SOFIA Edwin Erickson NASA Ames Research Center

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1 Rationale Science Status Program SOFIA Stratospheric Obsevatory for Infrared Astronomy SOFIA Edwin Erickson NASA Ames Research Center Stratospheric Observatory for Infrared Astronomy The Dusty and Molecular Universe: A Prelude to Alma and Herschel EFE 28 October

2 Rationale SOFIA Attributes - Wavelength range: UV to Radio : µm - Mobility: anywhere, any time : all sky, ephemeral events - Primary Mirror: 2.7 m diameter (Aperture 2.5 m) - Operating Altitude: km (37,000-45,000 feet) - Design Lifetime: 20 years - Observing Program: flexible; annual proposal opportunities - Science Instruments: wide variety, hands-on in-flight, late latest technologies in new instruments - Education/Public Outreach: teachers/media/public access SOFIA will be a mobile ground-based observatory operating in the lower stratosphere. 2

3 IR - FIR - Submm Missions Wavelength (µm) KAO IRAS COBE ODIN SWAS ISO ASTRO-F SPITZER Planck Herschel WISE JWST SAFIR SOFIA Frequency (THz) Rationale Year Airborne observatories provide temporal continuity and wide spectral coverage, complementing other facilities. 3

4 Facilities/Telluric Transmission vs.wavelength High Angular Resolution Pointed Infrared Capabilities Hubble Ground-Bound Herschel SOFIA JWST (2011?) SAFIR (2015?) SOFIA s wavelength coverage is unmatched by other FIR facilities. Rationale 4

5 The Atmosphere a closer look: 1 R ~ 100 Transmission Rationale 0 Wavelength (µm) SOFIA: 7 µm PWV, 12.5 km Dome C: 250 µm PWV, 2.8 km - Some telluric lines are saturated even at SOFIA altitudes. - Many important astrophysical lines are readily accessible, e.g. C + at 158 µm (T ~ 90%) R ~ 10, C + 5

6 SOFIA compared with other Far-IR missions Angular Resolution SOFIA and Herschel will provide ~ three times the angular resolution previously achieved in the Far-IR. Diameter (arcsec) Angular Resolution (arc seconds) KAO Spitzer SIRTF ISO IRAS SOFIA SOFIA Herschel Photometric Sensitivity 1 Sigma, 1 hr, Flux Density (mjy) KAO Photometric Sensitivity SOFIA SOFIA IRAS SIRTF Wavelength (µm) ISO Spitzer Herschel Wavelength (µm) Spitzer and Herschel will provide best sensitivity for direct Far-IR detector systems. SOFIA will provide the widest spectral coverage over the longest lifetime. Rationale 6

7 Science SOFIA s 9 First Generation Instruments Instrument * Type λλ (µm) Resolution PI Institution HIPO % fast imager filters E. Dunham Lowell Obs. FLITECAM % imager/grism filters/r~2e3 I. McLean UCLA FORCAST imager/(grism?) filters/(r~2e3) T. Herter Cornell U. GREAT heterodyne receiver , , R ~ 1E4-1E8 R. Güsten MPIfR CASIMIR heterodyne receiver FIFI LS imaging grating spectrograph , , R ~ 1E4-1E8 * Listed in approximate order of expected in-flight commissioning % Operational (August 2004) Uses non-commercial detector/receiver technology J. Zmuidzinas CalTech R ~1E3-2E3 A. Poglitsch MPE HAWC imager filters D. A. Harper Yerkes Obs. EXES imaging echelle R ~ 3E3-1E5 J. Lacy U. Texas spectrograph Austin SAFIRE F-P imaging spectrometer R ~ 1E3-2E3 H. Moseley NASA GSFC 7

8 cover a wide range of wavelengths and spectral resolutions First Generation SOFIA Instruments Spectral resolution FLITECAM EXES GREAT FIFI LS CASIMIR SAFIRE 10 2 (Grisms?) 10 1 HIPO FORCAST HAWC Science Wavelength [µm] 8

9 enabling a variety of studies Some SOFIA science topics Spectral resolution PLANETARY ATMOSPHERES MOLECULES IN COMETS YSO DISK DYNAMICS PAHs/ORGANIC MOLECULES COMPOSITION OF ISM GRAINS PLANETARY ATMOSPHERES INTERSTELLAR CHEMISTRY DYNAMICS/COMPOSITION IN YSO OUTFLOWS GC GAS DYNAMICS ISM PHYSICS IN EXTERNAL GALAXIES KBOs, PLANET TRANSITS DEBRIS DISK STRUCTURE YSO LUMINOSITIES, SEDs Science Wavelength [µm] 9

10 A few SOFIA Science Examples: Stellar Occultations by Solar System Objects: Shadows of SSOs cast by stars may appear anywhere on earth - Measureable sizes > ~ 200 km - Ground speed up to ~ 30 km/s SOFIA can be there, free from clouds and scintillation noise - High-speed photometry achieves ~ few km resolution - Numerous useful occultation events possible each year Simultaneous HIPO (visible) and FLITECAM (NIR) data will - Probe atmospheres & rings (Rings of Uranus were discovered from KAO) - Establish sizes of ~ 30 KBOs (eg Sedna), constraining geometric albedo - Confront details of solar system formation models (debris disks) Extrasolar Planet Transits: Possible with S/N comparable to HST - Estimate planet sizes - With Doppler velocity observations, estimate planet densities Dunham Science 10

11 HD observations with GREAT 112 µm HD is a GREAT priority; h high resolution minimizes line/continuum problem [D]/[H] abundance traces gas nuclear evolution and astration Deuterated molecules are key tracers for early phases of star formation; no freeze-out on grains HD is at the root of deuterium chemistry network: ζ o D e H H + D + D e H 2 ζ o H H H + ν HCO + 2 H + 3 e,h HD H 3 + e,h 2 H 2 D + CO DCO + Use HD to trace H 2 columns? HDO, OD, NH 2 D, Güsten 11

12 SOFIA + ALMA Studies of Protoplanetary Disks ALMA will image the millimeter dust continuum and CO emission, resolving scales ~10 AU, to examine morphology, and to estimate dust and gas content; gas kinematics will constrain the stellar mass. EXES on SOFIA can resolve line profiles of emission arising from warmer inner (<~10AU) parts of the disk, constraining the gas mass and morphology. Some lines expected are H 2 (28 µm), S I (25 µm), and Fe II (26 µm). Also H 2 O, CH 4, and CO should be detectable, and possibly HCN and C 2 H 2. Combination will challenge disk structure and chemistry models 12 µm 17 µm 28µm Theoretical H 2 line profiles from a disk with and without gap at 3 AU. Lacy Science 12

13 The Galactic Center Radio Arcs KAO FIR spectroscopy showed the thermal filaments are likely ionized by hot stars; led to discovery of the Arches Cluster (L ~ 2E7 L ) from the AAT Later KAO/KWIC data suggest other heating sources are required The higher spatial resolution of FORCAST on SOFIA will Reveal possible internal heating sources producing color temperature peaks in the arcs. 5 KAO/Cornell-KWIC 38 µm Continuum FORCAST/SOFIA Beam and FOV Map PDR and heating in the CNR and arches with the [SiII] 34.8 fine-structure line. Map the magnetic field structure with polarimetric imaging - requires a future FORCAST upgrade. 13

14 Other galaxies: Test of an AGN Torus Model Unification models for different types of AGNs feature an obscuring molecular torus This gas must be dense and hot (~ 1000K) Strong high-j CO line emission is predicted, peaking at J = (λ = 46µm) (Krolik & Lepp 1989) FIFI LS can detect a number of mid- to high-j lines in ~1h of integration 14

15 SOFIA and Herschel: Complementary, Synergistic Similar instrumentation at relatively unexplored long wavelengths: - Herschel s per-pixel direct detection sensitivity is ~10x that of SOFIA - Sensitivity of their coherent receivers is comparable. Resolving Power 1.E+6 1.E+4 1.E+2 Science Instruments SOFIA Herschel 1.E+0 λ (µm) SOFIA will complement Herschel observations: - Complete SEDs of YSOs in nearby clouds at shorter wavelengths - Chemistry and dynamics of interstellar gas at higher frequencies SOFIA s long life and accessibility will encourage new technology and enable its applications: - Coherent receivers: higher frequency, lower noise, wider bandwidth, imaging - Direct FIR detector arrays with larger formats - Imaging mid- and far-ir-polarimetry 15

16 SOFIA System - Status Observatory Science & Mission Operations Center Science Instruments Status 16

17 Telescope Configuration Science Pressure Aft Cavity Instrument Bulkhead Bulkhead ECS Status 17

18 Potential Proof Pressure Test Mishap Status Not SOFIA! 18

19 Proof Pressure Test Aircraft/Telescope 12 PSI, No Leaks! May, 2004 Status 19

20 Ground tests of telescope in Waco, Texas First Light! August

21 Ground tests of telescope in Waco, Texas August 04, with HIPO at the focal plane HIPO Team Aug. 04 HIPO Status 21

22 Telescope Testing Aug

23 Science and Missions Operations Center N-211, NASA Ames Research Center, Moffett Field California Status All major elements of the SOFIA program will be housed in NASA hangar N

24 Primary Mirror Coating Chamber in N-211 Status 24

25 EPO: the KAO FOSTER flight program Program Teachers assisted science teams. Media flew to report. SOFIA will also sponsor a vigorous EPO program. 25

26 Tentative Schedule for Completion Prepare/perform ~ 9 closed-door FAA flights (Waco) September 04 April 05 Debug telescope on ground, coat primary (Ames) May 05 - September 05 Prepare/perform ~ 20 FAA flights (Waco) October 05 March 06 Characterize/debug telescope ~ 6 flights (Ames) April 06 July 06 Ramp-up science flights to full operation (Ames) August 06 September 08 Program 26

27 Observations with SOFIA Science Instruments: All accessible to general investigators; descriptions and performance summaries are on website Proposal Opportunities: via annual peer review by U.S. TAC (~ 80%) or German TAC (~20%); international proposals (to either TAC) will be welcome! Observing: General Investigators need not fly Early Demonstration Science: Competitive opportunities for ramp-up period will be advertised Mature program: ~ 1000 flight hours per year Program 27

28 Summary SOFIA - is nearing completion of development - has unique capabilities which complement other facilities - will start 2 year ramp up into full operations beginning in affords great EPO and instrument technology involvement - plans observing opportunities for the international community Come fly with us! Program 28

29 Mid (?) SOFIA at NASA Ames! Program 29