[wyattearp]

I still can't figure out why they use spray-on insulation in the first place. If the tank needs to be insulated, and it needs to be insulated every time, why not make the insulation a permanent part of the tank? You know, like, something that can't fall off?

[dhuffman@awod.com]

The tanks are not reused. I believe that they break up on re-entry.

[ItsForTheChildren]

I'll ask a stupid question here. Aside from the weight what would be the reason(s) not to make the tank with a double hull? Sort of an insulation sandwich - the tank, the insulation material and then an outer hull of a material that can withstand the stress of liftoff. How much extra fuel would it take to lift that and how would it affect the tank's design?

[Viking2002]

Let's glue environmentalists to the external tanks. They'll stink like hell when they burn during reentry, but they're more organic than anything we're using now. Problem solved.

[Publius6961]

You know, like, something that can't fall off?

I don't think it was designed to fall off. But the idea is weight savings. So desperately so that they stopped painting th main tank to save weight.
The environmentally "bad" stuff originally used seems to have done the job satisfactorily.

Can we say it one more time? Mindless environmentalism kills.