The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint project of NASA and the German Aerospace Center (DLR). Universities Space Research Association (USRA) was awarded the prime contract by NASA in 1996 for development, operation of the observatory and management of the American part while the DSI (Deutsches SOFIA Institut) manages the German part (mainly science and telescope related).
SOFIA is based on a Boeing 747SP wide-body aircraft. The aircraft has been modified to carry a 2.5 meter diameter reflecting telescope in the aft section of the fuselage. This telescope is designed for infrared astronomy observations at altitudes of about 41,000 feet (about 12 km) in the stratosphere. The water vapor in the Earth's atmosphere blocks some infrared wavelengths from reaching the ground, but SOFIA's flight capability allows it to rise above almost all of the water vapor in the Earth's atmosphere. 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.
In mid-2009, the aircraft will undergo flight tests at high altitude cruising speed with the telescope door open. This test phase is scheduled to run through the end of 2009, after which SOFIA will begin limited science observation flights. Normal science observation flights should begin in 2011 and the observatory is slated for full capability by 2014.