Stacey by xuyuzhu

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									Universities Space Research Association



          NASA’s Stratospheric Observatory
           for Infrared Astronomy (SOFIA)




                                    Gordon J. Stacey, Cornell University
                                  (many slides borrowed from Robert Gehrz,
                                                U. Minnesota)
                                           Communications
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                            The SOFIA Observatory
             2.5 m telescope in a modified Boeing 747SP
              aircraft
                      Optical to millimeter-wavelengths
                      Emphasis on the obscured IR (30-300 m)
             Joint Program between the US (80%) and
              Germany (20%)
             First Light Will Occur in 2009
                      Built on NASA’ Airborne Astronomy Heritage




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                      SOFIA Forte: the Far -Infrared



  SOFIA is unique in the far-IR
   wavelength bands: 30 to 300 m
   – a region of the electromagnetic
   spectrum that is totally obscured
   by telluric water vapor for ground
   based observatories.
  Flying at > 39,000 feet gets you
   above 99% of the obscuring
   water vapor.
  Why do we do it?
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                      Why Study the Far -Infrared?
                      Extinction and Energetics…
                   Extinction The energy for most of the radiant light in
                     a galaxy originates in the photospheres of stars 
                     visible light.
                       However, stars form in dusty molecular clouds.
                        This dust is small r ~ 0.1 m ~ wavelength of
                        visible light  scattered and absorbed
                        (extinction)
                        Can’t see star formation regions in the
                        visible  must go to longer wavelengths
                   Effect is huge! Only one visible photon in 10 billion
                     from the Galactic Center reaches us, but > 90% at
                                      > 40 m reaches us!

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                     Extinction




         Far-IR (IRAS) Image: Warm m (2MASS) Image: Galactic
                                 2
         dust
Optical Image: Nearby stars      Center Cluster
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             Energetics: What glows in the far-
                           IR?
       The Planck Function
                    2hc 2                1
         F 
                       5        e hc / kt  1
                  Wien’s Law

       m axT  2898 m deg

     Far-IR = 30 µm ≤  ≤ 300
               µm
         10K ≤ T ≤ 100 K
                                                                   •Robert Gehrz, U. Minnesota
                                               Communications
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             Things Look Different at Different
                      Wavelengths!
                                                                      Warm eyes & ears




                                                                       Cool nose


                                                                10 m image of a cat
                                          Cool fur
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                                                        Energetics
  The same is true for stars Much of the
    light energy in the local Universe
    arrives in the far-IR bands as thermal
    radiation from warm dust
   Example 1 – Dust: Protostars glow
    in the submillimeter band
           Stars form in the dust cores of giant
            molecular clouds
           As the core collapses to form a
            protostar, its gravitational energy is
            converted into kinetic energy (heat) –
            the core heats up.
           The first glow of a protostar is in the
            far-IR band

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               Orion Nebula: Visible and Far -IR
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                                                               38 m Image: KWIC-Kuiper Airborne
                                           Communications
                                          Integrated Systems   Observatory Harry Latvakoski, Cornell PhD
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                               Energetics: Gas Cooling
                   Example 2 – Spectral Lines -- Dominate the
                    cooling and trace physical conditions of the gas
                      To form a star, gas clouds must collapse
                      As a cloud collapses under gravity, it heats up –
                       this would stop collapse unless it can cool
                       effectively
                      The spectral lines in the far-IR and submillimeter
                       bands are the primary coolants for the neutral
                       gas that forms stars
                   Most important cooling lines include H2O, SO2, H2
                    and CO rotational lines, [CI] [CII], [OI], and [NII] fine
                    structure lines – all of which lie in the far-IR band
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      The Far -Infrared Regime is Exciting –
        So Why Isn’t Everyone Doing it?

         14,000 feet




            41,000 feet




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                 The History of Airborne Astronomy
                                                                             1999
                                                               NASA Lear
                    1967 – 1983+                                   Jet
                                                               Observatory
                                                                             2002




      “Pioneering” Airborne Astronomical Telescope – 30 cm aperture
      2hr10m Flights – zip up to 45,000 feet
      First observations ever of many of the most important cooling
       lines – hadn’t even been seen in the lab!
      Produced many (~20) PhDs – you are looking at the last one…
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                  Kuiper Airborne Observatory (KAO)

      Natural Follow-on to the Lear
       Jet
      Modified C141 Starlifter
      Pressurized cabin – “shirt
       sleeve” environment
      Telescope balanced and
       floated on an “air-bearing”
      Gyro stabilized to within < 5”
      91.4 cm (36”) telescope                                  Guiding done with focal
                                                               plane camera and
      7.5 hr flights, 6.5 of which
                                                               computerized feedback to
       above 39,000 feet
                                                               torque motors on the telescope
      Produced > 60 PhDs

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                                              KAO Discoveries
        1977 – Five thin rings of Uranus discovered – flight from
         Perth, Australia over the Indian Ocean – mobility of telescope
         enables stellar occultation viewing
        Unexpectedly large far-infrared luminosities of galaxies
        Self luminosities of Jupiter, and Saturn
        Discoveries of young stars being formed
        First strong evidence for a massive (few million) solar mass
         black hole in the center of the Galaxy
        Water discovered in the atmosphere of Jupiter via impacts of
         Comet Shoemaker-Levi (1994)
        1985 – First detection of a natural interstellar infrared laser
           Many of Today’s Leaders in Infrared and Submillimeter
         Astronomy – Particularly in Instrumentation – Cut Their Teeth
                             on Airborne Astronomy:
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      SOFIA: The Stratospheric Observatory for
                Infrared Astronomy           1999


                               2009 – 2029…
                                                                             2002




                                                               2006   2006




                                           Communications
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                                      The SOFIA Observatory
          2.5 m telescope in a modified Boeing 747SP aircraft
          Operating altitude
                  39,000 to 45,000 feet (12 to 14 km)
                  Above > 99% of obscuring water vapor
          Joint Program between the US (80%) and Germany
           (20%)
          First Light Science 2009
                     20 year design lifetime
                     Based at NASA Dryden Research Center
                     Science Operations at NASA-Ames ~ 80-people, 20% German
                     Deployments to the Southern Hemisphere and elsewhere
                     >120 8-10 hour flights per year
                     Built on NASA’ Airborne Astronomy Heritage
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                                          Nasmyth: Optical Layout


                                                                       M2
                     Pressure bulkhead

              Spherical Hydraulic Bearing

                                 Nasmyth tube
     Focal Plane
                                                                            M3-1

                                                                            M3-2




                                                            Primary Mirror M1
                           Focal Plane
                                      Communications
                           Imager    Integrated Systems                            18
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                     Telescope and aperture assembly




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             2.7-meter (106 inch) f/1.28 Primary Mirror after final
                                   polishing
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                                                               Installing the bearing sphere
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                 Installation of the Secondary Mirror




                                           Communications
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                     Installation of the Tertiary Mirror




                                           Communications
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                        The Un-Aluminized Primary Mirror
                                   Installed




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                                          Science Capabilities

         8 arcmin diameter field of view allows use of very large
          detector arrays – first light cameras will have 10 times
          the number of pixels as those on KAO

         Image size is diffraction limited beyond 15 µm, making
          images 3 times sharper than the best previous facilities
          including KAO and the Spitzer Space Telescope

         Because of large aperture and better detectors,
          sensitivity for imaging and spectroscopy will be similar
          to the space observatory ISO


                                                               •Robert Gehrz, U. Minnesota

                                           Communications
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                   SOFIA Airborne!



     26 April 2007, L-3 Communications, Waco Texas: SOFIA takes to the
          air for its first test flight after completion of modifications
                                                               •Robert Gehrz, U. Minnesota
                                           Communications
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                       The First Test Flight of SOFIA
                                          April 26, 2007 at WACO, Texas




           •Robert Gehrz, U. Minnesota

                                              Communications
                                             Integrated Systems
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                       SOFIA’s Instrument Complement
          SOFIA is an airborne mission, with a long life-time.
           Therefore, unlike space missions, it supports a unique,
           expandable instrument suite
          SOFIA covers the full IR range with imagers and low,
           moderate, and high resolution spectrographs
          Nine instruments are under development now. Four will
           be available at first light in 2009
          SOFIA can take fully advantage of improvements in
           instrument technology so that the instruments will
           always be state-of-the-art.
          SOFIA will continue the airborne astronomy tradition of
           providing a platform where the next generation
           instrumentation scientists can be trained.
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         SOFIA Performance: Spectral Resolution of the
             First Generation Science Instruments
                                           8
                                      10

                                           7
                                      10

                                           6
                                      10                                                         GREAT
                Spectral resolution




                                           5
                                      10                                                                  CASIMIR

                                           4
                                                                           EXES
                                      10

                                           3
                                      10                     FLITECAM
                                                                                             FIFI LS
                                                                              FORCAST                      SAFIRE
                                           2
                                      10

                                           1
                                               HIPO
                                      10                                      FORCAST
                                                                                                   HAWC

                                           0
                                      10
                                                       1                     10                   100               1000
                                                                           Wavelength [µm]
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                 SOFIA’s 9 First Generation Instruments
              Instrument *                Type              λλ (µm)     Resolution            PI        Institution
             HIPO     %           fast imager     0.3 - 1.1           filters           E. Dunham      Lowell Obs.
             FLITECAM %           imager/grism    1.0 - 5.5           filters/R~2E3     I. McLean      UCLA
             FORCAST              imager/(grism?) 5.6 - 38            filters/(R~2E3)   T. Herter      Cornell U.
             GREAT    §           heterodyne      158 - 187,          R ~ 1E4 - 1E8     R. Güsten      MPIfR
                                  receiver        110 - 125,
                                                  62 - 65
             CASIMIR          §   heterodyne      250 -264,           R ~ 1E4 -1E8      J. Zmuidzinas CalTech
                                  receiver        508 -588
             FIFI LS         §    imaging grating 42 - 110,           R ~1E3 - 2E3      A. Poglitsch   MPE
                                  spectrograph    110 - 210
             HAWC             §   imager          40 - 300            filters       D. A. Harper       Yerkes Obs.
             EXES                 imaging echelle 5 - 28.5            R ~ 3E3 - 1E5 J. Lacy            U. Texas
                                  spectrograph    4.5-28.3                                             Austin
             SAFIRE          §    F-P imaging     150 - 650           R ~ 1E3 - 2E3 H. Moseley         NASA GSFC
                                  spectrometer


            * Listed in approximate order of expected in-flight commissioning
            % Operational (August 2004)
            § Uses non-commercial detector/receiver technology

                                            Communications
Science                                    Integrated Systems                                                         30
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Early Science Instruments and Observations




           Working FORCAST (Cornell)                           Successful lab demonstration
           instrument at Palomar in 2005                       of GREAT in July 2005
 Map the Orion Nebula at 38 µm with     High J CO and HCN observations
unprecedented angular resolution and of Orion protostars to quantify gas
sensitivity to investigating protostars cooling and density
                                                                            •Robert Gehrz, U. Minnesota
                                           Communications
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                                          Four First Light Instruments
                                                       Working/complete HIPO
                                                       instrument
                                                       in Waco on SOFIA
                                                       during Aug 2004



                                                                   Working/comple
                                                                    te FLITECAM
                                                                      instrument at
                                                                     Lick in 2004/5
                                                     Working
                                                     FORCAST
                                                     instrument at
                                                     Palomar in 2005

                                                                 Successful lab
                                                                 demonstration of
                                                                 GREAT in July
                                                                 2005

                                             Communications
 •Robert Gehrz, U. Minnesota                Integrated Systems                        32
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    Flight Profile 1                                       Performance with P&W JT9D-7J Engines:
   ASSUMPTIONS
                                                           Observations - start FL410, duration 7.1 Hr
   ZFW 381,000 LBS.
   ENGINES OPERATE AT 95% MAX CONT THRUST AT CRUISE
   25,000 LBS. FUEL TO FIRST LEVEL OFF
   CLIMB TO FIRST LEVEL-OFF AT MAX CRUISE WT
   LANDING WITH 20,000 LBS. FUEL
   BASED ON NASA AMI REPORT: AMI 0423 IR
                                                                                        FL430, 2.9 Hr
   BASED ON 747 SP FLIGHT MANUAL TABULATED DATA                                             GW 458.0
   STANDARD DAY PLUS 10 DEGREES C                                                            CRUISE
   CRUISE SPEED-MACH .84
                                                  FL410, 4.2                    Hr
                                                     GW 542.0                           52,000 LBS.FUEL
                                                                                       F.F. 17,920 LBS/HR.
                                                                       CRUISE
                                                                                                             DESCENT
                                                                  84,000 LBS. FUEL
                                                                                                             GW 406.0
                                                                 F.F. 20,200 LBS/HR.
                                                                                                             5,000 LBS. FUEL
                                   CLIMB                                                                     .5 HRS.
                                   25,000 LBS.
                                   FUEL
                                   .5 HRS.



                                                             TOTAL FUEL USED = 169,000 LBS.
                                                                               (24,708 Gallons)
                                                             TOTAL CRUISE TIME = 7.05 HRS.
                    START, TAXI, TAKEOFF
                                                             TOTAL FLIGHT TIME = 8.05 HRS                       LANDING
                    GW 570.0                                                                                    GW 401.0
                    3000 LBS TAXI FUEL                                                                          20,000 LBS
                                                                                                                FUEL
•Robert Gehrz, U. Minnesota

                                             Communications
                                            Integrated Systems                                                     33
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   Flight Profile 2
                                                              Performance with P&W JT9D-7J Engines:
                                                             Observations - start FL390, duration 10.2 Hr
   ASSUMPTIONS
   ZFW 381,000 LBS.
   ENGINES OPERATE AT 95% MAX CONT THRUST AT CRUISE
   25,000 LBS. FUEL TO FIRST LEVEL OFF
   CLIMB TO FIRST LEVEL-OFF AT MAX CRUISE WT
   LANDING WITH 20,000 LBS. FUEL
   BASED ON NASA AMI REPORT: AMI 0423 IR
                                                                                                  FL430, 2.9 Hr
   BASED ON 747 SP FLIGHT MANUAL TABULATED DATA                                                        GW 458.0
   STANDARD DAY PLUS 10 DEGREES C                                                                       CRUISE
   CRUISE SPEED-MACH .84
                                                  FL410, 4.2                      Hr
                                                     GW 542.0                                      52,000 LBS.FUEL
                                                                                                  F.F. 17,920 LBS/HR.
                          FL390, 3.1 Hr                                  CRUISE
                                                                                                                        DESCENT
                               GW 610.0                             84,000 LBS. FUEL
                                                                                                                        GW 406.0
                                                                   F.F. 20,200 LBS/HR.
                                                                                                                        5,000 LBS. FUEL
                              CRUISE                                                                                    .5 HRS.
CLIMB                    68,000 LBS. FUEL
25,000 LBS.             F.F. 21,930 LBS/HR.
FUEL
.5 HRS.


                                   TOTAL FUEL USED = 237,000 LBS.
                                                     (34,650 Gallons)
                                   TOTAL CRUISE TIME = 10.15 HRS.
                                   TOTAL FLIGHT TIME = 11.15 HRS.
START,TAXI,TAKEOFF                                                                                                         LANDING
GW 638.0                                                                                                                   GW 401.0
3000 LBS TAXI FUEL                                                                                                         20,000 LBS
                                                                                                                           FUEL
                                                                                         •Robert Gehrz, U. Minnesota

                                               Communications
                                              Integrated Systems                                                              34
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                    Example: 12.3h flight, 7h on Sgr A*




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                                                    Debris Disks
       Protoplanetary (debris?) dusty
       disks are common around young
       main sequence stars
       But dust is only 1% (by mass)
       of the interstellar medium
       Is there a much larger gas disk
       around these stars?

            The high resolution spectrograph EXES on SOFIA is
                uniquely sensitive for probing the abundance,
               kinematics, and evolution of the most abundant
                        molecule, molecular hydrogen:
         Is there only dust or also a much greater gas reservoir?
         What are the dynamics of these disks – dynamics
          reveal gas gaps created by Jupiter mass planets. Do
          we (indirectly) detect any?                  •Robert Gehrz, U. Minnesota
                                           Communications
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                                  The Debris Disk of Fomalhaut
                      FORCAST will provide the highest spatial
                         resolution measurements to date.
                                                                         450 m          850 m

  20

   0

 -20


              20        0      -20            20         0     -20
                                                                     FORCAST beam at 38 m

           Fomalhaut at 70, 160 (Spitzer), 450, and 850 m
            (SCUBA) (Images are on the same scale with north up
            and east on the left)
           FORCAST beam size is shown in red
                                                                                      •Robert Gehrz, U. Minnesota
                                           Communications
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              SOFIA Will Make Unique Contributions
                        to Comet Science
      Comets are the Rosetta Stone
     of the Solar System containing
     primordial material dating from the
     epoch of planet building.
      Water is the driving force in
     comets; water in comets was first
     discovered with the KAO
      Organic materials are also
     observable with SOFIA
      SOFIA enables:
       Access to water vapor and CO2 spectral features
      inaccessible from the ground
       Observations of comet apparitions from both hemispheres
                                                 •Robert Gehrz, U. Minnesota
                                           Communications
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                                 Extra-solar Planet Transits




            Artist’s concept of planetary transit and the lightcurve of HD 209458b
            measured by HST revealing the transit signature
      SOFIA flies in exceptionally stable atmosphere so that it is an
      excellent platform for observing extrasolar planetary transits
      SOFIA’s HIPO and FLITECAM instruments, which can be
      mounted simultaneously, will enable observations of the small
      variations in stellar flux due to a planet transit to:
          Provide good estimates for the mass, size and density of
           the planet
          Reveal the presence of star spots, satellites, and/or
           planetary rings
                                                                          •Robert Gehrz, U. Minnesota
                                           Communications
                                          Integrated Systems                                   39
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                    Occultation astronomy with SOFIA



       Pluto occultation light-curve observed on the
       KAO (1989) probes the atmosphere

        SOFIA can fly anywhere on the Earth, allowing it to position
        itself under the shadow of an occulting object
        Occultations yield sizes, atmospheres, and possible
        satellites of Kuiper belt objects and newly discovered planet-
        like objects in the outer Solar system.
        The unique mobility of SOFIA opens up some hundred
        events per year for study compared to a handful for a fixed
        observatory, and enables study of comets, supernovae and
        other serendipitous objects                      •Robert Gehrz, U. Minnesota
                                           Communications
                                          Integrated Systems                   40
Feeding the Black Hole in the Center of
              the Galaxy
One of the major discoveries of the KAO was
a ring of dust and gas orbiting the very
center of the Galaxy
                        Astronomers at
                        ESO and Keck
                        detected fast
                        moving stars
                        revealing a 4 x
                        106 solar mass
                        black hole at the
                        Galactic Center                  KWIC-KAO: Latvakoski
                                                         et al. 1999 (Cornell PhD)

  The ring of dust and gas will fall into the black hole
  SOFIA’s angular resolution and spectrometers will tell us:
      How much matter gets fed into the black hole?
      How much energy is released? – Will we have an outburst?
      What is the relationship to high energy active galactic nuclei?
                                                                •Robert Gehrz, U. Minnesota
Universities Space Research Association



                                                               Summary


        SOFIA is the next generation airborne observatory
        SOFIA promises lots of very exciting science from the
         first light instruments
        SOFIA’s long lifetime ensures a continuing platform for
         creation of state of the art instrumentation from the latest
         technologies – devices can be proven before being
         subjected to the unforgiving environment of space
        Airborne astronomy is a proven path for educating the
         next generation of instrumentation scientists – SOFIA
         promises to continue this vital tradition


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