Long Duration Exposure Facility (LDEF)

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Long Duration Exposure Facility (LDEF)

LDEF in Space The LDEF in Low Earth Orbit

The Long Duration Exposure Facility was placed in low-Earth orbit (LEO) by the space shuttle Challenger in April, 1984, and retrieved by the space shuttle Columbia in January, 1990. LDEF was a 14-faced (i.e., a 12-sided cylinder and two ends), gravity-stabilized spacecraft that was host to 57 individual scientific experiments. Several of these experiments were designed to characterize various aspects of the meteoroid and orbital-debris environment during the nominal nine month mission. However, as a result of LDEF's unexpectedly long exposure time (5.7 years) and the heightened awareness of the man-made debris collisional threat, it was decided to utilize the entire spacecraft as a meteoroid and orbital-debris detector. The Meteoroid and Debris Special Interest Group (M&D SIG) was organized to achieve this end.

As a result of the gravity-gradient stabilized orbital nature of LDEF (i.e., the same general surface pointed into the velocity vector during the entire mission), the large exposed surface area (~130 square meters) of LDEF provided a unique source of information concerning the LEO particulate environment and associated directionality effects for both natural and man-made particles.

Table 1. LDEF Specifications
Length 30 feet (9.14 m)
Width 14 feet (4.27 m)
Empty Weight ~9,000 pounds (3,629 kilograms)
Launch Weight 21,393 pounds (9,724 kilograms)
Experiment Bays 86 (72 peripheral & 14 end)
Number of Experiments 57  
Deployment Date April, 1984 by Challenger (STS-41C)
Retrieval Date January, 1990 by Columbia (STS-32)
Orbital Altitude 250 - 179 miles (400 - 286 kilometers) at deployment and retrieval, respectively
Exposed Surface Area ~130 square meters