Next shuttle launch

[Crimson Ghost]

Originally Posted by MaggieL

No, no, no...

The TPS (thermal protection system) on the *Orbiter* is ceramic tiles over most of the surface. The places where tiles won't work--like the leading edge of the wings-- are made from reinforced carbon-carbon composite. Fairly strong, if somewhat brittle. Both the tiles and the RCC are insanely heat-resistant.

The external tank (which doesn't fly to orbit and is not reused; it's a one-shot per flight) is coated with foam insulation just to keep the cryogenic liquid fuels from boiling away too fast. The issue is that the chuncks of foam sometimes crack off from being very cold, or having liquid hydrogen or liquid oxy boil off into gas between the foam and the tank.

Ok, I'm with ya so far...

Originally Posted by MaggieL

This didn't used to be viewed as a big deal...after all, it's approximately the density of a Nerf ball.

But imagine getting hit by a Nerf ball moving at 500 mph.

Oww. OwwOwwFuckingOww.

Originally Posted by MaggieL

Columbia was lost because a couple-pound chunk of foam came off the ET at the worst possible time during ascent...while still in the atmosphere moving supersonically. By the time the foam reached the leading edge it had been slowed by air friction (relative to the Orbiter) to a speed 500 mph less than the Orbiter. It smacked into the RCC leading edge of the wing and made a substantial (maybe 20 inches across) hole.

During reentry, hot air at the leading edge, instead of flowing over the wing, flowed into the hole and was trapped *inside* the Orbiter left wing...which is made mostly of aluminum.

It melted.

Got the picture now?

Now I understood the physics of the disaster, but at least now it's a lot clearer. Thanks.