Shuttle Workers May Have Erred

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.

Hale told the Associated Press on Tuesday that the space shuttle would not fly again until the foam insulation problem was resolved -- no sooner than spring.

A 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 it occurred again despite 2 1/2 years of improvements and assurances that this was the safest tank ever built.

What probably happened is that during modifications to the tank at the Michoud Assembly Facility in New Orleans, 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 ended up tearing away, allowing air to condense in the crevices against the tank, full of super-cold fuel, Hale said.

Another possibility, he said, was that workers leaned against the foam and fractured it. Yet another theory is that the foam cracked because of normal thermal stresses.

A spokesman for Lockheed Martin Corp., which builds the tanks at Michoud, said inadvertent worker damage was one of the potential causes being investigated.

Engineers have more work to do before confirming any of this, the shuttle manager said.