COSMIC DUST COLLECTION IN AEROGEL

Aerogel is an ultra-low-density material that can be used to capture small particles incident upon it at speeds in excess of 1 km s⁻¹. This permits capture of cosmic dust in space where the high speeds usually result in destructive impact events. The performance of aerogel in laboratory impact tests is described. Completely intact capture is rare; most studies show that between 10% to 100% of the incident particle's mass is captured. However, in all cases unaltered domains were found in the particles captured in the laboratory at speeds up to 6 or 7 km s⁻¹. Several analytic techniques can be applied in situ to particles captured in aerogel, yielding data on the preimpact composition of the particle. Extraction techniques for removing small particles from aerogel are described, and after extraction, handling and analysis in the laboratory can proceed as for any small-sized particle. Coupled with the survival of intact regions in the captured particles, this allows detailed identification of the composition of the dust. Examples are given of current space missions using aerogel dust collectors: Data on these will soon be supplemented by cometary dust particles captured in aerogel on the NASA Stardust spacecraft.