Does anyone know any of the physical properites of the foam used on the heat shield? Is it some kind of foamed ceramic that is real light and fragile. I recall NASA making sure the astronaut not bumping into it during the repair. could be great stuff for insulating a forge. tnx
Henry Kolesnik wrote: : Does anyone know any of the physical properites of the foam used on the : heat shield? Is it some kind of foamed ceramic that is real light and : fragile. I recall NASA making sure the astronaut not bumping into it : during the repair. could be great stuff for insulating a forge. : tnx
Don't think it will work well - it is an ablative material - removes heat be vaporizing - not really an 'insulatior'. But it does do that as well. I think its a laminate - but at something like $300+ a square foot - how much can you afford?
Several points: Shuttle tiles are not ablative. The tile material has the property of disapating heat nearly as quickly as its heated. You could touch it within seconds of heat removal. And yes it is very fragile, maybe more so than regular fire brick. Just thought you'd like to know.
The original foam that worked very well was replaced during the Clinton administration with a non Freon type of "environmentaly friendly" foam that does not stick at all well. What's more important people's lives or some tree huggers concerns over environmental theory.
I know nothing about space shuttle tiles, but I do know that the tiles _can't_ do this, from the sheer physics of the problem. They're not conductive (that's rather why they're there) and they can't radiate heat more efficiently then some pretty fundamental limits.
AFAIR, the white tiles were so problematic to develop that it would have been cheaper to simply insulate the shuttle all over with the "extreme conditions" black carbon tiles. These were an established technology (ICBM re-entry vehicles) and were pretty much problem free.
As an insulator, the Shuttle's tiles are well obsolete anyway. Aerogels (which post-date the Shuttle) are vastly more efficient as insulators and lightweight too. The state of the art (accoridng to European design studies) is an aerogel blanket as insulator, coated with a thin layer of a carbon compound (mesophase pitch, more ICBM spin-off) as a hard surface.
The tree huggers of course. Those particular tree-huggers are NASA themselves (and others) flying their U2R under the polar ozone holes and finding how much damage there already is. Secondly you're very confused over the four types of "tile" used as insulation on the shuttle and the fuel tank, and which one used CFCs.
China lost another couple of hundred coal miners today. Now obviously we regret the Shuttle deaths, but some sense of proportion please. We've lost fewer people exploring space than Columbus lost to scurvy on one voyage.
I'd have to agree with Andy, being of a vintage where the NASA public relations types visited our high school with samples long before the shuttle flew the first time (since they were the hot new thing, and they wanted to impress us future taxpayers, AFAICT). I recall that the tiles were nicely insulative (demonstrated by heating one side with a torch while the other side was hand held), but the red-hot spot from the torch took some time to become non-incandescent, much less cool. Less impressive now that I've done the same thing with lightweight fire brick, but presumably a bit more durable than lightweight fire brick is.
And this is indeed not the foam that would have had CFCs in it.
You have me mixed up with someone else. I made no mention at all of tiles just the crappy foam that killed a whole crew and cost us 20% of the original shuttle fleet. That added to the o-ring fubar which cost another 20% of the fleet. We can't afford any more shuttle losses as the whole space station project depends on them with no backup at all. Just because China has no regard for human life does not mean we should emulate them. The small amount of Freon in the original foam offered next to zero effect on the atmospheric ozone layer. The whole ozone hole problem has yet to be proved anyway. The ozone layer has waxed and wained for many thousands of years.