CAPE CANAVERAL - Workers may have accidentally cut or crushed the section of foam that broke off Discovery's fuel tank during its launch two months ago - a mishap that threatened the safety of the astronauts and grounded the shuttle fleet.
That is the leading theory for the cause behind the disturbing loss of foam insulation that cast a cloud over NASA's return to space, said Wayne Hale, the newly appointed manager of the space shuttle program.
In an interview with the Associated Press on Tuesday, Hale said the shuttle fleet will not fly again until the foam insulation problem is resolved - no sooner than spring.
He also said repair work has been set back because of hurricanes Katrina and Rita. The storms caused NASA to lose three months of work, he said.
In a memo soon after Katrina slammed two shuttle facilities on the Gulf Coast, Hale speculated the shuttles might be grounded until fall 2006. He has since backed off that estimate.
"We're working a spring kind of launch date, but we haven't established one," he said. May is the earliest, most likely target.
To the horror of NASA officials, a 1-pound, 3-foot chunk of insulating foam peeled away from Discovery's external fuel tank during liftoff in late July. It was the same kind of problem that doomed Columbia in 2003, and occurred despite 2 1/2 years of improvements.
What probably happened is that during modifications to the tank at Michoud, technicians inadvertently damaged the section that ended up coming off, while working on nearby areas, Hale said. "This foam, which normally is not touched after it's applied, clearly was touched," he said.
Workers using plastic knives to remove nearby foam may have made small cuts in the section that tore away, allowing air to condense in the crevices against the tank, full of supercold fuel, Hale said. Another possibility, he said, is that workers leaned against the piece of foam that broke off, and fractured it.
A spokesman for Lockheed Martin Corp., which builds the tanks, said inadvertent worker damage is one of the potential causes being investigated.
