Long Duration Exposure Facility

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.