2002-02-11 | MISSIONS, TECHNOLOGIES
Ideas that Gel

Aerogel is a silicon-based solid with a porous, sponge-like structure. Since 99.8 percent of its volume is empty space, aerogel is the world's lightest solid. It's 1,000 times less dense than glass, another silicon-based solid. Aerogel's airy lightness and its transparent, hazy blue appearance have earned it the nickname "frozen smoke." Discovered in the 1930s by a Stanford University researcher, its versatility was obscured until it got into the hands of some NASA researchers.

The Stardust mission, currently on its way to comet Wild 2 (pronounced Vilt 2), will use aerogel to catch and comet particles and interstellar dust and bring samples home in 2006. The tiny particles will strike the aerogel at up to 6 times the speed of a rifle bullet, embedding themselves deep in the material. The aerogel will gradually slow them to a stop without damaging them or altering their shape and chemical composition. Comets and interstellar dust are of great interest to astrobiology, because they may have showered the early Earth with the organic compounds that gave rise to life.

Aerogel provides 39 times more insulation than the best fiberglass insulation. That and its extremely low density make it an ideal insulator for Mars missions, since propelling extra weight into space is very expensive. Aerogel insulated the electronics box on the Mars Pathfinder Sojourner rover in 1997, and will insulate the batteries aboard the 2003 Mars Exploration Rovers (MER). The MER mission is tremendously important for astrobiology, as it will look for evidence of liquid water in the planet's past. Liquid water is a necessary condition for life.

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