CAPE CANAVERAL, Fla. - Spacewalking astronauts doing construction work outside the international space station Sunday made a disturbing discovery: what appear to be metal shavings inside a joint that is needed to turn a set of solar-power panels.
The rotary joint, 10 feet in diameter, has experienced intermittent vibrations and power spikes for nearly two months.
Space-station managers were hoping a thermal cover or bolt might be hanging up the mechanism, which would have been relatively easy to fix, and were disheartened when Daniel Tani radioed down that metal shavings were everywhere.
"It's quite clear that it's metal-to-metal grating or something, and it's widespread," Tani said.
The shavings resembled small flakes and were clinging to the joint as if to a magnet, Tani said.
The astronaut used tape to dab up some of the shavings. They will be returned to Earth aboard Discovery next week for analysis. NASA is uncertain whether the flecks are actually metallic or some other material.
This rotary joint, launched and installed just four months ago, controls the huge solar-panel wings on the right side of the space station, to make sure they're facing the sun. The joint for the left solar wings is working fine.
The right rotary joint will remain in a parked position as much as possible until the problem is solved, said Mike Suffredini, NASA's space-station program manager.
It's too soon to know whether the joint - if it continues to malfunction - will affect science operations aboard the European laboratory that is scheduled to fly to the space station in December, or the Japanese lab that will follow, Suffredini said.
"We have lots of time to work through this problem. It's not an immediate issue," Suffredini said at a news conference Sunday afternoon after the spacewalk.
The problem overshadowed the rest of Sunday's spacewalk, the second of five planned for Discovery's construction mission.
The spacewalkers' first job out the hatch was to disconnect bolts and cables holding a 35-foot-long, 35,000-pound girder to the orbiting complex, so astronauts working inside could pull it away with the robot arm. It was the first time the girder and its attached solar-power wings were moved since being installed seven years ago, and the job went well.
The girder will be reattached to another spot on the space station Tuesday, and its solar wings unfurled to their full 240 feet across. NASA considers this one of the most difficult construction jobs ever attempted in orbit.
During their 6 ½ hours outside, Tani and Scott Parazynski also added handrails and other equipment to the outside of Harmony, the school-bus-size compartment that was delivered by Discovery and attached to the space station last week. They did not have enough time to finish installing a grappling hook to Harmony, and they had to skip some other work, too.
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