Results of the LDEF meteoroid and debris special investigation group

Abstract

The Long Duration Exposure Facility was recovered in January, 1990, following 5.7 years of continuous exposure in low-Earth orbit. The gravity-stabilized nature of LDEF permits the resolution of the flux and trajectories of impacting meteoroids and spacecraft debris particulates. We have completed the collection of high-resolution, stereoscopic video imaging of all large impact features on the entire LDEF, and present here the preliminary results of our efforts to reduce these digitized images, and extract critical data. Contrary to our prior assumption, we find that impact craters in the T6 Al alloy are not paraboloid in cross section, but rather are better described by a 6th-order polynomial curve. We explore the implications of this discovery. We present results of detailed crater surveys of LDEF frame intercostal members, finding a unusual local variation in the impact frequency. In a discussion of impactor fluxes derived from LDEF results we explore apparent directionalities for impacting particulates which are not accounted for in current models. We briefly describe the special database designed and used by the M&D SIG. Finally, we present a list of recommendations for further LDEF analyses which will be necessary to ensure the safe design of spacecraft.