Silica aerogel captures cosmic dust intact

The mesostructure of silica aerogel resembles strings of pearls, ranging in size from 10 to 100 Å. This fine mesostructure transmits nearly 90% of incident light in the visible, while providing sufficiently gentle dissipation of the kinetic energy of hypervelocity cosmic dust particles to permit their intact capture. In 1987, silica aerogel was introduced as a capture medium to take advantage of its low density, fine mesostructure and, most importantly, its transparency, allowing optical location of captured micron sized particles. Without this feature, locating such captured particles in an opaque medium, e.g., polymer foams, is nearly impossible. The capture of hypervelocity particles has been extensively simulated in the laboratory. At the time of this 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, many useful features unique to aerogel have been identified.