CAPE CANAVERAL, Fla., Oct 28 (Reuters) Two spacewalking astronauts today prepared a section of the International Space Station's frame to be moved and found signs of a potential problem with a solar power wing rotator.
Space shuttle Discovery's Scott Parazynski, one of NASA's most experienced spacewalkers, and Dan Tani, who recently joined the space station crew, left the orbital outpost for a six-hour outing, the second of five spacewalks planned during Discovery's 10-day servicing call.
Their primary job was to prepare an 18-tonne section of the station's frame to be relocated from the top of the outpost to one of its outer edges. The segment contains a rolled-up pair of solar power wings that will be unfurled in their new location to provide power for European and Japanese laboratories due to begin arriving in December.
During the current shuttle mission's first spacewalk on Friday, astronauts installed the Italian-built Harmony module, which has berthing ports for Europe's Columbus and Japan's Kibo laboratories.
During today's spacewalk, Tani inspected a huge rotary joint that turns another pair of the station's solar wing panels so they can track the sun for energy.
Engineers have been tracking a slight vibration and higher-than-expected power draw from the joint and were curious about whether visual inspection by an astronaut would pinpoint the problem.
Tani did not find a protruding bolt, as some NASA engineers had expected, but did find evidence of something amiss: metal shavings in the joint. ''It's quite clear,'' Tani said after removing a thermal cover and finding the bits of metal clinging to the rotary joint. ''It's widespread.'' He collected a few of the scrapings to return to Earth for analysis.
The second spacewalk set the stage for a difficult maneuver scheduled for Tuesday, reattaching the third pair of solar wings to the end of the station's backbone.
''You have this big truss, the (robot) arm is fully extended and you're trying to thread a needle without really good visuals, so it's extremely complex,'' flight director Rick LaBrode said.
NASA is in the midst of a burst of construction activity on the station, which must be finished by 2010 when the aging space shuttles are set to be retired.
The space agency has 11 more construction missions planned to complete the 100 billion dollars space station and will also carry out two resupply missions. The US space agency also plans a final servicing call to the Hubble Space Telescope next year.
Discovery, which arrived at the station on Thursday, two days after launching from the Kennedy Space Center in Florida, is due back at the spaceport on November 6.
REUTERS GT AS2349