LDEF meteoroid and debris special investigation group investigations and activities at the Johnson Space Center

Since the return of the Long Duration Exposure Facility (LDEF) in January, 1990, members of the Meteoroid and Debris Special Investigation Group (M&D SIG) at the Johnson Space Center (JSC) in Houston, Texas have been examining LDEF hardware in an effort to expand the knowledge base regarding the low-Earth orbit (LEO) particulate environment. In addition to the various investigative activities, JSC is also the location of the general Meteoroid & Debris database. This publicly accessible database contains information obtained from the various M&D SIG investigations, as well as limited data obtained by individual LDEF Principal Investigators. LDEF exposed ~130 m2 of surface area to the LEO particulate environment, ~15.4 m2 of which was occupied by structural frame components (i.e., longerons and intercostals) of the spacecraft. The data reported here was obtained as a result of detailed scans of LDEF intercostals, 68 of which reside at JSC (Figure 1). The limited amount of data presently available on the A0178 thermal control blankets was reported last year (ref. 1) and will not be reiterated here. As was the case in Ref. 1, the data presented here are limited to measurements of crater diameters and their frequency of occurrence (i.e., flux). Since our last report (ref. 1) we have scanned another 14 intercostals and A B C D E F 1