NASA's B-52B launch aircraft takes off carrying the third X-43A hypersonic research vehicle on a captive carry evaluation flight September 27, 2004.

The X-43 is part of the Hyper-X hypersonic research program led by NASA's Aeronautics Research Mission Directorate, and operated jointly by NASA's Langley Research Center, Hampton, Va., and Dryden Flight Research Center, Edwards, Calif. The program aims to demonstrate air-breathing engine technologies that promise to increase payload capacity - or reduce vehicle size for the same payload - for future hypersonic aircraft and reusable space launch vehicles.