Impacts on Hubble Space Telescope solar arrays: Discrimination between natural and man-made particles Original Research Article

A Post-Flight Investigation was initiated by the European Space Agency to analyze impacts on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600 km altitude. The solar cells deployed during the first Service Mission (SM-1 in December 1993) were retrieved in March 2002 as part of Service Mission 3B (SM-3B). A sub-panel of 2 m2 was cut from the arrays for subsequent selection and removal of individual solar cells for analysis. Six cells (4.8 × 10−3 m2) were surveyed for flux of all craters of sizes greater than 5 microns. Analytical scanning electron microscopy was used to analyse residues in 111 features of 3–4000 micron conchoidal detachment diameter (Dco), examined on 23 solar cells. Eighty three show identifiable residue: 38 are Space Debris impacts and 45 Micrometeoroid impacts. Of the remaining 28, 2 contain residue of ambiguous origin, 1 is probably a minor manufacturing flaw, 1 is obscured by contamination, and 24 are unresolved, lacking recognizable residue.The majority of space debris impacts on the SM-3B cells are less than 80 microns Dco, dominated by Al-rich residue, probably of solid rocket motor origin, although three may be due to sodium metal droplet impacts. Three larger features include paint pigment and binder, ferrous alloy, and possible carbon-fibre composite material debris.