NASA Runs Into Potential Shuttle Launch Show-Stopper

NASA engineers have detected a potentially dangerous leak of gaseous hydrogen that could force the agency to scrap today's planned launch of shuttle Discovery and six astronauts on an International Space Station outfitting mission.

The leak of gaseous hydrogen was detected from a fixture that vents excess gaseous hydrogen from the external tank, through ground support lines to a flare stack 1,000 feet from the launch pad, where it is safely burned away.

Similar leaks caused delays in the launches of the STS-119 mission in March 2009 and the STS-127 mission in June 2009.

The STS-127 mission was delayed a month.

NASA must launch Discovery by Sunday or delay until a window that opens Dec. 1 and closes after Dec. 5.

The sun angle on the International Space Station between Monday and Nov. 23 will be such that the outpost could not generate enough power, and the shuttle could not dispel enough heat, for docked operations.

A three-man station crew also is scheduled to depart the outpost Nov. 29 and an ongoing shuttle mission would interrupt that operation.