A full year after the Columbia tragedy, NASA has finally determined how and why the large piece of foam insulation that doomed the space shuttle broke off from the fuel tank at liftoff.
NASA's top spaceflight official, Bill Readdy, said that through extensive testing, the agency has learned that air liquefied by the super-cold fuel in the tank almost certainly seeped into a crack or void in the foam, or collected around bolts and nuts beneath the foam.
