Quoted By:
The official word on why the SR-71 was retired is that satellites can do the job. The SR-71 (Blackbird to civilian, The Sled to those who flew it) was officially withdrawn from service in 1991. However, a number were turned over to NASA during the 1990's for high altitude research and operated as "poor man's space shuttles" preforming experiments at the edge of space. During the eight years the SR-71 operated with NASA, there were multiple times the Sleds and their support crews would disappear and there would be sightings of the planes on overseas bases without their NASA markings. Aviuation enthusiasts speculated that the NASA had agreed to absorb the operational cost of keeping the SRs flying in return for using them for research. As the 1990's wore on, aircraft enthusiasts haunting the edges of the Groom Lake Facility, otherwise known as Area 51, would spot odd "donuts on a rope" contrails that were probably the result of advanced hypersonic engines. Narrow wedge shaped craft and double sonic booms, usually only heard during Space Shuttle re-entry as the shuttle entered the atmosphere at MACH 23, were heard over Groom Lake. The SR-71 were finally and truly retired in 1999. Probably because their replacements had finally come on line.
