CAPE CANAVERAL, Fla. (AP) _ Leaving the orbiting outpost unmanned, the international space station's two astronauts floated outside on a spacewalk Friday to plug in new antennas and replace a worn-out piece of cooling equipment.
Gennady Padalka and Mike Fincke popped open the hatch on the Russian side of the orbiting outpost and got started on the fourth and final spacewalk of their six-month mission.
Their job: install three antennas for a new type of cargo carrier to be launched by the European Space Agency to the space station late next year, and replace the 2-foot-square Russian pump panel, part of a critical system for cooling station equipment.
``Be careful,'' Mission Control repeatedly warned the spacewalkers, telling them something like snow might float out when the old pump panel comes out. ``Go slowly.''
Because no one was left inside the 225-mile-high complex, flight controllers in both Moscow and Houston kept close watch over the two men and all their systems.
NASA prefers having a crew member inside during spacewalks but has had to settle for one less person on board for more than a year because of the grounding of the shuttle fleet. This was the fifth spacewalk with an empty outpost.
Padalka and Fincke have just 1 1/2 months remaining aboard the space station before they return to Earth. They will be replaced by another Russian and American.
The space station has been relying on Russia's much smaller spacecraft for deliveries ever since Columbia broke apart over Texas during re-entry on Feb. 1, 2003.
During Friday's outing, flight controllers hoped to better understand the mysterious force that tilted the space station 80 degrees off-center during the men's last spacewalk, one month ago.
Engineers suspect the extra force could have come from air gushing out when the hatch was opened, or from the spacesuits themselves.