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June 29, 2006

Space Shuttle Cleared for Saturday Launch in Florida

By Irene Klotz

CAPE CANAVERAL, Florida (Reuters) - NASA said on Thursday it is ready to lift its ban on space shuttle flights, convinced that only another launch will vanquish lingering safety concerns with the ship's fuel tank that were exposed by the 2003 Columbia disaster.

"It's been a long year with a lot of hard work," shuttle deputy program manager John Shannon said at a news briefing.

Mission managers cleared shuttle Discovery and its crew of seven for launch from the Kennedy Space Center in Florida on Saturday. Liftoff is scheduled for 3:49 p.m. EDT (1949 GMT).

NASA's top engineer and safety officials had argued to delay the launch until additional repairs could be made to the shuttle's fuel tank, which triggered the loss of Columbia and the deaths of seven astronauts.

Michael Griffin, the U.S. space agency chief who made the final call to proceed with launch, has acknowledged that any major technical problem likely would end the shuttle program permanently.

But with the fleet set to retire in four years, time is running out to finish building the International Space Station. Griffin decided that even if the worst-case scenario occurred and Discovery sustained Columbia-like damage from a debris impact during launch, the shuttle crew could live aboard the station while they awaited rescue.

Columbia was damaged when a piece of foam insulation fell off its fuel tank and hit the shuttle's wing during launch. It broke apart 16 days later as it flew through the atmosphere for landing.

NASA's first redesign of the tank was tested last year on the first post-Columbia mission, but it again shed large pieces of potentially dangerous foam. Managers decided to remove two foam wind deflectors from the tank, which were the primary sources of debris lost during Discovery's 2005 launch.

Additional work on foam covering 37 metal brackets, however, was deferred, despite the objections of some engineers and safety officials. NASA officially designated the hazard as "probable" during the life of the shuttle program, and potentially "catastrophic."

Shannon said he has no idea if that classification is accurate.

"We don't have enough information to characterize it. I think we will learn a lot on this flight," he said.

NASA's more immediate concern is the weather. Lighting and thunderstorms at the space center forced technicians on Thursday to delay loading the shuttle's onboard propellants, which are used to generate electricity during flight.

Forecasters predicted a 60 percent chance that poor weather will force NASA to delay Discovery's flight.