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 mission retrieve the payload and return it to Earth for measurements. The project was approved in 1974.

Engineers imagined that the first mission would last most of a year, and that several long-duration exposure missions would use the same frame. The frame was actually used for only one 5.7-year mission.

Fifty-seven science and technology experiments – involving government and university investigators from the United States, Canada, Denmark, France, Germany, Ireland, the Netherlands, Switzerland, and the United Kingdom – flew on the LDEF mission. These experiments examined:

• materials, coatings, and thermal systems
• power and spacecraft propulsion
• science
• electronics and optics

LDEF was built at NASA Langley Research Center.

Retrieval

At LDEF's launch, retrieval was scheduled for March 19, 1985, eleven months after deployment. Schedules slipped, postponing the retrieval mission first to 1986, then indefinitely due to the Challenger disaster. It was finally recovered by the Shuttle Columbia on January 12, 1990. Columbia approached LDEF in such a way as to minimize possible contamination to LDEF from thruster exhaust. While LDEF was still attached to the RMS arm, an extensive 4.5 hour survey photographed each individual experiment tray, as well as larger areas.

Columbia landed at Edwards Air Force Base on January 20, 1990. Through the orbiter window, LDEF Project staff viewed and took photographs of LDEF at Edwards. With LDEF still in its bay, Columbia was ferried back to the Kennedy Space Center (KSC) on January 26. Special efforts were taken to ensure protection against contamination of the payload bay during the ferry flight. On January 30-31, LDEF was removed from Columbia's payload bay in KSC's Orbiter Processing Facility, placed in a special payload canister, and transported to the Operations and Checkout Building. On February 1, 1990, LDEF was transported in the LDEF Assembly and Transportation System to the Spacecraft Assembly and Encapsulation Facility - 2, where the LDEF Project team led deintegration activities.

See also

• Mir Environmental Effects Payload
• Materials International Space Station Experiment

References

• NASA Langley LDEF site
• The Long Duration Exposure Facility (LDEF), Mission 1 Experiments, 1984. NASA SP-473
• Photographic Survey of the LDEF Mission report