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NASA Finds 4-5" Crack in Shuttle Insulation
PresidentKang writes "Spaceflight Now is reporting that a large crack has been found in an external tank foam of Space Shuttle Discovery on the launch pad. According to the article: "Engineers inspecting the shuttle Discovery's external tank following Sunday's launch scrub found a crack in the tank's foam insulation near a bracket holding a 17-inch oxygen feed line in place. Some engineers believe the crack must be repaired but senior managers say a variety of options are on the table, from fly as is to making repairs.""
The only reason why the foam is a problem is because the orbiter hangs from the side of the tank and can be hit by the foam when it falls off. In future generations of manned spacecraft, the crew vehicle will be on the top again, like in Apollo, Gemini and Mercury. In that case, it really doesn't matter what falls off.
"I wouldn't be suprised if the external tank is insulated just because of how the shuttle is mounted on the assembly."
It's more complicated than that. It is needed to stop ice forming that would trash the shuttle, but it also reduces fuel boiloff, protects the tank from aerodynamic heating, and keeps the metal cold... the metal in the tank gets stronger as it cools down, and that means they've been able to cut back on the amount they use. Since the tank goes most of the way to orbit, saving a pound of mass in the tank gives you close to a pound of extra payload in the shuttle.