SILICA AEROGEL CAPTURES COSMIC DUST INTACT

The mesostructure of silica aerogel resembles strings of pearls, rangi ng in size from 10 to 100 Angstrom. This fine mesostructure transmits nearly 90% of incident light in the visible, while providing sufficien tly gentle dissipation of the kinetic energy of hypervelocity cosmic d ust particles to permit their intact capture. In 1987, silica aerogel was introduced as a capture medium to take advantage of its low densit y, fine mesostructure and, most importantly, its transparency, allowin g optical location of captured micron sized particles. Without this fe ature, locating such captured particles in an opaque medium, e.g., pol ymer foams, is nearly impossible. The capture of hypervelocity particl es has been extensively simulated in the laboratory. At the time of th is symposium, more than 2.4 m(2) of 20 mg/ml silica aerogel will have been flown on Space Shuttle (STS-47, STS-57, STS-60, STS-64 and STS-68 ). Demonstration of capturing hypervelocity particles ushers in a new, simple avenue to science in capturing intact cosmic dust from space. Since our introduction of aerogel for intact capture of cosmic dust, m any useful features unique to aerogel have been identified.