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Stratospheric Observatory for Infrared Astronomy (SOFIA)
by
E. E. Becklina, A. G. G. M. Tielensb, R. D. Gehrzc,
and
H. H. S. Callisa
aUniversities Space Research Association, NASA Ames Research Center
bCode SST, NASA Ames Research Center, Moffett Field, CA
cDepartment of Astronomy, University of Minnesota
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Outline
• Infrared (IR) Astronomy and SOFIA Science Objectives
• Description of the Observatory and Project Status
• Instrument Complement and Performance Characteristics
• Anticipated Science Highlights
• Summary
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Infrared Physics
IR = 1 µm ≤ ≤ 1000 µm (yellow light = 0.5 µm)
3K ≤ T ≤ 3000 K
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Blackbody Physics and Infrared Astronomy
IR = 1 µm ≤ ≤ 1000 µm
3K ≤ T ≤ 3000 K
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Infrared Astronomy and the Chemical Evolution of the Universe
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Key Science Topics
• How stars form in our galaxy and other nearby galaxies
• Chemistry, Mineralogy, and Biology
• Solar System studies
• Targets of Opportunity, for example:
– Bright Comets
– Eruptive variable stars
– Galactic and LMC/SMC classical novae
– Supernova in our galaxy or other nearby galaxies
– Eclipses and Occultations in the Solar System
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• Above 99% of the water vapor
• Transmission at 14 km >80% from 1 to 800 µm
• Instrumentation: wide variety, rapidly interchangeable, state-of-the art
• Mobility: anywhere, anytime
• Twenty year design lifetime
• A near-space observatory that comes home after every flight
The Advantages of SOFIA
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SOFIA Overview
• 2.5 m (98 inch) telescope in a modified Boeing 747SP aircraft– Optical to millimeter-wavelengths
– Emphasis on the obscured IR (30-300 m)
• 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
– Science Ops at NASA-Ames and Flight Ops at NASA-Dryden
– Deployments to the Southern Hemisphere and elsewhere
– >120 8-10 hour flights per year
– Built on NASA Lear/Kuiper Airborne Observatory Heritage
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Primary Mirror M1
M2
M3-1
M3-2
Focal Plane
Focal Plane Imager
Pressure bulkhead
Nasmyth tube
Spherical Hydraulic Bearing
Nasmyth: Optical Layout
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The Un-Aluminized Primary Mirror Installed
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Unique Science Capabilities
• 8 arcmin diameter FOV allows use of very large detector arrays
• Image size is diffraction limited beyond 15 µm, making images 3 times sharper than Spitzer Space Telescope
• Because of large aperture and better detectors, sensitivity for imaging and spectroscopy will be similar to the space observatory ISO
• Ability to adapt to new technologies
• Ability to track temporal events
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SOFIA’s Instrument Complement
• As an airborne mission, SOFIA supports a unique, expandable instrument suite
• SOFIA covers the full IR range with imagers and low, moderate, and high resolution spectrographs
• 4 instruments at IOC; 9 instruments at FOC
• SOFIA can take full advantage of improvements in instrument technology
• Both Facility and PI Instruments
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1 10 100 1000Wavelength [µm]
Spectral resolution
HIPO
FLITECAM
FORCASTHAWC
FIFI LS
EXES
CASIMIR
GREAT
SAFIRE
SOFIA Performance: Spectral Resolution of the First Generation Science Instruments
FORCAST
SPITZER IRSIRAC
MIPS
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Four First Light Instruments
Working/complete HIPO instrument in Waco on SOFIAduring Aug 2004
Working/complete FLITECAM
instrument atLick in 2004/5
Working FORCAST instrument at Palomar in 2005
Successful lab demonstration of GREAT in July 2005
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Star and Planet Formation
SOFIA’s unique high resolution spectrographs can determine the abundances and chemical routes of organic and pre-biotic molecules :
• The organic inventory of newly forming planetary systems
• The spatial distribution of water and the “snow-line” in proto-planetary systems NASA strategic sub-goal 3D.3
SOFIA will study the molecular composition of regions of star and planet formation
Spectroscopy can reveal the presence of water, simple hydrocarbon molecules, and complex nitrogen-bearing organics
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Occultation astronomy with SOFIA
Pluto occultation lightcurve 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.
•Occultation studies with SOFIA will probe the 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.
•SOFIA’s mobility also enables study of comets, supernovae and other serendipitous objects.
SOFIA will study stellar occultations
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Resolving Star Formation: Spitzer & SOFIA
Antennae GalaxiesIRAC at 8 m (red; 160s, 4’ x 4’)FORCAST at 24 m
Henize 206- LMC high mass star formationMIPS at 24 µm (80s, 20’ x 20’)HAWC at 53 / 89 µm (mosaic)
NASA/JPL-Caltech/Z. Wang NASA/JPL-Caltech/V. Gorjian
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Evolution of the Universe
Atmospheric transmission around the HD line at 40,000 feet
Only the high resolution spectrograph on SOFIA can measure the deuterium abundance throughout our galaxy and answer questions about:
• The abundance of deuterium and its variation with the local star formation rate in galaxies.
• What the deuterium abundance tells us about the Big Bang and about the star formation history of galaxies?
Deuterium is created in the Big Bang, and the primordial deuterium abundance provides the best constraint on the mass density of baryons in the universe.
However, the Big Bang deuterium record is modified by stellar nuclear burning.
SOFIA will study the deuterium abundance in the galaxy, investigating the evolution of the universe
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Classical Nova Explosions
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R. D. Gehrz, et al. 2005, ApJ, in preparation [PID 124]
Spitzer Spectra of Nova V382 Vel
IRS Short-High IRS Long-High
IRS Short and Long-High Spectra: Abundances and Kinematics
H I[Ne II] [Ne V] [Ne III]
[Ne V]
[O IV] [Ne III]
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• The aircraft has flown in April 2007 and is now at NASA Dryden FRC for flight certification tests
• Early Science is expected to occur in 2009
• Two instruments have been selected for Early Science
- FORCAST: a US 5-40 μm imager
- GREAT: a German heterodyne 60 to 200 μm Spectrometer
- Both have been tested in the lab or on a telescope
Early Science with SOFIA
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• NASA Ames and USRA are ramping up for Observatory operations. Please visit the SOFIA booth or web site (http://www.sofia.usra.edu/) for Job opportunities.
• There will be community involvement in the Early Science Program.
• We will hold a “SOFIA’s 2020 Vision” Workshop at Caltech, December 6-8, 2007 – long term science
• We will hold a “SOFIA Early Science” Workshop at the January AAS meeting in Austin, TX, January 8, 2008
Preparations for Science Operations and Community Task Force Activities
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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
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Summary• SOFIA has unique spectral and temporal coverage
– Unique high-resolution spectroscopy: 28 < l < 150 μm
– (l/10 μm) arc-sec image quality, unique for 30 < l < ~60 μm
– Unique ability to obtain coverage of transient events
– Unique long operating lifetime
• SOFIA will increase its unique complement of capabilities in the future and will be a test-bed of technologies for future Far-IR missions
– State-of-the-art large format IR detector arrays
– Polarimeteric imaging and spectroscopy
• SOFIA is a hands-on Far-IR observatory
– Will train future mission scientists and instrumentalists
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Appendices
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The Initial SOFIA Instrument Complement
• HIPO: High-speed Imaging Photometer for Occultation
• FLITECAM: First Light Infrared Test Experiment CAMera
• FORCAST: Faint Object InfraRed CAmera for the SOFIA Telescope
• GREAT: German Receiver for Astronomy at Terahetz Frequencies
• CASIMIR: CAltech Submillimeter Interstellar Medium Investigations Receiver
• FIFI-LS: Field Imaging Far-Infrared Line Spectrometer
• HAWC: High-resolution Airborne Wideband Camera
•EXES: Echelon-Cross -Echelle Spectrograph
•SAFIRE: Submillimeter And Far InfraRed Experiment
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SOFIA’s 9 First Generation Instruments
* Listed in approximate order of expected in-flight commissioning % Operational (August 2004) § Uses non-commercial detector/receiver technology
Science
Instrument * Type 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 UCLAFORCAST imager/(grism?) 5.6 - 38 filters/(R~2E3) T. Herter Cornell U.GREAT ¤ heterodyne
receiver158 - 187, 110 - 125, 62 - 65
R ~ 1E4 - 1E8 R. Gsten MPIfR
CASIMIR ¤ heterodyne receiver
250 -264, 508 -588
R ~ 1E4 -1E8 J. Zmuidzinas CalTech
FIFI LS ¤ imaging grating spectrograph
42 - 110, 110 - 210
R ~1E3 - 2E3 A. Poglitsch MPE
HAWC ¤ imager 40 - 300 filters D. A. Harper Yerkes Obs.EXES imaging echelle
spectrograph5 - 28.5 R ~ 3E3 - 1E5 J. Lacy U. Texas Austin
SAFIRE ¤ F-P imaging spectrometer
150 - 650 R ~ 1E3 - 2E3 H. Moseley NASA GSFC
4.5-28.3
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Science Objectives
• Major Science Programs for SOFIA:
– Origin of stars and planetary systems– Planetary bodies that make up our Solar System– Life-cycle of dust and gas in galaxies– Composition of the molecular universe– Role of star formation and black hole activity in the energetics of luminous galaxies
• SOFIA has a unique suite of instruments that cover a wide range of wavelengths at a wide range of spectral resolution.
• SOFIA will be continuously upgraded with new instrumentation and will serve as an important technology development platform for future space missions.
• SOFIA is a highly visible icon for education and public outreach and will immerse educators in the scientific process.
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Current Activities of the SCTF
• Workshop during 6-8 December, 2007, at Caltech: "SOFIA’s 2020 Vision: Scientific and Technological Opportunities.” The LOC and SOC have been empanelled and are working.
• The first “SOFIA Community Task Force Workshop”
will be held at the 211th AAS Meeting in Austin, TX
on Tuesday January 8, 2008. Planning is underway.
• Formation of a subcommittee of general experts to advise the
project on the contributions SOFIA can make to currently
acknowledged outstanding scientific problems.
