Electrical Glitch and Weather May Threaten Shuttle Discovery's Thursday Launch

Shuttle Discovery's Gas Leaks Repaired In Time for Wednesday Launch
The space shuttle Discovery and its STS-133 crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. The launch attempt on Wed., Nov. 3 was delayed, however. (Image credit: NASA/Troy Cryder)

CAPE CANAVERAL, Fla. ? NASA engineers are working tounderstand a last-minute electrical glitch on the space shuttle Discovery and eyeingdismal weather forecasts for its planned launch on Thursday.

Discovery is slated to lift off on its final flight noearlier than tomorrow (Nov. 4) at 3:29 p.m. (1929 GMT) from NASA's Kennedy SpaceCenter here, but weather and issues with a backup engine computer on theorbiter could thwart those plans.

Officials delayed the liftoff to Thursday due to an electricalglitch in a backup computer controller in one of Discovery's main engines,which engineers discovered yesterday (Nov. 2).

The malfunction forced NASA to push back Discovery's alreadydelayed launch by at least another day. Earlier this week, the flight waspushed back because of unrelated issues in the spacecraft's aft orbitalmaneuvering system. [GRAPHIC:NASA's Space Shuttle ? From Top to Bottom]

Even if NASA settles the electrical issue on Discovery intime for a Thursday launch, the weather outlook is not promising.

There is an 80 percent chance that foul weather will causeyet another launch delay for the space shuttle, according to Kathy Winters,NASA's shuttle weather officer.

Discovery's ?mission management team will meet today at 2p.m. EDT (1800 GMT) to reviewthe available data and decide whether to fly the shuttle as is, or delayfurther to troubleshoot and make repairs, said Mike Moses, NASA's shuttle integrationmanager.

"We fly with known risks, not unknown risks,"Moses said late yesterday. "Right now this risk is a little bitunknown."

Discovery is slated to fly an 11-day mission to theInternational Space Station to deliver a new storage module and a humanoidrobot for the orbiting lab's crew. It will be the 39th and last flight forspace shuttle Discovery, which is the first of NASA's three shuttles to beretired as the agency winds down its orbiter program next year.

If NASA cannot launchDiscovery by Sunday, Nov. 7, it will miss the current window and have tostand down until Dec. 1 to try again.

Follow SPACE.com Staff Writer Denise Chow onTwitter @denisechow asshe covers Discovery's final space voyage from Cape Canaveral, Fla. Click here formission updates, new stories and a link to NASA's live webcast coverage.

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Denise Chow
NBC News science writer

Denise Chow is a former Space.com staff writer who then worked as assistant managing editor at Live Science before moving to NBC News as a science reporter, where she focuses on general science and climate change. She spent two years with Space.com, writing about rocket launches and covering NASA's final three space shuttle missions, before joining the Live Science team in 2013. A Canadian transplant, Denise has a bachelor's degree from the University of Toronto, and a master's degree in journalism from New York University. At NBC News, Denise covers general science and climate change.