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Test helped solve shuttle ‘puzzles’

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WASHINGTON — Columbia accident investigators said Friday the foam test that gouged a large hole in a replica of a space shuttle's wing has allowed them to "connect the dots even further" and solve some lingering puzzles about the disaster.

The experiment not only demonstrated the catastrophic effect of breakaway foam insulation but provided compelling evidence about the identities of a mystery object that floated from Columbia in orbit and the many parts that peeled away from the shuttle as it flew over the United States to its disintegration over Texas.

Those shedding pieces probably were fragments of the wing panel that had been damaged on takeoff two weeks earlier, said Scott Hubbard, the Columbia Accident Investigation Board member who managed the foam-impact experiments.

"This single test, together with what else we know, is really allowing us to really connect the dots even further and draw some lines between various pieces of evidence," Hubbard said.

The gaping 16-inch hole created by the chunk of foam insulation during Monday's test in San Antonio probably was larger than the gap in Columbia's left wing where scorching gases entered during re-entry Feb. 1, said James Hallock, a physicist on the investigation board. A hole that big would have let in so much heat all at once that the shuttle would have broken apart much sooner than it did.

"Columbia would not have made it to the state of Texas," he said.

Hallock said the hole in the leading edge of Columbia's wing was probably 6 inches to 10 inches in size, based on thermal and other calculations.

"For us to create a piece of damage which was so close to the predicted piece, we find to be compelling," said the board's chairman, retired Navy Adm. Harold Gehman Jr. "But yet, I wouldn't get into inches. The fact that this hole is even larger than what the thermodynamic analysis indicates and how much heat got into the wing, it's in the right ball park. We found this to be important."

Gehman said Monday's test will enable him and the 12 other board members to use stronger language when describing the accident's cause. They plan to release their final report by the end of August, a month later than planned.

Hubbard, a high-ranking NASA official, said Monday's test "brought home to people in a very visceral and emotional way what most of us had known intellectually" — that a piece of foam weighing just 1 1/2 pounds could mortally wound a space shuttle."

"At the beginning, there were people who didn't appreciate maybe the calculation. Or maybe they did the calculation, but it didn't sink in how much force can be transmitted at 500 mph by even a light material like foam," he said.

The chunk of foam from Columbia's external fuel tank broke off 81 seconds after liftoff in January and slammed into the vulnerable leading edge of the left wing.Camera views were so blurred that NASA could not make out the precise impact spot or any damage.

Based on Monday's foam-shooting test, the investigators believe the object that drifted away from Columbia on its second day in orbit probably was a shard of the damaged wing panel. No one knew about the mystery object until it was spotted after the accident as a result of poring through scores of Air Force radar images of the orbiting spaceship.

The foam almost certainly punched through the reinforced carbon wing panel along the leading edge, and fragments were wedged inside. One of those pieces easily could have been bumped out on Flight Day 2 after a shuttle maneuver, Hubbard said.

Besides creating a gaping hole, the foam strike in Monday's test left a maze of cracks in the wing panel — some nearly a foot long — and broke an attachment lug on an adjoining seal. If the same lug had been damaged aboard Columbia, the loose seal would have flapped back and forth, which is what the shuttle debris indicates happened because of the scorch marks, Hubbard said.

In addition, all the cracks in the panel would have caused sections of the reinforced carbon to rip off during Columbia's re-entry in zipperlike fashion, which probably was what witnesses saw dropping away from the shuttle as it descended over California, Nevada, Arizona, New Mexico and, finally, Texas.

The shuttle ultimately shattered into tens of thousands of pieces, and all seven astronauts were killed.

Gehman said he still believes NASA can resume shuttle flights in six to nine months, despite the dramatic foam-test results.

"My crystal ball tells me that probably the most difficult, challenging return to flight recommendation has already been issued, and that's the on-orbit repair," he said.

Gehman estimated the investigation will have cost as much as $20 million by its completion.

On the Net: Columbia Accident Investigation Board: www.caib.us