[XBob]

the tank is coated with a sprayed on foam, it weighs only about 66,000 lbs and carries about 500,000 gallons of fuel.

The foam is designed to keep the liquid hydrogen and the liquid oxygen cold, as the tank is expendible and usually burns up on re-entry

too many people are confusing the tank insulation (what came off) with the shuttle insulation (what was hit).

[strela]

I seem to vaguely recall some discussion, years ago, of replacing the current crew cabin configuration on the orbiters with an integral, reentry-survivable pod. If an emergency arose during launch, it could be ejected under its own power and soft-land. It could also re-enter the atmosphere from orbit if the orbiter failed the re-entry burn.

Do you recall why that option was never utilized? Cost? Technical hurdles?