CAPE CANAVERAL, Fla. — For the third time this week, NASA fueled space shuttle Discovery for a Friday night launch to the international space station after resolving a fuel valve problem.
The launch team began loading Discovery's external fuel tank at mid-afternoon, a few minutes late because of the potential for lightning. Liftoff was scheduled for 10:59 p.m. CDT.
Forecasters said there was a 60 percent chance of favorable weather. Thunderstorms were moving toward the launching site, however, raising some concern.
Discovery and its seven-member crew tried to blast off early Tuesday, but storms kept them on the pad. Then the fuel valve trouble struck and scuttled Wednesday's try.
Engineers suspected the hydrogen fuel valve inside Discovery was fine and that an indicator switch was faulty. Mission managers agreed to a workaround plan, if the indicator acted up again. But everything worked during Friday's fueling, and applause filled the firing room when the indicator switch properly showed the valve to be closed.
The 8-inch fill-and-drain valve is a critical part of the main propulsion system.
Discovery is packed with about 17,000 pounds of space station supplies. The most high-profile payload is a $5 million treadmill named after Comedy Central's Stephen Colbert.
Colbert tried to get a space station room named after himself and even won the online vote earlier this year, but NASA went with Tranquility instead in honor of the 40th anniversary of man's first moon landing.
Colbert said the treadmill - for "all those chubby astronauts" - is a consolation prize.
NASA must launch Discovery by Sunday, otherwise the 13-day mission will fall to October because of a forthcoming space station traffic jam. A Japanese cargo ship and a Russian spacecraft are scheduled for September launches.
Front Section, Pages 2 on 08/29/2009