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WORLD> America
NASA hopeful repairs will permit Discovery's Sunday launch
(Agencies)
Updated: 2009-03-15 14:19

CAPE CANAVERAL– NASA is unsure what caused the hydrogen gas leak that prevented space shuttle Discovery from flying, but nonetheless will attempt another launch Sunday.


In this image provided by NASA space shuttle Discovery sits on launch pad 39A at NASA's Kennedy Space Center in Cape Canaveral Florida. [Agencies] 

Shuttle managers are hopeful that repairs at the launch pad have solved the problem.

There's "a potential risk" that the leak will recur, said Mike Moses, chairman of the mission management team. That would mean yet another delay for the international space station construction mission, which already is running more than a month late.

"We did everything we could, which is to replace all the hardware," Moses told reporters Saturday. "Yeah, we'd like to have that root cause, because now you'd feel comfortable. But I'm still going to sleep just as good tonight knowing that our chances tomorrow are really good that we did lick this problem."

NASA has until Tuesday to launch Discovery before having to wait for a Russian Soyuz rocket that is set to blast off to the space station March 26.

The latest delay occurred Wednesday, just hours before liftoff, as NASA was almost finished loading Discovery's external fuel tank. Hydrogen gas began leaking where a vent line hooks up to the tank.

NASA replaced that hookup and a pair of seals and, in fact, fell a few hours behind in countdown preparations because of an assembly issue. Nothing obvious was wrong with the removed parts. One of the seals was slightly rolled up along the edge, and the hookup itself was discolored in one spot. But neither of those issues may have caused the leak, said launch director Mike Leinbach.

"I just don't have a smoking gun," Leinbach said. He acknowledged it's a little unusual to continue the countdown in such a case, but he stressed it's not a launch safety issue because the launch will be canceled again if there's a leak.

Discovery's previous delays - which have stretched over month - were caused by hydrogen gas valves in the shuttle engine compartment. NASA ordered extra tests and kept replacing the valves to make sure they were safe to fly. One of these valves broke on the last shuttle launch in November.

Waiting to fly since mid-February, Discovery and seven astronauts are set to carry up one last set of solar wings for the space station.

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