N747NA (21441) "SOFIA" Stratospheric Observatory for Infrared Astronomy.
SOFIA is an 80/20 partnership of NASA and the German Aerospace Center (DLR), consisting of an extensively modified Boeing 747SP aircraft carrying a reflecting telescope with an effective diameter of 2.5 meters (100 inches). The aircraft is based at NASA's Armstrong Flight Research Center in Palmdale, Calif. The SOFIA Program Office is at NASA Ames Research Center in Moffett Field, Calif., which manages SOFIA's science and mission operations in cooperation with the Universities Space Research Association (USRA; Columbia, Md.) and the German SOFIA Institute (DSI; University of Stuttgart).