Spacewalking Astronaut Found Metal Shards On Joint

NASA has scrapped a plan to test a shuttle heat shield repair technique so astronauts have time to study a critical part of the International Space Station's power system that is now in question, NASA said Monday.

As a result, NASA will delay the shuttle Discovery's departure from the station to November 5 -- giving the combined STS-120 and Expedition 16 crews a day off between the fourth and fifth planned spacewalks, and also cutting a day out of the already slim six-day window of opportunity for the next shuttle mission.

That mission is targeted for launch on December 6, according to Reuters. The shuttle Atlantis will fly the long-awaited Columbus laboratory to the station.

For almost two months, NASA has been aware of a potential problem with one of the station's massive rotary joints that spin the outpost's solar wing panels so they can track the sun and generate power.

Astronaut Dan Tani was dispatched on Sunday to investigate the problem during a space walk. He found shards of metal scrapings prevalent throughout the joint. "I was quite sure there was something anomalous with the mechanism," Tani said Monday during an in-flight interview.

Tani collected some samples to return to Earth for analysis... but space station commander Peggy Whitson, a biochemist, conducted an experiment on Monday and discovered the metal bits contained iron.

NASA had hoped the debris was from the devices aluminum-lined thermal covers from outside the joint. Engineers will now be looking at the internal parts of the rotary joint itself.

Mission managers decided to lock the affected solar panels in place to avoid working the rotary joint to prevent further damage. This procedure cuts the amount of power the station can produce, a situation that must be corrected before Japan's science laboratory, Kilo, is launched next year.

"We can move it around, but without knowing what the problem is there is the risk that we could do more damage," Whitson said.

The issue will supercede practicing a shuttle heat shield repair technique, one of several safety upgrades NASA developed after the 2003 Columbia disaster. Instead, space walkers will spend the fourth outing of the mission pulling off the rest of the troubled joint's thermal covers to see if the damage is widespread.

In addition, space walkers Scott Parazynski and Doug Wheelock, who are scheduled to leave the space station's airlock early Tuesday for the mission's third space walk, will inspect the station's healthy solar power panel joint to compare it with its troubled mate.

The primary goal of the October 30 outing is to move a third pair of solar wing panels to a new position on the far end of the station's frame.

The folded-up wings must then be unfurled, a maneuver that has become more critical in light of the power shortfall caused by the rotator problem.

Discovery's astronauts arrived at the station on October 25, for what was planned to be a 10-day stay. With the mission extension, Discovery's return to Earth has been postponed to November 7.

(Images courtesy of NASA and NASA TV)

FMI: www.nasa.gov, www.nasa.gov/mission_pages/station/main/