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 HOW
DUST IS CAPTURED
 Catching
comet dust is no easy feat. When the comet zooms past the Stardust
spacecraft, the particles will be moving at up to nine times the
speed of a bullet fired from a rifle. Although the captured particles
will each be smaller than a grain of sand, high-speed capture
could alter their shape and chemical composition -- or vaporize
them completely.
To
collect the particles without damaging them, Stardust will use
a foamed glass substance called Aerogel.
Aerogel
Factoids
 Light
and airy: Composed of 99.8 percent air, Aerogel is the lightest-weight,
lowest-mass solid known to science, with the feel of a soft foam
rubber. Mostly transparent, it is sometimes called "blue smoke."
 Making
tracks: When particles hit Aerogel, they become embedded,
leaving tiny, carrot-shaped tracks easily spotted under a microscope.
Using any other known material would make finding the minuscule
dust as unlikely as finding a needle in a haystack.
Excellent
insulation: It's 39 times more effective than the best fiberglass.
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