- The Washington Times - Wednesday, March 12, 2003

Investigators are trying to determine whether the leading edge of the Space Shuttle Columbia's left wing had tiny pockets of air beneath its tiles that could have weakened their bond with the orbiter.
If the tiles were weakened, Columbia may have been more vulnerable to a debris strike.
Air Force Maj. Gen. John L. Barry, a member of the independent Columbia Accident Investigation Board, said leading-edge tiles on Atlantis and Discovery showed pockets of air beneath them after previous shuttle missions.
Tiles on Columbia could have had the same problems, he said.
Columbia's leading edge has been the focus of investigators probing the Feb. 1 explosion of the shuttle. There were 22 U-shaped panels on the leading edge of the left wing. The panels are made of reinforced carbon-carbon and help the shuttles withstand temperatures of up to 3,000 degrees during re-entry to Earth's orbit.
Board members are speculating whether damage to protective tiles allowed superheated gases to penetrate a breach in the shuttle's left wing.
Debris could have hit panels 6, 7 and 8 during Columbia's liftoff, retired Adm. Harold W. Gehman, the head of the accident investigation board, said yesterday.
But investigators still are having difficulty drawing conclusions about the explosion. For instance, it is not clear whether foam that shed from the external tank contained either ice or metal, which would have strengthened the force of the blow.
"We have these tantalizing pieces of evidence that don't fit together," Adm. Gehman said during the investigation board's weekly press conference.
"We are moving along methodically in our understanding of the forces that were at work on the orbiter," he said. "We are narrowing down the part of the orbiter where the assault took place."
Investigators also raised the possibility that Columbia's left wing may have been made more vulnerable to debris damage because it was buffeted by unusual wind shear during liftoff.
"One of the scenarios we're looking at, it's possible that the foam striking a healthy orbiter would not have done enough damage to cause the loss," Adm. Gehman said.
He said Columbia's age could have made it more vulnerable than a newer orbiter.
"A normal event, which she could have survived at age 10, maybe she couldn't survive at age 21," the admiral said.
The board also revealed that Columbia's fuel tank was removed from its set of booster rockets last August because the two boosters were needed for another flight. In November, Columbia's tank was attached to another pair of boosters.
Gen. Barry said removing the boosters may have weakened foam around the bipod, a metal piece that connects the fuel tank to the orbiter. But he said there was an inspection of the bipod that determined there were no problems.
"Right now we're trying to follow the foam," Gen. Barry said.
Recovery crews have collected 28,286 pieces of the shuttle representing about 19 percent of the orbiter's weight. Of those, 25,404 have been identified, and 233 are from the left wing.

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