The crew of space shuttle Discovery arrived at Kennedy Space Center in Florida on Friday for the countdown ahead of next week's launch on a construction mission to the International Space Station.
Discovery, hauling a key connection node to the space station, is scheduled for liftoff at 11:38 a.m. EDT on Tuesday.
Before the 2003 Columbia disaster the launch of Discovery's cargo, a module called Harmony, would have completed the U.S. portion of the space station and opened the complex for expansion by European and Japanese-owned laboratories.
The latter function will still be served by Harmony's arrival at the station. But Europe and Japan will now have their labs launched prior to completion of the U.S. segment.
If Discovery can get off the launch pad with little or no delay, NASA plans to launch another shuttle on December 6 to put Europe's Columbus laboratory into position on the orbital outpost.
Half the engineering teams and safety experts that advise NASA's shuttle managers on technical issues suggested delaying Discovery's liftoff until later this year so questionable heat shield panels on the ship's wing could be replaced.
A postponement would bump launch of Columbus to 2008 as well as reduce NASA's allotted time to complete station assembly and retire the shuttle fleet by 2010, as mandated by presidential directive.
After a 12-hour debate on Tuesday, managers decided to press ahead with the launch while investigations are under way to determine the root cause of the problem, which involves a slight degradation of the silicon-carbide coating on three wing panels. ( Reuters )