Yesterday, a probe called Stardust intercepted comet Wild 2, where it scooped up particles for eventual return to earth (when they will then turn us all into naked space vampires.)
And what better time to read about this crazy material called "aerogel": it's basically a glass foam sponge with nanometer-scale cells. It has the density of air, and barely conducts heat. It's used in space shuttle tiles, and now they're using a giant scoop of the stuff to catch comet particles. More cool pictures here (the brick one is especially cool.) Lots more details at LBL.
Hey, I read that book when I was in high school. Must have been good cheese. I remember it vividly.
Not to nitpick, but aeorgel is ever so slightly denser than air. If it would be just as dense as air, it would be... umm, air.
But personally, I love the pic of the crayons on top of the aerogel, being heated from underneath by a torch. I've been trying to find somebody who would sell it to an individual, without success.
It could be less dense than air if the cells contained vaccuum, right?
Is that like air vs. anti-air? Does the universe explode if they come together?
Mebbe if they filled it with helium instead.
It looks like these guys would sell you some. It's not cheap, though (a 4x8x0.5" block costs $975)
It is 4 times the density of air. That is still VERY low density.
And they make jackets out of it, which are fantastically expensive and very warm.
My understanding is that the original jacket they made was good but people working in antarctica found that it was too warm, and they had to remove insulation.
That is the coolest stuff I'd seen in a while. Must... not.. buy... One of the manufacturer pages mentions that a lot of artists are using it... I wonder who and what they are doing with it.
I'm looking forward to the price of aerogel dropping precipitously if anyone figures how to make the stuff in quantity: I'm a big fan of hyperinsulated homes as energy-efficient, and this stuff looks like magic for that purpose. In a few years, maybe. We'll see.
The picture of Particle Tracks in Aerogel from an air gun used on some silica aerogel combined with the fact that silica aerogels are used as dectors for Cherenkov radiation made me wonder if there are visible tracks from in silica aerogels that have been used as dectors and if anyone has any picture references to this.
And guess what. You can buy it on eBay. $30 bucks a pop. Not bad.
It's not used in shuttle tiles. Well, not yet anyway. I've seen it suggested as a patch material, but IIRC it wouldn't be a very good choice. I.e. there's some doubt about how well it would cure in space minus air pressure and gravity. This article describes why it's being used in the Stardust probe. They used it for Pathfinder too. This is a mindblower:
Hmm, while I was googling around, I read something that seemed to say that it was being used in the shuttle tiles as of 1998 or so, but maybe I misunderstood.
Wow, awesome, now there's a practical application for this graphics rendering algorithm (picture of something that looks a lot like aerogel) I wrote a couple years ago.
[The algorithm renders 'volumetric fog', and the demo is of fog in a rectangular box shape. The simulated volumetric fog is as if the space within some fixed density of particles. In real life fog never has such a sharp cutoff, but hey, aerogel is a collection of some fixed density of particles with sharp finite boundaries.]