Source: Xinhua

11-19-2008 13:29

Special Report:   Tech Max

WASHINGTON, Nov. 18 (Xinhua) -- Two U.S. astronauts from the shuttle Endeavor partially cleaned and lubed a solar panel on the space station Tuesday during the first of four planned space walks.

Heidemarie Stefanyshyn-Piper on the end of the robot arm is aided by fellow spacewalker Steve Bowen (L) as the pair move a nitrogen tank assembly to the Space Shuttle Endeavour's cargo bay for storage in this image from NASA TV Nov. 18, 2008. (Xinhua/Reuters Photo)
Heidemarie Stefanyshyn-Piper on the end of the robot arm is aided by
fellow spacewalker Steve Bowen (L) as the pair move a nitrogen tank
assembly to the Space Shuttle Endeavour's cargo bay for storage in 
this image from NASA TV Nov. 18, 2008. (Xinhua/Reuters Photo)

Mission Specialists Heidemarie Stefanyshyn-Piper and Steve Bowen stepped outside the orbital outpost at 1:09 p.m. EST (1809 GMT) and wrapped up their work at 8:01 p.m. EST.

The astronauts first replaced a depleted nitrogen tank and a device used to help coolants flow along the station truss during the excursion that lasted nearly seven hours. They also removed covers from the front of the Japanese Kibo module to prepare for the installation of the module's exposed facility during the next Endeavor mission in 2009.

Heidemarie Stefanyshyn-Piper on the end of the robot arm with the earth in the background as she moves a nitrogen tank assembly to the Space Shuttle Endeavour's cargo bay in this image from NASA TV Nov. 18, 2008. (Xinhua/Reuters Photo)
Heidemarie Stefanyshyn-Piper on the end of the robot arm with the earth
in the background as she moves a nitrogen tank assembly to the Space
Shuttle Endeavour's cargo bay in this image from NASA TV Nov. 18, 2008.
(Xinhua/Reuters Photo)

The astronauts then began their main task -- inspecting, cleaning and lubricating the station's starboard solar array rotary joint (SARJ) -- or the right-side joint. The mechanism is a wagon-wheel-shaped joint on the station's truss that allows electricity-generating solar panels to rotate so that they can always collect as much sunlight as possible.

NASA ground controllers noticed last year that more power than normal was being required to rotate the starboard joint, and that the device was vibrating excessively.

During several space walks to inspect the joint, engineers narrowed the cause to insufficient lubrication.

The two astronauts began work on the problem by removing the joint's old bearings. They still have to clean metal shavings off the joint's surface, lubricate the device and install new bearings.