NASA postponed moving the space shuttle Discovery to a processing hangar on Wednesday so technicians could replace a leaking seal, likely delaying a key international space station assembly mission.
The shuttle was due to be transferred to the massive Vehicle Assembly Building at the Kennedy Space Center in Florida so it could be outfitted with a fuel tank and booster rockets needed to reach orbit. Launch had been targeted for October 23.
During routine checks however, technicians noted a leaking seal in the shuttle's main landing gear and managers ordered all the seals replaced as a precaution. Before the repair work, the shuttle had five contingency days in its schedule.
"They're all gone," said NASA spokesman George Diller, adding that the move to the assembly building has been re-targeted for the middle of next week.
The shuttle had been scheduled to be rolled out to the launch pad on September 27. That move will be delayed as well.
The effect on the launch date remains uncertain, although a few days' delay is likely, Diller said.
"We don't expect it'll be a big hit," he said.
The shuttle will carry a connecting hub to the space station so laboratories built by Europe and Japan can be attached to the outpost later this year and in 2008. The shuttle crew also will have to relocate solar array panels to make room for the new additions.
In addition to four spacewalks for space station work, the Discovery crew is training for a fifth outing to test a heat shield repair technique. Managers extensively debated whether slight damage to shuttle Endeavour's heat shield during the last mission in August needed to be fixed before the ship flew through the atmosphere for landing.
In the end, NASA decided a risky in-flight repair was unnecessary. The shuttle landed safely with no additional damage, but questions remained about whether the repair technique would have worked.
Spacewalkers will use a device similar to a caulking gun to squirt a filler into sample damaged tiles as practice in case future repairs are needed.
NASA plans to fly the shuttle 14 more times before retiring the ships in 2010. Eleven are to be construction missions to the station and two are resupply missions. NASA also plans a final servicing call to the Hubble Space Telescope.