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Ideas that Gel

Guest Contributors
March 11, 2002 | Science News

Jet Propulsion Laboratory
Pasadena, California
February 11, 2002
NASA Press Release

Top image: Although it has a ghostly appearance like a hologram, aerogel is very solid. It feels like hard styrofoam. (NASA/JPL photo)

The most obvious ideas are not always clear. Take aerogel for instance, a transparent, smoky blue substance that's been especially manufactured to bring home a piece of a comet, among other things.

This exotic substance, commonly referred to as "frozen smoke" for its hazy appearance, has many unusual properties and can withstand extreme temperatures. Its versatility was obscured until it got into the hands of some NASA researchers. They saw through the haze and realized the possibilities. The result was the development of a novel use of aerogel for space exploration.

Aerogel is the world's lightest solid. It is a silicon-based solid with a porous, sponge-like structure in which 99.8% of the volume is empty space. Aerogel is 1,000 times less dense than glass, another silicon-based solid. A Stanford University researcher discovered aerogel in the 1930s. NASA's Jet Propulsion Laboratory in Pasadena, California, altered the original recipe to come up with a way to use aerogel for space exploration. This particular aerogel approaches the density of air, but it is durable and easily survives launch and space environments. JPL used aerogel to insulate the electronics box on the Mars Pathfinder Sojourner rover, which explored the red planet in 1997.


A 2.5-kg brick is supported on top of a piece of aerogel weighing only 2 grams. (NASA/JPL photo)

The Stardust mission, currently on its way to comet Wild, will use aerogel to encapsulate interstellar and comet dust particles and bring samples home in 2006. When Stardust encounters the comet, the particles will be traveling up to six times the speed of a rifle bullet. To collect these delicate particles, each smaller than a grain of sand, aerogel will gradually slow them to a stop without damaging them or altering their shape and chemical composition.

Researchers at JPL are working to improve on the properties and performance of aerogel. By making aerogel more versatile, it might become competitive as a commercial material. Until then, researchers keep looking to the sky, anxiously awaiting the return of the smoky blue substance, which will bring home a souvenir from space.

If you are using the Planetary Science Course, you might ask your students to download and read the complete aerogel story and discuss how aerogel will work to capture comet particles and what scientists might learn after the samples are returned to Earth. Encourage them to do more research about the Stardust mission and report their findings to the rest of the class.

Tracks in aerogel

Tracks in aerogel mark particle entry. (NASA/JPL photo)