LDEF
LDEF, shortly before deployment, flies on the RMS arm of Space Shuttle Challenger over Baja California.
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| Mission type | Materials research |
|---|---|
| Operator | NASA |
| COSPAR ID | 1984-034B |
| SATCAT no. | 14898 |
| Website | setas-www |
| Mission duration | 2076 days |
| Distance travelled | 1,374,052,506 km (853,796,644 mi) |
| Orbits completed | 32,422 |
| Spacecraft properties | |
| Manufacturer | Langley |
| Launch mass | 9,700 kg (21,400 lb) |
| Start of mission | |
| Launch date | April 6, 1984, 13:58:00 UTC |
| Rocket |
Space Shuttle Challenger STS-41-C |
| Launch site | Kennedy LC-39A |
| End of mission | |
| Recovered by |
Space Shuttle Columbia STS-32 |
| Recovery date | January 12, 1990, 15:16 UTC |
| Landing date | January 20, 1990, 09:35:37 UTC |
| Landing site | Edwards Runway 22 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Low Earth |
| Eccentricity | 7.29E-4 |
| Perigee | 473.0 km (293.9 mi) |
| Apogee | 483.0 km (300.1 mi) |
| Inclination | 28.5 degrees |
| Period | 94.2 minutes |
NASA's Long Duration Exposure Facility, or LDEF (acronym pronounced "EL-deaf"), was a school bus-sized cylindrical facility designed to provide long-term experimental data on the outer space environment and its effects on space systems, materials, operations and selected spore's survival. It was placed in low Earth orbit by Space Shuttle Challenger in April 1984. The original plan called for the LDEF to be retrieved in March 1985, but after a series of delays it was eventually returned to Earth by Columbia in January 1990.
It successfully carried science and technology experiments for about 5.7 years, that have revealed a broad and detailed collection of space environmental data. LDEF's 69 months in space provided scientific data on the long-term effects of space exposure on materials, components and systems that has benefited NASA spacecraft designers to this day.
Researchers identified the potential of the planned Space Shuttle to deliver a payload to space, leave it there for a long-term exposure to the harsh outer space environment, and on a separate mission retrieve the payload and return it to Earth for analysis. The LDEF concept evolved from a spacecraft proposed by NASA's Langley Research Center in 1970 to study the meteoroid environment, the Meteoroid and Exposure Module (MEM). The project was approved in 1974 and LDEF was built at NASA's Langley Research Center.
The STS-41-C crew of Challenger deployed LDEF on April 7, 1984. Attitude control of LDEF was achieved with gravity gradient and inertial distribution to maintain three-axis stability in orbit. Therefore, propulsion or other attitude control systems were not required, making LDEF free of acceleration forces and contaminants from jet firings.
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