Thursday, February 23, 2006

Scientific Bets

Have the most interesting results. I can see many uses for this, but if we ever get to Janus IV, we might want to keep the process to ourselves.
Wired News: A Solid That's Light As Air: "Aerogel isn't exactly space-age technology. It was invented in 1931 by Steven Kistler, in response to a bet made by a fellow scientist. Kistler found a way to remove the liquid from a silica gel without destroying the long silica molecule chains that gave the gel its structure.

Holding a piece of aerogel is an uncanny experience. It's so light it feels nearly weightless, like a chunk of solidified fog or smoke. It feels a bit like Styrofoam, and it squeaks when you rub your finger on it. It's strong enough to support many times its own weight if the load is distributed evenly. But bend it or squeeze it too hard, as one Wired News editor discovered, and a chunk of aerogel will shatter into tiny fragments.

Ordinary gels, like Jell-O, are comprised of tangled chains of molecules -- polymers -- surrounding empty pockets of a liquid, such as water. If you try to dry out a cube of Jell-O at room temperature, the surface tension of the liquid will cause the polymer structures to collapse as the liquid evaporates. The result is that the gel cracks, shrinks and eventually crumbles to dust.

Modern scientists make aerogel by pressurizing and heating an ordinary gel to its 'supercritical' point, where the liquid's fluid and gaseous phases are indistinguishable, and then draining off the supercritical liquid. Because there's no gas-liquid interface, there is no surface tension and so the liquid can be removed without destroying the gel's polymer structure. With the liquid gone, air fills up the spaces between the polymers, and the result is a meringue-like aerogel.

Scientists aren't sure why aerogel works so well as a cosmic duster. One theory, says Brownlee, is that the porousness of the material gives particles a chance to slow down as they smash through the nanometer-scale silica structures. As they go, the particles pick up a 'paint' of melted glass on their front edge, which protects them from further collisions with the structure until they come to rest.

The transparency of aerogel was also critical to the Stardust mission because it allowed scientists to find the particles by following their tracks through the material."
Of course it could also be used as lingerie in a cold environment, there are plenty of people who would pay to appear naked and be warm at the same time. Or people who like houses that are mostly glass could move to snow country without an outrageous heating bill. Or the space station viewing area.

If those ideas help to move the project along, please feel free to use them as justification towards moving us into the future.

No comments:

Post a Comment