Two SR-71 aircraft were used by NASA as testbeds for high-speed, high-altitude aeronautical research. The aircraft, an SR-71A and an SR-71B pilot trainer aircraft were based at NASA's Dryden Flight Research Center, Edwards, Calif. They have been loaned to NASA by the U.S. Air Force. Developed for the USAF as reconnaissance aircraft more than 30 years ago, SR-71s are still the world's fastest and highest-flying production aircraft.
The aircraft can fly more than 2200 miles per hour (Mach 3+ or more than three times the speed of sound) and at altitudes of over 85,000 feet. This operating environment makes the aircraft excellent platforms to carry out research and experiments in a variety of areas -- aerodynamics, propulsion, structures, thermal protection materials, high-speed and high-temperature instrumentation, atmospheric studies and sonic boom characterization.
Pulled this from mdsea... gorgeous aircraft