NGAO Build to Cost Summary by AUGold

VIEWS: 15 PAGES: 37

									NGAO Build to Cost Summary


  Peter Wizinowich, Sean Adkins, Rich Dekany,
   Don Gavel, Claire Max & the NGAO Team

                  SSC Meeting
                  April 14, 2009
               Presentation Sequence
•   Success Criteria, Deliverables & Approach
•   Science Priorities
•   AO Design Changes
•   Science Impact
•   Revised Cost Estimate
•   Assessment of Review Deliverables & Conclusion




Build-to-Cost Review Materials (user name & password: NgaoSDR)




                                                                 2
            Review Success Criteria
 • The revised science cases & requirements continue to
   provide a compelling case for building NGAO
 • We have a credible technical approach to producing an
   NGAO facility within the cost cap and in a timely fashion
 • We have reserved contingency consistent with the level of
   programmatic & technical risk

 These criteria, plus the deliverables & assumptions, were
   approved by the Directors & presented at the Nov. 3, 2008
   SSC meeting
Reviewers found that these criteria were successfully met

                                                          3
           Cost Reduction Approach
• Review & update the science priorities
• Review other changes to the estimate (e.g. NFIRAOS cost
  comparison)
• Update the cost estimate in then-year $
• Evaluate the recommended cost reductions
   – As architectural changes
   – As a whole including performance predictions
• Revise cost estimate
• Revisit review success criteria & deliverables




                                                      4
Science Priorities
                 Key Science Drivers
Five key science drivers were developed for the NGAO SDR (KAON 455):
1. Galaxy assembly & star formation history
2. Nearby Active Galactic Nuclei
3. Measurements of GR effects in the Galactic Center
4. Imaging & characterization of extrasolar planets around nearby stars
5. Multiplicity of minor planets

•   We discussed how our recommended cost reductions impact this
    science.




                                                                   6
     Science Priority Input: SDR Report
From the SDR review panel report (KAON 588) executive
   summary:
•   The panel supported the science cases
•   The panel was satisfied with the science requirements flow down &
    error budget
•   The panel was concerned about complexity (especially the deployable
    IFS)
•   The panel had input on the priorities
    – Sky Coverage for NGAO is essential




                                                                    7
Science Priority Input: Keck Scientific Strategic Plan

 From the Keck SSP 2008:
 •   “NGAO was the unanimous highest priority of the Planetary, Galactic, &
     Extragalactic (in high angular resolution astronomy) science groups. NGAO
     will reinvent Keck and place us decisively in the lead in high-resolution
     astronomy. However, the timely design, fabrication & deployment of NGAO
     are essential to maximize the scientific opportunity.”
 •   “Given the cost and complexity of the multi-object deployable IFU instrument
     for NGAO, …, the multi-IFU instrument should be the lowest priority part of the
     NGAO plan.”
 •   Planetary recommendations in priority order: higher contrast near-IR imaging,
     extension to optical, large sky coverage.
 •   Galactic recommendations in priority order: higher Strehl, wider field, more
     uniform Strehl, astrometric capability, wide field IFU, optical AO
 •   Extragalactic high angular resolution recommendations a balance between the
     highest possible angular resolution (high priority) at the science  & high
     sensitivity

                                                                                8
Science Implications of no Multiplexed d-IFU
• Galaxy Assembly and Star Formation History
   – Reduced observing efficiency
       • Single target observed at a time
       • Calibrations (e.g., sky, telluric, PSF) may require dedicated observing
         sequences
   – Decreases overall statistics for understanding processes of galaxy
     formation and evolution
       •   Can be supplemented with complementary HST & JWST results at higher z

• General Relativity in the Galactic Center
   – Decreased efficiency in radial velocity measurements (fewer stars
     observed at once)
• Can gain back some of efficiency hit with a single on-axis
  IFU that has higher sensitivity (especially for galaxy assembly)
  & larger FOV (especially for GC)
                                                                               9
             Flowdown of Science Priorities
                      (resultant NGAO Perspective)
Based on the SDR science cases, SDR panel report & Keck Strategic Plan:
1. High Strehl
    •   Required directly, plus to achieve high contrast NIR imaging, shorter  AO, highest
        possible angular resolution, high throughput NIR IFU & high SNR
    •   Required for AGN, GC, exoplanet & minor planet key science cases
2. NIR Imager with low wavefront error, high sensitivity, ≥ 20” FOV & simple
   coronagraph
    •   Required for all key science cases.
3. Large sky coverage
    •   Priority for all key science cases.
4. NIR IFU with high angular resolution, high sensitivity & larger format
    •   Required for galaxy assembly, AGN, GC & minor planet key science cases
5. Visible imaging capability to ~ 800 nm
    •   Required for higher angular resolution science
6. Visible IFU capability to ~ 800 nm
7. Visible imager & IFU to shorter                                        Included in B2C
                                                                               Excluded
8. Deployable multi-IFS instrument (removed from plan)
    –   Ranked as low priority by Keck SSP 2008 & represents a significant cost
                                                                                      10
  AO Design Changes
to Support Build-to-Cost
NGAO System Architecture
             Key AO Elements:
             • Configurable laser tomography
             • Closed loop LGS AO for low
             order correction over a wide field
             • Narrow field MOAO (open loop)
             for high Strehl science, NIR TT
             correction & ensquared energy




                                           X

                                          12
Revised NGAO System Architecture
                 Key Changes:
                 1. No wide field science instrument 
                 • Fixed narrow field tomography
                 • TT sharpening with single LGS AO
                 • 75W instead of 100W
                 • Narrow field relay not reflected
                 2. Cooled AO enclosure smaller
                 3. Lasers on elevation ring
                 4. Combined imager/IFU instrument
                    & no OSIRIS
                 5. Only one TWFS




                                                   13
         AO Design Changes Summary
A. Architectural changes allowed by no deployable multi-IFS instrument
    1. LGS asterism & WFS architecture
    2. Narrow field relay location
B. New design choices that don’t impact the requirements
    1. Laser location
    2. AO optics cooling enclosure
C. Design choices with modest science implications
    1.   Reduced field of view for the wide field relay (120” vs 150” dia.)
    2.   Direct pick-off of TT stars
    3.   Truth wavefront sensor (one visible instead of 1 vis & 1 NIR)
    4.   Reduced priority on NGS AO science
          – Fixed sodium dichroic, no ADC & fewer NGS WFS subaperture scales
    5. No ADC implemented for LOWFS (but design for mechanical fit)
    6. OSIRIS role replaced by new IFS
– Significant reduction in complexity
    – 37% less motion control, 2 vs 8 dichroics, 9x smaller tomography volume
                                                                               14
                   Performance Analysis Summary
       •     “3+1” science asterism + 3 pointable lasers has excellent performance
             for narrow field science




       •     Overall performance comparable to estimates at SDR
                                   High order   Tip-Tilt    Effective         Science Performance           Performance at SDR
                                   wavefront      error    wavefront    Science Strehl      Ensquared      Effective  Ensquared
         Science Case              error (nm)    (mas)     error (nm)    Band     Ratio       Energy       WFE (nm)    Energy
Gal Center imaging (1" off-axis)      188          1.4         189         K       75%                        184
Exoplanets                            162          3.3         171         H       65%                        157
Minor Planets                         162          4.3         177         z       20%                        175
Galaxy Assembly                       162           7          204         K               71% in 70 mas      257    55% in 70mas
Nearby AGN                            162           5          182         z               24% in 34 mas


                                                                                                                        15
Wavefront Error versus Laser Power


               50W +
              median Na
               density




        50W in
        science
        asterism




                                     16
Strehl Ratio versus Laser Power

      50W in
      science
      asterism




                                  17
                                Performance versus Sky Coverage
                                              EE70mas and Tip-Tilt Error vs. % Sky Coverage
                                                         for Galaxy Assembly case, median seeing
                                16.00                                                                   100%

                                                                                                        90%
                                14.00
                                                                        % EE (70 mas)                   80%
                                12.00
1-D Tip-Tilt Error, RMS (mas)




                                                                                                                                                            1-D Tip-Tilt Error, RMS (mas)
                                                                                                               H-band Ensquared Energy
                                                                                                        70%
                                10.00
                                                                                                        60%
                                                   1d Tilt Error (mas)
                                 8.00                                                                   50%                               Tip-Tilt Error
                                                                                                        40%                               EE 70 mas
                                 6.00
                                                                                                                                          EE 41 mas
                                                                        % EE (41 mas)                   30%
                                 4.00
                                                                                                        20%
                                 2.00
                                                                                                        10%

                                 0.00                                                                   0%
                                        0%   10%   20%    30%   40%   50%    60%   70%   80%   90%   100%                                K-band
                                                                  Sky Fraction                                                           b = 30

                                                                                                                                                       18
                                              EE70mas and Tip-Tilt Error vs. % Sky Coverage
                                                       0%   10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

                                                                          Sky Fraction
               Performance versus Sky Coverage
                                                   Strehl Ratio and Tip-Tilt Error vs. % Sky Coverage
                                                                  for Minor Planets case, median seeing
                                               16.00                                                 100%

                                                                                                      90%
                                               14.00
                                                                                                      80%
                                               12.00
               1-D Tip-Tilt Error, RMS (mas)




                                                                                                      70%




                                                                                                            Z-band Strehl Ratio
                                               10.00
                                                                                                      60%

p-Tilt Error                                    8.00                                                  50%
                                                                                                                                  Tip-Tilt Error
 33 mas                                                                                               40%
                                                6.00                                                                              Strehl Ratio
 17 mas
                                                                                                      30%
                                                4.00
                                                                                                      20%
                                                2.00
                                                                                                      10%
                                                                                         Strehl
                                                0.00                                                 0%
                                                       0%   10% 20% 30% 40% 50% 60% 70% 80% 90% 100%                              Z-band
                                                                          Sky Fraction                                            b = 30

                                                                                                                                                   19
     Off-axis Performance

           Imaging radius
            requirement


Max. IFU
 radius


                            Max. imager
                              radius



                                     Median seeing

                                                     20
  Science Instrument Design Changes
• NGAO Proposal had three science instruments ($20M in FY06 $)
   – Deployable multi IFS instrument
   – NIR imager
   – Visible imager
• For the SDR we included OSIRIS integration with NGAO
• Science instrument design changes that impact the science
  capabilities
   –   No deployable multi IFS instrument
   –   Addition of single channel NIR IFS
   –   Removal of OSIRIS (science capabilities covered by NIR IFS)
   –   No visible imager
   –   Extension of NIR imager & IFS to 800 nm (possibly 650 nm)




                                                                     21
            NGAO Imaging Capability
• Broadband
   – z, Y, J, H, K (0.818 to 2.4 µm)
   – photometric filters for each band plus narrowband filters similar to
     NIRC2
• Single plate scale
   – selected to optimally sample the diffraction limit, e.g. /2D or 8.5 mas at
     0.818 µm
• FOV
   – 34.8" x 34.8" with 8.5 mas plate scale
• Simple coronagraph
• Throughput ≥ 60% over full wavelength range
• Sky background limited performance



                                                                              22
                 NGAO IFS Capability
• Narrowband
   – z, Y, J, H, K (0.818 to 2.4 µm)
   – ~5% band pass per filter, number as required to cover each wave band
• Spectroscopy
   – R ~4,000
   – High efficiency e.g. multiple gratings working in a single order
• Spatial sampling (3 scales maximum)
   – 10 mas, e.g. /2D at 1 m
   – 50 to 75 mas selected to match 50% ensquared energy of NGAO
   – Intermediate scale (20 or 35 mas) to balance FOV/sensitivity trade off
• FOV on axis
   – 4" x 4" at 50 mas sampling
   – possible rectangular FOV (1" x 3") at a smaller spatial sampling
• Throughput ≥ 40% over full wavelength range
• Detector limited performance

                                                                              23
    OSIRIS role replaced by new IFS
• Carefully reviewed OSIRIS role
   – In consultation with Larkin & McLean
• Determined that a new IFS was required by science
  requirements
   – Higher sensitivity, higher spatial resolution & larger FOV needed
• Minor science benefit to having both new IFS & OSIRIS
   – Perhaps some plate scales
   – Perhaps some multiplexing if new IFS deployable (extra cost)
• More overall science benefit to continuing to use OSIRIS
  on K1
• NGAO cost savings & design freedom in not having to
  implement OSIRIS



                                                                    24
Impact on Science Requirements
     Impact on ability to meet Science Requirements
 Key Science Driver         SCRD Requirement             Performance of B2C


Galaxy Assembly           EE  50% in 70 mas for       EE > 70% in 70 mas for
(JHK bands)               sky cov = 30% (JHK)          sky cov  90% (K band)        √
                                                       EE  25% in 33 mas 
Nearby AGNs                 EE  50% in 1/2 grav       MBH  107 Msun @ Virgo
(Z band for Ca triplet)    sphere of influence         cluster (17.6 Mpc )           √
General Relativity at                                  Need to quantify. Already
                           100 as astrometric
the Galactic Center
(K band)
                           accuracy  5” from GC
                                                       very close to meeting this
                                                       requirement with KII AO.
                                                                                     √
Extrasolar planets        Contrast ratio H > 10 at    Meets requirements
around old field brown
dwarfs (H band)
                          0.2” from H=14 star
                          (2 MJ at 4 AU, d* = 20 pc)
                                                       (determined by static
                                                       errors)
                                                                                    √
Multiplicity of minor     Contrast ratio J > 5.5 at   Meets requirements: WFE
planets (Z or J bands)    0.5” from J < 16 asteroid    = 170 nm is sufficient       √
                                                                                    26
       B2C Design Changes: only modest effect on
            meeting science requirements

√   • Galaxy Assembly: B2C exceeds SDR requirements

    • Nearby AGNs: B2C doesn’t meet EE requirement (didn’t meet at

√     SDR either). Still in interesting regime for BH mass measurements
      (MBH  107 Msun @ Virgo cluster). Need to review & more clearly
      define requirement.

    • General Relativity at the Galactic Center: Key variables (e.g.
√     differential tilt jitter, geometric distortion in AO & instrument,
      differential atmospheric refraction) not strongly affected by laser
      power. Confusion only slightly worse than SDR design.

√   • Extrasolar planets around old field brown dwarfs: contrast ratio not
      affected by B2C design changes. Static errors dominate.

√   • Multiplicity of minor planets: Meets SDR requirements

                                                                            27
    NGAO comparison to JWST & TMT
• Higher spatial resolution for imaging & spectroscopy than JWST
   – JWST much more sensitive at K. NGAO more sensitive at J & between OH lines at H
• Lots of NGAO science possible in 5 years prior to TMT 1st science
   – Key community resource in support of TMT science (do at Keck 1st if can)
   – Could push to shorter  or multi-object IFS or … as TMT arrives on scene
• NGAO could perform long term studies (e.g., synoptic, GC astrometry)
                                      WMKO NGAO               JWST               TMT NFIRAOS
    Diffraction-limit (mas) at 2 m        41                    63                     14
    Diffraction-limit (mas) at 1 m        20         limited by sampling                7
    Sensitivity                            1x         ~200x@K; ~1/6x@J                 ~80x
    Imager                            NGAO Imager           NIRCam        IRIS Imager         IRMS
      Detector                           H4RG               4x H2RG          H4RG            H2RG
      Wavelength range (m)             0.8-2.4             0.6-2.35         0.8-2.5         0.8-2.5
      Sampling (mas/pixel)                8.5                  31.7              4              60
      FOV (arcsec)                         35                   130             15             120
    Spectrometer                       NGAO IFS             NIRSpec         IRIS IFS          IRMS
      Detector                           H4RG               2x H2RG          H4RG            H2RG
      Wavelength range (m)             0.8-2.4             0.6-2.35         0.8-2.5         0.8-2.5
                                                        R~100 & ~1000                       R=3270
                                                      multi-object modes Two image         (0.24" slit)
                                                      R~3000 IFU or long-    slicers;       R=4660
     Spectral Resolution                 R~4000            slit modes       R~4000         (0.16" slit)
     Spatial Resolution (mas)         10, ~25 & ~60            ~100          4 to 50           160
                                                            200 FOR                                       28
      FOV (arcsec)                      0.8, 2 & 4       4 slit; 3x3 IFU     up to 3        120 FOR
    Projected 1st science paper           ~2015               ~2014                   ~2020
               NGAO comparison to JWST
  Evaluation of key science cases:

  Key Science Case                                   JWST & NGAO
                        JWST much more sensitive at K.
                        NGAO sensitivity higher between OH lines at H.
                        NGAO sensitivity higher for imaging & spectroscopy at J.
Galaxy Assembly         NGAO wins in spatial resolution at all .
(JHK)                   NGAO provides higher spectral resolution.

Nearby AGNs (Z)         Only NGAO provides needed spatial resolution (especially at Ca triplet).
                        Only NGAO provides needed spatial resolution (especially important to
General Relativity at   reduce confusion limit).
Galactic Center (K)     Long term monitoring may be inappropriate for JWST.
Extrasolar Planets      Only NGAO provides needed spatial resolution.
around old Field        JWST coronagraph optimized for 3-5 m, >1"; NGAO competitive ≤2
Brown Dwarfs (H)        m, <1".
Multiplicity of Minor
Planets (Z or J)        Only NGAO provides needed spatial resolution.




                                                                                           29
                 NGAO comparison to TMT
  • NGAO & NFIRAOS wavefront errors are ~ the same (162 vs 174 nm rms)
       – Similar Strehls but higher spatial resolution for TMT
       – Similar spatial resolution for IFU science but higher sensitivity for TMT
  Key Science Case                                     TMT & NGAO
                        NGAO & TMT have the same spatial resolution with ~20 & 50 mas IFUs,
                        but TMT has higher sensitivity.
Galaxy Assembly         NGAO may do most of Z < 2.5-3 targets either before TMT or because
(JHK)                   of scarce TMT time.
                        NGAO will screen most important targets.
Nearby AGNs (Z)         With 3x higher spatial resolution TMT will detect smaller black holes.
                        TMT wins in spatial resolution, sensitivity less important.
                        Significant value in continuing NGAO astrometry into TMT era (MCAO
General Relativity at   field stability concern; Keck access easier).
Galactic Center (K)     NGAO synoptic advantage.
                        TMT spatial resolution an advantage.
Extrasolar Planets      Control of static wavefront errors & PSF characterization will be critical
around old Field        (NGAO will have 5 year head start on experience).
Brown Dwarfs (H)        NGAO synoptic advantage.
                        TMT spatial resolution an advantage; NGAO could move to shorter .
Multiplicity of Minor   Much of this science may be done before TMT?
Planets (Z or J)        NGAO synoptic advantage.
                                                                                             30
Revised Cost Estimate
                          Revised Cost Estimate
    Including all proposed cost reductions & new cost estimates:
                               Actuals ($k)            Plan (Then-Year $k)
       NGAO System             FY07 FY08 FY09 FY10 FY11 FY12 FY13            FY14    FY15    Total
System Design                    739     495                                                   1234
Preliminary Design                       214 1240 1492                                         2946
Detailed Design                                   1600 5500     978                            8078
Full Scale Development                             400  500    7415   8715    5262            22293
Delivery & Commissioning                                                      1764    1825     3589
Contingency (24%)                                    466        1741  3014    3119     611     8951
              NGAO Total =      739    709   1240   3958  6000 10134 11729   10145    2436    47090
IFS Design                                     51    229    78                                  358
Imager and IFS Instrument                     123    443  4284  4264   486      12             9613
Contingency (10/30%)                           17     67  1309  1279   146       4             2822
  NGAO Instrument Total =                     192    739  5670  5544   632      15       0    12793
             Overall Total =    739    709   1432   4697 11670 15678 12361   10161    2436    59883




                                                                                             32
              Revised Cost Estimate
• Cost estimation methodology approved at SDR
• NFIRAOS comparison improved confidence in estimate
• Revised estimate incorporates new information
   – IFS design (ATI) & K2 center launch (MRI) proposal estimates
   – Better laser cost estimates (ESO, GMT, TMT, AURA collaboration)
• NGAO contingency has increased from 22.6% to 24.2%
   – Due to increased laser contingency (30% based on NFIRAOS comparison)
   – Contingency has not been decreased for the reduced complexity
   – Conservative in reducing labor hours for build-to-cost
• NGAO instruments at proposal level
   – Estimate well anchored to other instrument costs (NIRC2, OSIRIS,
      MOSFIRE, IRIS)
   – 30% contingency assumed post-design
                                                                     33
Assessment of Build-to-Cost Review
  Deliverables & Success Criteria
          + Conclusions
  Review Deliverables Summary (1 of 2)
• Revisions to the science cases & requirements, & the
  scientific impact
   – Galaxy assembly science case & requirements need to be
     modified for a single IFU instead of multiple deployable IFUs
   – Only minor impacts on all other science cases

• Major design changes
   – Design changes documented in KAON 642
   – Performance impact of design changes documented in KAON 644

• Major cost changes
   – All cost changes documented with comments & equations in cost
     book summary spreadsheet by WBS and phase
       • Viewed as better tool than cost book for tracking changes

                                                                     35
  Review Deliverables Summary (2 of 2)
• Major schedule changes
  – No major schedule changes assumed
     • 2 month slip in milestones assumed for cost estimate
  – New plan needs to be developed as part of preliminary design
     • Preliminary design phase replan is a high priority post this review

• Contingency changes
  – Reviewed contingency as part of NFIRAOS cost comparison
     • Laser, & potentially RTC, increase identified as needed
  – Laser contingency increased to 30%
  – Other bottom-up contingency estimates viewed as sufficient
    especially given reduction in complexity with design changes



                                                                             36
                           Conclusions
•   The build-to-cost guidance resulted in a simpler & therefore less
    expensive NGAO facility with similar science performance
    – Primarily achieved at the expense of a significant science capability (e.g.,
      the multiple deployable IFS)
•   We will address the recommendations from the B2C review during the
    preliminary design
    – And report on how we addressed these recommendations at the PDR

•   Our management priorities are switching to:
    – Replanning & completing the preliminary design in a timely fashion
    – Developing a viable funding & management plan for delivering NGAO in a
      timely fashion as a preliminary design deliverable




                                                                              37

								
To top