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The Guiness World Records has awarded a gel-like material, created by NASA to capture cosmic dust particles, with the record as the world's least dense solid. Aerogel is made from pure silicon dioxide glass, however, its light nature arises from the fact it is 99.8 percent air which gives it a density of a few thousandths of a gram per cubic centimetre. The volume of air within the gel comes from its unusually open atomic structure that consists of long twisted chains of silicate that resembles a string of pearls. The new record aerogel was made by Dr Steven Jones of NASA's Jet Propulsion Laboratory and is a low density version of the aerogel being used on the NASA Stardust mission to capture dust particles in space. Aerogel is used to collect dust particles since it can slow them down from high speed without destroying them. Dr Don Brownlee, principle invesigator of the Stardust mission says the aerogel being flown on Stardust can slow down dust particles more gently than the Earth's atmosphere. Stardust is to collect dust from comet Wild 2 and the aerogel has to decelerate particles intact from around 6 km per second. The dust particles returned to Earth by Stardust in 2006 will allow the materials from a known comet to be studied in detail in the laboratory for the first time. The only other samples of comets currently available to scientists are those collected by NASA at high altitude in the Earth's atmosphere and their exact sources are unknown.
More info: Stardust homepage
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