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NASA probes new space shuttle fuel tank problem

NASA will hold off launching any more space shuttles until it understands why strips of insulating foam peeled off the fuel tank used by shuttle Endeavour, the US space agency shuttle program manager said yesterday.

Endeavour arrived safely in orbit after Wednesday's liftoff from the Kennedy Space Center in Florida though video and images of the launch showed about a dozen pieces of debris flying off the fuel tank during the 8.5-minute climb to orbit.

Some smashed into the ship's heat shield, though NASA does not believe they caused any serious damage.

"We're not worried about this one, but we need to understand what's going on for the next flight," shuttle program manager John Shannon said at a news conference.

"This is new," Shannon said. "I don't know if we have a material issue or a process issue but we'll get to the bottom of it and clear it before the August flight."

He told Reuters in an interview that no new shuttle launches would take place until the foam loss problem was understood.

NASA has seven more shuttle launches planned to complete construction of the International Space Station. Its next flight is targeted for launch on Aug. 18.

The US space agency has been concerned about foam shedding from the tank since losing shuttle Columbia in 2003. A debris impact during Columbia's launch breached the ship's heat shield, which caused the shuttle to break apart as it flew through the atmosphere for landing. Seven astronauts died in the accident.

NASA redesigned the tanks to stem foam loss and implemented new procedures and equipment to check for damage after launch.

The images of Endeavour's launch showed patches of metal where thin strips of foam had peeled away from a part of the tank that previously had not been a problem, Shannon said.

"We have a bit of a mystery," Shannon said at the news conference. "It's from an area we don't typically expect to see foam to be lost."

The foam loss occurred relatively late during Endeavour's climb to orbit so that there was not much atmospheric force to slam debris into the ship and cause damage. If the foam had fallen off earlier during ascent, it could have been another story.


"It did not hurt us, apparently, on this flight, because it came off so late. But we'll need to understand that before the next flight," Shannon said.

A variety of tests are planned to determine if the problem on Endeavour's tank was an isolated incident or if there is a more generic issue.

Shannon told Reuters he believed it was possible to get to the bottom of the foam loss problem before the Aug. 18 launch of shuttle Discovery,

"I have pretty high confidence we'll get there but we have a lot of work to do," he said in a telephone interview.

He said he suspected a problem when Endeavour's tank was prepared for flight left the foam improperly bonded but said engineers may never able to determine the exact cause of the foam loss beyond all doubt.

Perhaps, he said. "the best we can do is prove that we're not suspect on future tanks."

The Endeavour astronauts, meanwhile, used the shuttle's robot arm to scan their ship's wings and nose cap with a sophisticated imaging system mounted at the end of a 50-foot (15-metre) boom. The pictures will be analyzed by engineers on the ground over the next several days.

Another inspection was scheduled for Friday before the shuttle docks at the International Space Station. Commander Mark Polansky will backflip Endeavour so astronauts aboard the station can photograph its heat-resistant belly tiles. Those images also will be relayed to the ground for analysis.

The shuttle, which is carrying the last piece of Japan's Kibo laboratory, is scheduled to spend 11 days at the outpost. Endeavour also is carrying supplies, spare parts and a new station crewmember, US astronaut Timothy Kopra, who will replace Japan's Koichi Wakata as one of the live-aboard flight engineers.


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