This photo shows NASA's SR-71B, one of three triple-sonic SR-71s initially loaned to NASA by the Air Force, cruises over the California desert en route to NASA's Ames-Dryden Flight Research Facility (later, Dryden Flight Research Center), Edwards, California, from Air Force Plant 42, Palmdale, CA, July 25, 1991. The aircraft, two SR-71As and the SR-71B, were loaned to NASA for high-speed, high -altitude testbeds for research in such areas as aerodynamics, propulsion structures, thermal protection materials, and instrumentation.