Golf-Ball Sized Hail Damages Shuttle

MattSparkes writes "The Shuttles March launch has been delayed to late April after golf-ball sized hail caused 7000 pits and divots in the foam that shields the fuel tank. NASA say it's the worst damage of its kind that they have ever seen, but hail is not a new problem for the agency. In 1982, a hailstorm damaged the sensitive heat shield tiles on the Columbia's wings. The damaged tiles then absorbed about 540 kilograms of rain. Once in space, the orbiter faced the Sun to allow the tiles to dry out."

Re:Rain

[Anonymous Coward]

The fuel costs are marginal. The costs of space flight are complexity and manpower. If the tank was big enough to carry enough fuel to reach the intended orbit, it would cost way more to delay the launch than it would to carry the water up.

Re:Face the sun to dry out?

[imsabbel]

Evaporation enthalpy.

At 80 Kelvin, ice will be fine even in ultrahigh vacuum. So energy has to come from somewhere to allow the ice to evaporate. Those headshields are very good insulators, which leaves the sun as energy source.

Re:Obviously

[KoshClassic]

One possible reason - save weight. Metal is heavier than foam. Imagine a tank similar to the current one in shape, size, and internal volume. Move the metal to the outside of the foam, you need more metal to cover the greater surface area on the outside of the resulting shape than it does on the inside of the current tank, hence more weight.

re: the liner idea - yeah, the tank was painted white for the first two or three launches. They got rid of the paint to save weight - apparently covering the foam with something relatively as light weight as paint, given the surface area involved, still added up to enough weight to make a difference. And, apparently it didn't really help keep the foam in place.