Update: Spacewalkers Charged for SARJ

Two American spacewalkers wearing battery-powered spacesuits have moved into a pressurized hatch that is their last stop before they leave the International Space Station for more than six hours.

Heidemarie Stefanyshyn-Piper and Steve Bowen will make the first of four planned spacewalks during shuttle Endeavour's 15-day mission.

"Got you loud and clear," mission commander Chris Ferguson told both after he and mission specialist Greg Chamitoff locked the airlock hatch.

The spacewalkers are working about 40 minutes ahead of schedule, so the spacewalk could begin closer to 1 p.m. It was scheduled to start at 1:45 p.m.

You can watch the entire spacewalk here at The Flame Trench, by clicking on the NASA TV picture above to launch a viewer.

This graphic shows the sections of the space station joint - called a Solar Alpha Rotary Joint - that the two spacewalkers plan to work on during the second half of the spacewalk.

The joint rotates American solar wing's on the station's starboard side, so they can track the sun like paddle wheels.

The portions in red show where Stefanyshyn-Piper and Bowen, both Navy captains, will clean and grease the joint's gear ring, or race ring, which measure's 10.5 feet in diameter. They'll also replace two sets of trundle bearing assemblies that roll around the ring as it rotates.

NASA believes inadequate lubrication caused those bearings to start grinding against the race ring a little over a year ago, increasing vibrations and the amount of power needed to rotate the solar wings.

Since then, NASA hasn't rotated the wings continuously, limiting how much power they can generate.

Officials hope the cleaning and greasing process will allow the joint to rotate more smoothly when needed, and they plan to analyze the bearing assemblies returning to the ground to see if they can confirm that inadequate lubrication was responsible for the damage to the joint.

Stefanyshyn-Piper and Bowen are now checking for any pressure leaks in their suits.

Click here for a primer on the suits they'll wear in during the spacewalk.