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imported_gemini
2005-Aug-03, 04:03 PM
www.newsmax.com (http://www.newsmax.com/archives/ic/2005/7/28/93055.shtml)

antoniseb
2005-Aug-03, 05:25 PM
Hi Gemini, Welcome to the UT Forum.

This version of the story has a slant that makes it sound like forward-looking environmental policy and one particular political party is to blame for the Columbia disaster and the delay in the return to flight.

It may well be that they haven't found something that makes good cold resistent foam the way freon does, and that is news (thanks).

I don't know precisely what the foam is needed for, but I suspect it could be replaced by some kind of sheath that gets removed from the tanks at T-10 seconds, leaving the tank insulation-free for the ascent into the cold upper atmosphere. I am confident that other solutions are out there, but suspect that with only about 20 launches left in the whole shuttle program, that they didn't want to invent something completely new.

aeolus
2005-Aug-03, 06:58 PM
I was just reading some publications today, some of which were published last month. Here's a curious quote from the July 5th issue of Flight International:


The independant Return to Flight Task Group has concluded that NASA has not met the CAIB reccomendations of hardening the thermal protection system (TPS), stopping external tank ice and foam from shedding or providing an in-flight TPS repair capability. But the group says the Shuttle is safer and could fly.

They fixed 80% of the stuff they were supposed to. 2/3rds of the stuff they didn't could very well have come back to bite them in the...

Looks like it won't. Thank heavens.

John L
2005-Aug-04, 04:29 PM
Just go back and use the old foam for the remaining launches! The foam would burn off in the upper atmosphere as the main tank re-enters the atmosphere, so any freon inside the foam would be lost in the upper atmosphere, and not closer to the ground where it matters most. Just accept that for this application it has no better option, and that since the remaining life of the system is short that it won't be a long term issue and DO IT!

ToSeek
2005-Aug-04, 07:04 PM
Originally posted by John L@Aug 4 2005, 04:29 PM
Just go back and use the old foam for the remaining launches! The foam would burn off in the upper atmosphere as the main tank re-enters the atmosphere, so any freon inside the foam would be lost in the upper atmosphere, and not closer to the ground where it matters most. Just accept that for this application it has no better option, and that since the remaining life of the system is short that it won't be a long term issue and DO IT!
Isn't the ozone layer in the upper atmosphere? And I wonder if they even still have the "old foam" or are in position to make it without significant retooling.

John L
2005-Aug-04, 10:10 PM
There are a lot of layers to the atmosphere. The ozone in the bottom-most layer, the one you and I live in, is actually a pollutant and we're trying to get rid of it. The ozone that protects the surface from UV radiation is only one or two layers up, still very near the surface. When things burn up they're burning up many miles above this and shouldn't present a problem. Besides, we used to be release tons of CFC's into the air from bad refridgerators and AC units, as well as from spray cans and foam manufacturers. This will be the only application where we will allow it and it will only be for the remaining shuttle launches. That won't even register on any measurements even if every molecule made it up there, which it won't.