Shuttle Endeavour's Leak Caused by Debris

CAPE CANAVERAL, Fla. ? Tests revealed that Endeavour's once-puzzling crew cabin leak was caused by small piece of debris, NASA officials said today during a mission status briefing at Kennedy Space Center (KSC).

After a week of hunting for the leak aboard the newly retrofitted space shuttle, the valve was replaced and tested.

"We found a tiny piece of debris in the sealing surface, which was causing that slight leak rate. There's nothing systemic wrong with any of the valves," said NASA test director Steve Payne, adding that removing the grit fixed the valve.

"We just finished a leak check ? early this morning, and it is very, very tight," Payne said of Endeavour's crew cabin.

Countdown starts tonight

The STS-118 launch countdown is expected to begin tonight at 8:00 p.m. EDT (2000 GMT). If all goes according to plan, Endeavour and its seven-person crew will lift off from Pad 39A on Wednesday at approximately 6:36 p.m. EDT (2236 GMT).

So far, said NASA's shuttle weather officer Kathy Winters, the forecast is looking favorable for launch, considering the turbulent seasonal conditions.

"We have 30 percent chance of KSC weather prohibiting launch," Winters said, which an eastern weather system is mainly responsible for. "We could get some isolated showers and ? some anvil [clouds] coming in from over the Gulf Stream."

Crew primed

Led by commander and veteran astronaut Scott Kelly, the seven-person STS-118 crew will dock with the International Space Station (ISS) two days after launch. Once there, astronauts will begin an 11-to-14 day mission to further assemble the space laboratory as well prepare it for future construction.

"There's a little bit of assembly, there's some re-supply, there's some repairs and there are some high-visibility education and public affairs events," said Matt Abbott, NASA's lead STS-118 shuttle flight director, of the mission last month. "It's a little bit of everything."

Barbara Morgan, NASA's teacher-turned-astronaut, will be part of Endeavour's crew delivering a 4,010-pound (1,820-kilogram) girder spacer for the Starboard-5 (S5) truss segment of the ISS. The piece will add another element to the space station's growing backbone and make way for its future expansion, but the shuttle's biggest haul will be 5,000 pounds (2,268 kilograms) of fresh cargo to re-supply the ISS.

NASA officials said today that the crew is continuing to train, review flight plans and undergo equipment and personal checks in preparation for launch.

• VIDEO: Teaching the Future: Teacher-Astronaut Barbara Morgan
• Complete Space Shuttle Mission Coverage
• IMAGES: NASA's STS-117 Shuttle Mission in Pictures