Science News
Endeavour's final spacewalk ends: next stop, Earth
By DPA
Mar 23, 2008, 10:59 GMT

Washington - Endeavour's space-walking duo, US astronauts Robert Behnken and Mike Foreman, ended the mission's fifth and final spacewalk early Sunday morning after stowing a post-Columbia-disaster boom at the space station.

Endeavour will leave the boom behind when it returns to Earth Wednesday to save space in the cargo bay of the next shuttle mission in May.

The 17-metre-long boom - known as the Orbiter Boom Sensor System (OBSS) - was designed as a safety backstop to help the ageing shuttles perform post-launch self examinations for tile damage. Tears in the outer thermal skin that occurred on liftoff were blamed for the 2003 Colombia disaster that killed its seven astronauts as they tried to return to Earth.

Because of the size of the next piece of Japan's Kibo laboratory being hauled to the station by Discovery shuttle in May, there won't be room enough in the cargo bay for the OBSS, NASA officials explained.

Discovery will retrieve the boom after unloading the next Kibo installation in May.

During the six-hour-two-minute-long spacewalk, Behnken and Foreman fastened a 'keep alive' cable to the boom to keep its sensitive instrumentation warm and protected from the 'harsh space environment' over the next two months, NASA said.

Behnken and Foreman were aided by two robot arms - the shuttle's own on-board robot, which fetched the OBSS out of Endeavour's cargo bay, and the space station's newly updated Canadian robot arm Dextre, which took over some of the work in stowing it outside station.

The spacewalkers also installed covers on the first part of Japan's Kibo, which was joined to the space station on an earlier spacewalk, and inspect a solar panel joint.

Endeavor is to undock on Monday and return to Earth on Wednesday.

NASA's shuttles are rushing to complete expansion of the orbiting space station before they are retired in 2010. The station will continue to be served by Russia's manned Soyuz programme, but only the shuttles are large enough to do the heavy lifting of laboratories and other pieces.