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NASA's 'frozen smoke' named lightest solid

The winning aerogel is made up mostly of air and almost as light.
The winning aerogel is made up mostly of air and almost as light.  

By Richard Stenger

(CNN) -- Cooked up in a NASA laboratory, a gel that is 99.8 percent air has been designated the least dense solid in the world by Guinness World Records.

The substance, described as "frozen smoke" for its hazy blue appearance, is a new variety of a silicon-based material designed to collect particles in deep space.

The record-breaking gel is composed of silicon dioxide and sand, just like glass, but 1,000 times less dense, according to NASA, which announced the triumph this week.

"It's probably not possible to make aerogel any lighter than this because it wouldn't gel," said Steven Jones, gel inventor and scientist with NASA's Jet Propulsion Laboratory in Pasadena, California.

The stuff is prepared from a liquid silicone compound and dried in a pressure cooker to retain its shape and produce a glassy silicon sponge.

The latest batch can endure temperatures as high as 2,600 degrees F (1,400 degrees C) and tips the scales at just .00011 pounds per cubic inch (3 milligrams per cubic centimeter), according to the Guinness Web site:

Drawing of Stardust craft approaching Comet Wild-2
Drawing of Stardust craft approaching Comet Wild-2  

Aerogels were developed decades ago by aerospace engineers looking for a durable, lightweight, heat-resistant material for airplanes and spacecraft.

The glass foam, which has flown on space shuttles, the Mir Space Station and the Mars Pathfinder, has also proved effective in collecting tiny particles.

The new title-holder is a refinement of an earlier recipe from NASA's Jones that JPL placed on the Stardust probe to catch interstellar and comet dust grains.

Launched in 1999, Stardust is slated to become the first to return space samples from beyond the moon. The $200 million mission should rendezvous with comet Wild-2 in 2004 and swing back by Earth to deliver the goods in 2006.


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