This STS-95 experiment will produce Aerogel--a low-density, open-pore foam--in the weightless environment of space. Aerogel transmits light, insulates against sound and electricity, and is only slightly heavier than air. A single window pane of Aerogel has the insulation equivalent of up to 30 panes of regular glass and trapped air. Aerogel--nicknamed "frozen smoke" for its blue hazy appearance--can be made transparent by decreasing the size of its pores, a procedure that presently can be achieved only in space. Previous microgravity experiments showed an almost 50-percent reduction in pore size compared to ground experiments, resulting in greater transparency and electrical resistance.
Many commercial applications, including sound- and temperature-insulating windows, depend on transparency. Aerogel's electrical resistance is similar to that of air, making it the least conductive substance of any known solid. Its resistance to electricity may be the key to faster computer processors by preventing signal crossover common in today's computer chips.
Two solutions, one water and one silicon-ethanol, will be carried in a double-barreled syringe. Once in microgravity, the two solutions will be mixed like a two-part epoxy and form a jelly-like mass. To make Aerogel upon return to Earth, this gel must be dried without allowing its pores to collapse. Drying will be performed by soaking the gel in liquid carbon dioxide and then evaporating the carbon dioxide at high pressure. The entire process will be studied in order to produce transparent Aerogel under gravity conditions.
|
