Impact studies of the HST solar arrays retrieved in March 2002

First results are presented of impact studies performed for the HST solar arrays retrieved in March 2002. The arrays have a total exposed area of 120m2 of which 40m2 are covered by solar cells. They had been 8.24 years in orbit at an altitude around 600 km. Most outer surfaces were surveyed for craters and holes resulting from hypervelocity impacts of meteoroids and orbiting debris. A total of 174 clear perforations of the 700μm thick arrays were found. Measurements of impact features on the front side of the solar cells for the size range 100μm–6mm are reported. Different resolutions, measurement techniques and sampled areas were used to obtain statistically relevant fluxes. Measured fluxes for craters larger than 1 mm are in the order of 1.5×10-7m-2s-1. A comparison with crater measurements on the first HST solar array retrieved in 1993 shows good agreement of the fluxes. Measurements of impact features smaller than 100μm, a chemical analysis of impact residues and a more detailed analysis of the impact data are ongoing or planned.