Compositional Analysis and Classification of Projectile Residues in LDEF ImpactCraters

摘要

This catalog contains preliminary analyses of residues of hypervelocityprojectiles that encountered gold substrates exposed by instrument A0187-1 on the Long Duration Exposure Facility (LDEF). This instrument was on LDEF's trailing edge where relative encounter speeds should be lowest for any non-spinning platform in low Earth orbit (LEO). Approximately 0.6 m(exp 2) of Au substrates yielded 198 impact craters greater than 20 micrometers in diameter. Some 30 percent of the craters were made by natural cosmic dust particles and some 15 percent by man-made objects. Some 50 percent of all features, however, have residues, if any, that are beyond the detection threshold of the SEM-EDXA method used. The purpose of this catalog is to provide detailed evidence and criteria that may be used to arrive at specific particle types on a case-by-case basis and to group such particles into compositional classes. Clearly this is a somewhat interpretative undertaking. For that reason, we encourage and solicit critique and comments from those interested in the systematic analysis of all impact features on LDEF.