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.
|Pete Nicolenko, NASA Test Director (L) talks to a reporter with Kathy Winters (R), shuttle weather officer, after a countdown status briefing for the launch of the space shuttle Discovery|
"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
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
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.
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."
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.