The flux of meteoroids and orbital space debris striking satellites in low Earth orbit

Abstract

Analysis of the large number of high-velocity impact craters found on surfaces of the Solar Maximum Mission spacecraft is providing an unprecedented opportunity to measure the near-Earth meteoroid flux over a wide range of particle sizes. Zook1 and Schramm et al.2 have reported size frequencies and compositions for particles that produced 40–520-µm penetration holes in the multi-layer plastic thermal insulation blanket from ‘Solar Max’. Here we report the results of analysis of 331 craters in the 0.09–250 µm size range, found in the solid aluminium of the thermal control louvers. By elemental analysis of particle residue in the craters and scanning electron microscope imaging, we were able to distinguish impacts by natural meteoroids from those of orbital spacecraft debris, and directly determine the time-averaged flux and size distribution of both particle types over the mass range 10−13–10−7 g. The most common natural meteoroid craters contain residue that has chondritic elemental composition, while the debris craters contain a variety of residue types including paint. For 10−12 g particles the debris flux exceeds the natural meteroid flux by two orders of magnitude, but at 10−8 g the fluxes are similar.