Astronauts conduct final spacewalk of Discovery mission
AFP
WASHINGTON - Astronauts from the US space shuttle Discovery ventured out of the International Space Station on Saturday for a third spacewalk that will be the last of their mission.
NASA astronaut Danny Olivas and European Space Agency astronaut Christer Fuglesang left the ISS at 2039 GMT for what is expected to be a 6.5 hour spacewalk, the US National Aeronautics and Space Administration said.
The pair are expected to "deploy an attachment system" and "replace a device designed to help the station determine its position relative to the Earth," NASA said.
The pair returned to the decompression chamber after six hours and 39 minutes in space, NASA said, and after bolting the 1,760-pound (800-kilogram) tank into place and linking up electrical and fluid lines.
The spacewalkers also moved a spent ammonia tank, which was removed Wednesday, into the shuttle's cargo bay to be taken back to Earth.
With this week's outing Fuglesang -- who was the first Swede in space in December 2006 -- became the first astronaut outside the United States or Russia to participate in more than three spacewalks.
The duo also fetched US and European equipment from the orbiting station's Columbus laboratory that will be brought back to scientists on Earth.
Earlier, a large piece of space debris drifted toward the ISS, but NASA said it would not affect the mission's spacewalks.
The shuttle brought 7.5 tons of supplies, including new station crew quarters, a freezer, two research racks and a treadmill named after US comedian Stephen Colbert, to the station.
The freezer will store samples of blood, urine and other materials that will eventually be brought back to Earth for study on the effects of zero-gravity.
The Combined Operational Load Bearing External Resistance Treadmill (COLBERT) is the ISS's second treadmill. Exercise is key for astronauts spending long periods of time in space, where zero-gravity can result in muscle atrophy.
Colbert originally won an online poll for NASA to name a new space station room after him, but the US space agency decided to instead name the new module Tranquility and allow the satirist to have his name placed on the treadmill.
The mission for Discovery, currently orbiting with the ISS 220 miles (354 kilometers) above the Earth, is the fourth of five planned for the shuttle program this year. The last is scheduled for November.
The shuttle will remain docked at the ISS until Tuesday, and is due to return to Earth on September 10.
Once the mission is complete, just six more shuttle flights remain before NASA's three shuttles are retired in September 2010.
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