NASA may delay launch of Discovery again

Dec 2 2010 - 6:10pm

CAPE CANAVERAL, Fla. -- NASA's plans to launch the space shuttle Discovery on Dec. 17 are looking increasingly unlikely as engineers continue to wrestle with what caused cracks in the shuttle's giant external fuel tank.

However, NASA spokesman Allard Beutel emphatically denied reports that the next launch attempt would be delayed at least until February. "We have not pushed back to February," said Beutel, adding that NASA still is considering a launch sometime in December.

However, he acknowledged, it's not clear if and when engineers will be satisfied that they know enough about the cracks in the fuel tank to enable the orbiter to fly safety.

"There's a lot of work we have ahead of us," he said, adding that X-ray machines are continuing to take pictures of the structure of the tank at the launch pad, where Discovery has sat since mid-October.

Beutel said engineers are also considering a "tanking" test, loading the tank with super-cold liquid hydrogen and oxygen to see if repairs made to the cracks hold up or if more cracks develop. It will take days to set up the test and then analyze the results, he said.

To launch Dec. 17, the countdown would have to start on Dec. 15, which doesn't give engineers much time, he acknowledged. The first launch window extends through Dec. 20, but Beutel said engineers are studying possibilities of launching through early January.

Earlier Thursday, a source had told The Orlando Sentinel that a February launch date was not likely.

The cracks were discovered in the shuttle's external fuel tank last month. NASA's Program Requirements Control Board has reviewed repairs on two 21-foot-long, U-shaped aluminum brackets, called stringers, in the middle portion of the tank. So far, engineers haven't been satisfied that the results show the shuttle can be launched safely.

NASA engineers have worked extensively on the fuel tank since 2003, when a briefcase-sized chunk of insulating foam came off the tank during the launch of shuttle Columbia and punched a hole in the heat-resistant tiles of the shuttle's left wing. The hole admitted fiery gases during Columbia' re-entry into the Earth's atmosphere, causing the orbiter to disintegrate and killing the seven-member crew.

Since then, modifications to the way foam is applied have resulted in significantly less of it coming off. But the cracks discovered last month in the tank's surface were the first ever seen by NASA engineers.

Another delay of Discovery would mark the third significant setback for a launch originally set for Nov. 1. The discovery of cracks in both the external foam and the body of the shuttle's giant external fuel tank forced an initial postponement until Dec. 3 and then, last week, to no earlier than Dec. 17.

Discovery is slated to take six astronauts and a cargo of spare parts to the International Space Station before it is retired and turned into a museum piece. The final launch of a shuttle had been scheduled for February, with the possibility of another flight later next year, but another Discovery delay would affect that schedule.

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