Experimental investigation of impacts by solar cell secondary ejecta on silica aerogel and aluminum foil: Implications for the Stardust Interstellar Dust Collector

We have shown in laboratory experiment that hypervelocity impacts on a solar cell produce ejecta that can be captured on aluminum (Al 1100) foil or in low density (33 kg m?3) aerogel. The origin of the secondary impacts can be determined by either analysis of the residue in the craters in the foils (which preserve an elemental signature of the solar cell components) or by their pointing direction for tracks in the aerogel (which we show align with the impact direction to ± 0.4°). This experimental evidence explains the observations of the NASA Stardust mission which has reported that the majority of tracks in the aerogel collector used to collect interstellar dust actually point at the spacecraft’s solar panels. From our results, we suggest that it should also be possible to recognize secondary ejecta craters in the Stardust mission aluminum foils, also used as dust sampling devices during the mission.