The Gerard P. Kuiper Airborne Observatory (KAO) was a national facility operated by NASA to support research in infrared astronomy. The observation platform was a highly modified Lockheed C-141A Starlifter jet transport aircraft (s/n: 6110, registration: N714NA, callsign: NASA 714) with a range of 6,000 nautical miles (11,000 km), capable of conducting research operations at altitudes of up to 48,000 feet.
The KAO's telescope was a conventional Cassegrain reflector with a 36-inch (91.5 cm) aperture, designed primarily for observations in the 1 to 500 μm spectral range. Its flight capability allowed it to rise above almost all of the water vapor in the Earth's atmosphere (allowing observations of infrared radiation, which is blocked before reaching ground-based facilities), as well as travel to almost any point on the Earth's surface for an observation.
The KAO made several major discoveries, including the first sightings of the rings of Uranus in 1977 and a definitive identification of an atmosphere on Pluto in 1988. The KAO was used to study the origin and distribution of water and organic molecules in regions of star formation, and in the vast spaces between the stars. Kuiper astronomers also studied the disks surrounding certain stars that may be related to the formation of planetary systems around these stars. It took infrared spectrum measurements of the planet Mercury in 1995.
The KAO was retired in 1995 and is viewable at Moffett Field, although it is no longer airworthy. It has been succeeded by a Boeing 747-based airborne observatory equipped with a larger aperture telescope, the Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA completed its first test flight on April 26, 2007 and its telescope saw first light on May 26, 2010. Initial "routine" science observation flights began in December 2010 and the observatory is slated for full capability by 2014 with about 100 flights per year.