Two crewmen leave space station for spacewalk

CAPE CANAVERAL, July 23 (Reuters) The Russian commander of the International Space Station and a NASA flight engineer floated out of the station's airlock today to dump overboard some obsolete equipment and prepare the outpost for future assembly missions.

Dressed in US spacesuits, Fyodor Yurchikhin and Clay Anderson left the station shortly after 6:30 a m Eastern time (1600 IST) to begin a planned 6.5-hour outing.

The third station crewmember, Oleg Kotov, remained aboard the orbital complex to operate the station's robot arm, the first Russian cosmonaut to do so.

With only 14 more shuttle missions to the station planned before the fleet is retired in 2010, NASA has shifted many station maintenance and construction tasks previously earmarked for visiting space shuttle astronauts to the live-aboard station crew to handle. The 100 billion dollars outpost, a project of 16 nations, is a little more than half-finished.

Anderson plans during today's outing to dump a piece of equipment NASA initially intended to bring home on a shuttle, but now has no room for because of the jam-packed flight schedule.

Mounted on the station's robot arm, Anderson will jettison a refrigerator-sized tank containing ammonia which was part of the station's first cooling system. The ammonia tank is no longer needed because an upgraded power and cooling system is now in place.

The equipment will remain free-floating in space for at least 300 days, before it is dragged back into Earth's atmosphere and incinerated. Pieces as large as 39 pounds (18 kg) however may survive the plunge through the atmosphere and eventually crash down on Earth. Military radars will be used to track the debris.

Anderson also plans to dump an old camera stand to free up space on an equipment platform for other gear.

Other tasks include cleaning debris off a docking port so the complex will be ready the arrival of new laboratories built by Europe and Japan, and replacing a faulty electronics switch in the mobile transporter that moves the station's robot arm to various work locations along the station's exterior support beams.

REUTERS JK VV1734