'What is this stuff?
It's called aerogel, and it's an extremely lightweight form of silicon dioxide. It's heat-resistant, relatively cheap to make, and can be used, say, to capture particles ejected off of a comet if you happen to be swooping down really close to one. Hey, didn't NASA just do that? Very astute of you. Yes, they did, and the aerogel was used to snag some of the stuff that comets are made of. The particles from the comet slammed into the aerogel held out by the Stardust probe as it swept by the comet, were gently decelerated by the weird nature of the gel, and came to a stop inside the foam. Now that Stardust has returned to Earth, scientists can investigate the guts of a comet inside the comfort of their own lab, assuming their lab is comfortable. Thousands of comet bits hit the aerogel, and you'd ...
