Martin X-23 PRIME

The Martin X-23 PRIME was an unmanned American lifting-body re-entry test vehicle built by Martin Marietta for the United States Air Force. PRIME, short for Precision Recovery Including Maneuvering Entry, was the second part of the Air Force START program and flew the SV-5D shape, a small vehicle of about 405 kilograms that was later also called the X-23A. Its job was to show that a wingless body could steer itself back from space to a chosen recovery point with a cross-range of up to about 1,100 kilometers, and to test spray-on ablative heat shields. Each flight began on an Atlas booster from Vandenberg Air Force Base and was suborbital, with the vehicle separating near the top of its path and using nitrogen thrusters, then flaps, to fly its re-entry. Three flights took place between December 1966 and April 1967; after the third succeeded, the remaining work was cancelled and the two unflown vehicles went to the Air Force museum at Wright-Patterson Air Force Base.