The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint project of NASA and the German Aerospace Center (DLR) to construct and maintain an airborne observatory. NASA awarded the contract for the development of the aircraft, operation of the observatory and management of the American part of the project to the Universities Space Research Association (USRA) in 1996.The DSI (Deutsches SOFIA Institut) manages the German parts of the project which are primarily science and telescope related. SOFIA's telescope saw first light on May 26, 2010. SOFIA is the successor to the Kuiper Airborne Observatory.
SOFIA is based on a Boeing 747SP wide-body aircraft that has been modified to include a large door in the aft fuselage that can be opened in flight to allow a 2.5 meter diameter reflecting telescope access to the sky. This telescope is designed for infrared astronomy observations in the stratosphere at altitudes of about 41,000 feet (about 12 km). SOFIA's flight capability allows it to rise above almost all of the water vapor in the Earth's atmosphere, which blocks some infrared wavelengths from reaching the ground. At the aircraft's cruising altitude, 85% of the full infrared range will be available.The aircraft can also travel to almost any point on the Earth's surface, allowing observation from the northern and southern hemispheres.
Once ready for use, the expectation is for observing flights to be flown 3 or 4 nights a week for the next 20 years. SOFIA is now based at NASA's Dryden Aircraft Operations Facility at LA/Palmdale Regional Airport, California, while staff at NASA Ames Research Center, in Mountain View, California, operate the SOFIA Science Center where astronomical observation missions are planned for the flying observatory.
SOFIA uses a 2.5-meter reflector telescope, which has an oversized, 2.7 meter diameter primary mirror, as is common with most large infrared telescopes.The optical system uses a Cassegrain reflector design with a parabolic primary mirror and a remotely configurable hyperbolic secondary. In order to fit the telescope into the fuselage, the primary is shaped to an f-number as low as 1.3, while the resulting optical layout has an f-number of 19.7. A flat, tertiary, dichroic mirror is used to deflect the infrared part of the beam to the Nasmyth focus where it can be analyzed. An optical mirror located behind the tertiary mirror is used for a camera guidance system.
The telescope looks out of a large door in the side of the fuselage near the airplane's tail, and will initially carry nine instruments for infrared astronomy at wavelengths from 1–655 micrometres and high-speed optical astronomy at wavelengths from 0.3–1.1 micrometres.The main instruments are the FLITECAM, a near infrared camera covering 1–5 micrometres; FORCAST, covering the mid-infrared range of 5–40 micrometres, and HAWC, which spans the far infrared in the range 42–210 micrometres.
The primary science objectives of SOFIA are to study the composition of planetary atmospheres and surfaces; to investigate the structure, evolution and composition of comets; to determine the physics and chemistry of the interstellar medium; and to explore the formation of stars and other stellar objects. While SOFIA aircraft operations are managed by NASA Dryden, NASA's Ames Research Center in Mountain View, California, is home to the SOFIA Science Center which will manage mission planning for the program.
Airborne Astronomy Ambassadors Program:
Once SOFIA is fully operational, more than 50 educators will be selected each year to participate in one or more research flights. Following their flight experience, SOFIA's Airborne Astronomy Ambassadors (AAA) will become part of a growing national network of master educators who conduct workshops, teacher in-service training, and other programs in their local school districts, science centers, and communities.
Altitude: Ground: 702 m (2,302 ft);
Airborne: 13.7 km (45,000 ft).