Shuttle pilot takes evasive action to avoid hurtling debris.
Astronauts Joseph Acaba and Richard Arnold began their third spacewalk Monday morning, a day after moving the Discovery shuttle to avoid a collision with space junk.
NASA said the astronauts moved Discovery in front of the International Space Station, placing it in an "undock" position, Sunday afternoon to create drag to slow their speeds and put them in a slightly lower orbit to avoid debris that posed a potential threat. The space junk was orbiting erratically and appeared to be about 4 inches in diameter, NASA said. It's believed to be part of a spent Chinese satellite.
Mission control in Houston warned the astronauts of the debris before 3 p.m., marking the second time in less than two weeks that astronauts had to take action to reduce the risks of space junk colliding with the space station. Eleven days ago, the crew hunkered down in the Russian Soyuz capsule as a precaution against another piece of debris that passed by without incident.
The debris that NASA spotted Sunday was expected to pass the space station repeatedly if NASA hadn't decided to change the station's position.
"Had we not taken this action, the first time of closest approach would have been about two hours into Monday's spacewalk," NASA said in a news announcement.
Early in the evening, NASA returned the Discovery back to its original position, behind the space station. After the maneuvers, Acaba and Arnold spoke with reporters, reviewed Monday's procedures, and "camped out" in the Quest Airlock module.
Monday morning, they began the mission's third spacewalk, which is expected to last more than six hours. The astronauts switched their spacesuits to internal battery power and exited the hatch for their second spacewalk, so they can perform maintenance and repairs. They will attempt to deploy an unpressurized cargo carrier attachment system, install a similar attachment on the right side of the station, lubricate moving parts, and reconfigure cables.
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