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NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA)

NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA). Gordon J. Stacey, Cornell University (many slides borrowed from Robert Gehrz, U. Minnesota). The SOFIA Observatory. 2.5 m telescope in a modified Boeing 747SP aircraft Optical to millimeter-wavelengths

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NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA)

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  1. NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) Gordon J. Stacey, Cornell University (many slides borrowed from Robert Gehrz, U. Minnesota)

  2. 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

  3. 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?

  4. 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!

  5. 2 m (2MASS) Image: Galactic Center Cluster Far-IR (IRAS) Image: Warm dust Optical Image: Nearby stars Extinction

  6. Energetics: What glows in the far-IR? The Planck Function Wien’s Law Far-IR = 30 µm ≤  ≤ 300 µm 10K ≤ T ≤ 100 K Robert Gehrz, U. Minnesota

  7. Things Look Different at Different Wavelengths! Warm eyes & ears Cool nose 10 m image of a cat Cool fur

  8. 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

  9. Orion Nebula: Visible and Far -IR 38 m Image: KWIC-Kuiper Airborne Observatory Harry Latvakoski, Cornell PhD

  10. 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

  11. The Far -Infrared Regime is Exciting – So Why Isn’t Everyone Doing it? 14,000 feet 41,000 feet

  12. The History of Airborne Astronomy 1999 NASA Lear Jet Observatory 1967 – 1983+ 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…

  13. 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 • 7.5 hr flights, 6.5 of which above 39,000 feet • Produced > 60 PhDs • Guiding done with focal plane camera and computerized feedback to torque motors on the telescope

  14. 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:

  15. SOFIA: The Stratospheric Observatory for Infrared Astronomy 1999 2009 – 2029… 2002 2006 2006

  16. 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

  17. M2 Pressure bulkhead Spherical Hydraulic Bearing Focal Plane M3-1 Nasmyth tube M3-2 Primary Mirror M1 Focal Plane Imager Nasmyth: Optical Layout

  18. Telescope and aperture assembly

  19. 2.7-meter (106 inch) f/1.28 Primary Mirror after final polishing

  20. Installing the bearing sphere

  21. Installation of the Secondary Mirror

  22. Installation of the Tertiary Mirror

  23. The Un-Aluminized Primary Mirror Installed

  24. 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

  25. 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

  26. The First Test Flight of SOFIA April 26, 2007 at WACO, Texas Robert Gehrz, U. Minnesota

  27. 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.

  28. 8 10 7 10 6 GREAT 10 5 10 CASIMIR EXES 4 Spectral resolution 10 3 FLITECAM 10 FIFI LS SAFIRE 2 10 HIPO FORCAST 1 10 HAWC 0 10 1 10 100 1000 Wavelength [µm] SOFIA Performance: Spectral Resolution of the First Generation Science Instruments FORCAST

  29. SOFIA’s 9 First Generation Instruments 4.5-28.3 * Listed in approximate order of expected in-flight commissioning % Operational (August 2004) § Uses non-commercial detector/receiver technology Science

  30. Early Science Instruments and Observations Working FORCAST (Cornell) instrument at Palomar in 2005 Successful lab demonstration of GREAT in July 2005 Map the Orion Nebula at 38 µm with unprecedented angular resolution and sensitivity to investigating protostars High J CO and HCN observations of Orion protostars to quantify gas cooling and density Robert Gehrz, U. Minnesota

  31. Four First Light Instruments Working/complete HIPO instrument in Waco on SOFIA during Aug 2004 Working/complete FLITECAM instrument at Lick in 2004/5 Working FORCAST instrument at Palomar in 2005 Successful lab demonstration of GREAT in July 2005 Robert Gehrz, U. Minnesota

  32. Flight Profile 1 Performance with P&W JT9D-7J Engines: Observations - start FL410, duration 7.1 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 BASED ON 747 SP FLIGHT MANUAL TABULATED DATA STANDARD DAY PLUS 10 DEGREES C CRUISE SPEED-MACH .84 FL430, 2.9 Hr GW 458.0 FL410, 4.2 Hr GW 542.0 CRUISE 52,000 LBS.FUEL F.F. 17,920 LBS/HR. CRUISE 84,000 LBS. FUEL F.F. 20,200 LBS/HR. DESCENT GW 406.0 5,000 LBS. FUEL .5 HRS. CLIMB 25,000 LBS. FUEL .5 HRS. TOTAL FUEL USED = 169,000 LBS. (24,708 Gallons) TOTAL CRUISE TIME = 7.05 HRS. TOTAL FLIGHT TIME = 8.05 HRS START, TAXI, TAKEOFF GW 570.0 3000 LBS TAXI FUEL LANDING GW 401.0 20,000 LBS FUEL Robert Gehrz, U. Minnesota

  33. 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 BASED ON 747 SP FLIGHT MANUAL TABULATED DATA STANDARD DAY PLUS 10 DEGREES C CRUISE SPEED-MACH .84 FL430, 2.9 Hr GW 458.0 FL410, 4.2 Hr GW 542.0 CRUISE 52,000 LBS.FUEL F.F. 17,920 LBS/HR. FL390, 3.1 Hr GW 610.0 CRUISE 84,000 LBS. FUEL F.F. 20,200 LBS/HR. DESCENT GW 406.0 5,000 LBS. FUEL .5 HRS. CRUISE 68,000 LBS. FUEL F.F. 21,930 LBS/HR. CLIMB 25,000 LBS. FUEL .5 HRS. TOTAL FUEL USED = 237,000 LBS. (34,650 Gallons) TOTAL CRUISE TIME = 10.15 HRS. TOTAL FLIGHT TIME = 11.15 HRS. LANDING GW 401.0 20,000 LBS FUEL START,TAXI,TAKEOFF GW 638.0 3000 LBS TAXI FUEL Robert Gehrz, U. Minnesota

  34. Example: 12.3h flight, 7h on Sgr A*

  35. 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

  36. The Debris Disk of Fomalhaut FORCAST will provide the highest spatial resolution measurements to date. • 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 450 mm 850 mm 20 0 -20 20 0 -20 20 0 -20 FORCAST beam at 38 mm Robert Gehrz, U. Minnesota

  37. SOFIA Will Make Unique Contributions to Comet Science • Comets are the Rosetta Stone of the Solar System containingprimordial 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

  38. 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 Extra-solar Planet Transits Artist’s concept of planetary transit and the lightcurve of HD 209458b measured by HST revealing the transit signature Robert Gehrz, U. Minnesota

  39. 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

  40. Feeding the Black Hole in the Center of the Galaxy • 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? 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) Robert Gehrz, U. Minnesota

  41. 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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