Live in Orbit: Spacewalk Proceeding Well

Two Endeavour spacewalkers are making good progress in their work today, despite a snag earlier when an untethered tool bag slipped away into space.

Heidemarie Stefanyshyn-Piper and Steve Bowen are more than 30 minutes ahead of schedule, and have replaced two sets of bearing assemblies on a damaged joint that rotates the International Space Station's starboard solar wings.

The pair is about five hours into the spacewalk, leaving about 90 more minutes scheduled. They are cleaning the area around a third bearing assembly, but it won't be replaced until the next spacewalk.

You can continue to watch the action live here by clicking on the NASA TV picture above.

NASA managers said before the mission that the large quantity of tools used on the joint work was one of the biggest challenges facing the spacewalkers, at least after the work was done.

John Ray, the mission's lead spacewalk officer, said getting all the tool back into their bags properly had been a challenge during training in a giant swimming pool.

"I kind of laugh, but it's something we don't take lightly, because we are carrying a lot of tools out," he said during a preflight briefing in Houston. "These all are going to go in a large bag. So we've made sure we budgeted plenty of time, and we try and work it out where the crew can work together at the end of the (spacewalk) to get all those tools back in the bag."

The following images show some of the tools that the two spacewalkers are using to go about their work:

Here, Bowen can be seen using a drill to replace a protective cover that he'd removed to expose the joint's gear ring.
This image shows the two sides of the 10-foot, hardened-steel gear ring, or race ring, which is damaged. One side turns to rotate the solar wings like paddle wheels.
Bowen holds a trundle bearing assembly, one of 11 on the joint that will be removed and stowed in bags so metal debris that has collected on them doesn't get loose in the space station or shuttle. NASA will analyze the bearings to see if a breakdown in gold-plated lubrication caused the damage to the gear ring.
Here, a grease gun - basically a modified caulking gun - with a J-hook tip is used to lubricate an interior face of the gear ring, which the spacewalkers can't see. The grease, called Braycote, is designed to work in microgravity.
Wearing terrycloth mitts, the spacewalkers dab and wipe loose metal shavings off the gear ring. One mitt is called a "dry" wipe, another coated with grease is called a "wet" wipe. Once used, they are turned inside-out to contain any debris.
A scraper is used to scrape off "pancakes" of metal debris that have been flattened onto the ring surface, adding to vibrations as it rotates.