NASA's Long Duration Exposure Facility, or LDEF, was a school bus-sized cylindrical space experiment rack that exposed various material samples to outer space for about 5.7 years, completing 32,422 Earth orbits. The STS-41-C crew of the Space Shuttle Challenger deployed LDEF April 7, 1984. Columbia retrieved LDEF on mission STS-32, January 12, 1990. Inception Researchers recognized the potential of the planned Space Shuttle to deliver a payload to space, leave it there, and on a separate mis… (More on Ldef)