra high
sensitivity, superb stability and low sky background, either an 8 m or 9.2 m ATLAST will achieve major
breakthroughs in astrophysics by enabling fundamentally new observations – both on its own and in
combination with other telescopes with different capabilities. ATLAST has the performance required to
detect the potentially rare occurrence of biosignatures in the spectra of terrestrial exoplanets, to reveal the
underlying physics that drives star formation, and to trace the complex interactions between dark matter,
galaxies, and the intergalactic medium. Because of the large leap in observing capabilities that ATLAST
provides, one cannot fully anticipate the diversity or direction of the investigations that will dominate its
use – just as the creators of HST did not foresee its pioneering roles in characterizing the atmospheres of
Jupiter-mass exoplanets or measuring the acceleration of cosmic expansion using distant supernovae. We
summarize here the scientific requirements, subsequent measurements, and flow-down to observatory
requirements for ATLAST (Table 1.1) for a representative set of science uniquely enabled by such a
facility.

The Search for Life in the Galaxy: ATLAST is the best option for an exosolar life-finding facility
and is consistent with the long-range strategy for space-based initiatives recommended by the Exoplanet
Task Force. An 8 meter or 9.2 meter ATLAST has the angular resolution and sensitivity to characterize
the atmospheres and surfaces of a substantial sample of Earth-sized exoplanets in the Habitable Zone
(HZ) at distances up to ~25 parsecs. ATLAST can determine planetary rotation rates, the presence of
continents, oceans, and clouds by obtaining multiple SNR>5 broadband (R=5) images spread over the


                                                      3
course of several days, with each integration lasting 6 hours or less (depending on the exoplanet’s
distance). ATLAST can determine planetary habitability and the possible presence of life by obtaining
SNR=10 low-resolution (R=70-100) spectroscopy covering key spectral features associated with ozone,
molecular oxygen, atmospheric column density and Rayleigh scattering, and water vapor. The spectral
features required to assess the above processes are all in the 300 – 2400 nm range and, hence, the
exoplanet characterization instrument on ATLAST is sensitive at these wavelengths. However, one must
also be able to survey a sufficient number of star
systems to allow for the likelihood that habitable
worlds are not common. Based on simulated exoplanet
observing programs using the spatial positions of
known stars and realistic sets of instrumental
performance parameters and background levels, Figure
1.1 shows the number of F,G,K stars as a function of
telescope primary mirror aperture for which an R=70
spectrum with signal-to-noise ratio (SNR) of 10 at 760
nm could be acquired in 500 ksec or less. The results
are averaged over different simulations done using           Figure 1.1. The average number of F,G,K
various starlight suppression options (internal              stars where SNR=10 R=70 spectrum of an
coronagraphs of various kinds as well as an external         Earth-twin could be obtained in < 500 ksec as
occulter). To estimate the number of potentially             a function of telescope aperture, D. The
inhabited worlds detected, one must multiply the             growth in the sample size scales as D3.
numbers in Figure 1.1 by the fraction of the F,G,K stars
that have an Earth-sized planet in their HZ (!") and also by the fraction of those exo-Earths that have
detectable biosignatures. The values of these fractions are currently not constrained but their product is
not likely to be close to unity. To maximize the chance for a successful search for life in the solar
neighborhood requires a space telescope with an aperture size of at least 8 meters. Specifically, an
8m and 9.2m ATLAST (with internal coronagraph) can observe, respectively, ~100 and ~150 different
star systems 3 times each in a 5-year interval and not exceed 20% of the total observing time available to
the community. The 8m or 9.2m ATLAST (with a single external occulter) can observe ~60 stars 3 times
each in a 5-year period, limited by the transit times of the occulter. If a life-bearing world is detected,
ATLAST has the sensitivity – given up to 1 Msec of integration – to obtain a SNR=10 spectrum at higher
resolution (R ~ 600) for a detailed study of key spectral features, which would provide constraints on the
thermodynamics and kinematics of the planet’s atmosphere.
    The science flow down to ATLAST observatory requirements for exoplanet characterization science
is provided in Table 1.1. The instrumentation required to perform the above observations on an Earth-
twin at up to 20 pc distance requires a starlight suppression system that allows detection of exoplanets
that are ~25 magnitudes fainter than their host star at an inner working angle of ~40 mas. This is the
baseline mission starlight suppression performance requirement. There are several options for the
suppression system – an internal coronagraph or external occulter. Achieving the above level of
suppression with a segmented telescope will require development of a nulling coronagraph and/or an
external occulter (starshade). See section 3 for more details1. While the design of the external occulter is
independent of the telescope’s optical design, the viable options for an internal coronagraph are
dependent upon the telescope’s optical design: a Lyot or masked-based coronagraph can be used with
telescope that employs an off-axis secondary mirror (SM) and a monolithic primary mirror (PM) and,
possibly, with one that has an on-axis SM and monolithic PM if the SM is supported by a single linear
structure (e.g., see Appendices B and C). However, for an on-axis SM with standard spider supports or


1
  A thorough discussion of starlight suppression for ATLAST is available in the appendices of our public NASA
study report at http://www.stsci.edu/institute/atlast, click on ATLAST Mission Concept Study in the lefthand gutter.


                                                         4
for a segmented PM, the only internal coronagraph concept that would, in principle, do the job is a visible
nulling coronagraph (VNC). As part of the early technology development plan for ATLAST, these
options would be investigated and a downselect made prior to entry into phase A. The impact on the
ATLAST science objectives if a starlight suppression system is not able to permit detection of sources
with a ~10-10 contrast ratio at the indicated inner working angle (IWA) would be the inability to directly
detect and characterize Earth-mass planets around solar-type stars (indirect detection via transit imaging
would be unaffected). Characterization of super-Earths (up to 10x Earth’s mass) or Earth-like planets
around M-dwarfs would still be possible, however, if contrasts of 10-9 are reachable. We adopt 10-9 as the
minimum mission criterion for starlight suppression performance.

ATLAST will reveal the nature of the interaction of the Intergalactic Medium (IGM) with galaxies.
Understanding how gas in the IGM gets into galaxies and how galaxies respond to inflow lies at the heart
of understanding galactic evolution. The nature of gas accretion and removal processes has observational
                                                               consequences (e.g., Figure 1.2) that can
                                                               be tested if the distribution of gas in the
                                                               cosmic web around galaxies can be
                                                               characterized through UV absorption and
                                                               emission line spectroscopy. Access to UV
                                                               wavelengths is required to observe the
                                                               (slightly redshifted) diagnostic lines (e.g.,
                                                               OVI, SiIII, Ly#, NV, SiIV, CIV) needed
                                                               to characterize the warm IGM at low
                                                               redshift or OIII, OV, NIV, NeVII for
                                                               characterization of the intermediate
 Figure 1.2. IGM gas temperature distribution for cosmological redshift (0.3 < z < 2) IGM. The
 models with and without supernova feedback.                   observational challenge is to acquire
                                                               datasets of sufficient spatial sampling
and with enough diagnostic power (i.e., spectral resolution) to identify and characterize the various
processes at work. The key requirement is to be able to observe a sufficient number of background
sources. Specifically, ATLAST must have sufficient UV absorption line sensitivity to be able to survey
up to ~100 quasars per deg2 (corresponds to a flux limit of ~1 x 10-17 erg cm-2 sec-1 Å-1) over an area that
subtends ~10 Mpc on a side (0.25 deg2 at z = 0.4) and obtain SNR=10-20 high-resolution (R=20,000)
spectra of each QSO in the region. At this limit, ~20% of randomly selected fields on the sky would have
a sufficient number of background sources to enable detailed mapping of the spatial distribution of IGM
structure around specific galaxies. ATLAST’s large aperture (8 to 9.2 meters) coupled with efficient
(~40% QE) UV detectors are needed to enable an individual QSO observation to be completed in ~25
ksec (which permits a 0.25 deg2 area to be surveyed in ~1 week). The UV Spectrograph (UVS) on
ATLAST is designed to perform such observations. See Table 1.1 for the science flow down.
   Many other scientific objectives require similar UV spectroscopic capabilities, namely high spectral
resolution (R ~ 20,000 up to R ~ 100,000) over the 110 – 300 nm band. These include spectroscopy of
evolved stars with complex structure and spectroscopy of protoplanetary disks. These investigations
simultaneously require high angular resolution (15 – 20 mas). The UVS on ATLAST can perform a
broad range of investigations. The biggest risk to the ability of ATLAST to accomplish all of its UV
scientific objectives is the availability of efficient UV detectors. With current UV detectors, the
observations would take ~4x longer but the investigations could still be accomplished.


ATLAST enables, for the first time, star formation histories to be reconstructed for hundreds of
galaxies beyond the Local Group, opening the full range of star formation environments to



                                                     5
exploration. A comprehensive and predictive theory of galaxy formation and evolution requires accurate
determination of how and when galaxies assemble their stellar populations, and how this assembly varies
with environment. The most powerful way to do this is by sifting through the resolved field populations
of the surviving giant galaxies to reconstruct the star
formation history, chemical evolution, and kinematics
of their various structures. Resolved stellar
populations are cosmic clocks. Their most direct and
accurate age diagnostic comes from resolving both the
dwarf and giant stars, including the main sequence
turnoff, but the main sequence turnoff rapidly becomes
too faint to detect with any existing telescope for any
galaxy beyond the Local Group. This greatly limits
ones ability to infer much about the details of galactic
assembly because the galaxies in the Local Group are
not representative of the galaxy population at large.
ATLAST reaches well beyond the Local Group as
shown in Figure 1.3. HST and JWST cannot reach any
large galaxies besides our Milky Way and M31 (see
Figure 1.3 2). An 8 meter (9.2 meter) space telescope
can reach 140 (160) galaxies including 12 (13) giant     Figure 1.3. Map of local universe (24
spirals and the nearest giant elliptical. Deriving ages  Mpc across) shown with the distances out
and other galactic properties from color-magnitude data  to which HST (yellow), JWST (orange),
requires photometry for thousands of stars spanning 4    and ATLAST (8 m, 16 m), can detect solar
orders of magnitude in luminosity. These observations    analogs in V and I passbands at SNR=5 in
require a wide-field imager on ATLAST over a field       100 hours. Giant spirals, like M31, are
of view of at least 4 arcminutes. ATLAST can work        indicated by the blue galaxy symbols,
in concert with 30-m class ground-based telescopes       giant ellipticals as orange blobs, and
(e.g., TMT), expanding our reach to other well-          dwarf galaxies as small green dots.
populated galaxy groups, with ATLAST obtaining
photometry of V~35 magnitude G dwarf stars and TMT obtaining kinematics of much brighter giants out
to the Coma Sculptor Cloud. The dwarf stars in the Coma Sculptor Cloud are effectively inaccessible to
TMT, requiring gigaseconds of integration even for an isolated star. See Table 1.1 for the science flow
down.

ATLAST provides fundamental constraints on Dark Matter: Dwarf spheroidal galaxies (dSph), the
faintest galaxies known, are extraordinary sites to explore the properties of non-baryonic dark matter
(DM). There are several reasons for this. First, their mass is dominated by DM – they are observed to
have mass-to-light ratios 10 to 100 times higher than the typical L* galaxy, such as M31 or the Milky
Way. Second, they are relatively abundant nearby – to date 19 dSph galaxies have been found in the
Local Group and more will be discovered. Third, and perhaps most striking, is the discovery that all
nineteen dSph satellites, covering more than four orders of magnitude in luminosity, inhabit dark matter
halos with the same mass ($107 MSUN) within their central 300 pc (see Figure 1.4).
         The ability of DM to cluster in phase space is limited by intrinsic properties such as mass and
kinetic temperature. Cold dark matter particles have negligible velocity dispersion and very large central
phase-space density, resulting in cuspy density profiles. Warm dark matter halos, in contrast, have smaller
central phase-space densities, so that density profiles saturate to form constant central cores. Owing to

2
 Figure 1.3 also shows the capabilities of a 16 m ATLAST concept, which was one of the concepts
explored in our NASA Strategic Astrophysics Mission Concepts study.


                                                    6
their small masses, dSphs have the highest average phase space densities of any galaxy type, and this
implies that for a given DM model, phase-space limited cores will occupy a larger fraction of the virial
radii. Hence, the mean density profile of dSph galaxies is a fundamental constraint on the nature of
dark matter.
         Current observations are unable to measure the density profile slopes within dSph galaxies
because of a strong degeneracy between the inner slope of the DM density profile and the velocity
                                                         anisotropy of the stellar orbits. Radial velocities
                                                         alone cannot break this degeneracy even if the
                                                         present samples of radial velocities are increased
                                                         to several thousand stars. Combining proper
                                                         motions with the radial velocities is the only
                                                         robust means of breaking the anisotropy-inner
                                                         slope degeneracy. While the radial velocities are
                                                         obtainable with 8 m class ground-based
                                                         telescopes, the astrometric measurements will be
                                                         extremely challenging even for the largest
                                                         planned ground-based telescopes. ATLAST,
                                                         however, can perform the astrometric
    Figure 1.4. The integrated mass within the inner 300 measurements. To accomplish this, ATLAST
    parsecs of local dSph galaxies as a function of the  will measure transverse stellar velocities to an
    luminosity.
                                                         accuracy of 5 km/sec. At a distance of 50 kpc,
this corresponds to an angular displacement of 0.1 mas over five years. This is approximately one two-
hundredths of a pixel, or equivalently, one two-hundredth of the FWHM of the point spread function
(PSF). For reference, the Advanced Camera for Surveys (ACS) on HST has centroiding errors of about
one-hundredth of the pixel and PSF (the pixel size and PSF have nearly identical widths). However, HST
suffers from large thermal stresses on orbit, which cause significant changes in the lengths, positions and
alignment of the supporting structures. At the Sun-Earth second Lagrange point (SE-L2), ATLAST is far
more thermally stable, and the sensors and actuators put in place to maintain the structure to the precision
necessary for exoplanet science allows ATLAST to achieve one-sigma astrometric errors of 0.005 pixels.
In addition to the instrumental capability for astrometry to 0.1 mas, background objects are needed to
provide a stable astrometric reference frame. Quasars alone are likely to be too sparse to provide this
frame, so they will be supplemented with background galaxies. While an individual galaxy is far less
valuable as an astrometric source than a quasar of a similar magnitude, if the imager used for this
investigation has a FOV wide enough to contain thousands of galaxies in a single exposure, then their
internal structures, which will be resolved down to 15 mas, will provide the required reference frame.
These observations require a wide-field imager on ATLAST with a field of view of ~5 arcminutes.
This experiment is not signal-to-noise limited, as solar mass stars at 50 kpc will have signal-to-noise
ratios exceeding 100 in ~1 ksec exposures. Thus, even in some of the faintest known dwarf spheriodals,
with mass to light ratios exceeding 10,000, the transverse velocity measurements for the 200+ stars per
dwarf required by this experiment can be obtained. The science flow down is given in Table 1.1.




                                                     7
                      Table 1.1: ATLAST Science Requirements Flow Down
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                                                                 8
2. Technical Implementation

    The following sections provide the technical details for the 8 m monolithic mirror and 9.2 m
segmented mirror concepts for ATLAST. There are commonalities in the concepts (science, mission
operations, and instruments) as well as differences in the optical telescope assembly, wavefront sensing
and control and the spacecraft. Where possible, a common answer is provided to questions about the
concepts. Separate responses were necessary, of course, for some sections due to the different
observatory architectures.
    The ATLAST-8m employs an 8m diameter monolithic mirror, and takes advantage of the unparalleled
lift capacity of the Ares V launch vehicle (~60 metric tons to SE-L2). No lightweighting of the mirror is
required, and due to the large volume of the fairing, the telescope can be launched with the secondary
mirror fully deployed3. One can consider the ATLAST-8m as being architecturally similar to HST,
although the optical design is a three-mirror anastigmat instead of a Ritchey-Chrétien design. From a
mission cost perspective, the availability of the Ares V breaks the paradigm of standard mass-cost
relationships in cost modeling. The lift capacity of the Ares V enables the launch a massive monolithic
mirror, with its advantages of heritage, large thermal inertia, and stiffness.
    The ATLAST-9.2m builds on the technology developments achieved for JWST. This segmented
primary mirror design allows the telescope to fit within an upgraded Evolved Expendable Launch Vehicle
(EELV). The packaging is very similar to that employed by JWST, and one could, architecturally
speaking, consider ATLAST-9.2 to be a larger non-cryogenic version of JWST operating at shorter
wavelengths. Hence, this telescope is highly leveraged off the technologies pioneered for JWST and this
should provide some cost savings in architecture re-use. The non-cryogenic (i.e., room temperature)
nature of the telescope also translates into significant savings in ground testing.
    Our responses are linked to the explicit questions posed in the RFI. To save space, we do not repeat the
questions in each section. Rather, our answers are preceded by the question number (e.g., Q2 is the
answer to question 2 in that particular segment of the RFI). The questions are reprinted in Appendix D.

2.1 Payload Instrumentation: ATLAST-9.2m Optical Telescope Assembly

Q1. Description: The Optical Telescope Assembly (OTA) for the ATLAST-9.2m observatory includes a
36 hexagonal segment primary mirror with two deployed wings, a Secondary Mirror Support Structure
(SMSS) that includes a secondary mirror, aft optics that feed the light from the secondary into the science
instruments, a deployed central baffle, a backplane structure that holds the primary mirror segments and
provides the structure that holds the science instruments, and the Instrument Command and Data
Handling unit (IC&DH) that provides centralized OTA electronics for control of telescope mechanisms
and heaters, wavefront sensing (WFS) processors, and science instruments. The design employs both a
two-mirror Cassegrain channel that employs MgF2 coatings for ultraviolet science and planet finding
instruments and aft optics that complete a four-mirror Wide Field Of View (WFOV) channel with high
throughput silver coatings for visible/NIR performance. The telescope architecture highly leverages the
telescope architecture for the JWST with modifications to address the size and UV-Optical performance.
Unlike JWST, the ATLAST-9.2m is not cryogenic, which simplifies designs and greatly simplifies
testing. These basic elements of this architecture are shown below in Figure 2.1.




3
  This is true for the on-axis version of ATLAST-8m. If an off-axis design is adopted, the SM and its
support tower will need to be deployed.


                                                     9
                                  Figure 2.1 – Schematic of the OTA
A new approach employed in the 9.2 m architecture is the use of an active wavefront sensing and control
(WFS&C) architecture, which includes updating the primary mirror segment positions approximately
every 5-30 minutes and updating of the secondary mirror once a day. This active architecture replaces the
passive thermal architecture of JWST that updates the primary every two weeks and the secondary mirror
approximately once a year. This change was deemed necessary to meet the diffraction limited
performance at 500 nm which drove a factor of four improvement in the wavefront error requirement and
thus in the stability of the individual segments. The approach uses a hybrid wavefront sensor and guider
(see Hybrid Instrument section) that shares light from the guide star to simultaneously provide wavefront
sensing updates and centroid pointing errors. While the update rate of this approach is considerably faster
than JWST, it is highly leveraged from JWST architecture and does not require much new technology
development.
Primary Mirror: The ATLAST-9.2m uses a lightweight ULE mirror architecture that leverages the
successful development of a 1.2 m flat-to-flat Advanced Mirror Systems Demonstrator (AMSD)
developed for JWST. This mirror technology is highly deterministic to polish and there are substantial
capabilities in the US and Europe to fabricate and polish ULE optics. The approach uses JWST’s 7-
degree of freedom architecture (a hexapod plus radius of curvature actuator), which minimizes the overall
cost and complexity of the actuation electronics and control.

      Table 2.1: Comparison of AMSD and ATLAST-9.2m Primary Mirror Segments
                                     ATLAST-9.2m            AMSD                   Comment
    Performance:
                                                                          10 nm achieved on smaller
    Total wavefront error (WFE)      10 nm rms           50 nm rms
                                                                          ULE mirrors
    Surface Roughness                5 Angstroms         40 Angstroms     Demonstrated on UV mirror
    Derived Matching RoC WFE         5 nm                N/A              JWST requirement ~ 10 nm
                                            2                   2
    Areal Density                    25 kg/m             15 kg/m          Comparable to JWST
    Edges                            5 mm                N/A              Comparable to JWST
    Design:
    Diameter (flat to flat)          1.315 m             1.2 m            Comparable to JWST
    Mirror depth                     62.09 mm            35.4 mm          Comparable to JWST
    Mirror stiffness                 220 Hz              150 Hz           Comparable to JWST
    Core cell size                   40.84 mm            30.0 mm          Comparable to JWST
    Mount interfaces                 6 mounts            3 mounts         Comparable to JWST




                                                    10
The ULE mirror architecture proposed for ATLAST-9.2m has a large staffing and facility infrastructure
in place at ITT, Tinsley and Corning, so very little facilitization is required. This is important because
facilitization is expensive and consumes schedule. Segmented mirror architecture does offer the unique
advantage of allowing parallelization of the polishing process, which is primarily area-driven (small tools
are used). The extra time provided by processing mirror segments in parallel enables the very smooth
mirror surface, required for both UV and high contrast applications.
Actuators: The actuators used as part of the hexapod and radius of curvature control require a step size
that is smaller than the 8 nm step resolution achieved for JWST by a factor of 2-4 with graceful
degradation. The baseline approach uses the JWST actuators developed by Ball Aerospace Technology
Corp. with slight improvements for the step reduction. The rest of the hexapod control and architecture is
identical to JWST, which is at Technology Readiness Level (TRL) 6.
Secondary Mirror: The secondary mirror for ATLAST-9.2m is made out of ULE and has comparable
requirements to the primary mirror, the key difference being it can be stiffer because it is smaller and can
have higher mass since it is just one mirror. Final performance is more challenging because it is convex
and, thus, cannot be tested at center of curvature. Its performance will be completely determined from
metrology. The secondary mirror assembly employs a six-degree-of- freedom hexapod, which is a smaller
version of that used on the primary mirror.
Instrument Command and Data Handler (IC&DH): The IC&DH is fairly standard and serves as the
primary controller for the science instruments and OTA. The one non-standard aspect is the use of a
dedicated Digital Signal Processor for the WFS&C phase retrieval algorithms, which are computationally
demanding. This approach has been demonstrated on the ground with scaled processor power and
adequate update rates have been achieved. However, development of a more efficient processor geared at
the specific computations of WFS&C is considered highly desirable.
Wavefront Sensing and Control (WFS&C) Algorithms: The WFS&C algorithms highly leverage
JWST and are quite similar in their architecture. In fact, the entire commissioning sequence is identical to
that of JWST, except that 36 segments are being aligned instead of 18. The fine-phasing algorithm and
multi-field algorithm for the secondary mirror are also identical to JWST. The only new feature of the
algorithm is the need for autonomous updates of the primary mirror, which involve windowing and data
quality checks similar to those used on other systems (e.g., the guider). JWST algorithms, which are at
TRL 6, have a human-in-the-loop. Achieving better performance is dictated by the sensing algorithm and
calibration described in the Hybrid Instrument section.
Backplane Structure: The backplane structure for ATLAST-9.2m is a cyanate ester graphite epoxy.
Although there is an active control system, the baseline stability requirement is comparable to JWST to
minimize required updates. The actual composite laminate for the ATLAST-9.2m is baselined to be the
same material used on high performance UV instrument benches such as those used on HST. However,
some of the techniques used to achieve better thermal stability on JWST (improved modeling and coupon
testing, bond-line control, etc.) will be employed on ATLAST-9.2m along with active thermal control.
The structure for the OTA also houses the instruments as was done on HST, providing a single optical
truss structure. The entire structure makes use of heaters as needed for active thermal control as was done
on HST.
Integration and Testing: The integration and testing of the OTA highly leverages the JWST I&T plan.
The assembly and alignment sequence is quite similar, consisting of fiducials and trackers for alignment.
Acoustics and vibration testing use similar configurations to those used on JWST. The critical test will be
thermal-vacuum testing; however, the non-cryogenic operation of ATLAST-9.2m greatly simplifies this
test, e.g., a liquid nitrogen shroud is required instead of a Helium shroud. Multiple facilities currently
exist that will accommodate the thermal-vacuum test, including the Johnson Space Center (JSC) chamber
(chamber “A”) used to test JWST and a large collimator at Lockheed Martin Corp.
Pointing Control: ATLAST-9.2m uses three guide stars for pointing and wavefront sensing. The
brightest guide star is used for high bandwidth pointing feedback to the pointing control system,



                                                    11
providing a robust margin to the 1.3 mas rms pointing stability over any integration period. Achieving
this is possible due to the combination of excellent dynamic isolation of spacecraft jitter disturbances
provided by the Disturbance Isolation and Precision Pointing System (DIPPS) and excellent thermal
stability provided by the SE-L2 environment and active thermal control. A second guide star, in another
sensor, many arcminutes away, is used to provide roll control about the bore-sight at a lower bandwidth to
much better than the 0.2 arcsec rms roll stability requirement. The telescope’s absolute pointing
knowledge and control error on the sky is dominated by the errors in the guide star catalog (about 0.3
arcsec for HST GSC-2). Since three guide stars are used, performance is 3^(1/2) better than the single star
catalog error; about 0.2 arcsec and much better than the 1 arcsec requirement.
Q2. TRL levels: The OTA element TRLs are shown in Table 2.2 below. Note that some performance
requirements experience graceful degradation when not met; this raises the TRL and reduces risk. For
example, a 4 nm actuator can be used with minimal impact to the error budget. Performance of mirrors is
required to be 10 nm rms wavefront error (WFE).
                             Table 2.2: Technology Readiness Levels
                                                   Example                          Rationale/state of
   Technology              Driver                                        TRL
                                                  Technology                              art
                   1.315m flat to flat       ULE semi-rigid               4-5      JWST, AMSD
     Mirrors       10 nm rms WFE             ULE w/actuation              4-5      AMSD
                                         2
                   Matched RoC <15 kg/m      Actuated hybrid mirror       3-4      Tech Dev
                   High speed processing     Digital signal processor     3-4      JWST Ground segment
     WFS&C
                   Autonomous updates        Automated S/W                3-4      JWST testbed
                   2-4 nm steps              Ball Stepper actuator        4-5      JWST, AMSD
    Actuators                                PMN/Piezo fine stage          3       HST, Tech Demo
                                             Moog actuators                4       AMSD

Q3. Key Technical Risks: The three primary technical risks are: (1) Primary Mirror Performance –
requires factor of 4 improvement over JWST, (2) development of autonomous and higher speed
wavefront sensing and control, 3) stability verification – demonstrating via modeling that stability is
achieved.
Q4 – Q6: See attached tables.
Q7. Responsible Organizations: It is anticipated that the development of the OTA would be similar to
that done for JWST and would be performed by aerospace corporations under contract to a NASA Project
Office.
Q8. Previous Studies: The Integrated Design Center (IDC) at NASA’s GSFC performed a concept study
of the OTA and WFS&C instrument in early 2009.
Q9. Operational Modes: The OTA operations fall into a few categories: (1) deployments during initial
commissioning, (2) ongoing active controls of heaters and actuators, and (3) typical C&DH modes for
safe-mode and operations. The only unique data volume issue is the processing of WFS&C images for
determining on-board updates. This consists of ingesting two defocused phase-retrieval images,
performing Fourier Transform operations in support of phase retrieval, and issuing mirror control
commands for the 252 primary mirror actuators every 5-30 minutes (less frequently for the secondary
mirror).
Q10. Instrument Flight Software: The primary functions of the flight software are described above.
We estimate that the lines of code at ~50,000, but much of this will be heritage code from JWST or the
JWST testbed. Approximately 5,000 lines of this is for WFS&C.
Q11. Non-US Participation: No external participation is needed for the OTA.
Q12. MEL: The MEL produced by the GSFC IDC is attached.
Q13. Flight Heritage: The deployment systems for ATLAST-9.2m are based heavily on those used for
JWST and will have flight heritage after the launch of JWST. The structure and thermal control system



                                                    12
has flight heritage from HST. Mirrors have heritage from HST (although HST mirrors have much higher
areal density). The IC&DH has heritage from many NASA missions. Actuators are an evolution of HST
instrument actuators and those of JWST. Flight qualification will be quite similar to JWST and include
subsystem environmental tests on individual segment assemblies, secondary mirror, aft optics, etc.




                                                 13
                           Instrument Table 2.3: ATLAST-9.2m OTA
                               Item                                       Value              Units
   Type of instrument                                              Optical Telescope
                                                                   Assembly
   Number of channels                                              2 (single telescope;
                                                                   TMA & Cassegrain
                                                                   channels)
   Size/dimensions (for each instrument)                           9.2 x 9.2 x ~14        mxmxm
                                                                   (deployed)
   OTA PM, SM, Aft Optics & associated Structure CBE* mass         4244                   kg
   OTA IC&DH CBE mass                                              42                     kg
   OTA Ancillary HW (ISS, Other Avionics) CBE mass                 1119                   kg
   OTA Instrument TOTAL CBE mass                                           5405           kg
   Instrument mass contingency                                              30            %
   Instrument mass with contingency (CBE+Reserve)                          7027           kg
   Instrument average payload power without contingency                    1198           W
   Instrument average payload power contingency                             30            %
   Instrument average payload power with contingency                       1557           W
   Instrument average science data rate^ without contingency                 4            kbps
   Instrument average science data^ rate contingency                        30            %
   Instrument average science data^ rate with contingency                    5            kbps
   Instrument Fields of View (if appropriate)                             8 x 20          arcmin
   Pointing requirements (knowledge)                                         1            arcsec
   Pointing requirements (control)                                           1            arcsec
   Pointing requirements (stability)                                      0.0013          arcsec/sec

*CBE = Current Best Estimate (without contingency).
^Instrument data rate defined as science data rate prior to on-board processing. Note: the OTA does not
produce “science data”. We have listed here an estimate for the engineering data rate.




                                                   14
2.2 Payload Instrumentation: ATLAST-8m Optical Telescope Assembly

Q1. Description: ATLAST-8m OTA is an 8 m diameter monolithic aperture telescope with a solid
meniscus glass mirror. It has a solid meniscus secondary mirror on a fixed hybrid optical bench, and two
aft optics assemblies. The only on-orbit deployments (for an on-axis SM) are release of the optical
component launch locks, the opening of protective doors and the extension of the forward sunshield.




                                                                          TMA #1



                                                                              Cass


                                                                          TMA #2



         Figure 2.2: Optical Layout of 8 m OTA showing the two TMA foci and Cass focus

    The ATLAST-8m OTA has a dual-field optical design with three foci. All three foci are diffraction
limited at a wavelength of 500 nm. The main telescope is a two-mirror system, which forms a narrow-
field-of-view (NFOV) 1 arcmin Cassegrain (Cass) image. Two pick-off fold mirrors, on either side of
Cass focus, direct off-axis portions of the Cassegrain image plane to two tertiary-mirror aft-optics
assemblies, which form two wide-field-of-view (WFOV) 8 x 22 arcmin three-mirror anastigmatic (TMA)
images. The TMA F/# provides a 13 mas plate scale. All three foci are directly accessible to a 4.0 m
diameter by 4.5 m deep instrument bay centered on-axis behind the primary mirror.
    The baseline ATLAST-8m concept has four science instruments and two facility instruments. The
exoplanet instrument and UV integral field spectrometer are at Cass focus. The WFOV imager and multi-
object spectrograph are each at one of the TMA focal planes. Additionally, each of the three foci has
wavefront sensors and each TMA focus has two Fine Guidance Sensors (FGS). Each instrument module
is a self-contained On-orbit Replaceable Unit (ORU) using HST-style mounting rails accessible from the
back of the instrument bay to facilitate servicing missions. The instrument bay provides all required
mechanical, electrical, data and thermal interface connections for the science modules using standard
HST-style ‘blind-mate’ connectors. Heat-pipe connections scavenge instrument heat to help maintain the
OTA at 280 deg K and route excess heat to external radiators. The spacecraft envelope surrounds the
instrument bay, which is isolated from both the primary mirror support structure and the instrument bay.
The IC&DH unit provides centralized OTA electronics for control of telescope mechanisms and heaters,
wavefront sensing processors, and science instruments.
    The two TMA fields of view are separated on the sky by approximately 0.5 degrees. This separation
helps the FGS pointing system control roll well enough to meet the 1.6 mas pointing stability
requirement. Separating the two WFOV instruments allows added flexibility in packaging as well as
future functionality after a servicing mission. The Cassegrain focus provides specific technical
advantages for two classes of high-priority science: It provides a high quality NFOV for exoplanet
characterization science, and it provides a high-throughput two-bounce path for UV spectroscopy. The
primary and secondary mirrors optical coatings are identical to what was used by HST: aluminum with
MgF2 overcoat to provide good spectral transmission from 110 nm to 2400 nm. These coatings are


                                                  15
important to the UV science instruments at Cassegrain focus. The aft optics are coated with protected
silver used on Kepler for enhanced transmission in the visible and Near-IR.
Structure: The ATLAST-8m structure contains several major elements (Figure 2.3): primary mirror
support structure, metering truss, instrument bay, secondary mirror spiders, aft optics structure and
payload adapter fixture. All structural elements are fabricated from a cyanate ester graphite epoxy
composite material with flight certified thermal and mechanical properties. The fundamental design
philosophies are simplicity, modularity, and redundancy. To mitigate assembly risk, the structure is
designed using a bolt-together truss structure of repeated components. Each component is fabricated with
a conservative design margin and tested individually. The most challenging engineering issue is the joint
interface between nearly 1300 components. The structure is designed to safely launch an 8 m primary
mirror and maintain the on-orbit optical alignment necessary to achieve a 500 nm diffraction limited
telescope. Using fault-tolerant design principles, the PM support structure provides a 10x margin of
safety by distributing the forces between 66 axial and lateral support points to keep the primary mirror
launch loads at least an order of magnitude below its design limit. Optical alignment between the primary
and secondary mirror is achieved by a hybrid metering structure that combines the HST cylindrical truss
with a four legged secondary mirror spider arm truss 4 and a JWST style SM hexapod. During launch, the
entire observatory load (telescope, instruments and spacecraft) is carried via the PM support structure and
transferred to the Ares V through the payload adapter fixture.




                        Figure 2.3: ATLAST-8m Observatory Structural Layout

   A key feature of ATLAST-8m is its extreme thermal and mechanical stability. The ATLAST-8m
passive thermal isolation system of MLI insulation, scarfed sun-shade and straylight baffles are such that
the observatory is cold-biased for all permitted observation angles relative to the sun. This allows the use
of an active thermal management system to bring the observatory up to the desired 280 deg K operating
temperature and to eliminate any systematic spatial or temporal thermal variations. The primary mirror
temperature is actively controlled using radiative heaters applied to the back and sides. Approximately 60
independently controlled heater zones are required to minimize gradients through and across the mirror.
The primary mirror axial through-thickness thermal gradient is a negligible: 0.02 deg K. The secondary
mirror and optical bench structure is heated using the same methodology as HST. Given the enormous
thermal mass of the ATLAST-8m system, it is virtually immune to transient thermal events. A 20 degree
slew or 30 degree roll produces only a 0.2 deg K change in thermal gradients. The primary mirror
thermal time constant is 500 hrs to produce a 1 nm rms figure change.



4
    See Appendices B and C for alternative SM supports that are optimized for high contrast coronagraphy.


                                                    16
Primary Mirror: The single most important element of ATLAST-8m is the primary mirror. While a
HST-style (or proposed TPF-C style) lightweight mirror could be used with a JWST-class design-margin
structure, the Ares V’s mass capacity allows us to reduce risk and cost by using a solid meniscus glass
mirror – the kind typically used for ground based telescopes (e.g., Gemini, VLT and Subaru). Such
mirrors are extremely thermally stable for a space-based telescope and are mechanically very stiff. A
solid meniscus mirror also allows one to cost effectively achieve a very smooth optical surface, a mirror
property that is important for ultra-high contrast imaging. Both REOSC and Brashear have demonstrated
the ability to fabricate 8 m class mirrors to better than 10 nm rms. This fact highlights another important
advantage of the proposed mirror: the infrastructure exists and is proven for handling,
manufacturing, and testing 8 m class mirrors. Currently there is one existing 8 m Zerodur mirror
blank at Schott Glass in Germany and Corning has a proven furnace capability to make ULE glass mirror
blanks.
Secondary Mirror: The ATLAST-8m secondary mirror can be made of ULE or Zerodur. While the SM
could be a lightweight mirror, the baseline is a solid meniscus. Again, the advantage of a solid meniscus
is a lower cost and smother mirror than can be achieved with a lightweighted mirror. A lightweighted
mirror will only be considered if analysis shows that reducing SM assembly mass is required to meet
launch environment design safety margins. A solid meniscus mirror also enables the ability to certify its
convex aspheric surface figure using a through the back test. The SM assembly employs a six-degree-of-
freedom hexapod virtually identical to the one to be used on JWST.
Actuators: The SM hexapod actuators require a step size that is smaller than the 8 nm step resolution
achieved for JWST by a factor of 2-4 with graceful degradation. The baseline approach is to use the
JWST actuators developed by Ball Aerospace Technology Corp. with slight improvements for the step
reduction. The rest of the hexapod control and architecture is identical to JWST, which is at TRL 6.
While, at present, the baseline primary mirror design is completely passive, such actuators could also be
used to provide on-orbit PM figure control.
Instrument Command and Data Handler (IC&DH): The ATLAST-8m IC&DH is standard and has no
special requirements. It serves as the primary controller for the science instruments and OTA. It accepts
data from the science and facility instruments, stores it onto the solid state recorder, then retrieves it and
formats it for communication to the ground.
Wavefront Sensing and Control (WFS&C): The ATLAST-8m WFS&C sub-system is a facility
instrument and is discussed in its own instrument input.
Integration and Testing: Because of its inherent mechanical stiffness, ATLAST-8m can be integrated
and tested on the ground similar to any conventional 8 m class ground telescope. Furthermore, NASA
has already invested $40M to clean and upgrade the large vacuum chamber at JSC (chamber A) that will
be used to test JWST. The ATLAST-8m OTA will fit in this upgraded chamber. There are also suitable
industry-based test chambers (e.g., at Lockheed Martin).
Pointing Control: The ATLAST-8m FGS is a facility instrument discussed in its own instrument input.
The system consists of four FGS modules, two in each WFOV TMA focus (one active and one backup).
ALTAST-8m controls pointing using guide stars in two FGS modules separated on the sky by 0.5 degree.
This separation provides roll control about bore-sight at a lower bandwidth and with much better stability
than the 0.2 arcsec rms requirement. Excellent pointing stability over any integration period is achieved
due to the combination of dynamic isolation of spacecraft jitter disturbances provided by an active
isolation system such as the Lockheed Disturbance Free Payload or Northrop Active Strut technology;
inertial mass of the observatory; thermal stability provided by the SE-L2 environment; thermal capacity
of the observatory; and active thermal control. The reaction wheels provide 698 N-m-s of momentum
storage capability for a minimum of 4500 minutes continuous observation time. ATLAST-8m uses two
solar panels on extendable booms with gimbal joints to balance solar pressure for extended observations.
Q2. TRL levels: The ATLAST-8m OTA is assessed to have a TRL of 5 because, while the ability to
manufacture an 8 m class OTA has been demonstrated and while many 1 m to 2.4 m glass mirrors and



                                                     17
their support systems have flown in space and are at TRL 9 (HST, Kepler, FUSE, commercial and DoD),
an 8 m class solid meniscus glass mirror and its support structure have not been flight qualified. These
many successful space telescopes fully validate the engineering methodology called ‘defect tolerant
design’. This capability enables one to properly design support systems for the safe launch of glass
mirrors into space. The only question is how to scale these practices to an 8 m system. Additionally, the
ability to manufacture 8 m solid meniscus glass mirrors to a surface figure of better than 10 nm rms has
been demonstrated, and the ability to handle 8 m class mirrors on the ground has been proven.
Q3. Key Technical Risks: The three biggest risks for ATLAST-8m OTA are: blank suitability, launch
survival and gravity sag release. The ability of an 8 m mirror in its support system to survive launch is
not proven. Mitigating this risk requires characterizing the primary mirror blank, detailed modeling,
statistical testing of full scale components and proof load testing. Currently, Schott has one Zerodur
blank. It or a new ULE mirror will be characterized to see if its flaw distribution is suitable for a flight
mirror. If not, then a new ULE mirror will need to be fabricated. Schott no longer makes 8 m Zerodur
blanks. ATLAST-8m mitigates this risk by procuring and flight qualifying an 8 m blank and elements of
its support structure during Pre-Phase A. Achieving this milestone eliminates a potential two-year
schedule risk to the program. Gravity sag is a risk because the ATLAST-8m uses a quasi-passive primary
mirror. Ground telescopes routinely actuate their PMs to remove gravity sag as a function of Alt-Az
angle. Since gravity sag is a linear phenomenon, the issues regarding gravity sag back-out are modeling
and full scale testing. Structural elements are tested in statistically meaningful quantities to provide
sufficient information for a high-fidelity structural model. During fabrication, an absolute test of the PM
gravity sag is performed using one or more well-known methods such as a 6-rotation horizontal test or a
vertical gravity vector angle test. Actuating the primary mirror or including a deformable mirror in each
science instrument can achieve additional mitigation against gravity sag risk.
Q4-Q6: See attached tables. Please note: more than half of the OTA 44,080 kg mass (with contingency)
is for a 25,000 kg, 175 mm thick solid meniscus Zerodur mirror. This is the thickest, most massive mirror
that can possibly be fabricated from the existing Schott blank. While the existing raw blank is close to
300 mm thick, it has a 28 m radius of curvature. Changing its radius to 24 m yields a 175 mm thick
mirror. If a 175 mm thick ULE mirror is used, its mass would be 21,750 kg for a 15% mass margin on
the max allocation of 44,080 kg. The 33,908 kg OTA mass without contingency baselines a 19,250 kg,
155 mm thick solid meniscus ULE mirror. For additional conservatism, the 33,908 kg OTA includes the
PM support structure, launch locks and payload adaptor fixture sized to a 25,000 kg PM.
Q7. Responsible Organizations: The NASA Project Office will maintain oversight of the development,
test and integration. A NASA Center, International Space Agency, academic or commercial aerospace
company with appropriate experience will be selected to design and build.
Q8. Previous Studies: ATLAST-8m FGS is the result of the ATLAST Astrophysics Mission Concept
Study: http://www.stsci.edu/institute/atlast/index_html_ATLASTMissionConceptStudy_Page and a
preliminary concept study conducted at MSFC in early 2007.
Q9. Operational Modes: ATLAST-8m has three operational modes: Off/Standby, Commissioning,
Operations. During commissioning, the OTA doors are opened; the forward sunshield is deployed; the
280 deg K steady-state thermal environment is established; and the OTA is aligned. Using star trackers
and fine guidance sensors, the spacecraft will point the telescope at its science target with a pointing
accuracy of better than 1.6 mas. The wavefront sensor system aligns the telescope by measuring the
wavefront at Cassegrain focus and in both TMA foci and commanding the secondary mirror hexapod and,
if necessary, the tertiary mirror hexapod. During operations, the OTA thermal environment is
maintained; OTA optical alignment is maintained; momentum buildup is managed; and IC&DH system
accepts data from the science instruments, stores that data in the solid state recorder, and then retrieves
data from the SSR for transmission to the ground via the communication system.
Q10. Instrument Flight Software: The only flight software associated with the OTA is for IC&DH and
active thermal control. The FGS and WFS software is discussed in their own sections. WFS data is



                                                    18
processed on the ground. The primary functions of IC&DH software are described above. The number
of lines of code is estimated to be ~50,000, but much of this will be heritage code from JWST and HST.
Q11. Non-US Participation: Non-US participation is possible but not required. The design and
manufacture of the ATLAST-8m OTA could be done either solely via U.S. organizations or with non-
U.S. participation. For example, Schott (Germany) currently has an 8 m Zerodur blank in storage, and
REOSC (Paris, France) has an existing 8 m optical fabrication capability. In the U.S., Corning has the
ability to make 8.4 m ULE blanks and Brashear has an 8 m optical fabrication capability.
Q12. MEL: attached
Q13. Flight Heritage: Given the mass capacities of the Ares V, ATLAST-8m uses completely
conventional solid meniscus glass mirrors for all optical components: primary, secondary, tertiary and
other mirrors. The ATLAST-8m primary-mirror support structure combines elements of the JWST
backplane structure and the Kepler PM support. The optical bench structure and active thermal control
system has heritage from HST. Additionally, there is nothing new in the optical coatings. We propose to
use the same coating used on HST for the ATLAST-8m PM and SM and the same coating used on Kepler
for all other components. All technologies for ATLAST-8m have flight heritage, just not at the 8 m scale.
In sum, the path to a flight qualified 8 m mirror is achievable; the only required development effort is to
perform a statistical study of strength analysis for full size mirror support-attachment bond joints and
other structural elements.




                                                    19
                            Instrument Table 2.4: ATLAST-8m OTA
                          Item                                          Value               Units
Type of instrument                                          Optical Telescope Assembly
                                                            2 (single telescope; TMA &
Number of module
                                                                Cassegrain channels)
Size/dimensions (for each module)                                   8 dia x 25.65         mxm
Instrument mass without contingency (CBE*)                              33908             Kg
Instrument mass contingency                                               30              %
Instrument mass with contingency (CBE+Reserve)                          44080             Kg
Instrument average payload power without contingency                     3000             W
Instrument average payload power contingency                              30              %
Instrument average payload power with contingency                        3900             W
Instrument average science data rate without contingency                Note 1            kbps
Instrument average science data rate contingency                        Note 1            %
Instrument average science data rate with contingency                   Note 1            kbps
Instrument Fields of View (NFOV & 2 WFOV)                             1 & 8x22            arcmin
Pointing requirements (knowledge)                                          1              arcsec
Pointing requirements (control)                                            1              arcsec
Pointing requirements (stability)                                       0.0016            arcsec/sec

Note 1: ALTAST-8m OTA facility instrument FGS and WFS data rates are discussed in their respective
instrument inputs. The OTA itself has no data rate. Similarly, data rates for science instruments are
discussed in their respective instrument inputs. The ATLAST-8m spacecraft communication system will
be sized to accommodate all requirements.




                                                  20
2.3 Mission Design: ATLAST-9.2m Observatory

Q1. Overview: ATLAST-9.2m, shown in Figures 2.4 and 2.5, is designed to be launched by an Evolved
Expendable Launch Vehicle (EELV). Any EELV with sufficient fairing diameter and lift capability is
compatible with the design. During the Concept Study, we assumed a launch of ATLAST-9.2m from
KSC on an enhanced version of the Delta IV-Heavy launch vehicle. The enhancements, which are
outlined in the Delta IV user’s guide, consist of fairing with a 6.5 m outer diameter, a more powerful main
engine (the RS68A which is already in testing) and the addition of 6 solid boosters already in use on the
smaller version of the Delta IV. Informal estimates indicate that this enhanced version could carry 18,000
kg of payload mass to a C3 of about -0.69 km2/sec2, which is required for reaching SE-L2.
    In this orbit, occasional small maneuvers are required for station-keeping and unloading momentum.
However, ATLAST-9.2m is able to unload momentum in two axes by using the pointing arm to move the
telescope center of gravity relative to the center of pressure (from solar photons). Also, ATLAST-9.2m
always has the same projected area of sunshade facing the sun. The net result is that fewer momentum-
unloading burns are required for ATLAST-9.2m (compared to JWST). Using the ATLAST-9.2m
pointing arm and planar sunshade, more than half of the sky is visible at any time, and the orbit allows all
of the sky to be seen every 6 months. ATLAST-9.2m has a required minimum mission lifetime of 5 years
and a desired lifetime of 10 years. The observatory is designed to enable servicing and, as such, could be
operated for up to 25 years.
    ATLAST-9.2m employs room temperature (280 deg K) optics with an open-baffle design, which
means that substantial heat is required to keep the primary mirror warm. To reduce electrical power
requirements, heat pipes conduct waste heat from the instruments and electronics to the primary mirror.
 Heater panels behind the primary mirror segments actively control the segment temperature to ±0.1 deg
K, and any morphology changes due to spatial/thermal gradients are addressed by the WFS&C system.

Q2. Mission Development: The vast majority of the flight software (FSW) development during Phases B
and C/D is for the science instruments and SC bus. The ground station and Level 0 through 3 processing
of the science data on the ground closely follows the JWST model, with high reuse of existing JWST
software.
   The science instrument FSW falls into 2 major areas: that required by the individual science
instruments and that required by the WFS&C and the FGS subsystems. Each science instrument requires
FSW to (1) format the digitized detector output into CCSDS packets, (2) manage the active thermal
control system, (3) command mechanisms such as filter wheels, shutters, and calibration mirrors and
verify their successful operation, and (4) operate in different modes such as inactive, science data taking
and calibration. The WFS&C FSW performs the following functions: (1) command filter wheels, (2)
control the star selection mirror, (3) readout detectors, (4) calculate star centroids for the FGS, and (5)
compute wavefront errors and corrective motions of mirror actuators.
   Another and higher level of instrument software lies in the IC&DH processors and provides standard
housekeeping functions (thermal control, fault detection and correction, science data handling and
packetization), and as well as relaying commands to instruments and to command actuators on the
primary mirror.
   The spacecraft bus FSW processes data from pointing control sensors (inertial rate units, fine guidance
sensors, sun sensor, etc.) and controls the Attitude Control System’s (ACS) actuators (Reaction wheels,
Pointing Arm, DIPPS). This is described further in the spacecraft section. The spacecraft FSW also
handles other standard tasks such as power management, SC thermal control, communications with the
ground, and propulsive maneuvers for orbit station-keeping.
.




                                                    21
             Solar Shade ~40 -                                                      Optical Telescope
                                                     Instruments                     Assembly (OTA)
             m Diagonal Tip-to-
              Tip, Total Area
                 ~801 2
                      -m               Spacecraft
                                          Bus




                                                                                Disturbance Isolator
                  28 m Ultra Flex
                      2
                                              Steerable                          Precision Pointing
                    Solar Array               High-Gain        Pointing Arm       System (DIPPS)
                 Deployable, Fixed             Antenna             (PA)

Figure 2.4: Front (sun-side) [left] and Rear (anti-sun side) [right] views of deployed ATLAST-9.2m with major
                                              components identified.




                                                              Delta IV-Heavy
                                                                  Fairing


                                                            Observatory in Stored
                                                               Configuration


                                                              Payload Adapter
                                                                Fitting (PAF)




              Figure 2.5: ATLAST-9.2m Stowed in Fairing with 6.4 m OD and 26 m length.




                                                    22
   Depending on mission element, there is substantial re-use of existing software. The science
instruments are similar in nature to those used on HST, Kepler, and JWST and those proposed for use on
JDEM, and more than 50% reuse of existing software is expected. The algorithms for WFS&C are very
similar to those used for JWST, and 75% reuse of existing software is expected. Software for common
SC items such as star trackers, IRUs, antennas, etc., have very high heritage and reuse. Systems requiring
substantial new software development include the pointing arm, DIPPS, and ACS. There is no new
software development for the ground station.
   In the area of science development, most of the instruments are standard (albeit large-format) cameras
and spectrographs, and the software development for data analysis have significant heritage from previous
missions. The one area where new data analysis and calibration algorithms will need to be developed is
for the two modes of the exoplanet instrument (ExoCam, ExoSpec). Development effort (included in our
ground system cost) is required to determine how to optimize the acquisition and analyses of this data.
Q3-Q4. See attached tables and figures.
Q5. Top 3 Primary Risks: The three primary risks are: (1) availability of the enhanced Delta IV-H with
6.5m fairing (mission risk and program risk), (2) wavefront sensing update frequency faster than opto-
thermal stability (payload risk), (3) imperfect ground verification of flight conditions (optical, thermal,
zero-g) (payload and SC risk and program risk).




                                                    23
                         Table 2.5: ATLAST 9.2m Mission Design Table
                          Parameter*                                      Value               Units
      Orbit Parameters (apogee, perigee, inclination, etc.)     Halo Orbit about Second        km
                                                               Sun-Earth Lagrange Point
                                                                  (Orbit Plane inclined
                                                               slightly wrt Ecliptic Plane)
      Mission Lifetime                                                60 for design,          mos
                                                                  120 for consumables,
                                                                   300+ with servicing
      Maximum Eclipse Period                                   ~180 (from launch to solar     min
                                                                 array deployment; zero
                                                                   eclipses thereafter)
      Launch Site                                                          KSC
      Science Payload Dry Bus Mass without contingency                    8363                 kg
      SC Bus Dry Bus Mass without contingency                             2539                 kg
      Observatory Dry Mass without contingency                            10902                kg
      Observatory Dry Mass contingency                                      30                 %
      Observatory Dry Mass with contingency                               14173                kg
      Observatory Propellant Mass without contingency                      604                 kg
      Observatory Propellant contingency                                    30                 %
      Observatory Dry Propellant Mass with contingency                     785                 kg
      Observatory Total Wet Mass with contingency                15117 (includes 160 kg        kg
                                                                allocation for the part of
                                                              separation system that stays
                                                                     attached to LV)
      Launch Vehicle                                          Delta IV Heavy (enhanced)       Type
      Launch Vehicle Payload Mass Capability                        18000 (estimate)           kg
      Launch Vehicle Mass Margin                                          2883                 kg
      Launch Vehicle Mass Margin (%)                                       19.1                %
      Spacecraft Bus Power without contingency                            4428                 W
      Spacecraft Bus Power contingency                                      30                 %
      Spacecraft Bus Power with contingency                               5757                 W

* Note: the table was considered to have some errors as provided. It is assumed that the parameter “SC
bus mass” was really meant to be “Observatory mass” (sum of SC bus and science payload masses).
Therefore the table entries were re-labeled and some additional rows were inserted to show the elements
that make up the observatory mass and how the observatory mass compares to the LV capability. SC Bus
power is the power generated by the SC Bus and used by the whole Observatory.




                                                    24
2.4 Technical Implementation: ATLAST-9.2m Spacecraft Implementation

Q1-Q2. Spacecraft (SC) Design and Technical Maturity: The basic role of the SC is to provide
utilities, such as electrical power, communications, propulsion, etc., for the overall observatory, which
includes both the SC and the science payload. See Table 2.6 for the SC mass and power summary. In the
case of ATLAST-9.2m, the SC also includes the following three major elements:
    ! Deployable Sunshield (SS), which attaches to the anti-sun side of the SC and prevents light from
      the Sun, Earth and Moon from reaching the science payload. The SS is treated as part of the SC
      Structures and Mechanisms System (SMS).
    ! Pointing Arm (PA), which is located behind the SS and has two primary roles: pitching the
      ATLAST-9.2m telescope so it can acquire any target located from 45 to 180 degrees from the Sun
      and rotating the telescope ±22.5 degrees about its bore-sight. The PA is treated as part of the
      Attitude Control System (ACS).
    ! Disturbance Isolation and Precision Pointing System (DIPPS), which is located between the PA
      and the science payload and is also treated as part of the ACS. The DIPPS has two functions.
      First, it isolates the science payload from SC bus disturbances, such as vibrations from the
      Reaction Wheel Assemblies (RWA). Second, it provides fine pointing control for the science
      payload, which requires a pointing stability of about 1.3 mas.

Structures & Mechanisms System (SMS). The ATLAST-9.2m requires a robust structure to carry the
loads generated by the mass of the ATLAST-9.2m observatory reacting to the accelerations of the launch
vehicle (LV). After separating from the LV, the SMS deploys the Solar Array (SA), the steerable
parabolic High Gain Antenna (HGA), and the Sunshield. After deployment, the SMS gimbals the HGA
as required, but the SA stays fixed. The SMS also supports SC Bus servicing by incorporating ORUs that
contain most of the active SC Bus components. The deployed sunshield for ATLAST-9.2m has a simple
flat square shape, 28 meters on a side and is deployed using four “Astromast” linear-deployment booms
in a cruciform arrangement similar to solar sail designs.
    Except for the deployable sunshield, all of the SMS components, including the “Astromast” are
considered TRL 8, i.e., they have already flown in space. Using lessons learned from the deployable
JWST SS, the ATLAST-9.2 SS has also been designed to be as simple as possible, with its planar shape
being a primary means of keeping it simple. The lowest SS TRL is how the large four-layer Kapton
membranes for the SS need to be folded and stowed so that four extendable Astromasts can reliably
deploy them. Smaller scale Astromast-deployed membranes have already been extensively used in space
as torque-balancing solar sails, thus, this TRL is estimated to be 5 (component or breadboard tested in
relevant environment).
Thermal Control System (TCS). The main functions of the TCS are to dissipate the heat from the power
consumed by the SC and to keep the SC Bus components in their operational temperature range. Thermal
analysis of the ATLAST-9.2m SC Bus is simplified by the fact that the heat load is relatively constant
because the orbit is always in full sunlight, and the SC Bus and SS are always angled 45 degrees from the
sun line. However, this also means that the side of the SC Bus angled towards the sun always receives a
higher solar heat load than the other sides, even though the Solar Array is located to block some of this
solar heating. To accommodate this variation, the TCS radiators use thermal louvers, which are designed
to operate in both shadow and sunlight. The other TCS components, MLI, heaters, thermal couples, etc.,
are standard items used in virtually all SC and do not reflect unique ATLAST-9.2m considerations. All
TCS components are considered to be TRL 8.
Propulsion System (PS). The PS is a relatively conventional dual mode (mono-prop and bi-prop) blow-
down system. The design of the ATLAST-9.2m PS is based on the JWST PS. It has two basic tasks: first
to keep ATLAST-9.2m on the 3-month long trajectory that carries it from LV separation into its SE-L2


                                                   25
operational orbit, and second, to keep it in the quasi-stable SE-L2 operational orbit for the rest of the
mission. The largest single propulsion requirement is to correct for LV dispersions within 24 hours of
separating from the launch vehicle. To reduce propellant mass, this maneuver uses higher performance
bipropellant thrusters. However, the delta-V required for station-keeping is better supplied with smaller
monopropellant thrusters, which are more controllable and less contaminating. Momentum unloading,
which is frequently a function of propulsion systems, is infrequently required on ATLAST-9.2m because
the pointing arm can unload pitch and yaw momentum by moving the payload center of gravity relative to
the solar photon pressure vector. All thrusters are located on the front of the sunshield to avoid
contaminating the optics. All PS components are TRL 8.
Attitude Control System (ACS). The ATLAST-9.2m ACS is a complex, distributed system that meets
high performance requirements and supports a variety of different operational modes. The main
components of the overall ACS include (1) the Fine Guidance Sensor integrated into the science payload,
(2) the Disturbance Isolation and Precision Pointing System between the science payload and the Pointing
Arm, (3) Pointing Arm (PA) between the DIPPS and the Sunshield/SC Bus, (4) Coarse pointing system
on the SC bus that includes gyros, star trackers, Reaction Wheel Assemblies (RWA) and sun sensors, (5)
a propulsion system that provides attitude control in certain situations, and (6) Software resident on the
SC Bus C&DH system that runs the ACS algorithms, which enable the ACS components to work together
as intended.
    The SC bus and Sunshield are always oriented at a 45-degree angle to the sun line, although they are
free to rotate any amount about the sun-line as long as this does not result in Earth- or Moon-light hitting
the Science Payload (see Figure 2.7). The PA has two roles: one is to pitch the science payload so it can
see any target located from 45 to 180 degrees from the Sun, and the other is to permit the telescope to roll
±22.5 degrees about its bore sight.




    Figure 2.6: The components of the Disturbance Isolation and Precision Pointing System (DIPPS)

   The DIPPS (see Figure 2.6 above), which is located between the PA and the Science Payload, also has
two roles. First, it isolates the science payload from SC bus disturbances, such as vibrations from the
Reaction Wheel Assemblies (RWA). Second, it provides fine pointing control for the science payload,
which requires a pointing stability of 1.3 mas.
   The DIPPS is key to achieving the low total Wavefront Error (WFE) required by ATLAST-9.2m.
Moreover, to some extent, the DIPPS performance can be traded against other error sources such as
mirror quality, WFS&C capability, and thermally-induced distortions in the optics. Thus, an optimum


                                                    26
design of ATLAST-9.2m requires integrated modeling that incorporates the DIPPS into an end-to-end
Structural-Thermal-Optical-Pointing (STOP) analysis. When built, the integrated system is tested and
verified, which is challenging due to the large size and precise pointing requirements of ATLAST-9.2m.
JWST design and testing experience so far indicates that this can be done.




          Figure 2.7: The ATLAST-9.2m Pointing Arm at two different sun-angle orientations.

   The main ACS operations modes include the following: (1) initially, the ACS has no active role as long
as ATLAST-9.2m is connected to the launch vehicle Payload Attach Fitting (PAF); (2) upon separation
from the PAF, the ACS uses sun-sensors for approximate orientation knowledge and the propulsion
system to quickly reach and stabilize in a power-positive attitude; (3) then the star trackers begin to
provide more precise attitude sensing and the RWAs take over attitude control; (4) should an anomaly
occur that causes ATLAST-9.2m to enter a safe-hold mode then the safe-hold computer tries to use the
sun-sensors and propulsion system to reach and stay in power positive attitude; (5) assuming no anomaly,
the observatory begins a science observation by first pointing the telescope bore-sight to within a few arc-
sec of the desired target. (6) To accomplish this, the star trackers, IRUs, and RWA first roll the whole
observatory to the proper orientation about the sun line, and then the sensors and motors in the rotary
joints of the pointing arm move the telescope to the desired elevation, as well as to the desired roll around
the target bore-sight. (7) The desired guide star is identified within the Guide Star acquisition Box of the
FGS, then any coarse errors are calibrated out, and the previous technique is used again to move the guide
star to the Track Box, which is its desired, but still approximate, position in the FGS FOV; (8) lastly, the
Precision Pointing System (PPS) of the DIPPS takes over by having the Voice Coil Actuators (VCA) in
the DIPPS use the FGS information to move the guide star into the much smaller Fine Guide Box and
initiate a track function to minimize the apparent motion of the guide star centroid for the duration of that
science exposure. If the linear displacement sensors (which are Differential Impedance Transducers) in
the DIPPS indicate that the contactless voice coil actuators (VCA) are gradually approaching their travel
limits, then the ACS software commands the RWAs to produce a small, gradual change in the orientation
of the SC bus. This causes the DIPPS VCAs to move back near the center of their travel as they adjust to
minimize the apparent movement of the guide star centroid. This feedback loop between the FGS,
DIPPS, and RWA continues until the end of the science exposure or observations.
    Part of minimizing the apparent motion is for the DIPPS to comply with (essentially to not resist) any
higher-frequency motions emanating from the SC bus (such as those caused by RWA vibrations). That
way these disturbances are not passed from SC side of the contactless VCAs to the payload side. This is



                                                     27
the Disturbance Isolation (DI) function of the DIPPS. Care is taken during design to ensure the wiring
harnesses crossing the DIPPS are pliable enough to allow the DIPPS to meet its performance
requirements. The data cable is made flexible by networking (multiplexing) the payload electronics to the
bus electronics. The power cable is made sufficiently flexible by using many small gauge wires in a
managed geometry to cross the gap.
    The ACS components on the SC bus (RWA, star trackers, IRU, Sun-sensors) are all TRL 8. The PA is
basically a low duty cycle robot arm with ample heritage in items such as the Shuttle and Space Station
Remote Manipulator Systems. Thus, a reasonable TRL for the PA is 7 (equivalent to engineering model
tested in space). The DIPPS is considered to have a TRL of 4 based on the Lockheed Martin
demonstration of their similar disturbance-free system (Pedreiro 2003, Journal of Guidance, Control and
Dynamics, Vol 26, No. 5).
Command and Data Handling System (C&DHS). The ATLAST-9.2m C&DH system is straightforward
and can be implemented with current technology, although it has a slightly different architecture than
JWST to support the ORU modularity of the SC Bus. All C&DHS components are TRL 8.
    The FSW is part of the C&DHS. The FWS architecture is built upon that of the Lunar Reconnaisance
Orbiter, which is the most modern one currently in use at GSFC. Using this approach the major
categories of FSW would include: (1) a commercially available real time OS (such as VxWorks), (2)
generic utility services (bootstrap loader, CCSDS formatting), (3) standard mission features (SSR
memory management, deployables management), and (4) specific mission features (e.g., control of
DIPPS and Pointing Arm). Note that the OS (VxWorks) and the FSFC core Flight Executive exist and
therefore do not contribute to the SLOC estimate, although their storage space requirements are given.
The remaining approximately 200,000 SLOC would be a combination of reused code, modification of
existing code, and new code. As expected, ACS related functions account for a substantial fraction (about
15%) of the SLOC total. No problem is foreseen in obtaining flight processors powerful to run this code
in real time.
Communications system (CS). The communications system is reasonably straightforward, although it is
unusually powerful. The CS could be augmented with a cross-link capability so that it can communicate
with an external occulter. The major communications components include a 1 m gimbaled parabolic HGA
with a 100 W Traveling Wave Tube Amplifier (TWTA) transmitting at 600 Mbps. This downlinks about
4 Tb of science data per day in ~2 hours to upgraded 34 m DSN ground antennas. If an external occulter
(starshade) were used then ATLAST-9.2m would communicate with it about 10% of the time using a
fixed HGA aligned with the telescope bore-sight and powered by a 20 W solid-state power amplifier.
Because 600 Mbps communications have not yet been demonstrated in SE-L2 orbit, the CS TRL is 7.
Electrical Power System (EPS). The ATLAST-9.2m EPS is relatively straightforward; in part because
full sunlight is constantly available both on the transfer trajectory to SE-L2 orbit and after entering SE-L2
orbit. As noted above, the EPS provides 120 (rather than 28) V DC power. The SC Bus battery supplies
ATLAST-9.2m with all required power from launch until when the SC has separated from the LV,
deployed its solar array, acquired the sun, and become power positive.
    Harnesses distribute power and data throughout the SC Bus. Typically, they are standard, passive
items with few if any unusual design features. However, the ATLAST-9.2m harness does have some
unique features, such as being redundant and supporting a 120 V DC bus, rather than a conventional 28 V
DC power bus, in order to reduce harness mass. While 120 V DC power is not that common, it does have
a solid flight heritage. More importantly, the harness has a special “spine” configuration to distribute
power and data between the ORU’s. This configuration locates the power and data connectors on the
outside of the ORU where they can be easily accessed for connection and disconnection, as well for
inspection, cleaning, etc. This marks a significant departure from the interior blind-mate connectors used
with the HST ORUs. The HST blind-mate connectors have proven troublesome due to the difficulty both
of accessing them and of not being able to make or break electrical connections independent of the
mechanical ones. All EPS components are TRL 8.



                                                     28
Q3. Three Lowest TRL Units: (1) The DIPPS has a TRL of 4 (critical function demonstrated). It will
be brought to TRL 6 by PDR via performance, lifecycle and environmental testing. (2) The deployment-
compatible folding and stowage for the sunshield has TRL of 5 (component tested in relevant
environment). It will be brought to TRL 6 by PDR through performance and environment testing. (3) The
600 Mbps communications system is considered to have a TRL of 7 (Engineering model tested in space)
based on the existing ability of GEO satellites to transmit at higher (~1 Gbps) rates. We expect that this
system will naturally mature to TRL 8 long before the ATLAST mission requires it.
Q4. Three Greatest SC Risks: The greatest risks associated with the SC have more to do with overall
ATLAST-9.2m observatory risks that involve the SC than with the actual SC itself. These include: (1)
the ability of the DIPPS to provide the required isolation vibration and fine pointing control. If the end-
to-end observatory performance is not adequately modeled, understood and designed, then the DIPPS
may not provide the required performance. Insuring that adequate resources are available for end-to-end
performance modeling early in the program mitigates this risk. (2) Stray light may be an issue in the open
OTA design, which would degrade science performance. This risk is mitigated by the use of adequate
baffling and inner membrane coatings that minimize stray light. Demonstrations of small membranes that
include stray light measurements would be performed early in the program. (3) Successful deployment of
the sunshield (SS) is critical to observatory operations. Deployment risks can be handled in a way similar
to JWST and involve a scaled (e.g., 1/3 size) engineering model for demonstrating deployment during the
development phase. The deployment risk for ATLAST-9.2m is less than JWST because the SS does not
have to cool the observatory to cryogenic temperatures and will benefit from lessons learned with JWST.
Q5. New SC Technologies & Open issues: There are no open SC issues, and no wholly new SC
technologies are required. Our response to Q3 above describes all of the developments required to
adequately advance low TRL levels.
Q6. SC Subsystem Requirements and Margins: The mass and power requirements (plus the associated
contingencies or margins) of all of the SC subsystems are given in the Spacecraft Mass Table. Given the
large size of the LV fairing, the subsystem volume requirements are not significant. The only data
coming from the subsystems is low rate housekeeping telemetry, and therefore this requirement is also
not significant. The significant requirements for each SC subsystem are summarized below.
SMS. The main performance requirement is to provide a robust structure that is designed to carry the
loads generated by the approximately 15,000 kg mass (including reserve) of the ATLAST-9.2m
observatory reacting to limit-case 10 g dynamic accelerations of the LV. No technical problems are
foreseen in meeting this performance requirement. All of the SMS deployments are conventional and
occur in microgravity after separating from the LV, so they do not present any known challenges. A total
deployed boom length of 19 m is required for the sunshield, and the booms are sized to provide the
required >0.2-Hz deployed frequency. Thorough stray light analyses show that this simple planar
sunshield approach in conjunction with a central primary mirror baffle is sufficient to limit stray light to
less than 10% of the zodiacal sky brightness while also eliminating “rogue path” light that would
otherwise skirt around the secondary mirror.
TCS. The main TCS performance requirement is to dissipate the approximately 1 kW of power used by
the SC while keeping the SC Bus components in their operational temperature range, which is typically
10 to 40 deg C. This is not a challenging performance requirement, and, if needed, the TCS capability
can be changed without significant impact.
PS. The PS is capable of providing ATLAST-9.2m with a total delta-V of about 120 m/sec. The most
demanding propulsion requirement is providing up to 42 m/s of delta-V within 24 hours of separating
from the launch vehicle in order to correct 3 sigma dispersions in the launch vehicle trajectory. However,
the approximately 4 m/s per year of delta-V required for station-keeping is better supplied with smaller
monopropellant thrusters, which are more controllable and less contaminating. With station-keeping thus
occurring about once a month, less than 0.5 m/s should be required per maneuver. The overall PS
performance requirement is not challenging; its capability can be changed without significant impact.



                                                    29
ACS. The combination of the star trackers, RWAs and gyros have a performance requirement to point
ATLAST-9.2m to an accuracy of ~1 arc sec and to provide ±22.5 degrees of roll about the sun line. The
PA has two performance requirements: To pitch the science payload so it can see any target located from
45 to 180 degrees from the Sun and the other is to permit the telescope to roll ±22.5 degrees about its
bore-sight. The PA does not have a demanding control requirement; about 1 deg should be adequate.
However, it would be useful but not necessary for the PA to have a pointing knowledge of ~ 1 arcsec so
that the telescope pointing can be that precisely determined from the star trackers on the SC bus. This
would require the PA to have high precision joints encoders and minimal thermally induced bending of
the links in the PA. However, if this is too difficult to accomplish, it will be easy to provide the required
arcsec pointing knowledge by mounting a star tracker on the telescope. The DIPPS provides fine pointing
control for the science payload, which requires a pointing stability of 1.3 mas.
C&DHS. The one defined quantitative C&DH requirement is that the Solid-State Recorder (SSR) needs
to have an 8.6 Tb capacity to hold two days of science downlink data to prevent loss of data in case one
daily communication pass is unsuccessful.
CS. The single significant performance requirement is to downlink science data at 600 Mbps from a SE-
L2 orbit to a 34 m DSN antenna.
EPS. The single 72 V, 40 Ah Li-Ion battery is sized for the launch mode. The lightweight Ultraflex solar
array uses 28% efficient Triple junction Gallium Arsenide (TjGaAs) photovoltaic cells and provides more
than 6600 W through the 10-year mission.
Q7. Flight Heritage and Space-Qualification Process: The ATLAST-9.2m SC incorporates extensive
flight heritage from HST and WMAP, as well as design heritage from JWST. The HST heritage is that of
supporting a UV-VIS-NIR space telescope using SC components that consist of ORUs. The WMAP
flight heritage derives from its successful and still ongoing multi-year mission in a SE-L2 orbit. The
JWST heritage is for the design of an architecturally similar SC to support a large telescope with precise
pointing in an SE-L2 obit, plus deploying a sunshield that keeps light away from the telescope and
instruments. The ATLAST-9.2m bus is simpler than the JWST bus in certain respects, such as not having
a requirement to house a cryo-cooler and having a simpler sunshield. A JWST-like design and testing
effort should be adequate to space-qualify the ATLAST-9.2m SC. The concept for the folding and
stowage system for the ATLAST-9.2m sunshield owes heritage to early studies undertaken for JWST.
The only item clearly requiring development is the DIPPS. Because it is relatively compact mechanism
(max dimension is < 1 m), it will be straightforward to perform the lifecycle and environmental tests
required to space-qualify it.
Q8. Accommodation of Science Instruments: Since all of the science instruments, including the OTA,
are contained in a single structure and interface to both the SC EPS and C&DHS through a single IC&DH
system, most of the accommodation requirements are fairly simple and straightforward. The science
instruments, including the hybrid instruments that include the guidance and wavefront sensors, were
designed to be removable (i.e., serviceable) from the back of the OTA structure. The instruments are
shielded from the sun at all times, and live in a benign environment. The instruments have their own
thermal control system (not provided by the SC). The ACS in the SC, working in concert with the FGS
and DIPPS provides accurate pointing control and stability for the science instruments.
Q9. Spacecraft Schedule and Responsible Organization: The SC schedule is shown in the Section on
Programmatics and Schedule. The organization responsible for the SC bus is chosen via a NASA-
approved process that ensures adequate experience with similar SC buses.
Q10. Requirements for Non-US Participation: From a technical perspective, no ATLAST-9.2m
instrumentation or SC hardware requires foreign contributions. However, as it common for missions of
this size and scope (for example, HST and JWST), it is expected that international partners will be given
and make use of the opportunity to make contributions in return for observing time.
Q11. Characteristics Tables: See Tables 2.6 and 2.7.




                                                     30
                     Table 2.6: ATLAST-9.2m Spacecraft Mass and Power
                     Current Best                  CBE Mass       CBE                   CBE Power
                                      Percent                               Percent
  Spacecraft Bus       Estimate                      Plus       Average                    Plus
                                       Mass                                 Power
     Element         (CBE) Mass                   Contingency    Power                  Contingency
                                    Contingency                           Contingency
                         (kg)                        (kg)         (W)                      (W)
Structures &                1298             30         1687          0            30             0
Mechanisms
Thermal Control               99             30          129        266            30           346
Propulsion (Dry               75             30           98         40            30            52
Mass)
Attitude Control             795             30         1034          4            30             5
Command & Data               100             30          130        274            30           356
Handling
Telecommunications            59             30           77         67            30            87
Power                        113             30          147        153            30           199
SC TOTAL                    2539                        3301        804                        1045




                                                  31
                      Table 2.7: ATLAST-9.2m Spacecraft Characteristics
                           Spacecraft bus                                Value/ Summary, units
Structure
Structures material (aluminum, exotic, composite, etc.)              Alum & Comp.
Number of articulated structures                                     2 (Pointing arm & HGA)
Number of deployed structures                                        4 (Pointing arm, HGA, SA, SS)
Thermal Control
                                                                     Active (Louvered Radiator, Heat
Type of thermal control used                                         Pipes, MLI, Heaters,
                                                                     Thermistors)
Propulsion
Estimated delta-V budget, m/s                                        120
                                                                     Dual Mode (Mono- & Bi-Prop)
Propulsion type(s) and associated propellant(s)/oxidizer(s)
                                                                     with Hz & NTO
Number of thrusters and tanks                                        18 thrusters, 2 tanks
Specific impulse of each propulsion mode, seconds                    Mono: 228; Bi-Prop: 309
Attitude Control
Control method (3-axis, spinner, grav-gradient, etc.).               3-axis
Control reference (solar, inertial, Earth-nadir, Earth-limb, etc.)   Inertial
Attitude control capability, degrees                                 See OTA instrument table
Attitude knowledge limit, degrees                                    See OTA instrument table
Agility requirements (maneuvers, scanning, etc.)                     Slew 90 deg in < 1 hour
                                                                     Fixed SA, 2 axis HGA, 5 axis
Articulation/#–axes (solar arrays, antennas, gimbals, etc.)
                                                                     pointing arm
Sensor and actuator information (precision/errors, torque,
                                                                     See OTA instrument table
momentum storage capabilities, etc.)
Command & Data Handling
Spacecraft housekeeping data rate, kbps                              ~10
Data storage capacity, Mbits                                         8E6 Mbits (8E12 bits)
Maximum storage record rate, kbps                                    5E4 (50 Mbps)
Maximum storage playback rate, kbps                                  600,000 (600 Mbps)
Power
Type of array structure (rigid, flexible, body mounted, deployed,
                                                                     Deployed but fixed Ultraflex SA
articulated)
Array size, meters x meters
Solar cell type (Si, GaAs, Multi-junction GaAs, concentrators)       Triple Junction GaAs
Expected power generation at Beginning of Life (BOL) and End         8300 BOL & 7100 EOL (both
of Life (EOL), watts                                                 when clodest to Sun)
On-orbit average power consumption, watts                            5757 (includes 30% contingency)
Battery type (NiCd, NiH, Li-ion)                                     Li-Ion
Battery storage capacity, amp-hours                                  40




                                                     32
2.5 Mission Design: ATLAST-8m Observatory

Q1. Overview: ATLAST-8m is planned to be launched from KSC on an Ares V launch vehicle
(configuration 51.01.48) into a transfer orbit with a C3 energy of approximately -0.7 km2/s2. This energy
is sufficient to send the observatory to a halo orbit about SE-L2. The current baseline configuration of the
Ares V with its 10 m diameter fairing (see Figure 2.8) can place 65mt of payload onto this transfer orbit
using a direct insertion trajectory. ATLAST-8m is specifically designed to take advantage of these
                                                  capabilities to reduce programmatic cost and risk.
                                                      The size and geometry of the target halo orbit about
                                                  SE-L2 can be traded during Phase A, but is assumed to be
                                                  the JWST orbit. This orbit has the advantage of not
                                                  requiring an insertion maneuver at SE-L2. Once at SE-L2
                                                  the spacecraft begins station-keeping duties. Given the
                                                  volume in the ATLAST-8 structure for propellant tanks
                                                  and the Ares V mass capacity, it is possible to carry
                                                  sufficient propellant for a 20 year mission (or longer).
                                                  Analysis indicates that only 5 m/s delta-V is needed per
                                                  year for station-keeping and momentum unloading.
                                                  Given the 6-month period of the halo orbit and the 60-
                                                  degree keep-out angle between the telescope’s line of
                                                  sight and the sun, the telescope can see the entire sky in
                                                  approximately six months.
                                                      Reaction wheels, or a combination of reaction wheels
                                                  and control moment gyros, are used to point the telescope.
                                                  Thrusters provide the means to unload momentum
                                                  periodically, but using the solar arrays as a kite tail
                                                  minimizes the build-up of momentum. ATLAST-8m uses
                                                  two solar panels on 10 m deployable booms to balance
                                                  solar pressure exerted on its sunshade tube. As the
   Figure 2.8: ATLAST-8m is shown in its
                                                  observatory slews relative to the sun, the solar panel
   launch configuration in an Ares-V ogival
   fairing. The scarfed end of the sunshade is    booms are extended to maintain the center of pressure at
   deployed once on-orbit. Length scales are in   the center of mass (see Figure 2.9). Additionally, the
   meters.                                        booms have gimbal joints that articulate during
                                                  observatory roll and pitch maneuvers to keep the solar
panels perpendicular to the sun. Analysis shows that, with 10 m booms extended from midpoint of the
spacecraft, only 35 N-m-s momentum is required for 6.25 days of continuous high-precision pointing
observation. By making slight adjustments in boom length, indefinite observation times can be achieved.
Q2. Mission Development: The vast majority of FSW development during Phases B and C/D is for
science instruments and SC bus. The ground station and Level 0 through 3 processing of science data on
the ground closely follows the JWST model, with high reuse of existing JWST software.
    Science instrument FSW falls into 2 major areas: that required by an individual science instrument and
that required by the WFS&C and FGS subsystems. Each science instrument requires FSW to (1) format
detector output into CCSDS packets, (2) manage the active thermal control system, (3) command
mechanisms such as filter wheels, shutters, and calibration mirrors and verify their successful operation,
and (4) operate in different modes such as inactive, science data taking and calibration. The facility FGS
and WFS FSW performs the following functions: (1) command spacecraft pointing control system to
place selected stars into module’s FOV, (2) readout detectors, (3) calculate star centroids for FGS, and (4)
communicate WFS data to ground where wavefront errors and alignment motions are computed.


                                                    33
    Another and higher level of instrument software lies in the IC&DH processors and provides standard
housekeeping functions (thermal control, fault detection and correction, science data handling and
packetization), and as well as relaying commands to instruments and to SM or TM hexapod actuators.
    The spacecraft bus FSW processes data from pointing control sensors (IRU, star trackers, FGS, sun
sensor, etc.) and controls ACS actuators (reaction wheels, CMGs, solar panel extendable gimbaled
pointing arm, and active vibration isolators). This is described further in the spacecraft section. The
spacecraft FSW also handles other standard tasks such as power management, SC thermal control,
communications with the ground, and propulsive maneuvers for orbit station-keeping.
    Depending on mission element, there is substantial re-use of existing software. The science
instruments are similar in nature to those used on HST, JWST and JDEM, and more than 50% reuse of
existing software is expected. The algorithms for WFS&C are very similar to those used for JWST, and
75% reuse of existing software is expected. Software for common SC items such as star trackers, IRUs,
antennas, etc., have very high heritage and reuse. Systems requiring substantial new software
development include the solar panel extendable gimbaled pointing arm, active vibration isolation, FGS,
and ACS. There is no new software development for the ground station.
   In the area of science development, most of the instruments are standard (albeit large-format) cameras
and spectrographs, and the software development for data analysis have significant heritage from previous
missions. The one area where new data analysis and calibration algorithms will need to be developed is
for the two modes of the exoplanet instrument (ExoCam, ExoSpec). Development effort (included in our
ground system cost) is required to determine how to optimize the acquisition and analyses of this data.




         Figure 2.9: Solar Torque / Momentum Build-Up Mitigation Scheme for ATLAST-8m

Q3-Q4. See attached tables and figures.
Q5. Top 3 Primary Risks: The three primary ATLAST-8m risks are: (1) availability of a heavy lift
launch vehicle with adequate mass and volume capabilities (mission risk and program risk), (2) ability to
           -10
achieve 10     starlight suppression at the desired inner working angle (mission risk and program risk),
and (3) ability to successfully launch an 8 m visible diffraction limited monolithic primary mirror
(payload, mission and program risk).




                                                   34
Figure 2.10: ATLAST-8m (with an on-axis SM) shown with the scarfed sunshield in its extended (on-
                                    orbit) configuration.




        Figure 2.11: ATLAST-8m exterior view showing twin gimbaled solar arrays.




                                               35
                             Table 2.8: ATLAST-8m Mission Design Table
                    Parameter                                              Value                     Units
Orbit Parameters (apogee, perigee, inclination, etc.)        Halo Orbit about Second Sun-Earth
                                                                       Lagrange Point
Mission Lifetime                                                         60 design,                  mos
                                                                      240 consumables
Maximum Eclipse Period                                         ~180 (from launch to solar array      min
                                                             deployment; zero eclipses thereafter)
Launch Site                                                                 KSC
Spacecraft Dry Bus Mass without contingency                                 4157                      kg
Spacecraft Dry Bus Mass contingency                                          30                       %
Spacecraft Dry Bus Mass with contingency                                    5404                      kg
Observatory Mass without contingency                                       35697                      kg
Observatory Mass contingency                                                 30                       %
Observatory Mass with contingency                                          46406                      kg
Spacecraft Propellant Mass without contingency                              3345                      kg
Spacecraft Propellant contingency                                           39.5                      %
Spacecraft Propellant Mass with contingency                                 4666                      kg
Total Payload Mass                                                         56476                      kg
Launch Vehicle                                                             Ares V                    Type
Launch Vehicle Payload Capability                                          65000                      kg
Launch Vehicle Mass Margin                                                  8524                      kg
Launch Vehicle Mass Margin (%)                                              15.1                      %
Spacecraft Bus Power without contingency                                    8589                      W
Spacecraft Bus Power contingency                                             30                       %
Spacecraft Bus Power with contingency                                      11165                      W




                                                        36
2.6 Technical Implementation: ATLAST-8m Spacecraft Implementation

Q1-Q2. Spacecraft (SC) Design and Technical Maturity: The spacecraft provides all pointing, power,
communication, data handling, station-keeping, momentum unloading, and thermal control for the
ATLAST-8m telescope and its science instruments, and provides the propulsive maneuvers for midcourse
corrections and SE-L2 halo orbit insertion. Key requirements include enabling the observatory to slew 60
degrees in 90 minutes (required) or 40 minutes (desired); ensuring a pointing stability of 1.6 mas;
enabling the observatory to roll about the telescope’s line of sight by ± 30 degrees in 30 to 60 minutes,
and provide a minimum of 4500 minutes continuous observing time before momentum unloading is
required. All subsystem components are sized with a 30% mass contingency and, when electrical power is
required, a 30% reserve is included.
    The spacecraft is packaged in a donut-shaped volume located at the rear of the OTA, surrounding the
science instrument bay. Designed for serviceability, key subsystem components are grouped into ORUs
to enable communication elements, reaction wheel assemblies, and other components to be removed and
replaced during robotic servicing. All ORUs, as well as the science instruments, are removed by pulling
them out of the rear of the spacecraft and science instrument bay. To prevent transmission of vibration
into the instruments, the spacecraft volume does not physically contact the instrument bay.
    The spacecraft physically attaches to the observatory structure with an active isolation system (e.g.
Lockheed disturbance free payload or Northrop active strut technology). The active isolation system is
part of the Attitude Control System. It isolates the science payload (OTA + science instruments) from
spacecraft bus disturbances (e.g., vibrations from the Reaction Wheel Assemblies), and provides fine
pointing control for the science payload. Details are given in the ACS section below.
Structures & Mechanisms System (SMS). During launch, the spacecraft is attached to the rear of the
telescope structure, and does not support the observatory nor transfer launch loads to the Ares V launch
vehicle (LV). Therefore, the structure is a lightweight and simple design, with aluminum tube and
aluminum-lithium plate elements being the main components. After separating from the LV, the SMS
deploys the Solar Array (SA) and the steerable High Gain Antenna (HGA). Each of the two solar arrays is
connected to a telescoping boom by an articulating mechanism, thus enabling the solar arrays to always
be perpendicular to the sun but allowing their distance to the observatory’s center of mass to vary. This
allows for optimal power from the arrays while utilizing the solar radiation pressure to help balance the
solar radiation torque from the telescope’s optical tube. The SMS also supports SC Bus servicing by
incorporating ORUs that contain most of the active SC Bus components.
    Except for the solar array deployment mechanisms, all SMS components are considered to be at TRL
6 or higher. For the solar array deployment, the telescoping boom and the articulation mechanism have
both flown in space, but both have not been used simultaneously for solar array control. The ATLAST
team estimates this component has a TRL of 5.
Thermal Control System (TCS). The TCS provides thermal control for the spacecraft and science
instruments, including the OTA primary mirror. Radiators (30 m2) are mounted around the circumference
of the OTA and spacecraft to dissipate the 11,160 W of heat load from the spacecraft components and
science instruments. Of the 2.4 kW required to maintain the primary mirror at 280 deg K, 2.0 kW is
scavenged from the science instruments via cold plates, although the TCS is designed with 1.6 kW of
backup in case the science instruments are powered down or are being serviced. The spacecraft is
wrapped in 50-layer MLI blankets, helping to maintain the spacecraft at an operational steady state sink
temperature of 300 deg K (±10 deg K). The main functions of the TCS are to dissipate the heat from the
power consumed by the SC, keep the SC Bus components in their operational temperature range, and
stabilize the temperature of the PM. All TCS components are commonly used in spacecraft designs and
are considered to be TRL 8.




                                                   37
Propulsion System (PS). The PS provides the launch vehicle injection error and mid-course correction
maneuvers during the transfer to the SE-L2 orbit, as well as station-keeping and momentum unloading.
These propulsive events vary greatly in size, and result in a conventional pressure-fed bipropellant MMH-
NTO system consisting of two 900 lbf thrusters and four banks of reaction control system thrusters, each
bank containing two 25 lbf thrusters and two 5 lbf thrusters. The current system design incorporates two
fuel tanks, two oxidizer tanks, and two pressurant tanks. The initial propellant load is sufficient for a 20-
year mission.
    The PS consists mostly of flight-proven components, including the engines, valves, filters, regulators,
etc., but the pressurant tank size does not exist and represents new hardware that needs to be designed,
built, and qualified. An option that would avoid this would be to use four smaller (existing) tanks instead
of two, which may allow the use of an existing pressure vessel from PSI-PCI (ATK Space Systems): the
propellant tank assumed for the spacecraft is also “new” but is very close in size to an existing tank; a
small reduction in required propellant will allow the use of this tank. The “lines and fittings” and
“structural mounts” are the lowest TRL for this system, with preliminary masses estimated as percentages
of the summed mass of the known quantities. The engines and existing feed system components are TRL
8 or 9 (as individual components). The non-existing items are at TRL 4 or lower due to the fact they need
to be built and then qualified in the expected spacecraft environment. The propulsion system as a whole
is very similar to previously flown systems but still needs to be assembled and rigorously tested.
    The initial propellant load is sufficient for a 20-year mission. On-orbit refueling could extend the
mission beyond 20 years. On-orbit servicing has been demonstrated with Orbital Express, and is
considered between TRL 5 and 6. With the necessity for servicing the International Space Station, the
TRL level of this technology will probably be raised before ATLAST is launched.
Attitude Control System (ACS). The main components of the ACS include the Fine Guidance Sensor
integrated into the science payload; a coarse pointing system on the SC that includes gyros, star trackers,
reaction wheel assemblies (RWA), and sun sensors; a propulsion system that provides attitude control (in
certain situations) and momentum unloading; Active Vibration Isolation System between the spacecraft
and the observatory; and software resident on the SC Bus C&DH system that runs the ACS algorithms,
which enable the ACS components to work together as intended.
    There are two potential approaches for the active vibration isolation system, Lockheed’s disturbance
free payload and Northrop’s active strut technologies. The active isolation system has two roles. First, it
isolates the science payload from SC bus disturbances, such as vibrations from the RWA. Second, it
provides fine pointing control for the science payload, which requires a pointing stability of 1.6 mas.
    During science observations, the OTA bore-sight is pointed to within a few arcsec of the desired target
using the RWA. The active isolation system then engages to minimize the apparent motion of the guide
star centroid for the duration of that science exposure. During a science observation, when sensors
indicate that the voice coil actuators (VCA) are approaching their travel limits, the ACS software
commands the RWAs to produce a small, gradual change in the orientation of the SC bus. This causes
the VCAs to move back near the center of their travel as they adjust to minimize the apparent movement
of the guide star centroid. This feedback loop between FGS, active isolation system, and RWA continues
until the end of the science observation.
    Except for active isolation, the ACS components on the SC bus are all TRL 8. Active isolation is
considered to have a TRL of 4 based on the Lockheed Martin demonstration of their disturbance-free
system (Pedreiro 2003, Journal of Guidance, Control and Dynamics, Vol 26, No. 5).
Command and Data Handling System (C&DHS). The ATLAST-8m C&DHS is identical to that
described in the ATLAST-9.2m spacecraft summary. All CDHS components are TRL 8.
Communications system (CS). The communications system is reasonably straightforward, although it is
unusually powerful, communicating at a rate of 600 Mbps. The communications system consists of a Ka-
band HGA for data downlink, a medium gain system for telemetry and engineering data links, and an S-




                                                     38
band transmitter for local communications with a servicing vehicle or for backup capability. Because 600
Mbps communications have not yet been demonstrated in SE-L2 orbit, the CS TRL is 7.
Electrical Power System (EPS). The ATLAST-8m EPS is a simple and robust system, providing the
observatory with 28 V DC power. The SC battery is sized to provide 3 hours of power to the observatory
prior to solar array deployment and during servicing operations as necessary. Solar arrays are triple
junction GaAs 100 W/kg, 258 W/m2, and sized with a 30% degradation margin for a ten year life. Total
solar array area is 72 m2. EPS elements are arranged in ORUs to allow for replacement during servicing
missions, and incorporate blind mate connectors. All EPS components are TRL 8.
Q3. Three Lowest TRL Units: (1) Active isolation has a TRL of 4 (critical function demonstrated). It
will be brought to TRL 6 by PDR via performance, lifecycle and environmental testing. (2) The solar
array deployment system, consisting of both telescoping booms and articulating mechanisms, is TRL 5.
It will be brought to TRL 6 by PDR through performance and environment testing. (3) The 600 Mbps
communications system is TRL 7 (engineering model tested in space) based on the existing ability of
GEO satellites to transmit at higher (~1 Gbps) rates. We expect that this system will naturally mature to
TRL 8 long before the ATLAST-8m mission requires it.
Q4. Three Greatest SC Risks: The three greatest risks relate to active isolation, on-orbit replacement of
components and science instruments, and rapid observatory slewing. (1) Active isolation must provide
sufficient isolation vibration and fine pointing control for the science instruments. If the end-to-end
observatory performance is not adequately modeled, understood and designed, then it may not provide the
required performance. This risk can be mitigated be insuring that adequate resources are available for
end-to-end performance modeling early in the program. (2) The on-orbit replacement of components and
instruments requires an architecture and component connections, which enables servicing while being
robust. Given the success of Orbital Express (and on-going space robot development) this technology will
mostly likely mature before it is needed for ATLAST-8m. (3) Given the mass of ATLAST-8m, it may be
impractical to fly reaction wheels or control moment gyros that achieve the desired slew rate of 1.5
deg/minute. It may be necessary to accept the required slew rate of 0.667 deg/minute.
Q5. New SC Technologies & Open issues: There are no open SC issues, and no wholly new SC
technologies are required. Our response to Q3 describes the developments required to adequately
advance low TRL levels.
Q6. SC Subsystem Requirements and Margins: The mass and power requirements (plus the associated
contingencies or margins) of all of the SC subsystems are given in the Spacecraft Mass Table. Given the
large size of the LV fairing, the subsystem volume requirements are not significant. The only data
coming from the subsystems is low rate housekeeping telemetry, and therefore this requirement is also
not significant. The significant requirements for each SC subsystem are summarized below.
SMS. The structure is a lightweight and simple design, with aluminum tube and aluminum-lithium plate
elements being the main components. Structural elements were sized for 5g axial and 2g lateral sustained
loads, with yield and ultimate factors of safety of 1.25 and 1.4, respectively. Since the observatory launch
loads do not pass through the spacecraft structure, the total structural mass is only 1690 kg, not including
the solar array deployment system and science instrument bay.
TCS. The TCS dissipates the 11,600 W of power required by the observatory, which includes spacecraft
power, science instrument power, and primary mirror thermal control. The spacecraft temperature is
maintained at 300 (±10) deg K, while the primary mirror temperature is maintained at ~280 deg K with a
stability of ±0.1 deg K.
PS. The PS is capable of providing a total delta-V of about 215 m/sec. Station-keeping at SE-L2 requires
approximately 20 m/s over 5 years, and momentum unloading requires an estimated 5.3 m/s over 5 years.
ACS. Key requirements include enabling the observatory to slew 60 degrees in 90; ensuring a pointing
control and pointing knowledge of 1.0 arcsec; and enabling the observatory to roll about the telescope’s
line of sight by ± 30 degrees in 30 to 60 minutes. Active isolation provides the 1.6 mas fine pointing
stability for the science payload.



                                                    39
CDHS. The one defined quantitative C&DH requirement is that the Solid-State Recorder (SSR) needs to
have an 8.6 Tb capacity to hold two days of science downlink data to prevent loss of data in case one
daily communication pass is unsuccessful.
CS. The single significant performance requirement is to downlink science data at 600 Mbps from a SE-
L2 orbit to a 34 m DSN antenna. Downlinks last ~2 hours and occur daily.
EPS. The power system must provide 11,165 W of power (which includes a 30% margin), and power the
observatory from launch vehicle separation through solar array deployment. The solar arrays also must
articulate and extend to aid in balancing the solar radiation pressure on the OTA.

Q7. Flight Heritage and Space-Qualification Process: Subsystem components are almost exclusively
high TRL, with heritage on various past and current spacecraft. The only system requiring significant
development is active isolation. Due to its size, it will be straightforward to perform the lifecycle and
environmental tests required to space-qualify it.
Q8. Accommodation of Science Instruments: Since all of the science instruments, including the OTA,
are contained in a single structure and interface to both the SC EPS and CDHS through a single
Instrument C&DH system, most of the accommodation requirements are fairly simple and
straightforward. The science instruments, including the FGS and WFS facility instruments, were designed
to be removable (i.e., serviceable) from the back of the OTA structure. The instruments are shielded from
the sun at all times, and live in a benign environment.
Q9. Spacecraft Schedule and Responsible Organization: The SC schedule is shown in the Section on
Programmatics and Schedule. The organization responsible for the SC bus will be chosen via a NASA
Headquarters-approved process that will insure that the organization has adequate experience with similar
SC buses.
Q10. Requirements for Non-US Participation: From a technical perspective, no ATLAST-8m SC
hardware requires foreign contributions. However, as it common for missions of this size and scope (for
example, HST and JWST), it is expected that international partners will be given and make use of the
opportunity to make contributions in return for observing time.
Q11. Characteristics Tables: See attached tables.




                                                   40
                Table 2.9: ATLAST-8m Spacecraft Mass and Power
                                 Current Best    Percent Mass       CBE Plus
       Spacecraft bus
                                Estimate (CBE)   Contingency     Contingency (kg)
Structures & Mechanisms             1345             30               1749
Thermal Control                      554             30               720
Propulsion (Dry Mass)                401             30               521
Attitude Control                     499             30               649
Command & Data Handling              140             30               182
Telecommunications                   114             30               148
Power                               1104             30               1435
Total Spacecraft Dry Bus Mass       4157             30               5404




                                           41
                  Table 2.10: ATLAST-8m Spacecraft Characteristics
                            Spacecraft bus                             Value/ Summary, units
Structure
Structures material (aluminum, exotic, composite, etc.)               Aluminium for tubes ;
                                                                      Aluminium-Lithium for
                                                                      plates
Number of articulated structures                                      5
Number of deployed structures                                         5
Thermal Control
Type of thermal control used                                          Active with cold plates,
                                                                      heat pipes, body mounted
                                                                      radiators (30 m2), MLI
Propulsion
Estimated delta-V budget, m/s                                         215
Propulsion type(s) and associated propellant(s)/oxidizer(s)           bi-prop MMH/NTO,
                                                                      pressure fed
Number of thrusters and tanks                                         2 x 900lbf thrusters; 8 x 25
                                                                      lbf thrusters; 8 x 5 lbf
                                                                      thrusters; 2 each of
                                                                      oxidizer, propellant, and
                                                                      pressurant tanks
Specific impulse of each propulsion mode, seconds                     in the order of above: 293,
                                                                      280, 294
Attitude Control
Control method (3-axis, spinner, grav-gradient, etc.).                3-axis
Control reference (solar, inertial, Earth-nadir, Earth-limb, etc.)    Inertial
Attitude control capability, degrees                                  1.6 mas by Active Isolation
                                                                      and Pointing System
Attitude knowledge limit, degrees                                     1 arcsec by Star Tracker
                                                                      and FGS
Agility requirements (maneuvers, scanning, etc.)                      60 deg in 90 min
Articulation/#–axes (solar arrays, antennas, gimbals, etc.)           Solar Arrays-2 axis
                                                                      High Gain Antenna-2 axis
Sensor and actuator information (precision/errors, torque, momentum   NG-SIRU
storage capabilities, etc.)                                              0.0003 deg/hr stability
                                                                         12 deg/sec rate range
                                                                      Teldix-Reaction Wheels
                                                                      0.10 N-m, 100 N-m-s each
                                                                           2 hexagonal sets
Command & Data Handling
Spacecraft housekeeping data rate, kbps                               40 Mbps
Data storage capacity, Mbits                                          8 Terabits
Maximum storage record rate, kbps                                     40 Mbps
Maximum storage playback rate, kbps                                   600 Mbps
Power
Type of array structure (rigid, flexible, body mounted, deployed,     Deployed Solar Arrays
articulated)                                                              on extendable booms
Array size, meters x meters                                           2; 3 m x 12 m each


                                                 42
                           Spacecraft bus                          Value/ Summary, units
Solar cell type (Si, GaAs, Multi-junction GaAs, concentrators)    Multi-junction GaAs,
                                                                      100 W/kg, 258 W/m^2
Expected power generation at Beginning of Life (BOL) and End of   BOL 17,373 W
Life (EOL), watts                                                 EOL 13,363 W
On-orbit average power consumption, watts                         11,165 W
Battery type (NiCd, NiH, Li-ion)                                  Li-ion, 100 Whr/kg
Battery storage capacity, amp-hours                               700 amp-hr @ 28 VDC




                                              43
2.7 Payload Instrumentation: ATLAST-9.2m Hybrid Instrument for Fine Guidance and Wavefront
Sensing

Q1. Description: Guidance and wavefront sensing on ATLAST-9.2m will be performed by four nearly
identical instruments known as Hybrid Instruments (HI), which draw heavily on technologies verified for
the JWST. A mechanical model of a single HI is shown in Figure 2.12. Light from the OTA is fed to the
HI via a pick-off mirror. A bi-directional star selection mirror (SSM) is used to access a 4!4 arcmin
                                                         field-of-view (FOV) to steer an isolated, bright
                                                         star onto the FGS and WFS detectors. The
                                                         beam of light is split three ways: 20% of the
                                                         light goes to the FGS detector (for guidance)
                                                         and 40% goes to each of two WFS detectors.
                                                         Each WFS detector is a 2k!2k CCD with 4.5
                                                         micron square pixels. The FGS detector is a
                                                         2k!2k CCD with 12 micron square pixels.

                                                             Figure 2.12 – Mechanical model                 of
                                                             FGS/WFS&C Hybrid Instrument.

The instantaneous FOV is defined as angular coverage per pixel and is 0.19 ! 0.19 arcmin/pixel. The
SSM allows that FOV to be extended to 4 ! 4 arcmin while keeping the overall length of the system
within reason.      The optical design is specified as a telecentric system (Opto Engineering,
http://www.opto-engineering.com/telecentric.php), which helps to remove uncertainty of the pupil
amplitude and shape, and in addition, makes the WFS algorithm simpler to implement by insuring a
constant plate scale with variations in diversity defocus (Dean & Bowers 2003, J. Opt Soc Am, 20, 1490).
    The FGS beam path consists only of imaging optics to form a broadband image of the star on the
detector for centroiding and guidance. Each WFS beam path contains a dual filter wheel and imaging
optics to form a narrowband, diversity defocus image of the star on each of the WFS detectors. One of
the two WFS beam paths also contains an actuated pupil-imaging lens (PIL) that may be inserted to create
an image of the OTA pupil on the detector.
    The current HI baseline represents an un-optimized “place-holder” design and several opportunities
have been identified to reduce the volume and mass of the instrument by 25-50%. The SSM allows a
further reduction of the instantaneous FOV, therefore reducing the overall length. Smaller filter wheels
containing fewer elements can be distributed along the beam path to further reduce mass and volume.
Finally, since the four HI’s are nearly identical, all four can be built for the design cost of a single
instrument.
Q2. Technical Maturity: Many elements of the HI design draw heavily on the development of similar
components for JWST, as well as a strong flight heritage from HST. The filter wheels, mechanisms and
optics used in the HI are all rated at TRL 6 or higher (Feinberg et al 2007, Proc SPIE, 6687, 668708).
The only component of the HI requiring additional technology development is a visible detector with
pixel sizes of 4.5 microns or smaller. Commercial CCDs with pixel sizes of 4.5 microns exist today, but
some additional development and testing is necessary for flight qualification.
Q3. Technical Risks: The three primary technical risks associated with the HI are: (1) achieving
adequate calibration of the static wavefront error, (2) repeatability and stability of calibrating the on-orbit
instrument wavefront error, (3) and the mechanisms needed to achieve (1) and (2).
Q4-Q6. See attached tables.
Q7. Responsible Organization: The NASA Project Office will maintain oversight of the development,
test and integration of the HI. A NASA Center, international space agency, university or commercial



                                                      44
aerospace company, with experience producing instruments similar to the HI, will be selected to build the
HI.
Q8. Prior Studies: The IDC at the NASA/GSFC performed a concept study of the HI in early 2009.
Q9. Operational Modes: For ATLAST-9.2m, there will be three operational modes for the HI WFS
channels: (1) primary mirror (PM) maintenance, (2) secondary mirror (SM) maintenance, and (3)
commissioning/diagnostic. The WFS algorithm is an iterative hybrid-diversity phase-retrieval algorithm
similar to what has been previously developed for the JWST (Dean et al 2006, Proc SPIE, 6265, 626511).
    The PM maintenance mode is completely automated with a duty cycle approximately every 5 – 30
minutes, depending on source brightness. In this mode, only a single HI is used to collect WFS images
for WFS&C. The images are sent to the IC&DH processor where the phase-retrieval algorithm is run and
segment-motion commands are generated.
    The SM maintenance mode will also be automated, but requires the use of 3 HIs and will be performed
about once a day. In this mode, each HI captures two WFS images from three different points in the
telescope FOV. All six images are then sent to the IC&DH processor where multi-field phase retrieval is
performed and then SM mirror motion commands are generated.
    As the name implies, the commissioning/diagnostic mode will only be used after the initial
deployment of the observatory, or as a diagnostic mode should the observatory become misaligned. The
mode is entirely manual, i.e., all images collected by the HIs are sent to ground for analysis by WFS&C
scientists.
    At any given time the FGS channels of two HIs are required for guiding ATLAST-9.2m. In another
separate HI, closed-loop centroiding will be performed to generate commands for the ACS and SSM. The
second HI, looking at a field point well separated from the first, will be used to detect observatory roll.
Calibration: Two additional components not shown in Figure 2.12 will be used to calibrate the HI
during integration and on-orbit. Near the OTA focal surface located just after the pick-off mirror, a series
of calibrating LEDs and point-diffraction interferometer (PDI) pinholes will be mounted. The LEDs will
be aimed towards the WFS detectors and provide point-like sources on which wavefront sensing can be
performed to calibrate the aberrations of the HI itself, which are non-common path with other instruments
on the observatory.
    A star aimed at a PDI pinhole will produce an interference pattern on the WFS detectors, which can
then be used to determine low-order OTA aberrations due to the location of the HI near the edge of the
FOV. Knowledge of these aberrations will be used in the wavefront-sensing algorithm to help meet the
WFS requirements for controlling mirror segments.
Q10. Instrument Flight Software: The software required to run the Hybrid is estimated to require about
40,000 lines of code residing on the instrument. The flight software group who supported the GSFC IDC
run estimates that roughly 50% of this will be re-used code. Additional code required for processing the
WFS and fine guiding data is contained in the IC&DH and is therefore addressed in the OTA section of
this document.
Q11. Non-US Participation: No external participation is required.
Q12. MEL: The MEL produced by the GSFC IDC is attached.
Q13. Flight Heritage: See the answer to item #2 (Technical Maturity) above, which addresses this.




                                                    45
         Instrument Table 2.11: ATLAST-9.2m Hybrid Instrument (FGS/WFS&C)
                                Item                                        Value              Units
    Type of instrument                                              Hybrid Fine
                                                                    Guidance and
                                                                    Wavefront Sensor
    Number of channels                                                         3
    Size/dimensions (for each instrument)                            2.5 x 1.225 x 0.676    mxmxm
    Instrument mass without contingency (CBE*)                               329            Kg
    Instrument mass contingency                                               30            %
    Instrument mass with contingency (CBE+Reserve)                          427.7           Kg
    Instrument average payload power without contingency                     69.3           W
    Instrument average payload power contingency                              30            %
    Instrument average payload power with contingency                        90.1           W
    Instrument average science data rate^' without contingency               213            kbps
    Instrument average science data^ rate contingency                         30            %
    Instrument average science data^ rate with contingency                   277            kbps
    Instrument Fields of View (if appropriate)                         0.0032 x 0.0032      degrees
    Pointing requirements (knowledge)                                     See OTA           degrees
    Pointing requirements (control)                                       See OTA           degrees
    Pointing requirements (stability)                                     See OTA           deg/sec

Note: these data are for one hybrid instrument. There are four of them in ATLAST-9.2m, although
only three would typically be used at any one time.

*CBE = Current Best Estimate.

^Instrument data rate defined as science data rate prior to on-board processing. The hybrid instrument
does not produce “science data” per se, but sensor data used for guidance and wavefront sensing
'
 A small fraction of this data is actually downlinked to ground. After processing and compression, an
average downlink data rate of 7.75 kbps per hybrid instrument is expected.




                                                   46
2.8 Payload Instrumentation: ATLAST-8m Fine Guidance Sensor

Q1. Description: ATLAST-8m Fine Guidance Sensor is a facility instrument. Its function is to identify,
acquire and track multiple (two or more) guide stars needed to control the observatory 3-axis attitude to
meet the pointing stability requirement of 1.6 mas rms. The FGS consists of four CCD detectors modules
and associated hardware. Two modules (one active and one redundant) are located in the outside corners
of each TMA focus. The active detector at one focus is paired with the active detector at the other focus,
tracking at least two stars with an angular separation of approximately 0.5 deg on the sky in order to
establish and maintain roll control. Locating the FGS detectors at the TMA focus eliminates the need for
re-imaging optics. As a single function instrument, there are no mechanisms, such as filter wheels, or
beam splitters reducing available irradiance. Conceptually, the FGS in combination with the ATLAST-
8m OTA is just a very-large very-precise star tracker.
    Each of the FGS detectors has a field of view (FOV) of 2 ! 2 arcmin. This FOV size was set, in part,
by the requirement that sufficient guide stars are available for at least 95% of all possible observations.
Two or more stars in separate FGS detectors are required to control all three pointing axes (roll, pitch,
yaw). The pointing stability requirement (1.6 mas 1-sigma) is the final driver. Following reasonable
assumptions regarding radiometric performance, detector noise characteristics, and design of the pointing
control system, analysis indicated that a 2 ! 2 arcmin FOV, per detector, is required to ensure that
sufficient guide stars are available at the Galactic Poles (where star density on the sky is lowest). The 2 !
2 arcmin FOV is based on a 16 Hz sampling rate. If the integration time is increased, the FOV can be
decreased.
    Each FGS detector module has four 4k ! 4k detector modules (covering 1 ! 1 arcmin) yielding an
angular sampling of 14.6 mas/pixel on the sky. The ATLAST-8m plate scale is 13.5 mas/micron. This
sampling is similar to the JWST FGS where each pixel samples 65 mas and the plate scale is 63.5
mas/micron.
Q2. TRL: The ATLAST-8m FGS facility instrument has an assessed TRL of 6.
Q3. Risks: The primary technical risk for ATLAST-8m FGS is the potential for severe focus error, as no
mechanism is included for focus adjustment, but even this risk is small. Guiders, like star trackers, are
relatively insensitive to focus errors. This is mitigated with sufficient detailed modeling and simulation
and/or testing to show that post-alignment focus change due to launch and on-orbit environments are
within limits.
Q4-Q6: See attached tables.
Q7. Organizations: The NASA Project Office maintains oversight of the development, test and
integration. A NASA Center, International Space Agency, academic or commercial aerospace company
with appropriate experience will be selected to design and build.
Q8. Studies: ATLAST-8m FGS is the result of the ATLAST Astrophysics Mission Concept Study:
http://www.stsci.edu/institute/atlast/index_html_ATLASTMissionConceptStudy_Page
Q9. Operational Modes: The ATLAST-8m FGS operational modes are identical to those of the JWST
FGS: Off, Standby, and Operate.
Operate provides all the functions necessary to support science:
     1. Identification: Obtain a full-frame image of the sky in a specific FOV and apply a pattern-
         matching algorithm to select the desired guide stars.
     2. Acquisition: Readout a large window (e.g. 128x128 pixels) at low rate and compute the centroid
         of the image as the first step towards achieving stable, fine pointing.
     3. Track: Readout a medium window (e.g. 32x32 pixels) at medium rate and compute the centroid
         of the image in order to continue transition to stable, fine pointing, OR to track moving targets or
         perform small dithers.




                                                     47
     4. Fine Guiding: Readout a small window (e.g. 8 ! 8 pixels) at high rate to achieve the best pointing
         stability.
     5. Calibration: Acquire the data needed for ground-based calibration of optical distortions and
         detector uniformity across the FOV.
Q10. Flight Software: The Flight Software/C&DH concept follows JWST heritage. The FGS unit itself
includes only the detector electronics. The Spacecraft C&DH will acquire and process the FGS data, as
well as command the FGS operational modes. The FGS data consists of acquisition and tracking images
and centroid telemetry. These data are stored onboard in a solid state recorder prior to downloading
during a single daily contact. All images are handled as science data, while centroid telemetry is handled
as engineering data. For nominal operations we assume FGS image data will consist of four full-frame
images per visit and all sub-array images from the guide star acquisition, tracking and fine guide. The fine
guide images will generate about 8 kbps of data for the duration of the visit. The FGS tracking data,
consisting of the guide star centroid at 16 Hz, is recorded continuously as engineering data. The tracking
data is also provided to the onboard Attitude Control System and used to command the reaction wheels to
achieve stable 3-axis pointing. A current best estimate from JWST is that the FGS software will contain
approximately 15,000 lines of code. However, that does not account for additional code that will be auto-
generated by a tool called Rational Rose. No count has been done that includes the auto-generated code.
Q11. Non-US Participation: Non-US participation is possible but not required for FGS.
Q12. MEL: attached
Q13. Flight Heritage: The FGS relies extensively on heritage. Visible-wavelength CCD detectors have
flown on numerous missions including HST WFC3. The flight software is based on the JWST code, with
the obvious modification that two or more guide stars are to be tracked as opposed to only a single star as
is the case for JWST.




                                                    48
            Instrument Table 2.12: ATLAST-8m Fine Guidance Sensor Facility
                                 Item                                  Value        Units
    Type of instrument                                                 Facility
    Number of modules                                                     4
    Size/dimensions (for each module)                               0.2x.0.2x0.1 m x m x m
    Note: Values below this line are summations for all 4 modules of the ATLAST-8 FGS
    Instrument
    Instrument mass without contingency                                   78     Kg
    Instrument mass contingency                                           30     %
    Instrument mass with contingency (CBE+Reserve)                      101.4    Kg
    Instrument average payload power without contingency                 120     W
    Instrument average payload power contingency                          30     %
    Instrument average payload power with contingency                    156     W
    Instrument average science data rate^ without contingency             8      kbps
    Instrument average science data^ rate contingency                     30     %
    Instrument average science data^ rate with contingency               10.4    kbps
    Instrument Fields of View (if appropriate)                            8      arcmin2
    Pointing requirements (knowledge)                                 See OTA    arcsec
    Pointing requirements (control)                                   See OTA    arcsec
    Pointing requirements (stability)                                 See OTA    arcsec/sec


^Instrument data rate defined as science data rate prior to on-board processing.   The FGS instrument does
not produce “science data” per se, but sensor data used for guidance control.




                                                    49
2.9 Payload Implementation: ATLAST-8m Wavefront Sensor & Control System

Q1. Description: ATLAST-8m Wavefront Sensor (WFS) is a facility instrument. Its function is to
establish initial telescope alignment and maintain that alignment over the life of the mission to a
wavefront requirement of 10 nm rms across the field of view. The WFS consists of six identical 14 ! 14
arcsec wavefront sensor modules: two in the on-
axis Cassegrain focus and two in each of the TMA
focus planes. These WFS modules are based on a
very simple, proven ±4" focus-diverse systems,
with no moving parts, that have been in use for
over a decade (Figure 2.13) [Reference: M. G.
Löfdahl, R. L. Kendrick, A. Harwit, K. E. Mitchell,
A. L. Duncan, J. H. Seldin, R. G. Paxman, and D.
S. Acton, Proc. SPIE 3356, 1190 (1998)]. Each             Figure 2.13: Optical Layout of Focus-Diverse Phase-
ATLAST-8m WFS module is very compact                                   Diversity Wavefront Sensor
(approx. 100 mm ! 50 mm ! 50 mm).
     The ATLAST-8m WFS are a slight modification illustrated sensor. The glass prism is replaced with
another glass beam splitter to form a third data channel. A plano-convex lens is epoxied to the outside
exit edge of the third channel. The function of this lens is to produce an image of the entrance pupil.
Defocused images are obtained at the two outputs illustrated in the figure. The addition of the pupil
image data channel is a direct lesson learned from JWST NIRCam. Imaging the telescope pupil facilitates
correction of the effects of intensity apodization and provides the actual exit-pupil shape with SM support
features. As was proven on HST, it is possible to use phase-retrieval without a pupil image, but having
one adds robustness. As an aside, the JWST NIRCam produces its pupil image with a very complex
opto-mechanical mechanism that inserts and removes a lens from the optical beam. Our design for the
ATLAST-8m WFS has no moving parts and acquires all three images simultaneously. Since the WFS
modules are located at the three foci, there are no re-imaging optics or associated structure. Each detector
is a 10.8 x 10.8 mm 1024 ! 1024 pixel array (14 ! 14 arcsec FOV with 13 mas plate scale).
     Wavefront sensing and control of the ATLAST-8m OTA is performed with focus-diverse phase
retrieval, an image-based method that determines the telescope performance using defocused images of
stars. The OTA wavefront within each module’s field of view is calculated using the Hybrid Diversity
Algorithm (HDA). The HDA is an image-based iterative-transform method phase retrieval algorithm
currently being implemented for fine phasing on JWST [Reference: B. H. Dean, D. L. Aronstein, J. S.
Smith, R. Shiri, and D. S. Acton, “Phase Retrieval Algorithm for JWST Flight and Testbed Telescope,”
Proc. SPIE 6265, 626511 (2006)]. The ATLAST-8m WFS instrument uses six modules to provide field-
diverse data necessary to resolve alignment redundancies.
Q2. TRL: The ATLAST-8m WFS facility instrument has an assessed TRL of 6. Image-based wavefront
sensing using HDA and wavefront control has achieved TRL 6 for JWST and will continue to be
developed for that mission. The beam-splitter and prism hardware module used to obtain pairs of
defocused images is a mature design that has been in use for over a decade. The only reason not to rate
the hardware at TRL 6 is because the hardware modules have not been through environmental testing
(vibe or acoustic) pertinent to an Ares V launch. The ATLAST-8m WFS&C is simpler than that for
JWST for two reasons. First, ATLAST-8m has a monolithic primary mirror and, therefore, there are
fewer degrees of freedom to be monitored and corrected (although this is not a major advantage because
the problem of WFS&C has been solved for large segmented, ground-based telescopes). Second,
ATLAST-8m has dedicated sensor modules with no moving parts while JWST’s WFS&C is performed
with science instruments and requires the insertion of lenses to create the phase-diversity data.




                                                     50
Q3. Risks: The primary risk is the potential that there are states of on-orbit deployment that will not
successfully lead to an alignment solution during commissioning given the locations for the individual
WFS modules. This risk can be mitigated with sufficient detailed modeling and simulation. A secondary
risk is if something unforeseen occurred on-orbit to change the exceptional thermal stability (1 nm with a
500 hour time constant) such that the WFS&C sampling rate was too slow to follow wavefront changes.
Q4-Q6: See attached tables.
Q7. Organizations: The NASA Project Office will maintain oversight of the development, test and
integration. A NASA Center, International Space Agency, university or commercial aerospace company
with appropriate experience will be selected to design and build.
Q8. Studies: ATLAST-8m FGS is the result of the ATLAST Astrophysics Mission Concept Study:
http://www.stsci.edu/institute/atlast/index_html_ATLASTMissionConceptStudy_Page
Q9. Operational Modes: The ATLAST-8m WFS has four modes: Off, Standby, Coarse Alignment and
Fine Alignment. In coarse alignment, the spacecraft’s star trackers point the telescope at a bright star
such that, if the secondary mirror is aligned to the primary mirror, then the image of the star will fall upon
the Cassegrain WFS module. The field of view (FOV) of each module is 14 ! 14 arcsec and the
uncertainty of the star trackers to point the telescope is 7 arcsec. If the star is not seen, an outward-
spiraling search will be followed to find the star and then proceed with aligning the secondary mirror to
the primary mirror. The WFS system points the telescope to each of the two WFS modules at the
Cassegrain focus, to check the primary-to-secondary alignment and to decide if it is necessary to align the
tertiary mirror. Once coarse alignment is achieved, pointing control is transferred to the Fine Guidance
System to provide highly stable star images to each of the Cassegrain and TMA WFS modules. Fine
alignment is performed by incrementally illuminating each module and acquiring wavefront data via
image-based focus-diverse PSFs. Each module provides an absolute estimate of the telescope’s wavefront
without the need for external calibration. Given the high mechanical and thermal stability of ATLAST-
8m, there is no requirement for on-board processing of data. WFS&C data will be acquired and
transmitted to the ground operation center for processing by the spacecraft C&DH system, and commands
for opto-mechanical corrections will be sent up to the telescope. This is exactly the same approach being
used for JWST. Analysis indicates that ATLAST-8m will sense and control its wavefront with less than 5
nm rms uncertainty.
Q10. Software: The WFS concept closely follows JWST heritage. Images from each module of the
WFS facility instrument (pairs of defocused PSFs and a pupil image) will be transmitted to the ground
operation center for processing, and optomechanical corrections will be sent up to the telescope based on
the analysis of these images. The key software thus resides at the ground operation center, and the
primary algorithm carries over from JWST. A current best estimate from JWST is that the WFS software
will contain approximately 5,000 lines of code.
Q11. Non-US Participation: Non-US participation is possible but not required for WFS.
Q12. MEL: attached.
Q13. Flight Heritage: The WFS will rely extensively on heritage. The WFS hardware has been in use
for over 10 years, is documented in the open literature and the subject of multiple on-going studies. The
WFS algorithms come from JWST fine phasing. Converting optical wavefront estimates into opto-
mechanical corrections to the telescope can be done using a simplified version of the JWST control
approach. (JWST control is more complex because of the segmented primary mirror, and thus many
more degrees of freedom and a higher level of redundancy among these degrees of freedom.)




                                                     51
           Instrument Table 2.13: ATLAST-8m Wavefront Sensor Facility
                           Item                                   Value          Units
Type of instrument                                               Facility
Number of module                                                     6
Size/dimensions (for each module)                           0.1 x 0.05 x 0.05 m x m x m
Note: Values below this line are summations for all 5 modules of the ATLAST-8m WFS
Instrument
Instrument mass without contingency (CBE*)                         68.8       Kg
Instrument mass contingency                                         30        %
Instrument mass with contingency (CBE+Reserve)                     89.5       Kg
Instrument average payload power without contingency                36        W
Instrument average payload power contingency                        30        %
Instrument average payload power with contingency                  46.8       W
Instrument average science data rate without contingency             3        kbps
Instrument average science data rate contingency                    30        %
Instrument average science data rate with contingency               3.9       kbps
Instrument Fields of View (if appropriate)                       15 x 15      arcsec
Pointing requirements (knowledge)                                    1        arcsec
Pointing requirements (control)                                      1        arcsec
Pointing requirements (stability)                                0.0016       arcsec/sec




                                         52
2.10 Payload Instrumentation: Exoplanet Imager (ExoCam) [8m and 9.2m]

Q1. Description: ExoCam can be considered to be a mode of the Exoplanet Instrument, since the
ExoCam and ExoSpec operate together. For exoplanet observations, the instrument operates behind a
starlight suppression system – either an internal coronagraph (such as a visible nulling coronagraph,
VNC) or an external occulter (a.k.a. starshade). When used with the external occulter, the optical beam is
taken directly from the telescope optics. This optical path can also be used without the starshade for
general astrophysics observations. For use with a starshade, the first mirror, at the telescope focal plane, is
a dichroic, allowing longer wavelengths to feed a shadow sensor instrument that helps to determine the
telescope’s lateral location within the occulter shadow, information needed to achieve proper alignment.
If exoplanets are detected then the ExoSpec mode can be used to obtain spectroscopic data of them.
    The Cassegrain focus of the OTA is used to allow wavelengths below 500 nm to be used for
examination of exoplanet atmospheres for ozone and Rayleigh scattering.
    ExoCam provides a 10 ( 10 arcsec FOV feeding four large format detectors from broad band
dichroics; this enables imagery spanning wavelengths from UV to NIR simultaneously. Angular
resolution will be critically sampled (2 pixels per resolution element) at the wavelength-limited
diffraction limit of the telescope (13 mas for a 9.2 meter aperture at 500 nm).
Q2. Technical maturity:
Optics: ExoCam optics consists of mirrors with Al/MgF2 coatings for the common path and shortest
waveband, and protected silver for bands above 500 nm, and dichroic filters. Dichroic filter technology
has improved greatly over the last 15 years resulting in very high reflectivity and transmissivity, excellent
radiation hardness and stable spectral separation, enabling instruments to have simultaneous coverage in
multiple bands over a wide wavelength range. This greatly shortens observing times compared with serial
use of broadband filters (TRL 9. Heritage: Spitzer, HST/ACS and WFC3). Currently available dichroics
are adequate for ExoCam, but higher performance could be achieved if dichroics are developed that have
wider wavelength ranges and, simultaneously, higher throughputs.
Detectors: ExoCam detectors require 1K x 1K pixel arrays. At wavelengths <900 nm, three back-thinned
CCDs will be used. N-channel CCDs from E2V are TRL 9 (Heritage HST/WFC3, ACS). Better red
response and radiation hardening (and, therefore, lifetime) could be obtained with p-channel CCDs from
Lawrence Berkeley Labs or E2V, TRL 5 (Heritage JDEM/SNAP, DES, other ground based telescopes).
Environmental testing will raise them to TRL 6. For wavelengths >900 nm, we use a HgCdTe array with
substrate removed, from Teledyne or Raytheon. Current TRL is 9 (Heritage HST/WFC3, JWST/NIRCam
and NIRSpec).
Q3. Technical issues and risks: None (Heritage : HST/NICMOS). ExoCam is a relatively simple camera
containing optics and detectors with high TRL and heritage to previous space instruments.
Q4-Q6: see attached tables.
Q7. Organization: NASA will select the ExoCam taking into consideration experience with building
similar space flight hardware. A NASA Center, international space agency, university or commercial
aerospace company will be selected to build ExoCam and the NASA Project Office will have oversight.
Q8. Studies: The IDC at GSFC has carried out a concept and feasibility study of the ExoCam for
ATLAST. This is detailed in the Astrophysics Strategic Mission Concept Study Report submitted to
NASA HQ and is available at http://www.stsci.edu/institute/atlast.
Q9. Instrument operations: The camera will obtain images of the sky using a starlight suppression
system in coronagraphic mode or without the starlight suppression system for direct observations of a
variety of general astrophysical sources. When used with an internal coronagraph, like a VNC, the images
will be modulated by the nulling interferometer. Analysis software will have tremendous heritage from
HST and JWST. Assuming NIR detector readouts every 100 sec, and CCD detector readouts every 1000




                                                      53
sec, the continuous data rate is 0.4 MB/sec (compressed 2:1) or 35 GB/day, which can be downlinked in
~12 minutes at today’s Ka band rates.
Q10. Flight software: The FSW for ExoCam is estimated to contain 40,000 lines of code, based on HST
instruments. For new instruments coded at GSFC, roughly 50% of the lines are re-used from earlier
projects. This is based on Ball Aerospace estimates for reused lines of code for the HST instruments.
Q11. Non-US Participation: None required; however, for a mission of this size it would be expected.
Q12. MEL: No MEL is available for the ExoCam instrument. Mass, power, volume were estimated
from conceptual designs and analogies with similar space flight instruments.
Q13. Heritage: Components of the camera (optics, filters, detectors) have heritage to HST instruments.
Also, 2 instruments (NIRCam and NIRSpec) are currently being built for JWST with similar NIR
detectors. Similar space qualified optical components can be found for all optical components in our
design.




                              Figure 2.14: Schematic for ExoCam




                                                 54
         Instrument Table 2.14: ExoCam (Imaging Mode of Exoplanet Instrument)
                                Item                                         Value          Units
 Type of instrument                                                   Dichroic Camera
 Number of channels                                                   4
 Size/dimensions (for each instrument)                                0.16 x 0.60 x 1.50   mxmxm
 Instrument mass without contingency (CBE*)                           40                   Kg
 Instrument mass contingency                                          30                   %
 Instrument mass with contingency (CBE+Reserve)                       52                   Kg
 Instrument average payload power without contingency                 300                  W
 Instrument average payload power contingency                         30                   %
 Instrument average payload power with contingency                    390                  W
 Instrument average science data rate^ without contingency            2670                 kbps
 Instrument average science data^ rate contingency                    30                   %
 Instrument average science data^ rate with contingency               3470                 kbps
 Instrument Fields of View (if appropriate)                           10 x 10              arcsec
 Pointing requirements (knowledge)                                     See OTA             arcsec
 Pointing requirements (control)                                       See OTA             arcsec
 Pointing requirements (stability)                                     See OTA             arcsec

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                                    55
2.11 Payload Instrumentation: Exoplanet Spectrometer (ExoSpec) [8m and 9.2m]

Q1. Description: ExoSpec provides two-dimensional spectral imaging of a selected field within a 10 ( 10
arcsec area of the sky. It is primarily intended for characterizing the atmospheres and surfaces of
exoplanets but has several general astrophysical applications as well. For exoplanet science, the initial
goal is to detect spectral features with spectral resolving power of 70 - 100, spanning the UV-NIR spectral
range. Higher spectral resolution (R=500-600) could be used if, for example, key biosignatures are
detected in a terrestrial-like planet in the Habitable Zone of its host star. For other astrophysical targets,
such as protostellar systems, propylids, and jets spectral resolving powers of 1000, 3000, and 10,000 are
desirable.
   To provide spectroscopy with both spatial dimensions while retaining reasonable detector array size
and diffraction limited spatial resolution using either reflective image slicers or transmissive microlens
arrays, we choose a 2.6 arsec sub-field within the 10 ( 10 arcsec field by re-pointing the telescope. A
dichroic mirror in the telescope image plane reflects the image into a magnifying mirror that images the
selected sub-field onto microlens arrays (as shown, but slicers could be used). Prior to the microlens
arrays, successive dichroic filters split the wavelength range into three bands.




                  Figure 2.15: ExoSpec optical design. One of four sub-fields is shown.



Q2. Technical Maturity:
Optics: ExoSpec optics consist of mirrors with Al/MgF2 coatings for the common path and shortest
waveband, and protected silver for bands above 500 nm, and dichroic filters, microlens arrrays, reflective


                                                     56
prisms for low resolving power exoplanet spectroscopy, and reflective gratings for general astrophysics.
(TRL 9. Heritage: Spitzer, HST/ACS and WFC3). As with ExoCam, currently available dichroics are
adequate for ExoSpec, but higher performance could be achieved if dichroics are developed that have
wider wavelength ranges and, simultaneously, higher throughputs. Microlens arrays (available in the
U.S.) have been used for many ground-based 3D spectrographs with TRL 5 (Heritage: Keck/OSIRIS,
CFHT/Tiger), and reflective image slicers (available in Europe) are being developed for JWST/NIRSpec
with TRL 6, and have been used on many ground-based instruments (Gemini).
Detectors: ExoSpec detectors require 8k ! 8k format. At wavelengths <900 nm, a back-thinned photon-
counting EMCCD array will be used. Analog N-channel CCDs from E2V have TRL 9 (Heritage
HST/WFC3, ACS). Current EMCCDs have 1.6k ! 1.2k formats, but could be built with larger formats
such as the E2V 2k ! 4k or larger with customer demand (TRL 4). Better red response and radiation
hardening and therefore lifetime could be obtained with p-channel CCDs from Lawrence Berkeley Labs
or E2V, TRL 5 for analog CCDs with 3.5k ! 3.5k formats (Heritage: JDEM/SNAP, DES, other ground
based telescopes), and further environmental testing would raise them to TRL 6, while photon-counting
versions are at TRL 3. There are current plans to develop large format photon counting CCDs. Above
900 nm, we use a HgCdTe array with substrate removed, from Teledyne or Raytheon. The current TRL 9
(Heritage HST/WFC3, JWST/NIRCam and NIRSpec). Further improvements in read noise and dark
current would greatly shorten spectroscopic exposure times.
Q3. Technical issues and risks: None (Heritage: HST/NICMOS)
Q4-Q6: see attached tables.
Q7. Organization: NASA will select the ExoSpec taking into consideration experience with building
similar space flight hardware. A NASA Center, international space agency, university or commercial
aerospace company will be selected to build ExoSpec and the NASA Project Office will have oversight.
Q8. Concept Study: A concept and feasibility study of the ExoSpec for ATLAST was conducted at
GSFC’s IDC. This is detailed in the Astrophysics Strategic Mission Concept Study Report submitted to
NASA HQ and is available at http://www.stsci.edu/institute/atlast.
Q9. Instrument operations: The ExoSpec will obtain 3D spectral images of the sky using a starlight
suppression system in coronagraphic mode or without the starlight suppression system for direct
observations of a variety of general astrophysical sources. When used with an internal coronagraph, like a
VNC, the images will be modulated by the nulling interferometer. Analysis software will have
tremendous heritage from HST and JWST. Assuming NIR detector readouts every 100 sec, and CCD
detector readouts every 1000 sec, the continuous data rate is 2.5 MB/sec (compressed 2:1) or 0.21
TB/day, which can be downlinked in 1.2 hrs at today’s Ka band rates.
Q10. Flight software: ExoSpec FSW is estimated to require ~40,000 lines of code, based on HST
experience. Based on GSFC experience with software for new instruments, the IDC estimates that
roughly 50% of the lines of code will be re-used from earlier programs.
Q11. Non-US Participation: None required; however, for a mission of this size it would be expected.
If image slicers are preferred to microlens arrays, European participation would be highly desirable as
they have substantial experience working and building instruments that use image slicers.
Q12. MEL: No MEL is available. Mass, power and volume of ExoSpec were estimated by the IDC
based on conceptual designs and analogies with other space flight instruments.
Q13. Heritage: Components of the camera (optics, filters, detectors) have heritage to HST instruments.
Also, 2 instruments (NIRCam and NIRSpec) are currently being built for JWST with similar NIR
detectors. Similar space qualified optical components can be found for all optical components in the
ExoSpec design.




                                                   57
      Instrument Table 2.15: ExoSpec (Spectroscopic Mode of Exoplanet Instrument)
                                   Item                                          Value         Units
    Type of instrument                                                    Integral Field
                                                                          Spectrograph
    Number of channels                                                    3
    Size/dimensions (for each instrument)                                 1.20 x 1.20 x 1.80   mxm
                                                                                               xm
    Instrument mass without contingency (CBE*)                            570                  Kg
    Instrument mass contingency                                           30                   %
    Instrument mass with contingency (CBE+Reserve)                        741                  Kg
    Instrument average payload power without contingency                  300                  W
    Instrument average payload power contingency                          30                   %
    Instrument average payload power with contingency                     390                  W
    Instrument average science data rate^ without contingency             2670                 kbps
    Instrument average science data^ rate contingency                     30                   %
    Instrument average science data^ rate with contingency                3470                 kbps
    Instrument Fields of View (if appropriate)                            2.6 x 2.6            arcsec
    Pointing requirements (knowledge)                                      NA                  arcsec
    Pointing requirements (control)                                        NA                  arcsec
    Pointing requirements (stability)                                      NA                  arcsec

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                                    58
2.12 Payload Instrumentation: Visible Nulling Coronagraph (VNC) [8m and 9.2m]

Q1. Description: For this RFI, we adopt an internal coronagraph instrument as our baseline starlight
suppression system for both ATLAST-8m and ATLAST-9.2m. However, we emphasize that the actual
flight implementation of the starlight suppression system will be selected during the pre-phase A
technology development program and the subsequent phase A study and will be optimized to the flight
telescope architecture. Suppression of
starlight is required to enable the
detection and characterization of much
fainter exoplanets at small angular
separations from their stars. The internal
coronagraph concept we have selected
for this RFI is the Visible Nulling
Coronagraph (VNC) because, in
principle, it can provide the required
level of starlight suppression with either
a monolithic or segmented mirror
telescope. The coronagraphic field of
view, defined as having suppression
           -10
ratios <10 , is 0.8 x 0.8 arcsec over the
spectral range of 480 – 960 nm with an
inner working angle (IWA) of 32 mas.
A CAD model of the VNC is shown in             Figure 2.16: Visible Nulling Coronagraph Design.
Figure 2.16. The VNC is on-axis with Light from the telescope enters at lower left and, after passing
respect to the telescope to take               through the VNC, the starlight is suppressed by 10 orders of
advantage of the minimal telescope             magnitude, or better. The beam is then passed into the science
wavefront error. Internally it consists of instruments (ExoCam and ExoSpec) at the top.
two     crossed      broadband       nulling
interferometers (nullers), relay optics, two segmented deformable mirrors (DM), two piston/shear
mechanisms, two achromatic phase shifters (APS), one spatial filter array (SFA) (a.k.a. a coherent fiber
bundle), two null control and pointing cameras, and a filter wheel. The output beam then goes to the
science instruments ExoCam and ExoSpec.
    Each nuller has two dielectric beam splitters to first split the beam into two equal components and the
second beam splitter to recombine the beams. The first nuller shears the beams within it in the X-direction
and the second shears in Y where shear refers to lateral translation of one of the arms of a nuller relative
to the other arm; the amount of shear (in fractional beam diameters), and its direction, sets the spacing and
direction of the transmission fringes on the sky to obtain the IWA. The path length difference between the
two arms is set to a # wavelength of light by a piston mechanism and segmented DM resulting in
destructive interference of the starlight. The APS insures destructive interference across the spectral
passband to null the starlight at the dark (nulled) output channel. Conservation of energy requires the un-
nulled starlight to exit at the bright channel outputs and this light is used both for fine pointing control via
the bright object sensor (BOS) and wavefront control. The dark channel of the first nuller is relayed to the
2nd nuller (Y-direction) where the residual starlight is destructively interfered but now in the Y direction
resulting in further nulling of the starlight in the 2nd dark output channel – this dark channel is used to
feed the science instruments. In order to achieve and hold nulling two DMs, working with the SFA, act to
minimize the wavefront and amplitude errors between the arms of the nuller and the APS maintains the
null achromatically.




                                                      59
   Selection of the VNC is based on system trade studies that show that sensing and control times drive
the requirements on the stability per unit time of the telescope. Rapid control (<100 sec / step) mitigates
long-term telescope stability requirements and yields more time at the needed suppression ratio for
exoplanet detection, i.e. less time is spent in control.
                                       Table 2.16: VNC Specifications
            Parameter                         Specification                       Comments
     Suppression (nulled-to-
                                                 < 10-10
      bright beam flux ratio)
        Wavelength Range                    460 nm – 980 nm               Full spectral passband
       Coronagraphic FOV                 0.8 arcsec ! 0.8 arcsec     Region where suppression <10-10
      Inner Working Angle                    32 milli-arcsec                2 )/D at ) = 500 nm
       Wavefront Stability           0.025 nm rms / 100 seconds
                                                                      Built, tested and flown at room
     Operating Temperature                  294 (±0.1) deg K
                                                                                 temperature

Q2. Technical Maturity: The VNC uses matured technology as much as possible. All optical
components are small (~ 2 cm diam) and flat and are either metallic or dielectric (beam splitters) coated.
The optics have TRL >6 and are readily manufactured by optics shops and coating companies. The
optical bench, mechanical parts, and thermal control are also at TRL 6. The segmented deformable
mirrors (DMs) are TRL 3 and SBIR funding with two vendors is advancing this technology. DMs have
been fabricated and tested and are being used in VNC testbeds at GSFC and JPL. The SFA is TRL 3 and
three SFA’s have been manufactured with the third one to begin testing in Sept/2009. Photon counting
detectors are under development by E2V (among others) and expect to reach TRL 6 by 2014. The TRLs
are in Table 2.17.

                                    Table 2.17: Component TRL level
                  Component name          TRL                             Rationale
                         Flats             >6        Glass lenses with designed size are flight qualified
                   Dichroic Beam
                                           >6      Common dichroic beam splitter in flight instruments
                       splitters
   Optical         Spectral filters        >6               Common filters in flight instruments
 components                                        Fibers used on flight missions but not packaged into a
                 Spatial Filter Array       3
                                                  coherent fiber bundle with lenslet on input/output side.
                 Achromatic phase                      All components are flat glass optics but not yet
                                            4
                        shifter                        demonstrated within nuller over full passband
                                                  Deformable mirrors are a critical technology needed by
                 Deformable mirrors         3     all exoplanet missions and multiple groups/vendors are
 Mechanisms                                                           advancing them
                    Piston / Shear                Mechanisms have flown but mechanism precision and
                                            4
                     mechanism                                     stability are advancing
Bright Object       Conventional
   Sensor        visible light silicon     >6      Multiple missions and instruments flown with CCDs
Detectors (2)      CCD detectors
                   Visible photon
 Null Control                                      Prototypes development by E2V – expected to reach
                      counting              4
  Detector                                                             TRL 6 in 2014
                    (512k!512k)
   Filter
                                          >6                Frequently used in flight instruments
 mechanism




                                                    60
Q3. Primary Technical Issues: (1) End-to-end demonstration of a wavefront controlled version of VNC
producing the stability and broadband contrast required for science; (2) Development of segmented DMs
to ~1000 segments; (3) development of spatial filter array with ~1000 coherent fibers.
Q4-Q6: see attached tables.
Q7. Organization: NASA would select the VNC after taking into consideration technical readiness and
risk. Most likely, a NASA Center or commercial aerospace company would be selected to build the VNC
instrument with NASA Project Office oversight.
Q8. Studies: The GSFC IDC and JPL Team-X have performed concept, feasibility and design studies for
the VNC. This is detailed in the Astrophysics Strategic Mission Concept Study Reports for the EPIC
mission submitted to NASA HQ. Detailed structural, thermal and optical modeling efforts are underway
by Lockheed Martin Corp.
Q9. Instrument operations: The VNC generates fine pointing signals to feedback into the pointing
control system at 75 Hz. Coarse and fine null control then follows and operates nominally in <1000
seconds (for 5th mag star) for the 1st step with successive steps nominally every 100 seconds. Sensing and
control times are star brightness dependent. Nominally the VNC operates autonomously in closed-loop
after a command sequence upload and only housekeeping data would be downlinked. However, during
on-orbit checkout and/or debugging, multiple frames of the BOS and null control detectors data may need
to be down linked. Assuming detector frame rates are every 100 seconds results in data rates of 7.2
Gbits/day (2 detectors x 5122 x 16 bits x 36 frames/hr x 24 hrs; worst case, uncompressed), and can be
downlinked in < 1 hr at Ka band rates during orbital checkout.
Q10. Flight software: Estimate of 40,000 lines of code mostly associated with the tasks affiliated with
wavefront control and the bright object sensor.
Q11. Non-US Participation: None required.
Q12. MEL: No MEL for ATLAST is available. Mass, power and volume were estimated by scaling up
the VNC concept provided to us by the EPIC team.
Q13. Heritage: Components of the VNC (optics, filters, detectors) have heritage to HST. The needed
improvement is to advance deformable mirror and spatial filter array technology and end-to-end sensing
and control. No VNC has yet flown but testbeds have been developed at NASA/GSFC and a testbed is
underway at NASA/JPL. Precision white light interferometers have flown as part of the HST fine
guidance sensors.


NOTE: If an external occulter (a.k.a. starshade) is flown with ATLAST in lieu of an internal coronagraph
then ATLAST will require a Shadow Sensor Instrument. The Shadow Sensor is used to measure the fine
lateral alignment (offsets of 0.1 m to ~20 m) between the telescope and the starshade. This instrument is a
small (2K x 2K), low-mass (~15 kg) CCD camera located at the Cass focus of the telescope.




                                                    61
                      Instrument Table 2.18: Visible Nulling Coronagraph
                                Item                                       Value              Units
    Type of instrument                                               Visible Nulling
                                                                     Coronagraph
    Number of channels                                               3
    Size/dimensions (for each instrument)                            0.32 x 0.47 x 0.74   mxmxm
    Instrument mass without contingency (CBE*)                       82                   Kg
    Instrument mass contingency                                      30                   %
    Instrument mass with contingency (CBE+Reserve)                   107                  Kg
    Instrument average payload power without contingency             130                  W
    Instrument average payload power contingency                     30                   %
    Instrument average payload power with contingency                169                  W
    Instrument average science data rate^ without contingency        0                    kbps
    Instrument average science data^ rate contingency                30                   %
    Instrument average science data^ rate with contingency           0                    kbps
    Instrument Fields of View                                        See Exocam and
                                                                     Exospec
    Pointing requirements (knowledge)                                See OTA
    Pointing requirements (control)                                  See OTA
    Pointing requirements (stability)                                See OTA

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing (without 2:1 compression).
The VNC produces no “science” data. It provides starlight suppression for the ExoCam and ExoSpec
instruments. The science data rate is provided in those tables. The data rate used for wavefront sensing is
described in the text.

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                                    62
2.13 Payload Instrumentation: UV Integral Field Spectrograph (UV IFS) [8m and 9.2m]

Q1. Description: This instrument expands the point source and single long slit capabilities on HST
(provided by COS and STIS) to two spatial dimensions, with spectral resolving powers of 100, 1000,
10,000 and 100,000. An all-reflective concept covers a 1 ! 1 arc sec field with 27 mas spatial samples, for
a total of 1360 spatial elements. A mapping capability would be possible using lens-lets or mirror-lets
providing 30 ( 30 pixel mappings at 100, 1000, 20,000, and 100,000.
   Such a UV IFS addresses science goals from solar system objects to young circumstellar evolution to
AGN, QSO, and their host galaxies. At R=100,000 and spatial resolutions approaching 20 mas, this
instrument can probe planetary storms (e.g., the Great Red Spot of Jupiter) in the solar system and
determine isotopic abundances in enriched stars. At R=20,000 QSO absorption lines reveal the structure
of the Lyman alpha forest and therefore of the IGM, the expected reservoir of the missing baryons, to a
finer spatial scale than is possible with smaller telescopes by accessing fainter QSOs. With spatial
resolutions approaching 20 mas, massive winds of stars such as Eta Carinae could be traced down to the
orbital dimensions and star spots on Alpha Orionis could be tracked along with the surrounding molecular
hydrogen clouds. Proto-planetary systems could be examined, determining metal ionization, molecule and
dust formation within the system, and influences on the exo-zodiacal structure. Winds and mass transfer
could be traced in visual binary systems. Abundance analysis could be accomplished in Galactic and
globular clusters.




                        Figure 2.17: Concept for UV IFS (credit: Ball Aerospace)

In order to maximize UV throughput, the number of optical surfaces or elements in the UV IFS is
minimized. The UV IFS contains only two more than COS, the most sensitive UV spectrograph on HST.
A relay mirror and an all-reflective image slicer provide the 2D capability. A method combining 2D
spatial information with high throughput uses a reflective image slicer at the telescope focus, with each
slice serving a concave grating, with all gratings feeding a common detector (see the Ball Aerospace
concept shown in Figure 2.17). Sets of gratings would be interchanged to change dispersion.




                                                    63
Q2. Technical maturity:
 Optics: UV IFS optics consist of only 2 reflections to maintain high UV throughput, using Al/MgF2
coatings on a focal plane reflective image slicer, and on parallel sets of concave pupil gratings, one
grating for each slice. The grating sets are interchanged to change the resolving power. The gratings are
similar to those on HST/STIS and COS (TRL 9), with expected groove structure improvements due to
ongoing development work. The image slicer requires very small mirror segments as smooth as standard
UV optics (Heritage: HST), but its location at the image plane reduces figure requirements (TRL ~ 3).
High quality optics, of similar sizes, are currently in use in medical imaging devices. Development work
has been proposed to NASA. Adaptation to the specific geometry of the image slicer, and for use in the
UV will be demonstrated.
 Detectors: The baseline of current technology detectors (CsI and CsTe) are well established at TRL 9
(Heritage HST STIS and COS. However, UV IFS detectors require higher quantum efficiencies than on
HST, which have been achieved at the photocathode level for the FUV using cesiated p-doped GaN
(>70% at 120 nm, >55% at 180 nm), and sealed into phototubes. Further work is needed and is ongoing to
combine this with large format arrays as in EBCCDs, EBCMOS, or microchannelplate detectors.
   For the NUV, CCDs can be extended to shorter wavelengths with delta-doping (JPL) and UV AR
coatings. Back-thinned photon-counting EMCCD arrays could be used. Analog N-channel CCDs from
E2V have TRL 9 (Heritage HST/WFC3, ACS). Current EMCCDs have 1.6k ! 1.2k formats, but could be
built with larger formats, such as the E2V 2k ! 4k device (TRL ~ 4). Better radiation hardening, and
therefore lifetime, could be obtained with p-channel CCDs from Lawrence Berkeley Labs or E2V, TRL~5
for analog CCDs with 3.5K x 3.5K formats (JDEM/SNAP, DES, other ground based telescopes), and
further environmental testing would raise them to TRL 6, while photon-counting versions are at TRL ~3.
Development proposals are being written for current NASA opportunities.
Q3. Technical issues: Current TRL 9 technology (Heritage: HST) will provide the sensitivity and spatial
resolution improvements that are commensurate with the large aperture of ATLAST but at a cost of
exposure times that are 3 - 5! longer than might be needed if investments are made in developing the
higher efficiency detectors and optics, as discussed above.
Q4-Q6: see attached tables.
Q7. Organization: NASA will select the UV IFS taking into consideration experience with building
similar space flight hardware. A NASA Center, international space agency, academic or commercial
aerospace company will be selected to build the instrument and the NASA Project Office will have
oversight. We would expect the instrument to be developed using a PI-led science team and his or her
industrial partners.
Q8. Concept Study: A concept and feasibility study of the UV IFS for ATLAST was conducted at the
GSFC IDC. This is detailed in the Astrophysics Strategic Mission Concept Study Report submitted to
NASA HQ and is available at http://www.stsci.edu/institute/atlast.
Q9. Instrument operations: The UV IFS obtains 3D spectral images of the sky while pointed under
stable control. Analysis software will have tremendous heritage from HST. Assuming CCD detector
readouts every 1000 sec, the continuous data rate is 2.7 MB/sec (compressed 2:1) or 0.23 TB/day, which
can be downlinked in 1.3 hrs at today’s Ka band rates.
Q10. Flight software: Estimate of 40,000 lines of executable code, based on HST instruments, and with
many lines that can be re-used.
Q11. Non-US Participation: None required; however, for a large mission it would be expected.
Q12. MEL: No MEL is available. Mass, power and volume of UV IFS were estimated by the IDC based
on conceptual designs and analogies with other space flight instruments.
Q13. Heritage: Components (optics, detectors) have heritage to HST/ FOS, GHRS, STIS, COS, and to
GALEX, SOHO, IUE, IMAPS, and OAO. The image slicer optics have heritage in medical endoscopy.




                                                   64
                          Instrument Table 2.19: Ultraviolet IFS
                               Item                                  Value            Units
   Type of instrument                                          UV Integral Field
                                                               Spectrograph
   Number of channels                                          1
   Size/dimensions (for each instrument)                       0.75 x 1.00 x 2.00     mxm
                                                                                      xm
   Instrument mass without contingency (CBE*)                       350               Kg
   Instrument mass contingency                                      30                %
   Instrument mass with contingency (CBE+Reserve)                   455               Kg
   Instrument average payload power without contingency             300               W
   Instrument average payload power contingency                     30                %
   Instrument average payload power with contingency                390               W
   Instrument average science data rate^ without contingency        2670              kbps
   Instrument average science data^ rate contingency                30                %
   Instrument average science data^ rate with contingency           3470              kbps
   Instrument Fields of View (if appropriate)                       2x2               arcsec
   Pointing requirements (knowledge)                                 NA               arcsec
   Pointing requirements (control)                                   NA               arcsec
   Pointing requirements (stability)                                 NA               arcsec

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                               65
2.14 Payload Instrumentation: WFOV Camera [8m and 9.2m]

Q1. Description: The Wide Field-of-View Camera (WFOV) is a panchromatic camera operating from
400 nm to at least 1.7 microns (extension to 2.4 microns with cooling at SE-L2 is possible). The WFOV
optical layout is shown below. Its main functions are (1) to relay the image at the TMA focal plane to the
image plane with desired critical sampling, (2) separate one beam into visible and NIR, and (3) add
spectral filters into each beam. Refractive components are selected for the collimator and imagers to
dramatically reduce the total volume and component sizes, as well as to improve image quality in a wide
FOV. The same camera, with different packaging, will be use for the 8m and 9.2m versions of ATLAST.

                          Pick-off mirror at
                          TMA focal plane



                                                  Collimator lens
                                                  group in common
                                                  path         Dichroic beam-
                                                                splitter
                                                                   IR channel Spectral
              Visible channel Spectral                             filter channel imaging lens group
                                                                     IR
              filter
         Visible channel imaging lens
         group
              Visible channel fold
              mirror                                                                                 IR detector
                                                                                                     array
                                                                                                     16k ! 16k

                                                                                                   CCD array
                                                                                                   32k ! 32k


                           Figure 2.18: Layout of ATLAST WFOV Camera

                             Table 2.20: WFOV Camera Specification
                                         Visible channel                           IR channel
                                                                          900 nm-1700 nm (Required)
       Wavelength                 450 nm – 900 nm (Required)
                                                                       1700 nm - 2400 nm (with cooling)
          FOV                         8 arcmin ! 8 arcmin                     8 arcmin ! 8 arcmin
      Magnification                             1:1                                  1:0.75
     Image space f/#                            18                                    13.5
        Sampling                 2 samples/Airy disc @ 500 nm           2 samples/Airy disc @ 1092 nm
    Detector pixel size                       9 $m                                   18 $m
      Detector size                  32k ( 32k (4 ( 4 array)                16k ( 16k (4 ( 4 array)
      Detector type                            CCD                     MCT (HgCdTe) photodiode array
      Image quality             rms spot size < detector pixel size    rms spot size < detector pixel size


                                                    66
Q2. Technical Maturity: The WFOV design uses matured technology through most of the instrument.
Most of the optical components have the TRL level >6, and can be made by many optics shops and
coating companies. The optical bench, mechanical parts and mechanism, and thermal control are also at
TRL 6. Larger format detectors, that have direct heritage to smaller detectors in use on HST and with
JWST, however, are currently at TRL 4-5. Both visible and IR large format detectors are under
development by various companies such as E2V and Teledyne, respectively. They expect to reach TRL 6
by 2014. The TRL for each element is listed in Table 2.21.

                                     Table 2.21: Component TRL level
                Component name           TRL                            Rationale
                      Lenses              >6      Glass lenses with designed size are flight qualified
                 Pick-off mirror          >6    Pick-off mirrors are frequently used in flight instruments
  Optical
components        Spectral filters        >6              Common filters in flight instruments
                  Dichroic beam
                                          >6      Common dichroic beam splitter in flight instruments
                     splitter
                  Visible CCD                   Fairchild Imaging and E2V indicate that TRL 6 detectors
                                          5
                    (8k!8k)                             could be produced in 2 years with funding
    FPE
               IR MCT (HgCdTe)                 2k!2k is at TRL 6. 4k!4k is currently under development
                                          4
                   (4k!4k)                        by Teledyne and expected to be at TRL 6 in 2014
  Filter
                                          >6              Frequently used in flight instruments
mechanism

Q3. Primary Technical Issues: large format detector fabrication, construction of large focal plane arrays
(CCD camera is 4 ( 4 array of 8k ( 8k detectors) and a large, low-jitter shutter for the visible detector.
Q4-Q6: see attached tables.
Q7. Organization: NASA will select the WFOV Camera organization taking into consideration
experience with building similar space flight hardware. A NASA Center, international space agency,
university or aerospace company will be selected to build the camera and the NASA Project Office will
have oversight.
Q8. Studies: A concept and feasibility study of the WFOV camera for ATLAST was conducted at the
GSFC IDC. This is detailed in the Astrophysics Strategic Mission Concept Study Report submitted to
NASA HQ and is available at http://www.stsci.edu/institute/atlast.
Q9. Instrument operations: The camera obtains broad, medium, and narrow-band images of the sky
while pointed under stable control. The level of complexity in analyzing the data is dependent on the
scientific investigation. Analysis software will have tremendous heritage from HST and JWST.
Assuming NIR detector readouts every 100 sec, and CCD detector readouts every 1000 sec, the
continuous data rate is 4.1 MB/sec (compressed 2:1) or 0.35 TB/day, which can be downlinked in 2 hrs at
today’s Ka band rates.
Q10. Flight software: Based on HST instruments and estimates made by the software engineers
supporting the GSFC IDC run, 40,000 lines of code are required to run the WFOV instrument. Roughly
50% of this code is expected to be re-used from earlier instruments.
Q11. Non-US Participation: None required; however, for a mission of this size it would be expected.
Q12. MEL: The MEL created in the GSFC IDC study is attached.
Q13. Heritage: Components of the camera (optics, filters, detectors, optical bench, mechanisms) have
heritage to HST instruments. Also, another wide field camera (NIRCam) is currently being built for


                                                    67
JWST with similar NIR detectors. Similar space qualified optical components and be found for all optical
components in our design. The needed improvement is to increase the number of pixels per detector chip,
create large focal planes, and increase the size of all elements.




                                                  68
                           Instrument Table 2.22: WFOV Camera
                             Item                              Value                  Units
   Type of instrument                                     WFOV camera
   Number of channels                                     2
   Size/dimensions (for each instrument)                  2.75!0.77!1.25          mxmxm
   Instrument mass without contingency (CBE*)             538.7                   Kg
   Instrument mass contingency                            30                      %
   Instrument mass with contingency (CBE+Reserve)         700.3                   Kg
   Instrument average payload power without contingency 288.7                     W
   Instrument average payload power contingency           30                      %
   Instrument average payload power with contingency      375.3                   W
   Instrument average science data rate^ without          25600 for visible       kbps
   contingency                                            42000 for NIR
   Instrument average science data^ rate contingency      30                      %
   Instrument average science data^ rate with contingency 32500 for visible       kbps
                                                          54600 for NIR
   Instrument Fields of View (if appropriate)             0.133!0.133             degrees
   Pointing requirements (knowledge)                      See OTA
   Pointing requirements (control)                        See OTA
   Pointing requirements (stability)                      See OTA

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing (without 2:1
compression)

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                               69
2.15 Payload Instrumentation: VIS/NIR Multi-Object Spectrograph (MOS) [8m and 9.2m]

Q1. Description: The VIS/NIR MOS provides a general purpose capability for simultaneously obtaining
spectroscopy of many objects in the field of view. For example, one could map the cosmic web by
obtaining redshifts and spectra of galaxies selected by ground-based surveys or with the ATLAST
VIS/NIR WFOV Imager. It also provides spectra of many stars in globular clusters and star formation
regions not only in the Milky Way, but also in the Local Group, thus enabling studies of star formation in
diverse settings.
   The MOS uses a 3 x 3 mosaic of Goddard Micro Shutter Arrays (MSA) for programmable selection of
targets over a 4 x 4 arcmin field, thus targeting many hundreds of objects at once and suppressing sky
noise from the spectra. Further noise suppression below 900 nm is obtained by using photo-counting
EMCCD detectors. The wavelength ranges are 500-900 nm and 900-1700 nm, observed simultaneously,
split by a dichroic filter. The spectral resolving power is selected by gratings and prisms. Typical
resolving powers are 100, 1000, 3000, 10000.
   The MSA can be moved out of the field for a slitless spectrograph mode for more complete spatial
coverage for brighter objects, for emission line galaxy surveys, dark energy surveys, etc. This mode can
be used for prime observations and for parallel observations when other instruments are prime, obtaining
~90% usage.




                    Figure 2.19: Layout of ATLAST Multi-Object Spectrograph




                                                   70
Q2. Technical maturity:
Optics: MOS optics are half-scale copies of the WFOV Camera, and thus the technology requirements are
covered within those of WFOV Camera, except for the gratings, which are commercially available.
Mechanisms: The primary MOS mechanism is the Micro Shutter Array. The baseline is a 3 x 3 mosaic of
200 x 400 shutter elements with magnetic opening and electrostatic closing as built for JWST/NIRSpec
(TRL 6), but not cryogenic as required for JWST. Non-magnetic versions are being proposed for
development, which would simplify operations and reduce risk. Other mechanisms such as grating wheels
and shutters have strong heritage from HST and many other flight missions.
Detectors: MOS detectors require 4K x 4K format. Below 900 nm a back-thinned photon-counting
EMCCD array will be used. Analog N-channel CCDs from E2V have TRL 9 (Heritage HST/WFC3,
ACS). Current EMCCDs have 1.6K x 1.2K formats, but could be built with larger formats such as the
E2V 2K x 4K or larger with customer demand (TRL ~ 4).
    Better red response and radiation hardening and therefore lifetime could be obtained with p-channel
CCDs from Lawrence Berkeley Labs or E2V, TRL~5 for analog CCDs with 3.5K x 3.5K formats
(Heritage JDEM/SNAP, DES, other ground based telescopes), and further environmental testing would
raise them to TRL 6, while photon-counting versions are at TRL ~3. Development proposals are being
written for current NASA opportunities.
    Above 900 nm use a HgCdTe array with substrate removed, from Teledyne or Raytheon. They have
TRL 9 (Heritage HST/WFC3, JWST/NIRCam and NIRSpec). Further improvements in read noise and
dark current would greatly shorten their spectroscopic exposure times.
Q3. Technical issues: A 3 x 3 mosaic of MSAs will be needed, but they are non-cryogenic. A non-
magnetic version could further improve reliability. Development of photon-counting p-channel EMCCDs
would improve observing times and lifetime.
Q4-Q6: see attached tables.
Q7. Organization: NASA will select the Vis/IR MOS taking into consideration experience with building
similar space flight hardware. A NASA Center, international space agency, academic or commercial
aerospace company will be selected to build the instrument and the NASA Project Office will have
oversight.
Q8. Concept Study: A concept and feasibility study of the Vis/NIR MOS for ATLAST was conducted at
the GSFC IDC. This is detailed in the Astrophysics Strategic Mission Concept Study Report submitted to
NASA HQ and is available at http://www.stsci.edu/institute/atlast.
Q9. Instrument operations: The Vis/NIR MOS will obtain 3D spectral images of the sky, directly for
general astrophysics, while pointed under stable control. Microshutter operations will follow those for
JWST. Analysis software, including that for slitless spectroscopy, will have tremendous heritage from
HST and JWST. Heavy use in slitless mode in parallel is expected, with analysis software following
HST/ACS. Assuming NIR detector readouts every 100 sec, and CCD detector readouts every 1000 sec,
the continuous data rate is 2.7 MB/sec (compressed 2:1) or 0.23 TB/day, which can be downlinked in 1.3
hrs at today’s Ka band rates.
Q10. Flight software: Estimate of 60,000 lines of code, primarily for microshutter and detector control,
based on HST and JWST instruments, and with many lines that can be re-used.
Q11. Non-US Participation: None required; however, for a mission of this size it is expected.
Q12. MEL: No MEL is available. Mass, power and volume of the MOS were estimated by the IDC
based on conceptual designs and analogies with other space flight instruments.
Q13. Heritage: Components of the camera (optics, mechanisms, detectors) have heritage to HST and
JWST instruments. Similar space qualified optical components can be found for all optical components in
our design.




                                                  71
                Instrument Table 2.23: VIS/NIR Multi-Object Spectrograph
                            Item                                Value                  Units
Type of instrument                                        Multi-Object
                                                          Spectrograph
Number of channels                                        2
Size/dimensions (for each instrument)                     0.25 x 0.75 x 1.50          mxmxm
Instrument mass without contingency (CBE*)                61                          Kg
Instrument mass contingency                               30                          %
Instrument mass with contingency (CBE+Reserve)            79.3                        Kg
Instrument average payload power without contingency      300                         W
Instrument average payload power contingency              30                          %
Instrument average payload power with contingency         390                         W
Instrument average science data rate^ without contingency 2670                        kbps
Instrument average science data^ rate contingency         30                          %
Instrument average science data^ rate with contingency    3470                        kbps
Instrument Fields of View (if appropriate)                240 x 240                   arcsec
Pointing requirements (knowledge)                           NA                        arcsec
Pointing requirements (control)                             NA                        arcsec
Pointing requirements (stability)                           NA                        arcsec

*CBE = Current Best Estimate.
^Instrument data rate defined as science data rate prior to on-board processing

Note: This instrument table applies to both the ATLAST-8m and ATLAST-9.2m concepts.




                                               72
2.16 Total Payload Mass Tables

                        Table 2.24: ATLAST-8m Payload Mass Table (kg)

          Payload Element            Current Best      Percent Mass        CBE Plus
                                    Estimate (CBE)     Contingency      Contingency (kg)
    Primary Mirror                       19250              30               25025
    Structure & Instrument Bay           11088              30               14414
    Secondary Mirror, Aft Optics,
    Avionics & Thermal (part of          3570               30               4641
    OTA)
    OTA Total (sum of above)            33908               30               44080
    Wavefront Sensors
                                          69                30                90
    (total for 5 units)
    Fine Guidance Sensors
                                          78                30                101
    (total for 4 units)
    TMA WFOV Camera                      539                30                701
    TMA MOS                              61                 30                 79
    Cass. VNC                            82                 30                107
    Cass. ExoCam                         40                 30                 52
    Cass. ExoSpec                        570                30                741
    Cass. UV IFS                         350                30                455
    Total Payload Mass                  35697               30               46406




                                                73
                   Table 2.25: ATLAST-9.2m Payload Mass Table (kg)

      Payload Element             Current Best     Percent Mass         CBE Plus
                                 Estimate (CBE)    Contingency       Contingency (kg)
OTA Subtotal                         5405               30                7027

TMA Hybrid (total for 4 units)       1316               30                1711
TMA WFOV Camera                       539               30                701
TMA MOS                               61                30                 79
Cass. VNC                             82                30                107
Cass. ExoCam                          40                30                 52
Cass. ExoSpec                         570               30                741
Cass. UV IFS                          350               30                455
Total Payload Mass                   8363               30               10872




                                          74
3. Enabling Technology
   The full (81-page) ATLAST Technology Development Project Plan 5 (TDP) outlines all the tasks and
programmatics to bring technologies required for three variants of ATLAST (including a 16 m concept)
to TRL 6 in six years. This section focuses only on those technologies for the 8 m and 9.2 m variants for
three most critical technology areas: 1) large-aperture space optics capable of diffraction-limited
performance at 500 nm, 2) gigapixel focal plane arrays and high-efficiency UV detectors, and 3) starlight
suppression systems for exoplanet studies. The technology baselined in the telescope and instruments for
ATLAST-8m and ATLAST-9.2m is summarized in Table 3.1.

      Table 3.1: ATLAST-8m and ATLAST-9.2m Technology Development Summary
                                                  Needed Product to        Current
       Technology               Need                                                      State of the Art
                                                     Achieve TRL6           TRL
                                                 Mirror blank vibration
     8 m Monolithic         Launch loads,
                                                    test and gravity         5             Gemini, VLT
       Telescope          zero gravity figure
                                                       calibration
                             <10 nm rms
    Visible Diffraction                2        Mirror segment tested to
                             < 25 kg/m ,                                             JWST Architecture, AMSD
      Limited Mirror               2                performance and          5
                            > 20 m /year,                                                  Segments
        Segments                      2              environments
                              < $1M/m
                          Figure knowledge       Image based sensing
       Wavefront
                          < 5 nm rms, every      tested to performance       4       JWST Testbed Telescope
       Sensing
                              5 minutes            and environments
        Segment                                  Actuator hexapod test
                          Resolution ~2 nm                                   4           JWST, Moog, PI
        Actuation                                  and environments
                            8k x 8k arrays,
                                                Prototype performance                   E2V and TI photon
    Visible Detectors          and photon                                   3-4
                                                  and environments                       counting CCDs
                                 counting
                          Higher QE, 4 Mpix     Prototype performance
      UV Detectors                                                           4         HST/ COS and STIS
                                  arrays          and environments
                          UV IFS, coatings,     Prototype performance
        UV Optics                                                            4             HST, FUSE
                                 dichroics        and environments
                             -10
        Internal          10 contrast over      Prototype performance
                                                                             4           JPL HCIT tests
     Coronagraphs          20% passband           and environments
                                                                                          Beamline tests,
                          Deployment and         Sub-scale and partial
       Starshade                                                             3        deployment design with
                           shape control             shade tests
                                                                                          high TRL parts


Telescope Technology: The diffraction-limited imaging at 500 nm that is needed for much of ATLAST
science requires HST-quality mirror surface errors (5-10 nm rms) to meet the overall system wavefront
error of 36 nm rms. For ATLAST-8m, solid meniscus monolithic glass, as demonstrated on ground-based
telescopes, requires no new technology, but will require engineering to ensure survival of launch
vibrations/acoustics and the proper gravity sag unloading. For ATLAST-9.2m design, hexagonal mirrors
measuring 1.3 m are baselined. Some potential options for the mirror composition include the Advanced
Mirror System Demonstrator (AMSD) ULE glass segments developed for JWST, Actuated Hybrid
Mirrors (AHM), and corrugated glass technology. ATLAST-9.2m has baselined the AMSD-like mirror
segments of 1.3m size and 25 kg/m2. At this mass and size, mirror segments are sufficiently stiff such that
demonstration of better than 10 nm rms wavefront error and vibration and acoustic testing will be
straightforward. The ATLAST TDP contains a downselect between AMSD-like and AHM mirror
segment technologies. Assuming both technologies meet launch loads and figure error, the downslect will


5
  The full details of our TDP are provided as a separate volume. It is available on-line. Go to
http://www.stsci.edu/institute/atlast and click on “ATLAST Mission Concept Study.”



                                                         75
be based on studies of thermal stability, cost, and manufacturing schedule. The TRL 6 milestone is a
mirror segment that meets environmental and wavefront error budget requirements.
   Wavefront sensing and control (WFS&C) also needs to be advanced from JWST to meet visible image
quality with an allocation of 10-15 nm rms wavefront error for WFS&C residual. The segment’s positions
must be measured to a few nanometers at a rate faster than their support structure’s time constants.
Periodic image-based WFS employs phase retrieval to measure the wavefront error. For ATLAST-8m,
this is done using WFS modules on each side of the three foci, updated every few weeks using stars of
opportunity. For the ATLAST-9.2m, this is done using several WFS modules that provide updates every
few minutes (without interrupting science observations) using the guide stars simultaneously for
wavefront sensing and guiding. Technology development requires a demonstration of WFS algorithms to
the required performance within the processing capabilities of a flight computer with realistic guide star
scenes. Actuators supporting the segments require a modest technology development to reduce the
resolution to 2 nm and increase bandwidth. Since WFS&C is inherently a system-wide performance of
the observatory, a demonstration of the telescope’s operation is planned with a subscale (6 m class),
partially populated (three-segment) testbed meeting error budgets under full thermal, vacuum, vibration,
and jitter environments.
   Technology Investment breaks existing telescope costing models: Ever since the first widely cited
costing model for telescopes (Cite: Meinel), there has been debate over the cost as a function of diameter.
Meinel quoted ground observatory costs prior to the 1970s, including foundation, mount, and dome, to be
to the 2.8 power of diameter. This has been broken repeatedly though ground telescope technology
advances of meniscus and segmented mirrors. In space the same is true: JWST, at 2.7 times the diameter
(and about half the mass) of HST, costs about the same. ATLAST will invest in the technology to get to
even larger apertures, again keeping the cost about the same as its flagship space precedents HST and
JWST. Unfortunately, costing models are built on prior data points and are notoriously poor both at
extrapolating to sizes larger than the knowledge base and on extrapolating into the future. Cost
estimators for the ATLAST mission should pay special attention to these:
         1) For the ATLAST-8m, a “heavy-weight” mirror is used. Costing based on ground mirrors will
             be relevant, not extrapolations of smaller lightweight space mirrors.
         2) For the ATLAST-9.2m, investment that will be made prior to Phase A start to prove the
             reduced cost of mirror segments. Extrapolation of telescope size using today mirror segment
             costs will result in an overestimate.

Detector Technology: Gigapixel detector arrays for visible imaging and ~500 Megapixel arrays for NIR
imaging are required for studies of resolved stellar populations, galaxy evolution, and structure formation.
Such arrays can be built with existing technology. However, development would result in better science
performance (lower noise), lower risk (less complex electronics), lower cost, and lower power
consumption. The wide field cameras in all ATLAST designs are envisioned to have ~1 to 1.6 gigapixels
per channel.
   Exposure times invested in exoplanet and other faint object spectroscopy could be reduced by up to
five times using photon counting detectors. Technology development of photon-counting CCDs is based
on the low-light level CCDs built by E2V and the similar technology of Texas Instruments. The current
TRL is 4; improvements in anti-reflection (AR) coatings, voltage swing, and charge induced clock noise
would be demonstrated before the completion of a TRL 6 qualification program. In the longer term,
CMOS based detectors are likely to be used. Detectors made by Fairchild, Sarnoff, and Fill Factory
represent the state-of-the-art. Improvements in dark current, AR coating, in-pixel gain structure, and
backside thinning would need to be demonstrated before the completion of a TRL 6 qualification
program.
   UV detectors have ample room for improvements in efficiency and format size. UV spectroscopy, in
particular, requires coatings, optics and detectors that are highly efficient. Current flight UV imaging



                                                    76
detectors use CsI and CsTe photocathodes with 10% - 30% quantum efficiencies (QE). Photocathodes
with QE of 30% - 80% using cesiated p-doped GaN have been produced in the lab, but have not yet been
integrated into detector systems. Materials such as p-doped AlGaN and MgZnO should be developed for
higher QE over a wider band, and better AR-coatings may be matched with p-channel radiation-hardened
photon-counting CCDs. For the far UV, higher QEs also are required, and III/V materials are effective.
All must be coupled with large-format intensifier and readout systems. EBCCDs and microchannel plate
methods (ceramic and glass) compete for the highest QE and largest formats, and both should be pursued.
The current TRL for high QE UV detectors is four; a downselect will precede TRL 6 qualification.

Starlight Suppression Technology: An internal coronagraph or external occulter that provides 10-10
starlight suppression (output-to-input beam flux ratio) is required to characterize Earth-sized exoplanets.
The best starlight suppression technology is not yet obvious. Fortunately, there are multiple options. The
technology development plan addresses the viability of 1) a visible nulling coronagraph (VNC) that any
telescope could use (development costs might be shared with large ground-based telescopes); 2) a Lyot-
type coronagraph (for use with monolithic telescopes); and 3) an external starshade (a separate spacecraft
creating a star shadow at the telescope). All three methods are currently at or below TRL 4. Recognizing
the importance of ATLAST to exoplanet science, we would fund development of all three methods for
starlight suppression, with a downselect three years before the scheduled TRL 6 milestone.
    There are a number of coronagraphic configurations, each having tradeoffs between achievable
contrast, IWA, throughput, aberration sensitivity, and ease-of-fabrication. Most techniques do not work
on conventional (4-arm spider) obscured or segmented systems, but some non-conventional spider
configurations (linear support) appear to allow performance competitive with off-axis systems (see also
Appendix C). The VNC approach is probably the only viable solution for internal suppression with a
segmented telescope. VNC development is required to demonstrate 10-10 suppression ratios over at least a
23% passband. This requires the development of a spatial filter array (1027 fiber bundle), deformable
mirror (MEMS 1027 segment), and an achromatic phase shifter. Testbeds at JPL and GSFC have
presently achieved suppression ratios of 10-7. Coronagraphic technology development is critically
dependent on advancements in high-precision, high-density deformable mirrors (>96 actuators across
pupil and sub-Angstom stroke resolution).
    Starshade technology development is well described in the New Worlds Observer (NWO) RFI
response. Starshade theoretical performance has been validated by at least 4 independent algorithms and,
in the lab, by two beamline testbeds. Detailed CAD models exist for the NWO 50 m starshade, which use
high TRL components (membranes, hinges, latches, booms). For ATLAST, a larger starshade is required:
80 m for an 8 m or 9.2 m telescope. The key challenges are primarily deployment reliability and shape
control. The ATLAST starshade separation of ~165,000 km, while large, does not present any challenging
formation flying or orbital dynamics issues but put additional requirements on the starshade propulsion
system. The starshade technology developments are addressed through increasingly larger subscale
models with TRL 6 being demonstrated through beamline tests, a half-scale quarter-section deployment,
and a full-scale single petal deployment, performance, and environmental testing. The astrometric sensor
and NASA’s Evolutionary Xenon Thruster (NEXT) ion engine needed to align the starshade already will
be TRL 6 or greater by other projects: USNO’s JMAPS and NASA’s in-space propulsion program.




                                                    77
3.1 Schedule and Cost for the ATLAST Technology Development Plan
    The ATLAST Technology Development Project Plan6 covers the technology portfolio for three
versions of ATLAST (the third version is a segmented 16 m telescope that was part of our original
concept study). The TDP is developed per NASA 7120.8. This roadmap (Figure 3.1) shows the TRL 5
and 6 milestones, downselect logic, funding profile, and interactions within the technology development
tasks. Assuming a 2011 start for technology development, the project would initially begin funding high
priority technology developments at a low level. The schedule is divided in to six periods. In a “full speed
ahead” scenario, each period would last one year and all technologies would reach TRL 6 in 2017. A
slower schedule of 1.5 years per period would be completed by 2020. Milestones are placed at the TRL 5
level and coincide with downselects in three areas (mirror segment technology, visible detector
technology, and starlight suppression technology). All technologies would plan to complete their TRL 6
milestones with at least a year margin before a mission PDR (NASA requires TRL 6 at PDR), allowing a
healthy schedule margin of two months per year. A parallel pre-formulation mission study would inform
the technology trades and downselects. Downselect decisions on the launch vehicle and primary mirror
architecture (monolith versus segmented) are made by the end of period three.




                  Figure 3.1: Proposed ATLAST Technology Development Plan & Schedule

   The cost estimates for the ATLAST TDP are given in Table 3.2. TDP costs are grassroots estimates
based on 3-5 tasks per technology and include purchased components and labor on a yearly basis. Task
objectives, schedules, TRL milestones, and costs were supplied by experts from MSFC, GSFC, JPL, Ball


        6
         The full details of our TDP are provided as a separate volume. It is available on-line. Go to
http://www.stsci.edu/institute/atlast and click on “ATLAST Mission Concept Study.”



                                                    78
Aerospace, Northrop Grumman, Xinetics, and ITT for the 14 technologies. In Table 3.2 we break out the
TDP costs for ATLAST-8m and ATLAST-9.2m.

        Table 3.2: Technology Development Cost Estimates (FY09 $M, No Reserves)
         Period:      1      2      3      4       5       6             Total: all
                                                                                      9.2m      8m
           Fast:    2011    2012   2013   2014    2015    2016    2017   ATLAST
                                                                         concepts*
                                                                                      Only     Only
          Slow:     2011    2013   2014   2016    2017    2019    2020

  8 m Telescope                                                               20.0      0.0     20.0
  Blank Vib.
                      5.0 5.0  5.0    5.0                                     20.0      0.0     20.0
  Test
  Segmented Telescope                                                        147.8     80.0      0.0
  AHM Seg.            4.6 5.8  6.4    9.3          12.9                       39.0     25.0      0.0
  Glass Seg.          2.2 3.0  3.8   11.0          20.0                       40.0     25.0      0.0
  - [downselect savings]            -11.3         -20.9                      -32.2    -19.0      0.0
  WFS/Truss           1.0 2.0  5.0    5.0           5.0                       18.0      5.0      0.0
  Testbed                      5.0   20.0          20.0    20.0               65.0     30.0      0.0
  Actuators               0.5  1.5    2.5           2.5                        7.0      7.0      0.0
  Modeling            1.0 1.5  1.5    2.0           2.0     3.0               11.0      7.0      0.0
  Instruments                                                                 60.1     60.1     60.1
  CCD Detectors       1.6 0.6  1.0    1.0           4.0     4.0               12.2     12.2     12.2
  CMOS Det.           0.9 1.2  0.9    0.9           4.0     4.0               11.9     11.9     11.9
  - [downselect savings]                           -4.0    -4.0               -8.0     -8.0     -8.0
  UV Detectors        3.0 5.0  6.4    5.3           5.5     2.7               27.9     27.9     27.9
  UV Optics           0.9 3.1  4.3    3.5           2.8     1.6               16.1     16.1     16.1
  Starlight Suppression
                                                                              59.6     40.0     59.6
  System
  Lyot / Pupil
                      6.3 7.7  5.6    6.0           5.5     4.0               35.1      0.0     35.1
  Coronagraph
  VNC                 0.9 1.7  4.4    2.5          16.9     5.2               31.5      31.5    31.5
  Starshade           1.5 1.5  5.0    5.0          10.5    10.5               34.0      34.0    34.0
  - [downselect savings]             -5.5         -20.9   -14.7              -41.1     -25.5   -41.1
  Technology Development Sub-Total:                                          287.4    180.1    139.7

  Mission Study                                                               48.0     48.0     48.0
  Science WG
   & Studies          4.0    4.0    4.0     4.0     4.0     4.0               24.0     24.0     24.0

  Project Office
                      4.0    4.0    4.0     4.0     4.0     4.0               24.0     24.0     24.0
  & Eng. Studies
   Totals               36.9 46.5 63.8   70.2   73.8    44.3                335.4 228.1 187.7
*Note: Our full TDP includes a 16 m segmented telescope concept. The last two columns show the
relevant totals if just ATLAST-8m or ATLAST-9.2m is pursued at the outset of the TDP.

        A full ATLAST technology development project would cost $287M if all downselects were kept
open until the TRL 5 milestones in period three. This does not include reserves, which would be held at
the program level. The range of technology development cost estimates for ATLAST-8m spans $55M -
$149M depending on the degree to which early downselects are taken. The cost estimate range for the


                                                  79
ATLAST segmented-mirror concepts spans $115M - $267M, again, depending on the timeline for early
downselects taken.
         If the ATLAST-8m variant were chosen from the beginning, there would be no need to develop
segmented telescope technologies. This results in a technology development cost estimate of $140 M
(FY09, no reserves). If the ATLAST-9.2m variant were chosen from the beginning, all tasks associated
with the 8 m monolithic mirror would be eliminated, the mirror segments scoped to 1.3 m and 25 kg/m2
only, the testbed and modeling simplified, and no Lyot coronagraph or laser truss optioned. This results in
a technology development cost of $180 M (FY09, no reserves).
         The tasks in our TDP are spread over six schedule periods. Downselects in three areas after
period three allow higher funding on the most promising technology for the final three periods. Informing
this downselect schedule requires mission decisions about launch vehicle and segmented versus
monolithic telescope. All estimated costs are in constant FY2009 dollars and do not include reserves. The
time phasing of the technology development cost grows nearly linearly from $29M in the first period to
$66M in the fifth period. The segmented telescope technology investment area is the greatest, at $148M.
This value is consistent with the sum of cost estimates for lightweight large aperture and WFS&C given
by the NASA Advanced Planning and Integration Office roadmap activity in 2005. That effort included
members from NASA, industry, and the National Reconnaissance Office. The detector development
benefits any space UVOIR instrument regardless of mission size. The starlight suppression technology
builds, in part, on the investment in TPF-C at JPL over the last decade. The ATLAST TDP costs here
assume full coverage of the VNC and starshade costs. We assume some of the Lyot/pupil internal
coronagraph technology development costs will be shared with a smaller exoplanet probe mission; only
70% of the grass roots cost estimate is included for the first three periods; 100% in the last 3, post-
downselect.




                                                    80
4. Mission Operations Development [8m and 9.2m]

Q1. Description: The mission operations concepts for both ATLAST-8m and ATLAST-9.2m are based
on the JWST operations plans. Mission Operations for both versions are largely identical, and the minor
differences are mentioned below where they apply.
   Observations at a single sky pointing will last several hours to several days. Hence, frequent large-
angle slews will not common. Schedules are planned weeks in advance, and command loads are uplinked
a week at a time. The on-board scheduling system is event-driven, like JWST. Occasional, but infrequent,
schedule interruptions to re-point the telescope to observe scientifically important transient events are
supported.
   ATLAST has a single, two-hour long DSN contact per day. During this contact about 530 GBytes of
science data are down-linked on KA band at 600 Mbps to a DSN 34 m antenna. Ranging and command
uplinks are also accomplished during this single daily DSN contact. Because the science downlink
antenna is gimbaled and an omni is used to receive commands, no SC reorientations are needed for
ground contacts. DSN usage is, thus, 14 hours per week. The ATLAST mission design lifetime is 5
years (260 weeks), but consumables (primarily station-keeping fuel) are adequate for 10 years (520
weeks). The mission life could be extended to 20-30 years if servicing were available.

Q2. Special Coverage: Continuous TDRSS coverage is required during the first week for launch and
initial checkout. Once on orbit at SE-L2, a few hours of continuous coverage every 3 weeks or so are
required during thruster firings for station-keeping and possible momentum unloading.
    The optional external starlight occulter (if it is developed) is used by ATLAST for up to 1 week or so
about every four weeks. In the intervening time, while the occulter is in transit to its next target
(averaging about 10 to 14 days), ATLAST will conduct science observations that do not require the
starshade. When occulter science observations are in progress, ATLAST transmits to the occulter in real
time what its relative position is, based on side-to-side displacements measured by a shadow sensor
instrument and distance measurements derived from an RF ranger on ATLAST (as well as an astrometric
sensor on the starshade). Once aligned, the occulter’s station-keeping thrusters will be fired every few
minutes to maintain its required position. The ATLAST science payload has been designed to permit the
incorporation of a small, dedicated communications system for this task. Because of the real time
requirement, these communications have to occur autonomously, but it is expected that there will be
continuous ground monitoring during the time that ATLAST is communicating with the external occulter.

Q3. Special Operations: As discussed above, if an external occulter (starshade) is needed for exoplanet
observations, that will impose certain viewing constraints, as well as alignment control between
ATLAST, the occulter, and the exoplanet’s star system.
    ATLAST-8m and ATLAST-9.2m both use similar methods to avoid momentum buildup and perform
station-keeping. Similar to JWST, ATLST-9.2m has a planar sunshade but ATLAST-9.2m is significantly
less constrained than JWST. Like JWST it is in full sunlight all of the time; however, ATLAST-9.2m
pointing does not require changing the orientation of the sunshade with respect to the sun. The sunshade
will only have to rotate about the sun line. The pointing arm behind the sunshade will not only provide
both telescope pitch and roll about its bore-sight, but also move the payload Cg to unload almost all
momentum build-up due to solar photon pressure. The only possible momentum build up will be a tiny
one due to “propeller” torque induced by the small deviations in the sunshield’s planarity and reflectively.
The periodic station-keeping burns will provide more than adequate opportunities to remove this minor
build-up of momentum.




                                                    81
   ATLAST-8m uses its two solar panels as a kite tail to minimize momentum buildup (see Figures 2.9
and 2.11). Its two solar panels on 10 m long deployable booms are used to balance the solar pressure
exerted on its sunshade tube. As the observatory slews relative to the sun, the booms extend to maintain
the center of pressure at the center of mass. Additionally, the boom has a gimbal joint that articulates
during observatory roll and pitch maneuvers to keep the solar panels perpendicular to the sun. Analysis
shows that, with a 10 m boom extended from midpoint of the spacecraft, only 35 N-m-s momentum is
required for 6.25 days of continuous high-precision pointing observation. By making slight adjustments
in boom length, significantly longer continuous observation times can be achieved. It is expected that
momentum unloading burns will not need to occur more frequently than station-keeping. The rate of
momentum build-up by the ATLAST-8m observatory will depend on the sequence of solar orientations
called for by the science observation schedule. Hence, minimization of build-up of momentum can be
dealt with, in part, using smart science operations. These momentum mitigation requirements do not
impact the scientific productivity or mission lifetime of ATLAST-8m.

Q4. Science/Data Products: Level 0 processing (time ordering and elimination of duplicate data) is
performed by the DSN. The SOC will provide raw archival data storage as well as Level 1 and 2
products, where Level 1 is the telemetry organized on a per-instrument basis and reformatted as raw FITS
files. In Level 2, the data are calibrated and all instrument signatures are removed. All data is archived
and is subsequently available for retrieval by the entire scientific community after any proprietary periods
expire. The science data pipeline will likely also provide high-level science data products (Level 3 and
beyond), such as co-added and mosaiced images, lists of detected objects in images, and extracted
spectral previews. A significant fraction (30% – 50%) of the software required for ATLAST level 0 – 2
science data processing will be re-used from preceding missions (e.g., HST, Kepler, JWST).

Q5. Science and Operations Center (SOC): The SOC is located at the Space Telescope Science
Institute, and is staffed and operated in a manner virtually identical to JWST. SOC activities include
proposal processing and selection, data capture from the Missions Operations Center (MOC), data ingest
into the archive, data calibration, data trending, data distribution, high-level science product development,
community support (helpdesk), and Education/Public Outreach activities. The MOC is normally staffed
for 8 hours/day, 5 days/week Anomalies are reported in near real-time to mission specialists via cell
phones and pagers. Like HST and JWST, there is a General Observer (GO) program that uses most of the
observing time (except for time spent on calibrations and discretionary time). There are expected to be
~100 to 200 accepted GO programs per year, involving up to 1000 scientists annually. Some research
funding for GO’s, as well as for archival-based research, will be available from the ATLAST project
office. Cost estimates for this are given in the Cost Section.

Q6. Archive: All science data (raw and calibrated) are archived at a NASA astronomy archive – the
Multi-Mission Archive at Space Telescope (MAST) is the logical home for the ATLAST mission data.




                                                     82
             Table 4.1: Mission Operations and Ground Data Systems

                Down link Information                      Value, units
Number of Contacts per Day                                       1
Downlink Frequency Band, GHz                                   26.5
Telemetry Data Rate(s), bps                                   600 M
S/C Transmitting Antenna Type(s) and Gain(s), DBi   1 m Gimbaled HGA, 46.3 DBi
Spacecraft transmitter peak power, watts.                  100 (TWTA)
Downlink Receiving Antenna Gain, DBi                           ~46.3
Transmitting Power Amplifier Output, watts                   20 (RF)
                  Uplink Information                       Value, units
Number of Uplinks per Day                                        1
Uplink Frequency Band, GHz                                2 Ghz (S band)
Telecommand Data Rate, bps                                    2 kbps
S/C Receiving Antenna Type(s) and Gain(s), DBi            Omni (-3 DBi)




                                           83
5. Programmatics & Schedule

Q1. Organization: The ATLAST organization follows that of typical NASA Flagship programs. NASA
Headquarters selects a managing Center, and development partners are identified from industry, academia
and international organizations during pre-Phase A activities. Early concept studies and technology
development partnerships are funded through the program office to maximize the relevance of the work to
the mission and to ensure parallel development of requirements and the technology to achieve them. As a
facility-class observatory, the instruments are selected through a competition with targeted science
objectives and funding limits. As with the HST program, post-commissioning mission and science
operations are conducted through the Space Telescope Science Institute (STScI), which will also
implement a funded guest observer program. The organizational chart below (Figure 5.1) is based on the
program office for the most recent Flagship mission, JWST.

                              Figure 5.1: ATLAST Organization Chart

                       ATLAST Program Office              (NASA Headquarters)



                                 ATLAST Project Management
   Science Working                                                         International Partnership
        Group                          (Managing NASA Center)                    Management


                   Mission                                      Safety and Mission
                   Systems                                          Assurance

     Observatory                   OTA                  Space Vehicle                  Operations

              Instrument Systems               Mission I&T              Launch Services


     Development partners from NASA, industry, academia and international agencies are cultivated
   during pre-Phase A activities to enable contributions to hardware elements and services in Phases A
                                                through E.




Q2. Risk Assessment: The top eight programmatic risks for ATLAST are the same for both the 8 m and
the 9.2 m concepts. However, in evaluating most of the risks, the differences in architecture result in
different ratings of likelihood and consequence for each concept. Therefore, a separate response for Risk
is included for each concept. Table 5.1 summarizes the risks and ratings for both the 8 m and 9.2 m
ATLAST missions. The detailed descriptions of each risk and associated mitigations for each concept are
presented in the text, with the 5x5 Risk Matrices for ATLAST-8m and ATLAST-9.2m in Figures 5.2 and
5.3, respectively. In the text below, each risk is crafted as an IF-THEN statement. The event that is
measured by the LIKELIHOOD parameter is described in the IF part of the statement; the result of the
event that is measured by the CONSEQUENCE parameter is described in the THEN part of the
statement.



                                                   84
                        Table 5.1: Top 8 Programmatic Risks for ATLAST

                                                           ATLAST-8m                   ATLAST-9.2m
                     Risk
                                                  Likelihood    Consequence      Likelihood      Consequence

1. Adequate Launch Vehicle                             4               5               2               4
                               -10
2. Starlight Suppression at 10 level                   3               3               4               3
3. Early and robust technology development
    funding                                            2               3               3               4
4. Observatory pointing and thermal stability          2               4               2               3
5. Pre-flight verification of observatory
    performance                                        2               3               3               3
6. Flight qualified visible diffraction limited
optics                                                 1               3               4               3
7. Roles and contributions for international
  partnering                                           3               3               2               2
8. Wavefront sensing with sufficient
  precision and frequency                              1               4               3               3

Risk 1. Adequate launch vehicle (Technical/Cost/Schedule): IF a launch vehicle with sufficient
payload mass and volume capacity is not developed THEN the mission aperture and mass will have to be
scaled down impacting science return.

ATLAST-8m: Baseline concept requires a heavy lift launch vehicle. MITIGATION: If the mass capacity
is decreased, ATLAST-8m baseline design has already identified 10,000 to 15,000 kg that can be
removed from the observatory without impacting science. But, if the fairing diameter is reduced, the
collecting aperture will have to be reduced. If a suitable heavy lift launch vehicle is not available, then the
ATLAST program will proceed with the ATLAST-9.2m concept.

ATLAST-9.2m: Requires an upgraded Delta IV-H with a 6.5m fairing and 18,000 kg mass capacity.
MITIGATION: ATLAST program will develop an alternative 8 m diameter segmented 12,000 kg design
that can fit into the existing Delta IV-H 5m fairing pending the qualification of the larger vehicle.
                                                                                           -10
Risk 2. Starlight suppression (Technical): IF the required starlight suppression of 10 is not achieved
                   -9
and instead only 10 is achieved THEN the full mission for exoplanet science will not be possible but the
minimum mission will be possible.

ATLAST-9.2m: This is the concept’s highest risk since internal coronagraphs impose tough requirements
on WFE. A Visible Nulling Coronagraph (VNC), while relaxing telescope requirements, has not yet been
demonstrated as an instrument to the required performance. Finally, an external starshade has it’s own
technical risks. MITIGATION: At least three starlight suppression techniques are pursued in the TDP
improving chances of overall success.

ATLAST-8m: The ATLAST-8m eliminates the technical problems discovered on TPF-C. By employing
a solid meniscus primary mirror, it is possible to achieve an ultra smooth <10 nm rms surface figure with


                                                      85
exceptional thermal stability. Therefore, ATLAST-8m could work very well with an internal occulting
coronagraph. But, ATLAST-8m has baselined an on-axis symmetric telescope because of its benefits for
general purpose astrophysics and its ease and reduced risk of implementation. MITIGATION: ATLAST-
8m offers three options if the VNC or external occulter does not demonstrate the required suppression.
The off-axis configuration (Appendix B) will work with any coronagraph but impacts general
astrophysics. The alternative secondary mirror spiders (Appendix C) does not impact general
astrophysics and may work with any coronagraph over each sub-aperture or a linear mask coronagraph
over the full aperture.

Risk 3. Early and robust technology development funding (Cost/Schedule): IF the technology
development is not funded robustly while holding other programmatic milestone dates THEN the flight
program cost and schedule will be impacted due to uncertainty in the capabilities of the supporting
technologies. Allowing technologies to continue development up to PDR may be fine for smaller
missions, but for ATLAST, many of the programmatic choices depend on selection of technologies where
uncertainty breeds overruns. MITIGATION: The three critical technologies of telescope, instruments, and
starlight suppression should be programmed to reach TRL 6 well before the NASA required milestone of
PDR.

In addition, fully funding the effort to flight qualify the ATLAST-8m primary mirror and its support
structure during Pre-Phase-A mitigates a potential 3 year schedule risk. This activity must be completed
before final Phase-B design begins and should be done before preliminary Phase-A design begins.

Risk 4. Observatory pointing and thermal stability (Technical): IF unanticipated (un-modeled)
thermal paths or disturbances cause image motion or wavefront error resulting in loss of the 500 nm
diffraction limit and the 600 nm diffraction limit is still met THEN the full mission for imaging science
may not be possible but the minimum mission will be possible.

ATLAST-9.2m: Uses a sun shield and TCS to provide thermal stability and an active disturbance
isolation and precision pointing system to provide image motion stability. MITIGATION: The TDP
includes a system testbed where thermal and pointing stability can be tested on the ground.

ATLAST-8m: Uses a passive, insulated sun shield tube and an active thermal management system to
provide thermal stability. Pointing stability is provided by active vibration isolation. MITIGATION:
Because of its large thermal mass, thermal stability is excellent. Active vibration techniques for such a
large mass system will need to be tested on the ground as part of the TDP. Large mass reaction wheels
and control moment gyros have flight heritage on the international space station.

Risk 5. Pre-flight verification of observatory performance (Technical): IF the lack of fidelity in
creating a flight-like test environment (gravity suspension, thermal boundaries, optical aperture size)
allows for errors to be overlooked THEN those errors may cause performance degradation making the
diffraction limit slip to the minimum mission level of 600 nm.

ATLAST-9.2m: Payload will fit in the JSC chamber, which is testing JWST, with modifications.
MITIGATION: A robust, parallel, integrated modeling effort will model both the flight observatory and
the observatory in the test environment to mitigate suspension or thermal path artifacts that would mask
observatory errors.

ATLAST-8m: Manufacturing and testing of 8 m mirrors for ground-based telescopes is a mature, proven
technology. Since ATLAST operates at 280 deg K, some optical testing can be done under ambient



                                                   86
atmosphere. Zerodur and ULE glass both have very low CTE over the range from 280 to 300 deg K and
will have negligible impact of surface figure error. The Payload will fit in the JSC vacuum chamber. A
modification to the JSC door may be required. MSFC has facilities, used on Saturn V and Shuttle, to run
the vibe/acoustic tests on ATLAST-8m. The biggest risk is characterizing the primary mirror gravity sag.
MITIGATION: A robust, parallel, integrated modeling effort will model both the flight observatory and
the observatory in the test environment to mitigate suspension or thermal path artifacts that would mask
observatory errors. Additionally, the primary mirror gravity sag will be characterized via standard
vertical and horizontal rotation tests.

Risk 6. Flight qualified visible diffraction limited optics (Technical): IF the observatory performance
of diffraction limited imaging at 500 nm and instead only a diffraction limit at 600 nm is achieved THEN
the full mission for imaging science may not be possible but the minimum mission will be possible.

ATLAST-9.2m: Mirror segments will undergo polishing and environmental testing to prove 5 nm rms
surface errors, but if this fails, even current AMSD mirrors would allow a total error budget to meet a 600
nm diffraction limit. MITIGATION: There is a robust mass allocation for mirror segments to allow for
growth up to 25 kg/m2 to allow for design fixes in from the state of the art 1.3 m AMSD mirror segment
technology.

ATLAST-8m: Primary mirror specification of < 10 nm rms is proven. Several 8-m class primary mirrors
have been manufactured with surface figures of 7.8 nm rms. And, there is a long heritage of monolithic
glass mirror telescopes in space (TRL-9). But, there is no heritage for launching an 8-m class monolithic
glass telescope into space. MITIGATION: ATLAST-8m will flight qualify its primary mirror during
Pre-Phase-A/Phase-A using the routine engineering practice of defect tolerant design: characterize the
mirror substrate, characterize full scale bond lines, joints and structural elements, model then perform
qualification tests.

Risk 7. Roles and contribution for international partnering (Cost/Schedule): IF the partner roles and
contributions remain uncertain into Phase A THEN the programmatic uncertainty will yield “churn” that
will cause inefficiency on the US side and lead to overruns. MITIGATION: Partner contributions should
be solidified before entering Phase A.

ATLAST-8m has slightly more exposure to this risk because one potential source for the 8 m mirror
blank is Schott in Germany and one potential source for the 8 m mirror fabrication is REOSC in France.
Schott has an existing mirror blank and REOSC has an existing fabrication capability. MITIGATION:
ATLAST-8m plans to run a competitive procurement for its mirror blank and mirror fabricator in Pre-
Phase-A because both are needed to flight qualify the primary mirror.

Risk 8. Wavefront sensing with sufficient precision and frequency (Technical): IF the wavefront
sensing does not perform to the required 5-10 nm rms on orbit and instead gives 20 nm rms THEN the
full science mission will not be possible but the minimum mission will be possible.

ATLAST-9.2m: MITIGATION: The technology development plan invests in proving the method of
using the guide stars for continuous WFS. If the problem were found only after deployment, operational
mitigations, such as dedicated WFS observations, would allow higher imaging performance at the cost of
observing efficiency.

ATLAST-8m: Expects to be an extremely thermally and mechanically stable observatory. Therefore,
WFS data will be acquired from 6 field points in the 3 foci and that data will be transmitted to the ground



                                                    87
for analysis. Alignment commands will be subsequently up linked to the observatory. If the observatory
is not as thermally or mechanically stable as anticipated, then the WFS frequency might be inadequate to
control alignment. MITIGATION: Detailed modeling and thermal vacuum testing will be performed.


                      Figure 5.2: ATLAST-8m Risk Matrix



                           5
                       L
                       i                                           1
                           4
                       k
                       e                         2 5
                       l   3
                                                  7
                       i
                       h   2                      3
                       o                                  4
                       o
                       d   1                      6       8

                                 1        2        3     4         5
                                              Consequences


                        Figure 5.3: ATLAST-9.2m Risk Matrix



                           5
                       L
                       i                         2 6
                           4
                       k
                       e
                       l   3                     5 8       3
                       i
                       h   2              7       4        1
                       o
                       o
                       d   1

                                 1        2        3     4         5
                                              Consequences




                                                  88
Q3. Schedule: As described in earlier sections, there are two potential concepts for the ATLAST
Observatory. And, while there may be differences of implementation, both concepts consist of the same
basic elements: Payload (OTA, instruments, structure and subsystems) and Space Vehicle. For either
ATLAST concept, the mission I&T plan calls for full environmental qualification of all subsystems and
instruments, then two cycles of I&T. In the first cycle, the Payload is fully integrated and tested as a
subsystem, and, in parallel, the Space Vehicle is fully integrated and tested as a subsystem. Once both are
fully qualified, the Payload and Space Vehicle are assembled into the Observatory, and the Observatory
completes I&T.

This response contains a single timeline for both ATLAST concepts as illustrated in Figure 5.4 and in the
Key Phase Duration Table and Key Event Dates Tables. These tables and figure come from the GSFC
IDC study, which defined a ten-year development cycle for ATLAST-9.2m. Assuming that the
Technology Development Plan is fully funded, ATLAST-9.2m expects that all critical technologies will
be at TRL 6 to start Phase A in 2018. The MSFC study team concluded that ATLAST-8m requires a
shorter Pre-Phase-A period (Figure 3.1) and could be fully developed in nine years, however, the timeline
in Figure 5.4 is used to generate costs for both concepts in their respective cost sections.

                                           Figure 5.4: ATLAST Mission Timeline
                                                                                         Preliminary Design          Critical Design
   Phase A Start                   Phase B Start             System Definition           Review (PDR)                Review (CDR)
   01/2018                             01/2020                Review (SDR)               01/2022                            01/2024

     Mission Phase A     24 mo.                    Mission Phase B       24 mo. Mission Phase C      24 mo.
      Preliminary Analysis and                        System Definition and             Final Design
         Mission Definition                             Preliminary Design
       Payload (OTA, subsystems, SIs)                      Payload Phase B                            Payload Phase C
                  Phase A
     Ins. Phase A       Instr. Phase B        Instrument Phase C                          Instrument Phase D
         8 mo.              12 mo.                 18 months                                   46 months

        Space Vehicle (Bus, Sunshield;                   Space Vehicle Phase B                     Space Vehicle Phase C
     + Pointing Arm and DIPPS for 9.2m)
                  Phase A



                                                                                          Funded Reserve
                                                                                          03/2028

     Mission Phase D                                   50 mo.                             Mission Reserve            10 mo.
     Subsystem Development, Integration and Test, Launch Prep
                      Payload Phase D                            Observatory
                        Build, I&T                            (Payload + Vehicle)              Mission Phase D2          3 mo.
     Finish Instr.
       Phase D
                         28 months                                                                   Launch/Cruise
                                                                I&T (18 mo.)
                                                           and Launch Prep (4 mo.)
                   Space Vehicle Phase D                                                        Mission Phase E            60 mo.
                        Build, I&T
                         28 months                                 22 months
                                                                                                         Operations
        Instrument Delivery          Payload & Space Vehicle Delivery                Launch     Transition to
              01/2025                            05/2026                             01/2029    Science Operations
                                                                                                05/2029




                                                                    89
                    Table 5.2: ATLAST Key Phase Durations
Project Phase                                         Duration (Months)
Phase A – Conceptual Design                           24 months
Phase B – Preliminary Design                          24 months
Phase C – Detailed Design                             24 months
Phase D – Integration & Test                          50 months
Phase E – Primary Mission Operations                  60 months
Phase F – Extended Mission Operations                 n/a
Start of Phase B to PDR                               24 months
Start of Phase B to CDR                               48 months
Start of Phase B to Delivery of Instrument #1 to #n   60 months
Start of Phase B to Delivery of Spacecraft            51 months
Start of Phase B to Delivery of Observatory           94 months
System Level Integration & Test                       18 months
Project Total Funded Schedule Reserve                 10 months
Total Development Time Phase B - D                    108 months



                   Table 5.3: ATLAST Key Event Dates
Project Phase                                             Milestone Date
Start of Phase A                                      January 2018
Start of Phase B                                      January 2020
Preliminary Design Review (PDR)                       January 2022
Critical Design Review (CDR)                          January 2024
Delivery of Instrument #1 (DoI-1) to DoI-n)           January 2025
System Integration Review (SIR)                       May 2026
Pre-Ship Review (PSR)                                 December 2027
Launch Readiness Date (LRD)                           March 2028
End of Mission – Primary (EoM-P)                      May 2034
End of Mission – Extended (EoM-E)                     n/a




                                       90
6. Cost Section for ATLAST-9.2m

         The IDC at NASA/GSFC estimated the cost for the ATLAST-9.2m in February 2009 using a
combination of grassroots and parametric estimation tools. The IDC study concentrated to a large extent
on technically challenging parts of the mission: the optical telescope assembly, wavefront sensing,
sunshield and thermal design and packaging. Several of the instruments – the Wide field-of-view camera
(WFOV), and the combined fine guidance and wavefront sensor (called a hybrid instrument here), were
studied sufficiently to produce detailed designs, master equipment lists (MELs) and grassroots cost
estimates. The other instruments (the Exoplanet instrument suite: VNC, ExoCam, ExoSpec, the UV IFS
instrument and the TMA MOS) were not studied beyond simple optical design concepts. For these
instruments, the IDC provided an estimate of mass, power, volume and an analogous cost by comparison
to similar space flight instruments on the HST or JWST. Consequently, the concepts for these
instruments are immature and are certainly not optimized. We believe that there are significant gains that
could be made in reducing the mass and size of the hybrid instrument, and also in combining the exo-
planet instruments into a single instrument on a common optical bench. This work is ongoing, but has yet
to be completed.
         In the standard NASA work breakdown structure (WBS), costs for the following WBS elements
were estimated using “mission wraps”, or percentages of hardware costs: WBS 1 (Project management),
WBS 2 (Systems Engineering), WBS 3 (Safety & Mission Assurance) and WBS 11 (Education & Public
Outreach). Costs for WBS 4 (Science/technology), WBS 6 (spacecraft bus), WBS 7 (Mission
Operations), WBS 9 (Ground System), WBS 10 (Systems Integration & Test) were estimated bottoms-up
in a grassroots exercise. The cost of the payload (WBS 5) was estimated from grassroots and parametric
data. Finally, the cost of the launch vehicle (WBS 8) was provided by the IDC as a rough order of
magnitude estimate. The mapping between NASA WBS and the cost elements requested in the “Total
Mission Cost Funding Profile Template” is as follows:

                            Table 6.1: Mission Cost WBS Definitions
                      Mission Cost Template          NASA WBS #
                      element
                      PM/SE/MA                       WBS 1/2/3
                      Instrument PM/SE               WBS 5
                      Instrument A, B, etc           WBS 5
                      Spacecraft including MSI&T     WBS 6 + 10
                      Prelaunch science              WBS 4
                      Ground Data system             WBS 9
                      Launch services                WBS 8
                      MO&DA                          WBS 7
                      Education & Public Outreach    WBS 11

        All costs were originally computed by the IDC in constant FY08$, as requested by NASA HQ for
the Astrophysics Strategic Mission Concept studies. For the tables requested here, we have used an
assumed inflation rate of 3% per year to calculate costs per year in real year dollars and in FY09$.
        The upgraded Delta-IV Heavy launch vehicle with 6.5m outer diameter fairing and lift capacity
of >15,000 kg to earth escape trajectory does not currently exist. ULA indicates that such an upgrade is
within family and could be built with no vehicle or launch pad modifications. However, there is currently
no stated cost for this vehicle. The IDC estimated a cost of $400M (FY08). We have used this estimate
and distributed the total cost over a standard development schedule in the tables below.


                                                   91
Q1. Science Team: As with any NASA flagship mission, the ATLAST-9.2m science team is distributed
throughout the management and hardware development teams. In line with the standard definition of
science development (NASA WBS 4), three primary groups of scientists that manage and direct science
investigations, lead technology demonstrations, and develop algorithms for data analysis are identified.
These include the NASA Project scientists, the scientists on the instrument teams, and the scientists at the
Science Operations Center (STScI). There are 6 NASA Project scientists, about 25 instrument team
scientists (5 scientists per team for 5 instruments), and a group of scientists at STScI that expands from
about 20 at the start of phase A to 100 by launch. After launch, a large number of junior scientists
(graduate students and postdocs) will join the instrument teams to analyze the data. The table below
provides estimates of FTEs and cost by fiscal year for Phases A-E, in constant FY09$. The numbers here
are also contained in the Mission Cost Funding Profile Table. Prior to launch, these costs are book-kept
in the “Pre-launch science” category, and after launch they are contained within the MO&DA program.
This table does not capture the large number of community scientists that will competitively win
observing time on ATLAST-9.2m. A flagship mission such as ATLAST-9.2m will have ~100 – 200
accepted science programs per year, with 500-1000 scientists working on the data. The ATLAST-9.2m
General Observer (GO) program is expected to have funding of about $25M/year (FY09$). This is also
included in the MO&DA program in the Mission Cost Funding Profile Tables.

                            Table 6.2: Scientist FTEs for Phase A-E*
                   Fiscal       Mission          Scientist     Cost                ($M
                   Year         Phase            FTE           FY09)
                          2018              A               26                      5.5
                          2019              A               56                     11.7
                          2020            A/B               60                     12.5
                          2021              B               65                     13.5
                          2022            B/C               70                     14.5
                          2023              C               75                     15.5
                          2024            C/D               80                     16.5
                          2025              D               85                     17.5
                          2026              D               90                     18.5
                          2027              D              100                     20.5
                          2028              D              130                     26.0
                          2029            D/E              155                     28.0
                          2030              E              155                     28.0
                          2031              E              155                     28.0
                          2032              E              155                     28.0
                          2033              E              155                     28.0
                          2034              E               75                      14.
                                * 2018 and 2034 are partial years

Q2. International Partners: As a NASA flagship mission, it is expected that international partners, as
well as industry partners, will play an important role in the development the ATLAST-9.2m. For flagship
missions, such partnerships are created through NASA HQ. The concept studies completed to date do not
include international partners, so the mission costs outlined here and in earlier responses assumed all
development is completed inside the US.




                                                    92
Q3. Phase A: The 24-month Mission Phase A includes the mission analysis and early development of
mission requirements. Accomplishing this requires staffing up essential management, science and
engineering teams, and releasing the Announcements of Opportunity and selecting partners for major
hardware elements including the space vehicle elements, the OTA, and instruments. The schedules for
individual subsystems are accelerated with respect to the mission schedule, so during Mission Phase A,
the OTA, instruments, and space vehicle all complete Phase A, many elements reach a System
Requirements Review, and some subsystems reach the end of Phase B and conduct a Preliminary Design
Review (see Table 6.3).     The robust Technology Development Program enables this schedule by
ensuring all key technologies reach TRL 6 by the start of Phase A. The Phase A cost breakdown is
reported by year and by WBS in the Total Mission Cost Funding Profile Template.

             Table 6.3: Subsystem Milestones Reached During Mission Phase A
                          January 2018 through December 2019

                  Subsystem Milestone                       Date
                  Release of AOs and RFPs                   January 2018
                  Instruments complete Phase A              August 2018
                  Instruments complete Phase B (PDR)        August 2019
                  Space Vehicle Phase A complete            December 2019
                  OTA Phase A complete                      December 2019


Q4-Q5. Mission Funding Profiles. As stated above, the mission funding profiles are provided assuming
only U.S. participation. While it is expected that ATLAST-9.2m will have some international
participation, no formal international partnerships have yet been established.

Changes since RFI#1: In preparing the requested ATLAST-9.2m mission funding profile tables, we
discovered several inadvertent errors in our earlier costing exercises. In addition, after some
consideration, we have increased the cost of Ground System development. The net change is +2.8% over
our earlier cost estimate provided in RFI#1.




                                                 93
     TOTAL ATLAST-9.2m MISSION COST FUNDING PROFILE TEMPLATE – US Only

                   (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                          This is Page 1 of 3                   table continues on next page

            Item                  FY2018     FY2019       FY2020       FY2021   FY2022      FY2023      FY2024

              Cost
Phase A Concept Study*                500         680            174
PM/SE/MA                               76         104            140      154         90          69            58
Instrument PM/SE**                     65          89            123      136         68          45            26
Instrument: OTA, ISS, IC&DH           150         204            281      311        156         104            60
Instrument: FGS/WFSC                   19          26             36       40         20          13             8
Instrument: WFOV camera                42          58             79       90         44          29            17
Instrument: TMA MOS                    16          22             31       34         17          11             7
Instrument: VNC                         9          12             17       19          9           6             4
Instrument: ExoCam                      5           7             10       10          5           4             2
Instrument: ExoSpec                    21          29             39       43         22          14             8
Instrument: UV IFS                     24          34             46       51         25          17            10
Spacecraft including MSI&T             57          77             89       94        114         122           144
Pre-Launch Science                      7          15             16       18         20          21            23
Ground Data Systems Dev.                1           2              3        3          4           4            24
Total Dev. w/o Reserves               494         679            909     1000        593         459           391
Development Reserves                  148         204            272      300        178         138           117
Total A-D Development Cost            642         882           1182     1301        769         596           509
Launch services                         0           0             40       55         56          57            64
MO&DA3                                   0           0             0        0           0           0            0
MO&DA Reserves                           0           0             0        0           0           0            0
Education/Outreach                     0.3         0.4           2.2      2.8         2.9         2.9            3
                     Total Cost    $643M      $883M       $1223M       $1359M    $829M       $657M       $577M


        NOTES:           (*) The Phase A Concept Study costs are included in the rows below it.

                         1. Costs should include all costs including any fee
                         2. MSI&T - Mission System Integration and Test and preparation for operations
                         3. MO&DA - Mission Operations and Data Analysis




                                                     94
     TOTAL ATLAST-9.2m MISSION COST FUNDING PROFILE TEMPLATE – US Only

                   (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                             This is Page 2 of 3                 table continues on next page

            Item                  FY2025     FY2026       FY2027       FY2028   FY2029    FY2030      FY2031

              Cost
Phase A Concept Study*
PM/SE/MA                               55          43          26          15        7            0             0
Instrument PM/SE**                     20          12           0           0        0            0             0
Instrument: OTA, ISS, IC&DH            46          27           0           0        0            0             0
Instrument: FGS/WFSC                    6           4           0           0        0            0             0
Instrument: WFOV camera                13           8           0           0        0            0             0
Instrument: TMA MOS                     5           3           0           0        0            0             0
Instrument: VNC                         3           2           0           0        0            0             0
Instrument: ExoCam                      2           1           0           0        0            0             0
Instrument: ExoSpec                     6           4           0           0        0            0             0
Instrument: UV IFS                      8           5           0           0        0            0             0
Spacecraft including MSI&T            154         135         106          68        0            0             0
Pre-Launch Science                     25          27          31          39        0            0             0
Ground Data Systems Dev.               33          34          36          16       13            0             0
Total Dev. w/o Reserves               375         304         198         138       20            0             0
Development Reserves                  112          91          60          41        6            0             0
Total A-D Development Cost            487         394         258         178       26            0             0
Launch services                        68          74          82          28       64            0             0
MO&DA3                                   0           0             0        0       66         123         125
MO&DA Reserves                           0           0             0        0       20          37          38
Education/Outreach                       3           3             3        3        3           3           3
                     Total Cost    $558M      $471M       $342M        $208M    $178M       $164M      $167M


        NOTES:           (*) The Phase A Concept Study costs are included in the rows below it.

                         4. Costs should include all costs including any fee
                         5. MSI&T - Mission System Integration and Test and preparation for operations
                         6. MO&DA - Mission Operations and Data Analysis




                                                     95
TOTAL ATLAST-9.2m MISSION COST FUNDING PROFILE TEMPLATE – US Only

           (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                             Page 3 of 3

                                                                      Total       Total
              Item                  FY2032    FY2033       FY2034
                                                                    (Real Yr)   (FY2009)
               Cost
  Phase A Concept Study*                                                1354          1070
  PM/SE/MA                               0           0          0        836           623
  Instrument PM/SE**                     0           0          0        584           443
  Instrument: OTA, ISS,
  IC&DH                                  0           0          0       1339          1016
  Instrument: FGS/WFSC                   0           0          0        172           130
  Instrument: WFOV camera                0           0          0        378           286
  Instrument: TMA MOS                    0           0          0        146           111
  Instrument: VNC                        0           0          0         80            61
  Instrument: ExoCam                     0           0          0         46            35
  Instrument: ExoSpec                    0           0          0        187           141
  Instrument: UV IFS                     0           0          0        220           167
  Spacecraft including MSI&T             0           0          0       1158           835
  Pre-Launch Science                     0           0          0        242           172
  Ground Data Systems Dev.               0           0          0        175           123
  Total Dev. w/o Reserves                0           0          0       5562          4143
  Development Reserves                   0           0          0       1668          1243
  Total A-D Development Cost             0           0          0       7231          5386
  Launch services                        0           0          0        585           412
  MO&DA3                               127        129          77        649            401
  MO&DA Reserves                        38         39          23        194            120
  Education/Outreach                     4          4           2         45             30
                       Total Cost   $169M      $172M       $102M     $8704M         $6349M


  NOTES:         (*) The Phase A Concept Study costs are included in the rows below it.

                 7. Costs should include all costs including any fee
                 8. MSI&T - Mission System Integration and Test and preparation for operations
                 9. MO&DA - Mission Operations and Data Analysis




                                             96
7. Cost Section for ATLAST-8m

         The NASA MSFC Engineering Cost Office has generated three cost estimates for large
monolithic space telescopes over the past 2.5 years: first in early 2007 for the initial 6-meter study and
twice this year for the ATLAST-8m study and the Decadal input. In each case, cost was estimated using
a MEL derived from a technical point design produced by the NASA MSFC Advanced Concepts Office
and Optics Office for the Optical Telescope Assembly (including sun shade tube and instrument bay, etc.)
and the Spacecraft (including solar panels, etc.). Detailed optical, structural, mechanical, thermal, ACS
and propulsion engineering analysis were performed. Reports are available upon request. Northrop
provided independent engineering services to cross check the MSFC spacecraft and thermal analysis.
         The MSFC Cost Office generated cost estimate of the ATLAST-8m OTA, FGS, WFS and
Spacecraft using NAFCOM (NASA Air Force Cost Model). Given that a key cost estimating parameter
for NAFCOM is mass and given that the primary mirror is the most massive object in ATLAST-8m,
followed by the structure, ROM quotes were obtained to anchor the cost estimates for these elements. For
the primary mirror blank, two ROM quotes were obtained from Schott Glass for their existing Zerodur
blank ($10M) and from Corning for a new ULE blank ($16M). REOSC provided a ROM quote to
fabricate a blank into a finished mirror with a better than 10 nm rms surface figure for $10 to $15M. This
is consistent with the $20M that Brashear charged to manufacture the Subaru primary mirror and its
mirror cell. And, it is consistent with the approximately $20M that the University of Arizona Mirror Lab
charges to cast a blank, fabricate a mirror and mount it into a cell. Other independent ROM quotes were
obtained for the secondary and tertiary mirrors. The cost of the structure (PM support, optical bench and
head truss, SM spiders and mount) was estimated by NAFCOM at $156M and cross-checked via a ROM
quote of $114M to $140M from ATK. Cost drivers for structure include mass and number of elements.
 Standard percentage 'wraps' were applied to estimate Phase A and PM/SE/MA.
         The costs for the science instrument suite (WFOV, MOS, UV IFS, VNC, Exo-Cam and Exo-
Spec) were incorporated verbatim from the GSFC ATLAST-9.2m study. Other costs incorporated
verbatim from ATLAST-9.2m are: Pre-Launch Science, Ground Data Systems Development, MO&DA,
Education/Outreach and Flight Dynamics. ATLAST-8m could have used standard wraps for Pre-Launch
Science and Education/Public Outreach, but does not wish to ‘short-change’ these areas just because its
OTA concept might be less expensive to implement. Finally, at present the cost for an Ares V launch is
unknown. However, it is expected to cost no more than a Delta IV-H. Therefore, ATLAST-8m assumes
the same launch services cost as ATLAST-9.2m.
         All costs are in Fiscal Year (FY) 2009 dollars based on NASA inflation tables. The cost estimate
includes System Test Hardware and all applicable system integration (wrap) costs. Subsystem costs are
limited to prime contractor incurred, exclusive of fee and those costs outside the scope of the prime
contractor. Subcontractor effort, including fee in support of the prime contractor effort, is considered
prime contractor incurred. Individual subsystem totals contain all hardware costs and engineering and
manufacturing labor costs charged to that subsystem. These totals include all management, engineering,
testing, and assembly functions, including the labor, materials, specific test equipment, and ground
support equipment associated with the integration of the components or assemblies in the subsystem.

Q1. Science Team: As with any NASA flagship mission, the ATLAST-8m science team is distributed
throughout the management and hardware development teams. In line with the standard definition of
science development, three primary groups of scientists that manage and direct science investigations,
lead technology demonstrations, and develop algorithms for data analysis are identified. These include
the NASA Project scientists, the scientists on the instrument teams, and the scientists at the Science
Operations Center (STScI). There are 6 NASA Project scientists, about 25 instrument team scientists (5
scientists per team for 5 instruments), and a group of scientists at STScI that expands from about 20 at the


                                                    97
start of phase A to 100 by launch. After launch, a large number of junior scientists (graduate students
and postdocs) will join the instrument teams to analyze the data. The table below provides estimates of
FTEs and cost by fiscal year for Phases A-E, in constant FY09$. The numbers here are also contained in
the Mission Cost Funding Profile Table. Prior to launch, these costs are book-kept in the “Pre-launch
science” category, and after launch they are contained within the MO&DA program. This table does not
capture the large number of community scientists that will competitively win observing time on
ATLAST-8m. A flagship mission such as ATLAST-8m will have ~100 – 200 accepted science programs
per year, with 500-1000 scientists working on the data. The ATLAST-8m General Observer (GO)
program is expected to have funding of about $25M/year (FY09$). This is also included in the MO&DA
program in the Mission Cost Funding Profile Tables.

                             Table 7.1: Scientist FTEs for Phase A-E*
                     Fiscal Year   Mission Phase Scientist FTE      Cost ($M FY09)
                            2018              A             26                 5.5
                            2019              A             56                11.7
                            2020            A/B             60                12.5
                            2021              B             65                13.5
                            2022            B/C             70                14.5
                            2023              C             75                15.5
                            2024            C/D             80                16.5
                            2025              D             85                17.5
                            2026              D             90                18.5
                            2027              D            100                20.5
                            2028              D            130                26.0
                            2029            D/E            155                28.0
                            2030               E           155                28.0
                            2031               E           155                28.0
                            2032               E           155                28.0
                            2033               E           155                28.0
                            2034               E            75                 14.
                                   * 2018 and 2034 are partial years

Q2. International Partners: As a NASA flagship mission, it is expected that international partners, as
well as industry partners, will play an important role in the development the ATLAST-8m. For example,
Schott Glass in Germany has an existing 8.4 m diameter mirror blank and REOSC in France has an
existing 8 m class optical fabrication capability. Some U.S. based firms capable of fabricating 8 m class
mirrors include Corning Glass in New York, which has the ability to make 8.4 m ULE blanks and
Brashear in Pennsylvania, which has an 8 m optical fabrication capability. For flagship class missions,
international partnerships are established through channels at NASA HQ. It is expected there will be
international partners on ATLAST-8m but as these are not yet established all of the mission costs outlined
here and in earlier responses assume all development is completed inside the U.S.

Q3. Phase A: The 24-month Mission Phase A includes mission analysis and early development of
mission requirements. Accomplishing this requires staffing up essential management, science and
engineering teams; releasing the Announcements of Opportunity; and selecting partners for major
hardware elements including: the space vehicle elements, OTA, and instruments. The schedules for
individual subsystems (OTA, instruments and space vehicle) are accelerated with respect to the mission
schedule. All elements reach a System Requirements Review, and some subsystems reach the end of
Phase B and conduct a Preliminary Design Review (Table 7.2). This schedule assumes a successful Pre-


                                                   98
Phase-A Engineering Risk Reduction Effort to ensure all key technologies (such as the primary mirror
blank) reach TRL 6 by the start of Phase A. The Phase A cost breakdown is reported by year and by
WBS in the Total Mission Cost Funding Profile Template.

             Table 7.2: Subsystem Milestones Reached During Mission Phase A
                          January 2018 through December 2019

                               Subsystem Milestone                  Date
                        Release of AOs and RFPs                January 2018
                        Instruments complete Phase A           August 2018
                        Instruments complete Phase B (PDR)     August 2019
                        Space Vehicle Phase A complete         December 2019
                        OTA Phase A complete                   December 2019


Q4-Q5. Mission Funding Profiles. As stated above, the mission funding profiles are provided assuming
only U.S. participation. While it is expected that ATLAST-8m will have some international participation,
no formal international partnerships have yet been established.

Bottoms-Up Structure Cost Estimate Verification for ATLAST-8m

         MSFC asked ATK, which is the supplier of the JWST flight structure, to give a rough cost
estimate of the ATLAST-8m structure. While NAFCOM estimated the ATLAST-8m structure cost to be
$156M (PM support structure, SM support structure and spiders, and telescope structure less MLI), ATK
has provided a ROM estimate of $114 to $144M with the potential of reducing that cost by $20 to $30M
via targeted technology investments of $2 to $3M.
         The total cost of the JWST Primary Mirror Bench Support Structure (PMBSS) is approximately
$100M. The split between non-recurring cost (engineering and development) and recurring cost (actually
building the article) is approximately $64M to $36M. For JWST, two issues drive non-recurring cost: a
very tight mass margin and cryogenic operation. Both of these issues require extensive engineering
design and analysis. The ATLAST-8m negates both of these concerns because it operates at 280 deg K
and because the Ares V allows for a very health mass margin. ATK estimates that the non-recurring cost
for ATLAST-8m will be in the range of $30M to $40M.
         The PMBSS recurring cost of $36M can be roughly divided between material and billet costs,
component layout labor costs and integration, assembly labor costs and fittings and other miscellaneous
costs. On JWST, material costs and fabrication of the composite billets is a negligible cost. For the
PMBSS, ATK will make approximately 1,200 kg of material at a cost of less than $2M and the touch
labor to layup the components will be approximately $10M. Thus the total cost for the composite
components is approximately $12M. The cost for fittings, machining, in-process testing, etc is
approximately $12M. And, the remaining $12M is the labor to put all the pieces together.
         The JWST PMBSS has approximately 800 significant piece-parts and fittings, excluding gusset
plates, clips, and incidentals. While ATLAST-8m is larger than JWST, it has a similar piece-part count.
 It is estimated that the cost to integrate and assemble ATLAST-8m as well as the cost for fittings,
machining, in-process testing, etc will be approximately the same as for JWST - approximately $24M.
 But, the same is not true for the composite components. ATLAST-8m will use about 10X more material
and maybe 5X more labor to layup the components or $80M. ATK estimates that the total recurrent cost
for ATLAST-8m will be in the range of $84 to $104M.
         There are several potential cost reductions that could be implemented with targeted technology
development efforts. One example is M55J fiber. The cost of M55J fiber is approximately $1,300 per


                                                  99
kg. ATLAST-8m is going to consume probably in excess of 15,000 kg of material worth over $20M.
Aside from the cost, this is more material than the entire space community uses in 5 years. Fortunately,
there are other materials that are available in bulk quantities and only cost $200 per kg. The problem is
that they are not space qualified. Therefore, spending $1.5M to space qualify an alternative material to
M55J could result in a $15M in material cost savings. And, it will mitigate a supply risk. There are other
potential similar cost savings by investing in layup technology improvements.




                                                  100
      TOTAL ATLAST-8m MISSION COST FUNDING PROFILE TEMPLATE – US Only

                   (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                          This is Page 1 of 3                   table continues on next page

            Item                  FY2018     FY2019       FY2020       FY2021   FY2022      FY2023      FY2024

              Cost
Phase A Concept Study*                436         606            167
PM/SE/MA                               64          90            124      138         76          46            26
Instrument PM/SE                       65          89            123      136         68          45            26
Instrument: OTA, IB, IC&DH            120         167            239      267        142          97            62
Instrument: FGS                        10          12             19       22         12           8             5
Instrument: WFS                        12          17             25       28         15          10             6
Instrument: WFOV camera                42          58             79       90         44          29            17
Instrument: TMA MOS                    16          22             31       34         17          11             7
Instrument: VNC                         9          12             17       19          9           6             4
Instrument: ExoCam                      5           7             10       10          5           4             2
Instrument: ExoSpec                    21          29             39       43         22          14             8
Instrument: UV IFS                     24          34             46       51         25          17            10
Spacecraft including MSI&T             40          52             65       72         80          94            83
Pre-Launch Science                      7          15             16       18         20          21            23
Ground Data Systems Dev.                1           2              3        3          4           4            24
Total Dev. w/o Reserves               436         606            836      931        539         406           303
Development Reserves                  130         181            251      279        162         122            91
Total A-D Development Cost            566         787           1087     1210        701         528           394
Launch services                         0           0             40       55         56          57            64
MO&DA3                                   0           0             0        0           0           0            0
MO&DA Reserves                           0           0             0        0           0           0            0
Education/Outreach                     0.3         0.4           2.2      2.8         2.9         2.9            3
                     Total Cost    $567M      $788M $1129M             $1268M    $760M       $588M       $461M


        NOTES:           (*) The Phase A Concept Study costs are included in the rows below it.

                         10. Costs should include all costs including any fee
                         11. MSI&T - Mission System Integration and Test and preparation for operations
                         12. MO&DA - Mission Operations and Data Analysis




                                                    101
      TOTAL ATLAST-8m MISSION COST FUNDING PROFILE TEMPLATE – US Only

                   (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                             This is Page 2 of 3                 table continues on next page

            Item                  FY2025     FY2026       FY2027       FY2028   FY2029    FY2030      FY2031

              Cost
Phase A Concept Study*
PM/SE/MA                               20          14          10           7         5           0             0
Instrument PM/SE                       20          12           0           0         0           0             0
Instrument: OTA, IB, IC&DH             38          26           0           0         0           0             0
Instrument: FGS                         3           2           0           0         0           0             0
Instrument: WFS                         4           3           0           0         0           0             0
Instrument: WFOV camera                13           8           0           0         0           0             0
Instrument: TMA MOS                     5           3           0           0         0           0             0
Instrument: VNC                         3           2           0           0         0           0             0
Instrument: ExoCam                      2           1           0           0         0           0             0
Instrument: ExoSpec                     6           4           0           0         0           0             0
Instrument: UV IFS                      8           5           0           0         0           0             0
Spacecraft including MSI&T             78          80         101          12         0           0             0
Pre-Launch Science                     25          27          31          39         0           0             0
Ground Data Systems Dev.               33          34          36          16        13           0             0
Total Dev. w/o Reserves               258         221         178          74        18           0             0
Development Reserves                   77          66          53          22         5           0             0
Total A-D Development Cost            335         287         231          96        23           0             0
Launch services                        68          74          82          28        64           0             0
MO&DA3                                   0           0             0        0        66        123         125
MO&DA Reserves                           0           0             0        0        20         37          38
Education/Outreach                       3           3             3        3         3          3           3
                     Total Cost    $406M      $364M       $316M        $127M    $176M       $164M      $167M


        NOTES:           (*) The Phase A Concept Study costs are included in the rows below it.

                         13. Costs should include all costs including any fee
                         14. MSI&T - Mission System Integration and Test and preparation for operations
                         15. MO&DA - Mission Operations and Data Analysis




                                                    102
TOTAL ATLAST-8m MISSION COST FUNDING PROFILE TEMPLATE – US Only

          (FY costs1 in Real Year Dollars, Totals in Real Year and 2009 Dollars)
                                            Page 3 of 3

                                                                     Total       Total
             Item                  FY2032    FY2033       FY2034
                                                                   (Real Yr)   (FY2009)
              Cost
 Phase A Concept Study*                                                1209           955
 PM/SE/MA                               0           0          0        620           460
 Instrument PM/SE                       0           0          0        584           443
 Instrument: OTA, IB, C&DH              0           0          0       1158           860
 Instrument: FGS                        0           0          0         93            69
 Instrument: WFS                        0           0          0        120            89
 Instrument: WFOV camera                0           0          0        378           286
 Instrument: TMA MOS                    0           0          0        146           111
 Instrument: VNC                        0           0          0         80            61
 Instrument: ExoCam                     0           0          0         46            35
 Instrument: ExoSpec                    0           0          0        187           141
 Instrument: UV IFS                     0           0          0        220           167
 Spacecraft including MSI&T             0           0          0        757           539
 Pre-Launch Science                     0           0          0        242           172
 Ground Data Systems Dev.               0           0          0        175           123
 Total Dev. w/o Reserves                0           0          0       4806          3556
 Development Reserves                   0           0          0       1442          1067
 Total A-D Development Cost             0           0          0       6248          4623
 Launch services                        0           0          0        585           412
 MO&DA3                               127         129         77        649           401
 MO&DA Reserves                        38          39         23        194           120
 Education/Outreach                     4           4          2         45            30
                      Total Cost   $169M      $172M       $102M     $7721M         $5586M


 NOTES:         (*) The Phase A Concept Study costs are included in the rows below it.

                16. Costs should include all costs including any fee
                17. MSI&T - Mission System Integration and Test and preparation for operations
                18. MO&DA - Mission Operations and Data Analysis




                                            103
Appendix A: Master Equipment Lists

                                  ATLAST-9.2m OTA Master Equipment List

                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component           Composition     Quantity                           Mass                 Maturity
               Description
                                                    Cold         Hot        Total     Mass      Subtotal
Component                                                                                                  Heritage          Mass
                                                   Backup     (operating    flown     each       Mass                 TRL
  type                                                                                                     Missions         source
                                                    units       units)     quantity   (kg)        (kg)

              Optical                                 0!          1!          1!      4241.5!   4241.5     JWST
             Telescope
             Assembly!
                Primary                               0!          1!          1!      1479.3!   1479.3
             Mirror
             Assembly!
                  Primary                             0!          6!          6!       41.1!     246.6
             Mirror (PM)
             Segment A1
             Assembly!
Optical             Primary      ULE; MgFl            0!          1!          1!       26.6!     26.6      JWST        6     CI
             Mirror (PM)         (UV) coating;
             Segment A1!         1309 mm x 1512
                                 mm
                   PM                                 0!          1!          1!       12.5!     12.5      JWST
             Control
             Mechanism !
Mechanical           Whiffle     M55J                 0!          1!          1!       3.9!       3.9                  6     EJ
             Tree Assembly!
                     Bipod                            0!          1!          1!       7.8!       7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!       0.7!       4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!       3.4!       3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!       0.1!       0.2                  6     EJ
             Launch
             Restraint Ball !
Mechanical                       M55J                 0!          1!          1!       0.2!       0.2                  6     EJ
             AThermalizatio
             n Bracket!
                                 M55J                 0!          1!          1!       0.8!       0.8
             Strongback
             Assembly!
Mechanism                        bearing, Steel,      0!          1!          1!       0.7!       0.7                  4     EJ
             Actuator (no        Ti, Lead Screws
             LVDTs)!
Mechanical                       M55J                 0!          1!          1!       0.2!       0.2                  6     EJ
             Actuator
             Mounts!
                    5%                                0!          1!          1!       2.0!       2.0
             misc Hardware!
                  Primary                             0!          6!          6!       41.1!     246.6
             Mirror (PM)
             Segment B1
             Assembly!
Optical            Primary       ULE; MgFl            0!          1!          1!       26.6!     26.6      JWST        6      C
             Mirror (PM)         (UV) coating;
             Segment B1!         1309 mm x
                                 1512mm




                                                              104
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component           Composition     Quantity                           Mass               Maturity
               Description
                                                    Cold         Hot        Total     Mass    Subtotal
Component                                                                                                Heritage          Mass
                                                   Backup     (operating    flown     each     Mass                 TRL
  type                                                                                                   Missions         source
                                                    units       units)     quantity   (kg)      (kg)
             PM Control                              0            1            1      12.5     12.5      JWST
             Mechanism
Mechanical          Whiffle      M55J                 0!          1!          1!      3.9!      3.9                  6     EJ
             Tree Assembly!
                   Bipod                              0!          1!          1!      7.8!      7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!      0.7!      4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!      3.4!      3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!      0.1!      0.2                  6     EJ
             Launch
             Restraint Ball !
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             AThermalizatio
             n Bracket!
                                 M55J                 0!          1!          1!      0.8!      0.8
             Strongback
             Assembly!
Mechanism                        bearing, Steel,      0!          1!          1!      0.7!      0.7                  4     EJ
             Actuator (no        Ti, Lead Screws
             LVDTs)!
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             Actuator
             Mounts!
                    5%                                0!          1!          1!      2.0!      2.0
             misc Hardware!
                  Primary                             0!          6!          6!      41.1!    246.6
             Mirror (PM)
             Segment B2
             Assembly!
Optical            Primary       ULE; MgFl            0!          1!          1!      26.6!    26.6      JWST        6      C
             Mirror (PM)         (UV) coating;
             Segment B2!         1309 mm x
                                 1512mm
                   PM                                 0!          1!          1!      12.5!    12.5      JWST
             Control
             Mechanism !
Mechanical           Whiffle     M55J                 0!          1!          1!      3.9!      3.9                  6     EJ
             Tree Assembly!
                   Bipod                              0!          1!          1!      7.8!      7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!      0.7!      4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!      3.4!      3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!      0.1!      0.2                  6     EJ
             Launch
             Restraint Ball !
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             AThermalizatio
             n Bracket!




                                                              105
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component           Composition     Quantity                           Mass               Maturity
               Description
                                                    Cold         Hot        Total     Mass    Subtotal
Component                                                                                                Heritage          Mass
                                                   Backup     (operating    flown     each     Mass                 TRL
  type                                                                                                   Missions         source
                                                    units       units)     quantity   (kg)      (kg)
             Strongback          M55J                0            1            1       0.8       0.8
             Assembly!
Mechanism                        bearing, Steel,      0!          1!          1!      0.7!      0.7                  4     EJ
             Actuator (no        Ti, Lead Screws
             LVDTs)!
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             Actuator
             Mounts!
                    5%                                0!          1!          1!      2.0!      2.0
             misc Hardware!
                  Primary                             0!          6!          6!      41.1!    246.6
             Mirror (PM)
             Segment C1
             Assembly!
Optical            Primary       ULE; MgFl            0!          1!          1!      26.6!    26.6      JWST        6      C
             Mirror (PM)         (UV) coating;
             Segment C1!         1309 mm x
                                 1512mm
                   PM                                 0!          1!          1!      12.5!    12.5      JWST
             Control
             Mechanism !
Mechanical           Whiffle     M55J                 0!          1!          1!      3.9!      3.9                  6     EJ
             Tree Assembly!
                   Bipod                              0!          1!          1!      7.8!      7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!      0.7!      4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!      3.4!      3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!      0.1!      0.2                  6     EJ
             Launch
             Restraint Ball !
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             AThermalizatio
             n Bracket!
                                 M55J                 0!          1!          1!      0.8!      0.8
             Strongback
             Assembly!
Mechanism                        bearing, Steel,      0!          1!          1!      0.7!      0.7                  4     EJ
             Actuator (no        Ti, Lead Screws
             LVDTs)!
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             Actuator
             Mounts!
                   5% misc                            0!          1!          1!      2.0!      2.0
             Hardware!
                  Primary                             0!          6!          6!      41.1!    246.6
             Mirror (PM)
             Segment C2
             Assembly!
Optical            Primary       ULE; MgFl            0!          1!          1!      26.6!    26.6      JWST        6      C
             Mirror (PM)         (UV) coating;
             Segment C2!         1309 mm x
                                 1512mm




                                                              106
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component           Composition     Quantity                           Mass               Maturity
               Description
                                                    Cold         Hot        Total     Mass    Subtotal
Component                                                                                                Heritage          Mass
                                                   Backup     (operating    flown     each     Mass                 TRL
  type                                                                                                   Missions         source
                                                    units       units)     quantity   (kg)      (kg)
                   PM                                0!           1!           1!     12.5!    12.5      JWST
             Control
             Mechanism !
Mechanical   Whiffle Tree        M55J                 0           1           1       3.9       3.9                  6     EJ
             Assembly
                   Bipod                              0!          1!          1!      7.8!      7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!      0.7!      4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!      3.4!      3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!      0.1!      0.2                  6     EJ
             Launch
             Restraint Ball !
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             AThermalizatio
             n Bracket!
                                 M55J                 0!          1!          1!      0.8!      0.8
             Strongback
             Assembly!
Mechanism                        bearing, Steel,      0!          1!          1!      0.7!      0.7                  4     EJ
             Actuator (no        Ti, Lead Screws
             LVDTs)!
Mechanical                       M55J                 0!          1!          1!      0.2!      0.2                  6     EJ
             Actuator
             Mounts!
                   5% misc                            0!          1!          1!      2.0!      2.0
             Hardware!
                  Primary                             0!          6!          6!      41.1!    246.6
             Mirror (PM)
             Segment C3
             assembly!
Optical            Primary       ULE; MgFl            0!          1!          1!      26.6!    26.6      JWST        6      C
             Mirror (PM)         (UV) coating;
             Segment C3!         1309 mm x
                                 1512mm

                   PM                                 0!          1!          1!      12.5!    12.5      JWST
             Control
             Mechanism !
Mechanical           Whiffle     M55J                 0!          1!          1!      3.9!      3.9                  6     EJ
             Tree Assembly!
                   Bipod                              0!          1!          1!      7.8!      7.8
             Assembly!
Mechanism                        bearing, Steel,      0!          6!          6!      0.7!      4.0                  4     EJ
             Actuator            Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical               Delta   M55J                 0!          1!          1!      3.4!      3.4                  6     EJ
             Frame!
Mechanism                        Steel                0!          3!          3!      0.1!      0.2                  6     EJ
             Launch
             Restraint Ball !




                                                              107
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component        Composition       Quantity                           Mass                Maturity
               Description
                                                   Cold         Hot        Total     Mass     Subtotal
Component                                                                                                Heritage          Mass
                                                  Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                   Missions         source
                                                   units       units)     quantity   (kg)       (kg)
Mechanical                    M55J                  0!           1!           1!      0.2!       0.2                 6     EJ
             AThermalizatio
             n Bracket!
                              M55J                   0!          1!          1!       0.8!      0.8
             Strongback
             Assembly!
Mechanism                     bearing, Steel,        0!          1!          1!       0.7!      0.7                  4     EJ
             Actuator (no     Ti, Lead Screws
             LVDTs)!
Mechanical                    M55J                   0!          1!          1!       0.2!      0.2                  6     EJ
             Actuator
             Mounts!
                   5% misc                           0!          1!          1!       2.0!      2.0
             Hardware!
                PM                                   0!          1!          1!      750.5!    750.5
             Backplane
             Assembly!
Mechanism         PM          60% Analog;            0!         37!         37!       4.4!     161.7     JWST        6     EJ
             Multiplexer      40% digital
             Unit Side
             A/Side B!
Mechanical        PM          composite tubes;       0!          1!          1!      261.0!    261.0     JWST        6      C
             Center           wall t=0.1250"
             Backplane!
                  PM                                 0!          2!          2!      141.5!    283.0
             Chord
             Backplane
             Assembly!
Mechanical          PM        composite tubes;       0!          1!          1!      130.5!    130.5     JWST        6      C
             Chord            wall t=0.1250"
             Backplane !
                     PM                              0           1           1!      11.0      11.0
             Chord
             Deployment
             Mechanism!
Mechanism                     NEA Device             0           4           4!       0.5       2.0      JWST        7     EJ
             Launch
             Restraint
             Mechanism!
Mechanism                     Motor, Bearing,        0           1           1!       3.0       3.0      JWST        6     EJ
             Drive Hinge!     Hinge, Sensor;
                              Steel, Ti
Mechanism                     Bearing, Hinge,        0           1           1!       2.0       2.0      JWST        6     EJ
             Passive Hinge!   Sensor; Steel, Ti
Mechanism                     Motor, Bearing,        0           4           4!       1.0       4.0      JWST        6     EJ
             Latch Preload    Steel Crawl
             Devices!
Electrical         Junction   50% Analog,            0           2           2!       4.5       9.1      JWST        6     EJ
             Box internally   50% Digital
             redundant!
                   5% misc                           0           1           1!      35.7      35.7
             Hardware!
                Primary                              0           1           1!      242.9     242.9
             Mirror Baffle
             Assembly!
Mechanical          PM        MLI                    0           1           1!       2.0       2.0                  6     EJ
             Baffle!




                                                             108
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component          Composition     Quantity                           Mass                Maturity
               Description
                                                   Cold         Hot        Total     Mass     Subtotal
Component                                                                                                Heritage          Mass
                                                  Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                   Missions         source
                                                   units       units)     quantity   (kg)       (kg)
Mechanical          PM          Composite; t        0            1            1!      8.0        8.0                 6     EJ
             Baffle !           =0.1250"
                    PM                               0           1           1!      225.0     225.0     SRTM
             Baffle
             Deployment
             Mechanism - !
Mechanism                       ATK                  0           1           1!      220.0     220.0                 6     EJ
             ADAM Boom
             Mast!
Mechanism                                            0           1           1!       5.0       5.0                  6     EJ
             Brushless DC
             Motor!
Electrical                      60% Analog;          0           1           1!       4.4       4.4      JWST        6     EJ
             Multiplexer        40% digital
             Unit internally
             redundant!
                    5% misc                          0           1           1!      11.6      11.6
             Hardware!
                Secondary                            0!          1!          1!      68.5!     68.5
             Mirror
             Assembly!
Optical                         ULE, MgFl            0!          1!          1!      14.6!     14.6      JWST        6      C
             Secondary          Coating
             Mirror !
                  SM            same as PM           0!          1!          1!      11.7!     11.7      JWST       2-3    EJ
             Control            Control
             Mechanism !        Mechanism
Mechanical            Whiffle   M55J                 0!          1!          1!       3.9!      3.9      JWST        6     EJ
             Tree Assembly!
                   Bipod                             0!          1!          1!       7.8!      7.8
             Assembly!
Mechanism                       bearing, Steel,      0!          6!          6!       0.7!      4.0      JWST        4     EJ
             Actuator           Ti, Lead Screws
             (contains
             LVDTs)!
Mechanical   Delta Frame!       M55J                 0!          1!          1!       3.4!      3.4      JWST        6     EJ


Mechanism    Launch             Steel                0!          3!          3!       0.1!      0.2      JWST        6     EJ
             Restraint Ball !
Mechanical   AThermalizatio     M55J                 0!          1!          1!       0.2!      0.2      JWST        6     EJ
             n Bracket!
Mechanical        SM            Composite; t         0!          1!          1!      34.5!     34.5      JWST        6      C
             Baffle!            =0.1250"
                                (L=1.1M)
Electrical                      60% Analog;          0           1           1!       4.4       4.4      JWST        6     EJ
             Multiplexer        40% digital
             Unit internally
             redundant!
                   5% misc                           0!          1!          1!       3.3!      3.3
             Hardware!
                 Secondary                           0!          1!          1!      140.9!    140.9
             Metering
             Assembly!
             Secondary                               0!          1!          1!      119.7!    119.7
             Metering
             Structure!




                                                             109
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component            Composition    Quantity                           Mass                Maturity
               Description
                                                    Cold         Hot        Total     Mass     Subtotal
Component                                                                                                 Heritage          Mass
                                                   Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                    Missions         source
                                                    units       units)     quantity   (kg)       (kg)
Mechanical           "A"       Composite tubes;      0!           1!           1!     50.6!     50.6      JWST        6      C
             Beam!             wall t=0.125"
Mechanical                     Composite tubes;       0!          2!          2!      15.0!     30.0      JWST        6      C
             Folding Beam !    wall t=0.125"
Mechanical                     Composite;             0!          1!          1!      19.1!     19.1      JWST        6      C
             Mount Panel!      t=0.1250"
Mechanical                     Ti                     0!          4!          4!       5.0!     20.0      JWST        6      C
             Metering
             Tower Mounts!
                    SM                                0!          1!          1!      14.5!     14.5
             Metering
             Structure
             Deployment
             Mechanism!
Mechanism                      NEA Device             0           3           3!       0.5       1.5      JWST        7     EJ
             Launch
             Restraint
             Mechanism!
Mechanism                      Motor, Bearing,        0           1           1!       3.0       3.0      JWST        6     EJ
             Inboard Drive     Hinge, Sensor;
             Hinge!            Steel, Ti
Mechanism                      Bearing, Hinge,        0           1           1!       2.0       2.0      JWST        6     EJ
             Outboard          Sensor; Steel, Ti
             Passive Hinge!
Mechanism                      Bearing, Hinge,        0           2           2!       2.0       4.0      JWST        6     EJ
             Dual Hinges!      Sensor; Steel, Ti
Mechanism                                             0           3           3!       1.0       3.0      JWST        6     EJ
             MagneticTuned
             Mass Dampers!
Mechanism               Mid    Motor, Bearing,        0           1           1!       1.0       1.0      JWST        6     EJ
             Hinge (latch) !   Steel Crawl
                  5% misc                             0!          1!          1!       6.7!      6.7
             Hardware!
Electrical       Actuator      80% analog;            1           1           2!      21.0      42.0      JWST        6     EJ
             Drive Unit        20% Digital;
             (ADU)             381mmx279mm
             internally        x229mm
             redundant Box
             -including
             2mech board; 1
             thermal board;
             1 housekeeping
             board, 1 LVPS
             board and
             enclosure!
                OTA                                    !          1!          1!      451.0!    451.0
             Support
             Structure!
Mechanical        Lower        Composite tubes;        !          1!          1!      14.7!     14.7                  6      C
             OTA Support       wall t=0.1250"
             Frame!
Mechanical        Lower        Composite tubes;        !          1!          1!      137.0!    137.0                 6      C
             Support           wall t=0.1250"
             Structure!
Mechanical        Support      composite tubes;        !          2!          2!      136.2!    272.4                 6      C
             Panels !          wall t=0.1250"




                                                              110
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component         Composition     Quantity                           Mass                Maturity
               Description
                                                  Cold         Hot        Total     Mass     Subtotal
Component                                                                                               Heritage          Mass
                                                 Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                  Missions         source
                                                  units       units)     quantity   (kg)       (kg)
Mechanical        Flexure      composite; wall      !           1!           1!      5.4!       5.4                 6      C
             Interface Box !   t=0.1250"
                 5% misc                             !          1!          1!      21.5!     21.5
             Hardware!
                AFT Optics                           !          1!          1!      232.8!    232.8
             Subassembly!
                  Fold                               !          1!          1!      34.5!     34.5
             Mirror 1/ M3
             Assembly!
Optical            Fold        ULE                   !          1!          1!      26.9!     26.9      GSFC        6      C
             Mirror 1/ M3 !
Mechanical         Fold        h/c panel;            !          2!          2!       2.3!      4.6                  6      C
             Mirror 1/ M3      1"alum core;
             Mount!            0.040"
                               composite f/s
Mechanical          Fold       h/c panel;            !          1!          1!       1.4!      1.4                  6      C
             Mirror 1/ M3      1"alum core;
             Brace!            0.040"
                               composite f/s
                  5% misc                            !          1!          1!       1.6!      1.6
             Hardware!
                 Tertiary                            !          1!          1!      70.1!     70.1
             Mirror/M4
             Assembly!
Optical            Tertiary    ULE, Silver           !          1!          1!      59.4!     59.4      GSFC        6      C
             Mirror/M4!        Coating
Mechanical         Tertiary    h/c panel;            !          2!          2!       2.5!      4.9                  6      C
             Mirror/M4         1"alum core;
             Mount!            0.040"
                               composite f/s
Mechanical         Tertiary    h/c panel;            !          1!          1!       2.5!      2.5                  6      C
             Mirror/M4         1"alum core;
             Brace!            0.040"
                               composite f/s
                  5% misc                            !          1!          1!       3.3!      3.3
             Hardware!
                 Pupil                               !          1!          1!       2.2!      2.2
             Mirror/M5
             Assembly!
Optical            Pupil       ULE, Silver           !          1!          1!       0.4!      0.4      GSFC        6      C
             Mirror/M5!        Coating
Mechanical         Pupil       h/c panel;            !          2!          2!       0.7!      1.3                  6      C
             Mirror/M5         1"alum core;
             Mount!            0.040"
                               composite f/s
Mechanical         Pupil       h/c panel;            !          1!          1!       0.4!      0.4                  6      C
             Mirror/M5         1"alum core;
             Cross Member!     0.040"
                               composite f/s
                  5% misc                            !          1!          1!       0.1!      0.1
             Hardware!
                 Fold                                !          1!          1!       1.9!      1.9
             Mirror
             2A//M6A
             Assembly!




                                                            111
                 ATLAST-9.2m Optical Telescope Assembly Master Equipment List
               Subsystem/
               Component         Composition      Quantity                           Mass                Maturity
               Description
                                                   Cold         Hot        Total     Mass     Subtotal
Component                                                                                                Heritage          Mass
                                                  Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                   Missions         source
                                                   units       units)     quantity   (kg)       (kg)
Optical            Fold        ULE                   !           1!           1!      1.4!       1.4     Orbital     6      C
             Mirror 2A !
Mechanical         Fold        h/c panel;             !          2!          2!       0.2!      0.4                  6      C
             Mirror 2A         1"alum core;
             Mount!            0.040"
                               composite f/s
                  5% misc                             !          1!          1!       0.1!      0.1
             Hardware!
                 Fold                                 !          1!          1!       5.1!      5.1
             Mirror 2B/M6B
             Assembly!
Optical            Fold        ULE                    !          1!          1!       1.4!      1.4      Orbital     6      C
             Mirror 2B/M6!
Mechanical         Fold        h/c panel;             !          1!          1!       3.4!      3.4                  6      C
             Mirror 2B/M6      1"alum core;
             Mount!            0.040"
                               composite f/s
                  5% misc                             !          1!          1!       0.2!      0.2
             Hardware!
                  AOS                                 !          1!          1!      119.1!    119.1
             Structure!
Mechanical         AOS         h/c panel; 2"          !          1!          1!      21.9!     21.9                  6      C
             Optical Bench!    alum core;
                               0.060" compisite
                               f/s
Mechanical         AOS         Ti                     !          3!          3!       0.5!      1.5                  6      C
             Flexures!
Mechanical        AOS          M55J                   !          1!          1!      90.0!     90.0
             Enclosure !
                  5% misc                             !          1!          1!       5.7!      5.7
             Hardware!
                OTA                                   !          1!          1!      564.2!    564.2!
             Thermal
             Subsystem!
Thermal           OTA          33 m2, 0254 cm         !          1           1!      228.0     228.0                 7     EJ
             Center Heater     thick Al
             Panel !
Thermal           OTA Side     16.5 m2, 0254          !          2!          2!      114.0     228.0                 7     EJ
             Heater Panels !   cm thick Al
Thermal           OTA          3 m long; 2.8575       !         64!         64!       1.5      96.0                  7     EJ
             Heat Pipes for    cm diam.;
             Center Heater     aluminum;
             Panel!            ammonia
Thermal           OTA                                 !          8!          8!       4.6      36.8                  7     EJ
             Propylene Loop
             Heat Pipes
             from Center
             Heater Panel to
             Side Heater
             Panels!
Thermal           MLI          14 m2                  !          1!          1!       8.4       8.4                  9     EJ
             Closeout
             between
             Primary Mirror
             and Heater
             Panels !



                                                             112
                ATLAST-9.2m Optical Telescope Assembly Master Equipment List
              Subsystem/
              Component           Composition      Quantity                           Mass                Maturity
              Description
                                                    Cold         Hot        Total     Mass     Subtotal
Component                                                                                                 Heritage          Mass
                                                   Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                    Missions         source
                                                    units       units)     quantity   (kg)       (kg)
Thermal          MLI on         15-Layers; 45         !           1!           1!     27.0      27.0                  9     EJ
            Heater Panels !     m2
Thermal           MLI           15-Layers; 20          !          1!          1!      12.0      12.0                  9     EJ
            Thermal             m2
            Tunnel between
            ISIM and
            Heater Panel !
Thermal           MLI on        15-Layers; 28          !          1!          1!      16.8      16.8                  9     EJ
            Secondary           m2
            Mirror
            Enclosure !
Thermal           MLI on        15-Layers; 4.3         !          3!          3!       2.6       7.7                  9     EJ
            Secondary           m2
            Mirror Support
            Struts !
Thermal           MLI on        15-Layers; 36.6        !          1!          1!      22.0      22.0                  9     EJ
            Central Baffle !    m2
Thermal          OTA            Kapton Film 67         !         190!        190!      0.3      57.0                  9     EJ
            Operating           cm x 78 cm
            Mode Heaters
            (redundancy
            included) -- !
Thermal          OTA                                   !         232!        232!      0.0       0.2                  9     EJ
            Thermistors for
            Heater
            Controllers
            (redundancy
            included)!
Thermal          OTA            Kapton Film            !         250!        250!      0.0       4.5                  9     EJ
            Survival            16.5 cm x 19.2
            Heaters             cm
            (redundancy
            included) !
Thermal          OTA                                   !         140!        140!      0.0       0.8                  9     EJ
            Survival
            Thermostats
            (ADU,
            Multiplexers,
            Mechanisms,
            loop heat pipes)!
Thermal           Z307                                 !          1!          1!       9.2       9.2                  9     EJ
            Black Paint on
            Primary Mirror
            Backside and
            Heater Panels
            (200 m2)!
                  5% misc                                         1           1!      37.7      37.7
            Hardware!
Harness        Harness!                               0!          1!          1!      267.2!    267.2


Harness        ICDH to          1.5 M                 0!          2!          2!       0.8!      1.5                  6     EJ
            ADU Side A/B!
Harness          ADU to         0.5 M                 0!          4!          4!       0.3!      1.0                  6     EJ
            Junction Boxes
            SideA/B!
Harness          Junction       7 meters average      0!         72!         72!       3.5!     252.0                 6     EJ
            Boxes to
            Muxes !




                                                              113
                ATLAST-9.2m Optical Telescope Assembly Master Equipment List
              Subsystem/
              Component       Composition   Quantity                           Mass               Maturity
              Description
                                             Cold         Hot        Total     Mass    Subtotal
Component                                                                                         Heritage          Mass
                                            Backup     (operating    flown     each     Mass                 TRL
  type                                                                                            Missions         source
                                             units       units)     quantity   (kg)      (kg)
                5% misc                        !           1!           1!     12.7!    12.7                  6     EJ
            Hardware!
                                                !          1!          1!      2.1       2.1
            Contamination !


* MEL assembled by Integrated Design Center at NASA/Goddard Space Flight Center
  Mass Source: Model (c), Engineering Judgement (EJ) or weighed (w), Customer input (CI)




                                                       114
                      ATLAST 9.2 m Hybrid WFS&C/FGS Master Equipment List

             ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                Subsystem/
                Component           Composition       Quantity                           Mass                Maturity
                Description
                                                       Cold         Hot        Total     Mass     Subtotal
Component                                                                                                    Heritage          Mass
                                                      Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                       Missions         source
                                                       units       units)     quantity   (kg)       (kg)

!              FGS/WFS &C                                0           1           1!      1316.5   1316.5     !           !
              Instrument +
              Harness !
!               FGS/WFS&C                                1           3           4!      323.88   1295.5     !           !
              Instrument
              Assembly less
              Harness !
                 Pick-off                                0           1           1!      1.475     1.475
              Mirror
              Assembly!
Optical            Pick-off       Glass; Silver          0           1           1!      1.105     1.105                 6     EJ
              Mirror !            Coating
Mechanical         Pick-off       M55J                   0           1           1!      0.300     0.300                 6     EJ
              Mirror Mount!
                   5% misc                               0           1           1!      0.070     0.070
              Hardware!
Optical          PDI LED !        Glass                  0           4           4!      0.001     0.004                 6     EJ
Mechanism        PDI              M55J                   0           4           4!      0.050     0.200                 6     EJ
              Pinhole/mounts!
                 Star Select                             0           1           1!      9.707     9.707
              Mirror /
              Mechanism
              (Tip/Tilt)!
                   Star Select                           0           1           1!      0.257     0.257
              Mirror
              Assembly!
Optical              Star         Glass; Silver          0           1           1!      0.045     0.045                 6     EJ
              Select Mirror!      Coating
Mechanical           Star         M55J                   0           1           1!      0.200     0.200                 6     EJ
              Select Mirror
              Mount!
                     5% misc                             0           1           1!      0.012     0.012
              Hardware!
                   Star Select                           0           1           1!      9.450     9.450
              Mirror
              Mechanism
              (Tip/Tilt)!
Mechanism            Acuators !   Stainless Steel,       0           1           1!      7.000     7.000                 6     EJ
                                  Al, Cu
Mechanism           Structure!    Ti, Al, Stainless      0           1           1!      2.000     2.000                 6     EJ
                                  Steel
                   5% misc                               0           1           1!      0.450     0.450
              Hardware!
                Collimator                               0           1           1!      1.155     1.155
              Assembly!
Optical           Lens 1!         SF57                   0           1           1!      0.184     0.184                 6     EJ
Mechanical        Lens 1          M55J                   0           1           1!      0.200     0.200                 6     EJ
              Mount!
Optical           Lens 2!         LAK8                   0           1           1!      0.134     0.134                 6     EJ
Mechanical        Lens 2          M55J                   0           1           1!      0.200     0.200                 6     EJ
              Mount!
Optical           Lens 3!         PK51A                  0           1           1!      0.182     0.182                 6     EJ



                                                                 115
             ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                Subsystem/
                Component              Composition   Quantity                           Mass                 Maturity
                Description
                                                      Cold         Hot        Total     Mass      Subtotal
Component                                                                                                    Heritage          Mass
                                                     Backup     (operating    flown     each       Mass                 TRL
  type                                                                                                       Missions         source
                                                      units       units)     quantity    (kg)       (kg)
Mechanical         Lens 3         M55J                 0            1            1!     0.200      0.200                 6     EJ
              Mount!
                  5% misc                               0           1           1!      0.055      0.055
              Hardware !
                Fold Mirror                             0           1           1!      0.257      0.257
              Assembly!
Optical           Fold Mirror!    Glass, Silver         0           1           1!      0.045      0.045                 6     EJ
                                  Coating
Mechanical         Fold Mirror    M55J                  0           1           1!      0.200      0.200                 6     EJ
              Mount!
                  5% misc                               0           1           1!      0.012      0.012
              Hardware !
                 WFS                                    0           1           1!      77.960    77.960
              Channel 1!
                  60/40 Beam                            0           1           1!      0.257      0.257
              Splitter
              Assembly!
Optical             60/40         Silica                0           1           1!      0.045      0.045                 6     EJ
              Beam Splitter !
Mechanical          60/40         M55J                  0           1           1!      0.200      0.200                 6     EJ
              Beam Splitter
              Mount!
                    5% misc                             0           1           1!      0.012      0.012
              Hareware !
!                  Filter Wheel                         0           1           1!      74.197!   74.197     !           !       !
              Assembly!
Mechanism!           Filter!                            0          24          24!      0.111!     2.664     !           6!    EJ
Mechanism!           Optic        Ti                    0           1           1!      5.000!     5.000     !           6!    EJ
              Cells !
Mechanism!           DC Motor !                         0           1           1!      10.000!   10.000     !           6!    EJ
Mechanism!          Bearings !    Stainless Steel       0           1           1!      4.000!     4.000     !           6!    EJ
Mechanism!          Wheels !      Al                    0           1           1!      20.000!   20.000     !           6!    EJ
Mechanism!          Structure!    Al                    0           1           1!      20.000!   20.000     !           6!    EJ
Mechanism!          Mount         Ti                    0           1           1!      9.000!     9.000     !           6!    EJ
              Plate !
!                    5% misc                            0           1           1!      3.533!     3.533     !           !       !
              Hardware!
                   Imaging                              0           1           1!      0.961      0.961
              Lens Assembly!
Optical             Imaging       PK51A                 0           1           1!      0.249      0.249                 6     EJ
              Lens 1!
Optical             Imaging       LAK8                  0           1           1!      0.199      0.199                 6     EJ
              Lens 2!
Optical             Imaging       SF57                  0           1           1!      0.267      0.267                 6     EJ
              Lens 3!
Mechanical          Imaging       M55J                  0           1           1!      0.200      0.200                 6     EJ
              Lens Mount!
                    5% misc                             0           1           1!      0.046      0.046
              Hardware!
!                  WFS-1          4.5um for 5.6         0           1           1!      0.024      0.024     !           !       !
              Detector (CCD)      mas/pixel
              Assembly!
Detector!           WFS-1         Silicon 2k X 2k       0           1           1!      0.0002     0.000     !           5!    EJ
              Detector (CCD)
              - 4.5um pixel!
Detector!           WFS-1         Molybdenum            0           1           1!      0.023      0.023     !           5!    EJ
              Detector Mount!




                                                                116
              ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                 Subsystem/
                 Component         Composition       Quantity                           Mass                Maturity
                 Description
                                                      Cold         Hot        Total     Mass     Subtotal
Component                                                                                                   Heritage          Mass
                                                     Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                      Missions         source
                                                      units       units)     quantity    (kg)      (kg)
!                    5% misc                           0            1            1!     0.001     0.001     !           5!    EJ
               Hardware!
!                  Sidecar+                             0           1           1!      2.520     2.520     !           !       !
               Assembly!
Electrical!           Sidecar    100% Analog            0           1           1!      1.000     1.000     !           6!    EJ!
               ASIC +            electronics:
               Electronics (1    clocks and biases
               board)
Mechanical!          Housing!    Al                     0           1           1!      1.400     1.400     !           6!    EJ!
!                   5% misc                             0           1           1!      0.120     0.120     !           !       !
               Hardware!
                 FGS Channel!                           0           1           1!      3.947     3.947
                  1/3 / 2/3                             0           1           1!      0.305     0.305
               Beam Splitter
               Assembly!
Optical             1/3 / 2/3    Silica                 0           1           1!      0.090     0.090                 6     EJ
               Beam Splitter !
Mechanical          1/3 / 2/3    M55J                   0           1           1!      0.200     0.200                 6     EJ
               Beam Splitter
               Mount!
                    5% misc                             0           1           1!      0.015     0.015
               Hardware!
                  Imaging                               0           1           1!      0.961     0.961
               Lens Assembly!
Optical              Imaging     PK51A                  0           1           1!      0.249     0.249                 6     EJ
               Lens 1!
Optical              Imaging     LAK8                   0           1           1!      0.199     0.199                 6     EJ
               Lens 2!
Optical              Imaging     SF57                   0           1           1!      0.267     0.267                 6     EJ
               Lens 3!
Mechanical           Imaging     M55J                   0           1           1!      0.200     0.200                 6     EJ
               Lens Mount!
                     5% misc                            0           1           1!      0.046     0.046
               Hardware!
                  FGS            12um for 15            0           1           1!      0.162     0.162
               Detector (CCD)    mas/pixel;
               Assembly !        3x5x1cm3
Detector            FGS          Silicon 2k X 2k        0           1           1!      0.001     0.001                 5     EJ
               Detector (CCD)
               -12um pixel!
Mechanical          FGS CCD      Molybdenum             0           1           1!      0.153     0.153                 5     EJ
               Mount!
                    5% misc                             0           1           1!      0.008     0.008                 6     EJ
               Hardware!
!                  Sidecar+                             0           1           1!      2.520     2.520     !           !       !
               Assembly!
Electrical!            Sidecar   100% Analog            0           1           1!      1.000     1.000     !           6!    EJ!
               ASIC +            electronics:
               Electronics (1    clocks and biases
               board)
Mechanical!           Housing!   Al                     0           1           1!      1.400     1.400     !           6!    EJ!
!                   5% misc                             0           1           1!      0.120     0.120     !           !       !
               Hardware!
                  WFS                                   0           1           1!      84.065   84.065                         !
               Channel 2!
                   Fold Mirror                          0           1           1!      0.257     0.257                         !
               assembly!
Optical             Fold         Glass                  0           1           1!      0.045     0.045                 6     EJ!
               Mirror!



                                                                117
             ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                Subsystem/
                Component               Composition   Quantity                           Mass                 Maturity
                Description
                                                       Cold         Hot        Total     Mass      Subtotal
Component                                                                                                     Heritage          Mass
                                                      Backup     (operating    flown     each       Mass                 TRL
  type                                                                                                        Missions         source
                                                       units       units)     quantity    (kg)       (kg)
Mechanical         Fold            M55J                 0            1            1!     0.200      0.200                 6     EJ!
              Mirror Mount!
                   5% misc                               0           1           1!      0.012      0.012                         !
              Hardware!
!                 Filter Wheel                           0           1           1!      74.197!   74.197     !           !       !
              Assembly!
Mechanism!          Filter!                              0          24          24!      0.111!     2.664     !           6!    EJ
Mechanism!           Optic         Ti                    0           1           1!      5.000!     5.000     !           6!    EJ
              Cells !
Mechanism!           DC Motor !                          0           1           1!      10.000!   10.000     !           6!    EJ
Mechanism!          Bearings !     Stainless Steel       0           1           1!      4.000!     4.000     !           6!    EJ
Mechanism!          Wheels !       Al                    0           1           1!      20.000!   20.000     !           6!    EJ
Mechanism!          Structure!     Al                    0           1           1!      20.000!   20.000     !           6!    EJ
Mechanism!            Mount        Ti                    0           1           1!      9.000!     9.000     !           6!    EJ
              Plate !
!                    5% misc                             0           1           1!      3.533!     3.533     !           !       !
              Hardware!
                  Imaging                                0           1           1!      0.961      0.961
              Lens Assembly!
Optical             Imaging        PK51A                 0           1           1!      0.249      0.249                 6     EJ
              Lens 1!
Optical             Imaging        LAK8                  0           1           1!      0.199      0.199                 6     EJ
              Lens 2!
Optical             Imaging        SF57                  0           1           1!      0.267      0.267                 6     EJ
              Lens 3!
Mechanical          Imaging        M55J                  0           1           1!      0.200      0.200                 6     EJ
              Lens Mount!
                    5% misc                              0           1           1!      0.046      0.046
              Hardware!
                  Insertable                             0           1           1!      6.106      6.106
              Pupil Image
              Lens /
              Mechanism!
                    Insertable                           0           1           1!      0.961      0.961
              Pupil Image
              Lens Assembly!
                      Insertable                         0           1           1!      0.715      0.715
              Pupil Image
              Lens !
Optical                 Lens 1!    PK51A                 0           1           1!      0.249      0.249                 6     EJ
Optical                Lens 2!     LAK8                  0           1           1!      0.199      0.199                 6     EJ
Optical                Lens 3!     SF57                  0           1           1!      0.267      0.267                 6     EJ
Mechanical           Insertable    M55J                  0           1           1!      0.200      0.200                 6     EJ
              Pupil Image
              Lens Mount!
                     5% misc                             0           1           1!      0.046      0.046
              Hardware!
                    Insertable                           0           1           1!      5.145      5.145
              Pupil Image
              Lens
              Mechanism!
Mechanism             Rotating     Ti                    0           1           1!      1.000      1.000                 6     EJ
              Arm!
Mechanism                          Al, Stainless         0           1           1!      1.900      1.900                 6     EJ
              Mechanism!           Steel, Ti
Mechanism           Structure!     Al, Ti                0           1           1!      2.000      2.000                 6     EJ




                                                                 118
              ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                 Subsystem/
                 Component          Composition       Quantity                           Mass                Maturity
                 Description
                                                       Cold         Hot        Total     Mass     Subtotal
Component                                                                                                    Heritage          Mass
                                                      Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                       Missions         source
                                                       units       units)     quantity    (kg)      (kg)
                       5% misc                          0            1            1!     0.245     0.245
               Hardware!
!                   WFS-2         4.5um for 5.6          0           1           1!      0.024     0.024     !           !       !
               Detector (CCD)     mas/pixel
               Assembly!
Detector!            WFS-1        Silicon 2k X 2k        0           1           1!      0.000     0.000     !           5!    EJ!
               Detector (CCD)
               - 4.5um!
Detector!            WFS-1        Molybdenum             0           1           1!      0.023     0.023     !           5!    EJ!
               Detector (CCD)
               Mount!
!                    5% misc                             0           1           1!      0.001     0.001     !           6!    EJ!
               Hardware!
!                   Sidecar+                             0           1           1!      2.520     2.520     !           !     EJ!
               Assembly!
Electrical!            Sidecar    100% Analog            0           1           1!      1.000     1.000     !           6!    EJ!
               ASIC +             electronics:
               Electronics (1     clocks and biases
               board)
Mechanical!           Housing!    Al                     0           1           1!      1.400     1.400     !           6!    EJ!
!                    5% misc                             0           1           1!      0.120     0.120     !           !       !
               Hardware!
!                 Instrument                             1           1           2!       12.3    24.600     !           !       !
               Control
               Electronics
               (FGS/WFS&C)!
Electrical         PowerPC        5% analog; 90%         0           1           1!      0.800     0.800                 6     EJ
               Processor Board    digital; 5%
               (1A/1/B)!          connectors
Electrical!        Sidecar 1/F    55% analog;            0           3           3!      0.800     2.400     !           6!    EJ
               Board !            40% digital; 5%
                                  connectors
Electrical        Thermal         70% analog;            0           1           1!      0.800     0.800                 6     EJ
               Control Board      25% digital; 5%
               (1A/1/B)!          connectors
Electrical                        70% analog;            0           1           1!      0.800     0.800                 6     EJ
               Housekeeping       25% digital; 5%
               Board (1A/1/B) !   connectors
Electrical        Mechanism       70% analog;                        3           3!      0.800     2.400                 6     EJ
               Drive Board!       25% digital; 5%
                                  connectors
Electrical        DC/DC           90% analog; 5%         0           1           1!      0.800     0.800                 6     EJ
               Converter          digital; 5%
               (1A/1/B)!          connectors
Electrical        Backplane       G-10                   0           1           1!      1.100     1.100                 6     EJ
               (1A/1B)!
Mechanical        Enclosure!      Al                     0           1           1!      2.800     2.800                 6      C
                   5% misc                               0           1           1!      0.595     0.595
               Hardware!
               FGS/WFS&C                                 0           1           1!      71.925   71.925
               Structure!
Mechanical          Enclosure!    h/c panel; 1"          0           1           1!      46.000   46.000                 6     EJ
                                  alum core;
                                  0.040" compisite
                                  f/s
Mechanical         Instrument     h/c panel; 2"          0           1           1!      21.000   21.000                 6     EJ
               Optical Bench!     alum core;
                                  0.060" compisite
                                  f/s




                                                                 119
             ATLAST-9.2 Hybrid instrument (WFS&C and FGS) Master Equipment List*
                Subsystem/
                Component             Composition   Quantity                           Mass                Maturity
                Description
                                                     Cold         Hot        Total     Mass     Subtotal
Component                                                                                                  Heritage          Mass
                                                    Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                     Missions         source
                                                     units       units)     quantity    (kg)      (kg)
Mechanical        Instrument     Ti                   0            3            3!     0.500     1.500                 6     EJ
              Optical Bench
              Flexures!
                  5% misc                              0           1           1!      3.425     3.425
              Hardware!
                 Thermal                               0           1           1!      48.586   48.586
              Subsystem!
Thermal                          2.5 m long            0!          4           4!       0.75     3.000                 9     EJ
              FGS/WFS&C
              Ethane Heat
              Pipes !
Thermal                          20 m2                 0!          1           1!       0.92     0.920                 9     EJ
              FGS/WFS&C
              Z307 Black
              Paint !
Thermal                          6 m2                  0!          1           1!       41.2    41.200                 7     EJ
              FGS/WFS&C
              170K Radiator !
Thermal                          6 m2                  0!          1           1!       0.3      0.300                 7     EJ
              FGS/WFS&C
              170K Radiator
              NS43G Paint !
Thermal                          Kapton Film 5.5       0!         60          60!      0.002     0.120                 9     EJ
              FGS/WFS&C          cm x 6.4 cm
              Op Mode
              Heaters for
              Detectors
              (redundancy
              included) !
Thermal                                                0!         60          60!      0.001     0.060                 9     EJ
              FGS/WFS&C
              PRTs for Heater
              Controllers and
              Telemetry!
Thermal                          Kapton Film           0!         32          32!      0.018     0.576                 9     EJ
              FGS/WFS&C          16.5 cm x 19.2
              Survival Heaters   cm
              (redundancy
              included) !
Thermal                                                0!         16          16!      0.006     0.096                 9     EJ
              FGS/WFS&C
              Survival
              Thermostats!
                   5% misc                             0!          1           1!      2.3136    2.314
              Hardware!
                 Harness for                           0           1           1!      21.000   21.000                 6     EJ
              the entire
              FGS/WFS&C!
Harness            ICDH to       3.5M each             0           2           2!      7.000    14.000                 6     EJ
              FGS/WFS&C
              ICE Boxes
Harness                          1M each               0          12          12!      0.500     6.000                 6     EJ
              FGS/WFS&C
              ICE Boxes to 12
              Sidecars
                  5% misc                              0           1           1!      1.000     1.000
              Hardware

* MEL assembled by Integrated Design Center at NASA/Goddard Space Flight Center
  Mass Source: Model (c), Engineering Judgement (EJ) or weighed (w), Customer input (CI)



                                                               120
                                  ATLAST-9.2m IC&DH Master Equipment List
                                  ATLAST-9.2m IC&DH Master Equipment List*
                Subsystem/
                Component          Composition     Quantity                           Mass                Maturity
                Description
                                                    Cold         Hot        Total     Mass     Subtotal
Component                                                                                                 Heritage          Mass
                                                   Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                    Missions         source
                                                    units       units)     quantity   (kg)       (kg)

!              ICDH                                   0           1           1!      41.992   41.992     !           !       !
              Assembly!
!               IC&DH Box !                           0           1           1!      17.115   17.115     !           !       !
Electrical       PowerPC          5% analog; 90%      0           1           1!      1.600     1.600                 6     EJ
              Processor Board     digital; 5%
              (1A/1/B)!           connectors
Electrical!      FPPA Board       5% analog; 90%      0           1           1!      1.600     1.600     !           4!    EJ
              (1A/1/B)!           digital; 5%
                                  connectors
Electrical!      Memory           5% analog; 90%      0           1           1!      1.600     1.600     !           6!    EJ
              Board (1A/1/B) !    digital; 5%
                                  connectors
Electrical!       Spacewire       5% analog; 90%      0           1           1!      1.600     1.600     !           6!    EJ
              I/F Board           digital; 5%
              (1A/1/B)!           connectors
Electrical       Thermal          5% analog; 90%      0           1           1!      1.600     1.600                 6     EJ
              Control Board       digital; 5%
              (1A/1/B)!           connectors

Electrical                        5% analog; 90%      0           1           1!      1.600     1.600                 6     EJ
              Housekeeping        digital; 5%
              Board (1A/1/B) !    connectors

Electrical       DC/DC            90% analog; 5%      0           1           1!      1.600     1.600                 6     EJ
              Converter           digital; 5%
              (1A/1/B)!           connectors
Electrical       Backplane        G-10                0           1           1!      1.600     1.600                 6     EJ
              (1A/1B)!
Mechanical       Enclosure!       Al                  0           1           1!      3.500     3.500                 6      C
                  5% misc                             0           1           1!      0.815     0.815
              Hardware!
                ICDH                                  0           1           1!      24.877   24.877
              Thermal
              Subsystem!
Thermal           IC&DH           20 m2               0!          1           1!       0.92     0.920                 9     EJ
              Z307 Black
              Paint !
Thermal           IC&DH                               0!         32          32!      0.018     0.576                 9     EJ
              Survival Heaters!
Thermal           IC&DH                               0!         16          16!      0.006     0.096                 9     EJ
              Survival
              Thermostats!
Thermal           ISIM MLI        20 m2               0!          1           1!       12      12.000                 9     EJ
              Enclosure for
              Utilizing
              Electronics
              Waste Heat !
Thermal           Buttons,                            0!          1           1!       10.1    10.100                 9     EJ
              Velcro and Tape
              for MLI !
                 5% misc                              0           1           1!      1.1846    1.185
              Hardware!
* MEL assembled by Integrated Design Center at NASA/Goddard Space Flight Center
  Mass Source: Model (c), Engineering Judgement (EJ) or weighed (w), Customer input (CI)


                                                              121
                         ATLAST-8m OTA Master Equipment List

               ATLAST-8m Optical Telescope Assembly Master Equipment List
Type                                   Quantity       Mass [kg]      Maturity     Source
Note   Description   Material     Cold Hot Total Each Total Flight TRL            Note 2
 1
       OTA Total                                             33908
       PMA                                                   24988
       SMA                                                    637
       AO                                                     1481
       Structure                                              5350
       Thermal                                                1323
       IC&DH                                                   81
       Mechanisms                                              48
       PMA                                                   24988
 O     Primary        ULE or            0   1     1    19250 19250          5.5     C
       Mirror         Zerodur
                      8 m dia x                               See
                      155mm thick                             Note
                      MgFl (UV)                                3
                      coating
 M     PM Support     M55J              0   1      1   5500   5500   JWST   6       EJ
 M     PM Flexures    Ti                0   3      3     2     6            6       EJ
 M     Launch Lock    mechanism         0   66    66     2    132    JWST   7       EJ
 M     PM Baffle      M55J              0   1      1    100   100    JWST   6       EJ
       SMA                                                    637
 O     Secondary      1m dia x 0.1 m    0   1     1    200    200           5.5     C
       Mirror         thick glass
                      MgFl coating
 M     SM Hexapod     6 actuators,      0   1     1     40     40    JWST   6       EJ
                      LVDTs &
                      structure
 M     SM Mount       M55J              0   1     1     50     50           6       EJ
 M     SM Flexures    Ti                0   3     3      2     6            6       EJ
 M     Launch Locks   mechanism         0   3     3      2     6     JWST   7       EJ
 M     SM Baffle      M55J              0   1     1     35     35    JWST   6       C
 M     SM Spiders     M55J              0   4     4     75    300    JWST   6       EJ
       Aft-Optics                                             1481
       TM Assembly                                            409
 O     Tertiary       1.2 x 0.6 x 0.1   0   2     2    160    320           6       C
       Mirror         m glass
                      Silver coat
 M     TM Mount                         0   2     2     10     20    JWST   6       EJ
 M     TM Hexapod     PI corp           0   2     2     30     60    JWST   6       CI
 M     TM Flexures    Ti                0   6     6     .5     3            6       EJ
 M     Launch Lock    mechanism         0   6     6      1     6     JWST   7       EJ
       FM Assembly                                            203



                                            122
                ATLAST-8m Optical Telescope Assembly Master Equipment List
Type                                    Quantity       Mass [kg]      Maturity    Source
Note    Description   Material     Cold Hot Total Each Total Flight TRL           Note 2
 1
 O     Fold Mirror     0.75 x 0.4 x   0    2     2     40     80            6       C
                       0.05 m glass
                       Silver Coat
 M     FM Mount                       0    2     2    10      20    JWST    6       EJ
 M     FM Flexures     Ti             0    6     6     .5     3             6       EJ
 M     FM Structure    M55J           0    1     1    100    100    JWST    6       EJ
       at CASS         for 2 FMs
       Pupil                                                  69
       Assembly
 O     Pupil Mirror    0.2 dia x 30   0    2     2    2.5     5             6       C
                       mm thick
                       Silver Coat
 O     Pupil Fold      0.3 x 0.15 x   0    4     4     5      20
                       0.05 m, Ag
 M     Flexures        Ti             0   18    18    .5       9            6       EJ
 M     Mount                          0   6      6    2.5     15    JWST    6       EJ
 M     Structure       M55J           0   2      2    10      20    JWST    6       EJ
       AO Structure                                          800
 M     Optical Bench   Al & M55J      0    1     1    600    600    JWST    6       EJ
 M     Flexures        Ti             0    3     3    0.5     1.5   JWST    6       EJ
 M     Enclosure       M55J           0    2     2    100    200    JWST    6       EJ
       Structure                                             5350
 M     Head Truss      M55J           0    1     1    1800   1800   HST     6       EJ
 M     Instrument      M55J           0    1     1     500   500            6       EJ
       Bay
 M     Sunshield       M55J           0    1     1     750   750             6      EJ
 M     Doors           M55J           0    4     4     75    300            5.5     EJ
 M     PAF             ATK            0    1     1    2000   2000   Orion    3      EJ
       Thermal                                               1323
 T     12 m Tube       50 layer       0    1     1    300    300            9       EJ
       MLI             300 m2
 T     Tube Heater     50 m2, Al      0    1     1    350    350            7       EJ
                       12 zones
 T     PM Heater       50 m2, Al      0    1     1    350    350            7       EJ
                       46 zones
 T     Center Heater   16 m2, Al      0    1     1     112   112            7       EJ
 T     SM Heater       0.5m2, Al      0    1     1       3    3             7       EJ
 T     Heat Pipes                     0    36   36     1.5    54            7       EJ
 T     Heater MLI      (50+16)m2      0    1     1     66     66            9       EJ
 T     SM MLI          28 m2          0    1     1     28     28            9       EJ
 T     Fine Heaters    Kapton Film    0   200   200     .3    60            9       EJ
 T     Thermistors                    0   400   400   .001    .4            9       EJ
 T     Survival                       0    20   20    0.05    1             9       EJ
       Heaters



                                          123
                 ATLAST-8m Optical Telescope Assembly Master Equipment List
Type                                     Quantity       Mass [kg]      Maturity                 Source
Note     Description   Material     Cold Hot Total Each Total Flight TRL                        Note 2
 1
       Radiators        Spacecraft
       IC&DH                                                             81
  E    Flight           5%analog           0      1      1       1.6     1.6               6       EJ
       Computer         90%digital
                        5%cable
  E    Memory           5 : 90 : 5         0      1      1       1.6     1.6               4       EJ
       Board
  E    Controllers      5 : 90 : 5         0      2      2       8.5     17                6       EJ
  E    Data                                0      2      2       10      20                6       EJ
       Acquisition
  E    Data                                0      1      1       30      30                6       EJ
       Recorder
  E    Thermal          5: 90 : 5          0      1      1       1.6     1.6               6       EJ
       Controller
  E    DC/DC            90 : 5 :5          0      1      1       1.6     1.6               6       EJ
       Converter
 E     Backplane        G-10               0      1       1      1.6     1.6               6       EJ
 M     Enclosure        Al                 0      1       1       5       5                9       EJ
 T     Survival                            0      20     20     0.05      1                9       EJ
       Heaters
       Mechanisms                                                        48
 M     Door Hinges      bearing, hinge,    0      8      8        2      16     JWST       6       EJ
                        sensor, steel,
                        Ti
 M     Door Motors      motor              0      4      4        2      8      JWST       6       EJ
 M     Sunshade         rails              0      4      4        4      16                6       EJ
       Deploy
 M     Sunshade         motor              0      4      4        2       8                6       EJ
       Motors

Note 1: Optical (O), Mechanical (M), Detector (D), Electrical (E), Thermal (T)
Note 2: Model(C), Engineering Judgment (EJ), Actual (W), Customer Input (CI)
Note 3: The 19,250 kg primary mirror mass is based on an 8 meter solid meniscus ULE glass mirror with
a 155 mm thickness. This mass was chosen because it allows a 30% margin to the maximum possible
primary mirror mass. The maximum possible mass for the Primary mirror using the existing Schott
Zerodur blank is 25,000 kg. While the existing raw blank is close to 300 mm thick, it has a 28 m radius
of curvature. Removing the outer damage layer and changing its radius of curvature to 24 m results in an
8 m solid meniscus mirror that is 175 mm thick with a mass of 25,000 kg. If a 175 mm thick ULE mirror
were used, the mass would be 21,750 kg. Zerodur is denser than ULE. Both materials are space qualified
and have been used to make 8 m class mirrors. The PM Support Structure and Launch Locks are sized
based on a 25,000 kg PM.




                                                 124
            ATLAST-8m Fine Guidance Sensor Facility Master Equipment List

               ATLAST-8m Fine Guidance Sensor Facility Master Equipment List
Type      Description      Material         Quantity         Mass [kg]       Maturity   Source
Note                                    Cold Hot Total      Each Total     Flight TRL   Note 2
 1
        FGS Total                                                    78     Note   6     EJ
                                                                             3
        FGS Module                       2      2      4     16     55             6     EJ
  O     Filter            glass          2      2      4     0.1    0.4            6     EJ
  D     CCD Detector      4kx4k          8      8     16    0.04    0.6            6     EJ
  E     ASIC Sidecar      analog         8      8     16      1     16             6     EJ
  M     Mount Plate       Al             2      2      4      2      8             6     EJ
  M     Baffles           Al             2      2      4     .5      2             6     EJ
  M     Structure         Al             2      2      4      3     12             6     EJ
  M     Enclosure         Al             2      2      4      2      8             6     EJ
  E     Sidecar                          8      8     16     0.5     8             6     EJ
        Harness
        Electronics                      0      1      1     13      13            6     EJ
  E     Power PC          5%analog       0      1      1     .8      .8            6     EJ
                          90%digital
                          5%cable
  E     Sidecar           55%analog      0      4      4      .8    3.2            6     EJ
        Interface         40%digital
                          5%cable
  E     Thermal           70%analog      0      1      1      .8     .8            6     EJ
        Control           25%digital
                          5%cable
  E     DC/DC             90%analog      0      1      1      .8     .8            6     EJ
        Converter         5%digital
                          5%cable
  E     Backplane         G-10           0      1     1      1.1    1.1            6     EJ
  M     Enclosure         Al             0      1     1      2.8    2.8            6     EJ
  E     ICDH Harness                     0      1     1      3.5    3.5            6     EJ
        Thermal                          2      2     4      2.5    10             9     EJ
  T     Cooler            TEC            2      2     4      1.5     6             9     EJ
  T     Heat Pipes        2.5m long      2      2     4     0.75     3             9     EJ
  T     Radiators         spacecraft    NA     NA    NA     NA      NA             9     EJ
  T     Thermostats                      2      2     4     0.25     1             9     EJ
        Heaters           Kapton
Note 1: Optical (O), Mechanical (M), Detector (D), Electrical (E), Thermal (T)
Note 2: Model(C), Engineering Judgment (EJ), Actual (W), Customer Input (CI)
Note 3: ATLAST-8m FGS MEL is based on JWST and HST WFC3




                                               125
              ATLAST-8m Wavefront Sensor Facility Master Equipment List

                ATLAST-8m Wavefront Sensor Facility Master Equipment List
Type                                   Quantity         Mass [kg]     Maturity       Source
Note     Description   Material   Cold Hot Total Each Total Flight TRL               Note 2
 1
       WFS Total                                                     68.8        6     EJ
       WFS Module                         0      6     6     6.45    39.2        6     EJ
 O     3 Channel Beam    glass 50 x 50    0      6     6     0.75     4.5        6     C
       Splitter Cube     x 100 mm
 D     CCD Detector      1k x 1k          0     18     18    0.01     0.2        6     EJ
 E     ASIC Sidecar      analog           0     18     18     .5       9         6     EJ
 M     Mount Plate       Al               0     6       6      1       6         6     EJ
 M     Baffles           Al               0     6       6    0.25     1.5        6     EJ
 M     Structure         Al               0     6       6      1       6         6     EJ
 M     Enclosure         Al               0     6       6     0.5      3         6     EJ
 E     Sidecar Harness                    0     18     18     0.5      9         6     EJ
       Electronics                        0     1       1    14.6    14.6        6     EJ
 E     Power PC          5%analog         0     1       1     .8      .8         6     EJ
                         90%digital
                         5%cable
 E     Sidecar           55%analog        0      6     6      .8     4.8         6     EJ
       Interface         40%digital
                         5%cable
 E     Thermal           70%analog        0      1     1      .8      .8         6     EJ
       Control           25%digital
                         5%cable
 E     DC/DC             90%analog        0      1     1      .8      .8         6     EJ
       Converter         5%digital
                         5%cable
 E     Backplane         G-10             0      1     1      1.1    1.1         6     EJ
 M     Enclosure         Al               0      1     1      2.8    2.8         6     EJ
 E     ICDH Harness                       0      1     1      3.5    3.5         6     EJ
       Thermal                            0      6     6      2.5    15          9     EJ
 T     Cooler            TEC              0      6     6      1.5     9          9     EJ
 T     Heat Pipes        2.5m long        0      6     6     0.75    4.5         9     EJ
 T     Radiators         spacecraft      NA     NA    NA     NA      NA          9     EJ
 T     Thermostats                        0      6     6     0.25    1.5         9     EJ
       Heaters           Kapton

Note 1: Optical (O), Mechanical (M), Detector (D), Electrical (E), Thermal (T)
Note 2: Model(C), Engineering Judgment (EJ), Actual (W), Customer Input (CI)




                                               126
                               ATLAST Wide-Field Imager Master Equipment List

              ATLAST Wide Field of View Camera (WFOV) Master Equipment List*
               Subsystem/
               Component           Composition    Quantity                           Mass                Maturity
               Description
                                                   Cold         Hot        Total     Mass     Subtotal
Component                                                                                                Heritage          Mass
                                                  Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                   Missions         source
                                                   units       units)     quantity   (kg)       (kg)

              WFOV                                   0           1           1!      538.68   538.68
               WFOV Pick                             0           1           1!      11.067   11.067
             Off Mirror
             Assembly
Optical          WFOV Pick       Glass Silver        0           1           1!      8.840     8.840                 6     EJ
             Off Mirror          Coating
Mechanical       WFOV Pick       M55J                0           1           1!      1.700     1.700                 6     EJ
             Off Mirror
             Mount
                 5% misc                             0           1           1!      0.527     0.527
             Hardware
              Flat Field                             0!          1!          1!      3.116!    3.116
             Subsystem!
                Lamps                                0!          2!          2!      0.058!    0.116
             Assembly!
Optical           Lamps!                             4!          4!          8!      0.001!    0.008                 6     EJ
Optical          Lamp                                0!          2!          2!      0.025!    0.050                 6     EJ
             Holder!
Electrical      Electronics!     75% analog;25%      1!          1!          2!      1.000!    2.000                 6     EJ
                                 digital
Harness         Harness!                             1!          1!          2!      0.500!    1.000                 6     EJ
                5% misc                              0!          1!          1!      0.156!    0.156
             Hardware!
               Collimator/1st                        0           1           1!      8.988     8.988
             Three Refractive
             Lens Group
Optical          Lens 1          LAK8                0           1           1!      2.837     2.837                 6     EJ
Optical          Lens 2          LASF33              0           1           1!      2.898     2.898                 6     EJ
Optical          Lens 3          PSK2                0           1           1!      1.325     1.325                 6     EJ
Mechanical       Lens Mount      M55J                0           1           1!      1.500     1.500                 6     EJ
                5% misc                              0           1           1!      0.428     0.428
             Hardware
               Dichroic                              0           1           1!      1.141     1.141
             Assembly
Optical         Dichroic         Glass               0           1           1!      0.887     0.887                 6     EJ
Mechanical      Dichroic                             0           1           1!      0.200     0.200                 6     EJ
             Mount
                5% misc                              0           1           1!      0.054     0.054
             Hardware
               VIS Channel                           0           1           1!      148.70   148.70
                VIS Filter                           0           1           1!      37.027   37.027
             Wheel
             Assembly
Optical          Filters                             0           8           8!      0.408     3.264                 6     EJ
Mechanism        Filter                              0           2           2!      16.000   32.000                 6     EJ
             Wheel
                 5% misc                             0           1           1!      1.763     1.763
             Hardware




                                                             127
               ATLAST Wide Field of View Camera (WFOV) Master Equipment List*
                Subsystem/
                Component          Composition     Quantity                           Mass                Maturity
                Description
                                                    Cold         Hot        Total     Mass     Subtotal
Component                                                                                                 Heritage          Mass
                                                   Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                    Missions         source
                                                    units       units)     quantity    (kg)      (kg)
!                VIS Three                           0            1            1!     8.780     8.780     !           !       !
              Refractive Lens
              Group
Optical!           Lens 1        LAK33                0           1           1!      2.373     2.373     !           6!    EJ!
Optical!           Lens 2        SF57                 0           1           1!      2.787     2.787     !           6!    EJ!
Optical!           Lens 3        PK51A                0           1           1!      1.802     1.802     !           6!    EJ!
Mechanical!        Mount         M55J                 0           1           1!      1.400     1.400     !           6!    EJ!
!                 5% misc                             0           1           1!      0.418     0.418     !           !       !
              Hardware
!                Fold Mirror                          0           1           1!      0.875     0.875     !           !       !
              Assembly
Optical!          Fold Mirror    ULE                  0           1           1!      0.633     0.633     !           6!    EJ!
Mechanical!        Fold Mirror   M55J                 0           1           1!      0.200     0.200     !           6!    EJ!
              Mount
!                  5% misc                            0           1           1!      0.042     0.042     !           !       !
              Hardware
Mechansim!       High Speed                           0           1           1!      7.000     7.000     !           !       !
              Shutter
              Assembly
!                VIS CCD                              0           1           1!      63.525   63.525     !           !       !
              Assembly
Detector!          CCD           Silicon 8k X 8k      0          25          25!      0.020     0.500     !           5!    EJ!
Detector!         CCD            Molybdenum           0           1           1!      60.000   60.000     !           5!    EJ!
              Mount
!                 5% misc                             0           1           1!      3.025     3.025     !           !       !
              Hardware
!                VIS CCD                              0           1           1!      31.500   31.500     !           !       !
              Sidecar Box
Detector          Cards in                            0          25          25!        1      25.000                 6     EJ
              CCD ASIC+
              Box
Detector          Sidecar        50% Analog,          0          25          25!       0.2      5.000                 6     EJ
              ASICS              50% Digital
                  5% misc                             0           1           1!       1.5      1.500
              Hardware
!               IR Channel                            0           1           1!      81.779   81.779     !           !       !
Optical!         Cold            Silica               0           1           1!      0.354     0.354     !           6!    EJ!
              Window/pupil
Mechanical!      Cold Shield     h/c panel; 1"        0           1           1!      25.000   25.000     !           6!    EJ!
                                 alum core;
                                 0.040" Al f/s
!                IR Three                             0           1           1!      7.672     7.672     !           !       !
              Refractive Lens
              Group
Optical!           Lens 1        LAK33                0           1           1!      1.984     1.984     !           6!    EJ!
Optical!           Lens 2        SF57                 0           1           1!      2.413     2.413     !           6!    EJ!
Optical!           Lens 3        PK51A                0           1           1!      1.710     1.710     !           6!    EJ!
Mechanical!        Mount         M55J                 0           1           1!       1.2      1.200     !           6!    EJ!
!                  5% misc                            0           1           1!      0.365     0.365     !           !       !
              Hardware
!                IR Filter                            0           1           1!      33.972   33.972     !           !       !
              Wheels
              Assembly




                                                              128
               ATLAST Wide Field of View Camera (WFOV) Master Equipment List*
                Subsystem/
                Component          Composition     Quantity                           Mass                Maturity
                Description
                                                    Cold         Hot        Total     Mass     Subtotal
Component                                                                                                 Heritage          Mass
                                                   Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                    Missions         source
                                                    units       units)     quantity    (kg)      (kg)
!                  Filter                            0            1            1!     0.354     0.354     !           6!    EJ!
Mechanism!         Filter                             0           2           2!      16.000   32.000     !           6!    EJ!
              Wheel
!                  5% misc                            0           1           1!      1.618     1.618     !           !       !
              Hardware
Mechanism!       IR Shutter                           0           1           1!      7.000     7.000     !           6!    EJ!
              Mechanims
              Assembly
!                IR                                   0           1           1!      7.781     7.781     !           !       !
              MCT/FPE
              Assembly
Detector!         IR MCT         M55J                 0           1           1!      3.891     3.891     !           6!    EJ!
              Focal Plane
              Mosaic
Detector!         IR MCT         Mercury              0          16          16!      0.020     0.320     !           5!    EJ!
              Detector:          Cadmium
              Teledyne           Telluride on Si
              HAWAII4-RG         ROIC
Detector          Sidecar        50% Analog,          0          16          16!       0.2      3.200                 6     EJ
              ASICS              50% Digital
!                 5% misc                             0           1           1!      0.371     0.371     !           !       !
              Hardware
!               WFOV ICE                              1           1           2!      21.630   43.260     !           !       !
              Boxes
Electrical       PowerPC         5% analog; 90%       0           1           1!      0.800     0.800                 6     EJ
              Processor Board    digital; 5%
              (1A/1/B)           connectors
Electrical!      FPPA Board      5% analog; 90%       0          12          12!      0.800     9.600     !           6!    EJ
              (1A/1/B)           digital; 5%
                                 connectors
Electrical       Thermal         70% analog;          0           1           1!      0.800     0.800                 6     EJ
              Control Board      25% digital; 5%
              (1A/1/B)           connectors
Electrical                       70% analog;          0           1           1!      0.800     0.800                 6     EJ
              Housekeeping       25% digital; 5%
              Board (1A/1/B)     connectors
Electrical       Mechanism       70% analog;                      2           2!      0.800     1.600                 6     EJ
              Drive Board        25% digital; 5%
                                 connectors
Electrical       DC/DC           90% analog; 5%       0           1           1!      0.800     0.800                 6     EJ
              Converter          digital; 5%
              (1A/1/B)           connectors
Electrical       Backplane       G-10                 0           1           1!      2.000     2.000                 6     EJ
              (1A/1B)
Mechanical       Enclosure       Al                   0           1           1!      4.200     4.200                 6      C
                 5% misc                              0           1           1!      1.030     1.030
              Hardware
                Harness                               0           1           1!      34.125   34.125
Harness           ICDH-          2 M each             0           4           4!      0.500     2.000                 6     EJ
              WFOV ICE
              Boxes
Harness          WFOV ICE        1M each              0          32          32!      0.500    16.000                 6     EJ
              Boxes - Sidecar
              ASICS
Harness          WFOV ICE        2M each              0           4           4!      0.500     2.000                 6     EJ
              Boxes - Sidecar
              +1/F Box
Harness          Sidecar + I/F   1M each              0          25          25!      0.500    12.500
              Box -Sidecars



                                                              129
               ATLAST Wide Field of View Camera (WFOV) Master Equipment List*
                Subsystem/
                Component             Composition   Quantity                           Mass                Maturity
                Description
                                                     Cold         Hot        Total     Mass     Subtotal
Component                                                                                                  Heritage          Mass
                                                    Backup     (operating    flown     each      Mass                 TRL
  type                                                                                                     Missions         source
                                                     units       units)     quantity    (kg)      (kg)
                 5% misc                              0            1            1!     1.625     1.625
              Hardware
                WFOV                                   0           1           1!      31.448   31.448                 6     EJ
              Sidecar+ I/F
              Box!
                 Sidecar I/F     5% analog; 90%        0          25          25!      0.830    20.750                 6     EJ
              Board !            digital; 5%
                                 connectors
                 LVPC!           90% analog; 5%        0           1           1!      0.800     0.800                 6     EJ
                                 digital; 5%
                                 connectors
                 Backplane!      G-10                  0           1           1!      2.800     2.800                 6     EJ
                 Housing!                              0           1           1!      5.600     5.600                 6     EJ
                  5% misc                              0           1           1!      1.498     1.498
              Hardware!
!                WFOV                                  0           1           1!      115.57   115.57     !           !       !
              Structure
Mechanical!        WFOV                                0           1           1!      24.000   24.000     !           6!    EJ!
              Optical Bench
Mechanical!       Optical        Ti                    0           3           3!      0.500     1.500     !           6!    EJ!
              Bench to
              Enclosure
              mounts
Mechanical!        WFOV                                0           1           1!      45.000   45.000     !           6!    EJ!
              Enclosure
Mechanical!        WFOV          Ti                    0           3           3!      10.000   30.000     !           6!    EJ!
              Enclosure to
              ISIM 3 point
              mounts
!                  5% misc                             0           1           1!      15.075   15.075     !           !       !
              Hardware
                 Thermal                               0           1           1!      59.479   59.479
              Subsystem
Thermal            WFOV          2.5 m long            0!          4!          4!       0.75     3.000                 7     EJ
              Ethane Heat
              Pipes
Thermal            WFOV          20 m2                 0!          1!          1!       0.92     0.920                 9     EJ
              Z307 Black
              Paint
Thermal            WFOV 80K      6 m2                  0!          1           1!       41.2    41.200                 7     EJ
              Radiator
Thermal            WFOV          1.5 m2                0!          1           1!       10.3    10.300                 7     EJ
              170K Radiator
Thermal            WFOV 80K      6 m2                  0!          1           1!       0.3      0.300                 7     EJ
              Radiator NS43G
              Paint
Thermal            WFOV          1.5 m2                0!          1           1!      0.075     0.075                 7     EJ
              170K Radiator
              NS43G Paint
Thermal            WFOV Op       Kapton Film 5.5       0!         60          60!      0.002     0.120                 9     EJ
              Mode Heaters       cm x 6.4 cm
              for Detectors
              (redundancy
              included)
Thermal            WFOV                                0!         60          60!      0.001     0.060                 9     EJ
              PRTs for Heater
              Controllers and
              Telemetry
Thermal            WFOV          Kapton Film           0!         32          32!      0.018     0.576                 9     EJ
              Survival Heaters   16.5 cm x 19.2



                                                               130
             ATLAST Wide Field of View Camera (WFOV) Master Equipment List*
              Subsystem/
              Component      Composition   Quantity                           Mass               Maturity
              Description
                                            Cold         Hot        Total     Mass    Subtotal
Component                                                                                        Heritage          Mass
                                           Backup     (operating    flown     each     Mass                 TRL
  type                                                                                           Missions         source
                                            units       units)     quantity   (kg)      (kg)
            (redundancy     cm
            included)
Thermal         WFOV                          0!         16          16!      0.006    0.096                 9     EJ
            Survival
            Thermostats
                5% misc                       0!          1           1!      2.832    2.832
            Hardware

* MEL assembled by Integrated Design Center at NASA/Goddard Space Flight Center
  Mass Source: Model (c), Engineering Judgement (EJ) or weighed (w), Customer input (CI)




                                                      131
Appendix B: Off-Axis 8 m Telescope Design

    In addition to the on-axis concept, an off-axis concept was investigated. The motivation of this
concept is to provide an unobscured aperture to maximize the starlight suppression performance of an
internal coronagraph. However, the off-axis study was not taken to the same level of detail as the on-axis
concept. Therefore, a MEL does not exist. But, it is the intuition of the team that, to first order, the off-
axis concept details are similar to the ATLAST-8m on-axis concept.
    The fundamental assumptions of this analysis are that 1) the primary mirror is a solid meniscus glass
mirror without a central hole, 2) that the mirror would not be light-weighted (this is particularly important
for this particular application because it will result in the absolutely smoothest most stable mirror surface
possible) and 3) that the mirror would be located face up in the Ares V fairing. The starting point for the
optical design was the primary mirror for the Arizona Large Binocular Telescope. The secondary mirror
is set at approximately 12 meters from the primary. There is an on-axis Cassegrain focus and a folded aft-
optics system with provides an off-axis WFOV TMA focus. An optical design for an off-axis monolithic
ATLAST is shown in Figure B.1.




        Figure B.1: The optical design for an off-axis 6 x 8 meter monolithic dual-field telescope.
        Left: side view, Right: front view (with Ares V dynamic envelope shown as outer circle).

    There is one practical constraint on this design concept. The cylindrical portion of the Ares V faring
is only 9.7 meters tall (compared to 17.2 meters in the center). Therefore, it is not possible to have a fixed
secondary mirror. Thus, a deployed secondary mirror tower will be required (see Figure B.2). Another
practical constraint on this design concept is that the Ares V dynamic envelope diameter is only 8.8
meters. Therefore, the maximum off-axis circular-aperture primary mirror that can fit into the Ares V
fairing is 6 to 6.5 meters. Alternatively, somewhat greater collecting aperture (and resolution) can be
obtained by going with a 6 x 8 meter elliptical mirror (as shown in Figure B.1).




                 Figure B.2: SM tower in its stowed (left) and deployed (right) position.


                                                    132
Appendix C: ATLAST-8m Spider Options

    Finally, two spider options have been considered. This study is again motivated by the high-contrast
imaging requirements for exoplanet detection and characterization. The conventional four-spider X
configuration generates orthogonal diffraction, which does not permit a mask-based (Lyot-type) internal
coronagraph to achieve starlight suppression (output-to-input flux ratio) of 10-10.
    One idea is to replace the X spiders with double arched spiders. Each arch would create a 3 x 6 meter
elliptical clear aperture – approximately the same size as the original TPF-C concept. With relay pupil
aperture masking, it is possible to place an internal coronagraph behind each sub-aperture. Preliminary
dynamic analysis indicates that the double arch spiders have a 7.5 Hz first mode versus the conventional
X spider, which has a 10.5 Hz first mode. Regardless, the double arch spider meets the Ares V launch
requirement and is a viable concept.




                                                             6x3 m




                              Figure C.2: Double Arch SM Spider Concept

     A second idea is to launch a single linear spider with lateral support provided by the doors or by a
lateral spider built into the doors. Once on orbit the doors and the temporary lateral launch support can be
jettisoned. The result would be a single linear spider to which an internal linear occulting mask would be
completely ‘blind’.
     Regarding the spider options, no substantive change to the on-axis OTA MEL or Instrument Table is
required to implement either option.




                                                   133
Appendix D: List of Questions Addressed in this RFI

For completeness, we reprint in this appendix the specific questions received from the Astro2010
committee for each of section of the RFI. The answers are can be cross referenced because they are
preceded by Qn where n corresponds to the question numbers given below.

Questions for Technical Implementation – Payload Instrumentation segments:

 1. Describe the proposed science instrumentation, and briefly state the rationale for its selection.
    Discuss the specifics of each instrument (Inst #1, Inst #2 etc) and how the instruments are used
    together.

 2. Indicate the technical maturity level of the major elements and the specific instrument TRL of the
    proposed instrumentation (for each specific Inst #1, Inst#2 etc), along with the rationale for the
    assessment (i.e. examples of flight heritage, existence of breadboards, prototypes, mass and power
    comparisons to existing units, etc). For any instrument rated at a Technology Readiness Level
    (TRL) of 5 or less, please describe the rationale for the TRL rating, including the description of
    analysis or hardware development activities to date, and its associated technology maturation plan.

 3. In the area of instrumentation, what are the three primary technical issues or risks?

 4. Fill in entries in the Instrument Table. Provide a separate table for each Instrument (Inst #1, Inst #2
    etc). As an example, a telescope could have four instruments that comprise a payload: a telescope
    assembly, a NIR instrument, a spectrometer and a visible instrument each having their own focal
    plane arrays.

 5. If you have allocated contingency please include as indicated along with the rationale for the
    number chosen. If contingency is unknown, use 30% contingency.

 6. Fill in the Payload table. All of the detailed instrument mass and power entries should be
    summarized and indicated as Total Payload Mass and Power as shown in the table.

 7. Provide for each instrument what organization is responsible for the instrument and details of their
    past experience with similar instruments.

 8. For the science instrumentation, describe any concept, feasibility, or definition studies already
    performed (to respond you may provide copies of concept study reports, technology implementation
    plans, etc).

 9. For instrument operations, provide a functional description of operational modes, and ground and
    on-orbit calibration schemes. This can be documented in Mission and Operations Section. Describe
    the level of complexity associated with analyzing the data to achieve the scientific objectives of the
    investigation. Describe the types of data (e.g. bits, images) and provide an estimate of the total data
    volume returned.

 10. Describe the instrument flight software, including an estimate of the number of lines of code.

 11. Describe any instrumentation or science implementation that requires non US participation for


                                                   134
     mission success.

 12. Please provide a detailed Master Equipment List (MEL) for the payload sub-categorized by each
     specific instrument indicating mass and power of each component.

 13. Describe the flight heritage of the instruments and its subsystems. Indicate items that are to be
     developed, as well as any existing hardware or design/flight heritage. Discuss the steps needed for
     space qualification.

Questions for the Technical Implementation – Mission Design sections:

   1. Provide a brief descriptive overview of the mission design (launch, launch vehicle, orbit, pointing
      strategy) and how it achieves the science requirements (e.g. if you need to cover the entire sky,
      how is it achieved?).

   2. Describe all mission software development, ground station development and any science
      development required during Phases B and C/D.

   3. Provide entries in the mission design table. For mass and power, provide contingency if it has
      been allocated. If not, use 30% contingency. To calculate margin, take the difference between
      the maximum possible value (e.g. launch vehicle capability) and the maximum expected value
      (CBE plus contingency).

   4. Provide diagrams or drawings showing the observatory (payload and s/c) with the instruments
      and other components labeled and a descriptive caption. Provide a diagram of the observatory in
      the launch vehicle fairing indicating clearance.

   5. For the mission, what are the three primary risks?

Questions for the Technical Implementation – Spacecraft Implementation sections:

   1. Describe the spacecraft characteristics and requirements. Include a preliminary description of the
      spacecraft design and a summary of the estimated performance of the key spacecraft subsystems.
      Please fill out the Spacecraft Mass Table.

   2. Provide a brief description and an overall assessment of the technical maturity of the spacecraft
      subsystems and critical components. Provide TRL levels of key units. In particular, identify any
      required new technologies or developments or open implementation issues.

   3. Identify and describe the three lowest TRL units, state the TRL level and explain how and when
      these units will reach TRL 6.

   4. What are the three greatest risks with the S/C?

   5. If you have required new S/C technologies, developments or open issues describe the plans to
      address them (to answer you may provide technology implementation plan reports or concept
      study reports).




                                                 135
   6. Describe subsystem characteristics and requirements to the extent possible. Describe in more
      detail those subsystems that are less mature or have driving requirements for mission success.
      Such characteristics include: mass, volume, and power; pointing knowledge and accuracy; data
      rates; and a summary of margins. Comment on how these mass and power numbers relate to
      existing technology and what light weighting or power reduction is required to achieve your
      goals.

   7. Describe the flight heritage of the spacecraft and its subsystems. Indicate items that are to be
      developed, as well as any existing hardware or design/flight heritage. Discuss the steps needed for
      space qualification.

   8. Address to the extent possible the accommodation of the science instruments by the spacecraft.
      In particular, identify any challenging or non-standard requirements (i.e. Jitter/momentum
      considerations, thermal environment/temperature limits etc).

   9. Provide a schedule for the spacecraft, indicate the organization responsible and describe briefly
      past experience with similar spacecraft buses.

   10. Describe any instrumentation or spacecraft hardware that requires non US participation for
       mission success.

   11. Fill out the Spacecraft Characteristics Table.

Questions for the Enabling Technology sections:

   1. For any technologies rated at a Technology Readiness Level (TRL) of 5 or less, please describe
      the rationale for the TRL rating, including the description of analysis or hardware development
      activities to date, and its associated technology maturation plan.

   2. Describe the critical aspect of the enabling technology to mission success and the sensitivity of
      mission performance if the technology is not realized.

   3. Provide specific cost and schedule assumptions by year for Pre-Phase A and Phase A efforts that
      allow the technology to be ready when required.

Questions for the Mission Operations Development sections:

   1. Provide a brief description of mission operations, aimed at communicating the overall complexity
      of the ground operations (frequency of contacts, reorientations, complexity of mission planning,
      etc). Analogies with currently operating or recent missions are helpful. If the NASA DSN
      network will be used provide time required per week as well as the number of weeks (timeline)
      required for the mission.

   2. Identify any unusual constraints or special communications, tracking, or near real-time ground
      support requirements.

   3. Identify any unusual or especially challenging operational constraints (i.e. viewing or pointing
      requirements).




                                                   136
    4. Describe science and data products in sufficient detail that Phase E costs can be understood
       compared to the level of effort described in this section.

    5. Describe the science and operations center for the activity: will an existing center be expected to
       operate this activity?; how many distinct investigations will use the facility?; will there be a guest
       observer program?; will investigators be funded directly by the activity?

    6. Will the activity need and support a data archive?

Questions for the Programmatics & Schedule sections:

    1. Provide an organizational chart showing how key members and organizations will work together
       to implement the program.

    2. Provide a table and a 5 by 5 risk chart of the top 8 risks to the program. Briefly describe how
       each of these risks will be mitigated and the impact if they are not. (Mass, power, schedule,
       money, science etc)

    3. Provide an overall (Phase A through Phase F) schedule highlighting key design reviews, the
       critical path and the development time for delivery required for each instrument, the spacecraft,
       development of ground and mission/science operations etc.

    4. Fill out the Key Phase Duration table indicating the length of time required (months) for: each
       Phase (A through F), ATP to PDR, ATP to CDR, and other key metrics for schedule analysis
       (ATP to instrument delivery, spacecraft delivery, observatory delivery and launch).

    5. Fill out the Key Event Dates table indicating the dates (month/year) for the key development and
       operations milestones.

Questions for the Cost sections:

    1. Provide manpower estimates and cost by year/Phase for all expected scientists that will be
       involved in the mission.

    2. If ESA or another key partner is assumed to be a partner or a major contributor, provide an
       estimate by year and Phase for the breakdown between NASA and ESA (or other) contributions.
       This should be separate, but consistent with Total Mission Cost Funding Table.

    3. Provide a description and cost of what will be performed during Phase A by year. Also include
       total length of Phase A in months and total Phase A estimated costs.

    4. Please fill out the Mission Cost Funding Profile table assuming that the mission is totally funded
       by NASA and all significant work is performed in the US.

    5. For those partnering with ESA, JAXA, or other organizations, provide a second Mission Cost
       Funding Profile table and indicate the total mission costs clearly indicating the assumed NASA
       and contributed costs.




                                                    137
Appendix E: Acronym Definitions

ACS: Advanced Camera for Surveys (HST);              HST: Hubble Space Telescope
      Attitude Control System                        I&T: Integration and Test
AGN: Active Galactic Nuclei                          IC&DH: Instrument Command and Data
AHM: Actuated Hybrid Mirror                                 Handling
AMSD: Advanced Mirror Systems                        IDC: Integrated Design Center (at GSFC)
      Demonstrator                                   IFS: Integral Field Spectrograph
APS: Achromatic Phase Shifter                        IGM: Intergalactic Medium
AR: Anti-Reflective (coating)                        IMAPS: Interstellar Medium Absorption Profile
ATLAST: Advanced Technology Large-                          Spectrograph
      Aperture Space Telescope                       IRU: Inertial Rate Unit
BOS: Bright Object Sensor                            IUE: International Ultraviolet Explorer
C&DH: Command and Data Handling                      IWA: Inner Working Angle
CAD: Computer Aided Design                           JDEM: Joint Dark Energy Mission
Cass: Shorthand for Cassegrain                       JMAPS: Joint Milli-Arcsecond Pathfinder
CBE: Current Best Estimate                                  Survey
CCD: Charge Coupled Device                           JPL: Jet Propulsion Laboratory
CCSDS: Consultative Committee for Space              JSC: Johnson Space Center
      Data Systems                                   JWST: James Webb Space Telescope
Cg: Center of Gravity                                KSC: Kennedy Space Center
CMG: Control Momentum Gyro                           LV: Launch Vehicle
CMOS: Complementary Metal Oxide                      MAST: Multi-mission Archive at Space
      Semiconductor                                         Telescope
COS: Cosmic Origins Spectrograph (HST)               MCT: HgCdTe (Mer-Cad-Telluride)
CS: Communications System                            MEL: Master Equipment List
DES: Dark Energy Survey                              MLI: Multi-Layer Insulation
DIPPS: Disturbance Isolation and Precision           MMH: di-Methyl Hydrazine
      Pointing System                                MOC: Mission Operations Center
DM: Dark Matter; Deformable Mirror                   MSA: Micro Shutter Array
DoD: Dept Of Defense                                 MSFC: Marshall Space Flight Center
DSN: Deep Space Network                              NAFCOM: NASA Air Force Cost Model
dSph: Dwarf Spheroidal (galaxy)                      NASA: National Aeronautics and Space
EELV: Enhanced Extendable Launch Vehicle                    Administration
EPS: Electrical Power System                         NEXT: NASA Evolutionary Xenon Thruster
FGS: Fine Guidance Sensor                            NFOV: Narrow Field of View
FOC: Faint Object Camera (HST)                       NICMOS: Near-Infrared Camera and Multi-
FOS: Faint Object Spectrograph (HST)                        Object Spectrograph (HST)
FOV: Field of View                                   NIR: Near Infrared
FSW: Flight Software                                 NIRCam: Near Infrared Camera (JWST)
FUSE: Far Ultraviolet Spectroscopic Explorer         NIRSpec: Near Infrared Spectrograph (JWST)
GALEX: Galaxy Evolution Explorer                     NTO: di-Nitrogen Tetroxide
GHRS: Goddard High Resolution Spectrograph           NWO: New Worlds Observer
      (HST)                                          OAO: Orbiting Astronomy Observatory
GO: Guest (or General) Observer                      ORU: Orbital Replaceable Unit
GSFC: Goddard Space Flight Center                    OS: Operating System
HDA: Hybrid Diversity Algorithm                      OTA: Optical Telescope Assembly
HGA: High Gain Antenna                               PA: Pointing Arm
HI: Hybrid Instrument                                PAF: Payload Attach Fitting



                                               138
PDR: Preliminary Design Review                         WFE: Wavefront Error
PIL: Pupil Imaging Lens                                WFOV: Wide Field of View
PM: Primary Mirror                                     WFS: Wavefront Sensor (or Sensing)
PMBSS: Primary Mirror Bench Support                    WFS&C: Wavefront Sensing and Control
      Structure
PS: Propulsion System
PSF: Point Spread Function
QSO: Quasi-Stellar Object (a.k.a. Quasar)
RFI: Request for Information
rms: Root Mean Square
RoC: Radius of Curvature
ROM: Rough Order of Magnitude (for cost
      estimation)
RWA: Reaction Wheel Assembly
SA: Solar Array
SC: Spacecraft
SE-L2: Sun-Earth Second Lagrange Point
SFA: Spatial Filter Array
SLOC: Software Lines of Code
SM: Secondary Mirror
SMS: Structures and Mechanisms System
SNAP: Supernova Acceleration Probe
SNR: Signal To Noise Ratio
SOC: Science Operations Center
SOHO: Solar and Heliospheric Observatory
SS: Sunshield
SSM: Star Selection Mirror
SSR: Solid State Recorder
STIS: Space Telescope Imaging Spectrograph
      (HST)
STScI: Space Telescope Science Institute
TCS: Thermal Control System
TDP: Technology Development Plan
TDRSS: Tracking and Data Relay Satellite
      System
TM: Tertiary Mirror
TMA: Three-Mirror Anastigmat(ic)
TMT: Thirty Meter Telescope
TPF-C: Terrestrial Planet Finder Coronagraphic
      Mission
TRL: Technology Readiness Level
TWTA: Traveling Wave Tube Amplifier
ULE: Ultra Low Expansion
UV: Ultraviolet
UVOIR: Generally, the wavelength range from
      ~110 to ~2500 nm
UVS: Ultraviolet Spectrograph
VCA: Voice Coil Actuator
VNC: Visible Nulling Coronagraph
WBS: Work Breakdown Structure
WFC3: Wide-Field Camera 3 (HST)


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