Astronauts On Space Shuttle Atlantis Begin Spacewalk

This morning, just after 6:30 a.m. ET, two astronauts from the Space Shuttle Atlantis embarked on a spacewalk.

Steve Bowen and Michael Good spent 15 minutes untangling a cable that was snagged on the shuttle's Orbiter Boom Sensor System, which prevented a camera from maneuvering correctly. Now, as NPR's Tamara Keith reports, they're working on the International Space Station.

The spacewalk is scheduled to last more than six hours. Mission Specialists Stephen Bowen and Michael Good will replace three -- maybe four -- batteries on the station's solar array. According to Keith, "each battery weighs more than 360 lbs., and will require careful coordination between the space walkers to swap out safely.:

On its website, NASA explains what will happen:

Good will remove an old battery from the solar array's integrated electrical assembly using two "scoops" that Bowen will installed to make it possible to maneuver the batteries. After removing two bolts, Good will hand off the first old battery, battery 1, get out of the foot restraint in which he was working, move closer to Bowen and take hold of the battery again. Bowen then will release the battery, move slightly farther down the station's backbone, or truss, and position himself to take hold of the battery.

Then, the zero-gravity ballet will continue:

Good will hand the battery to Bowen then move himself closer to once again take hold and control the battery. The process is called "shepherding," and might appear as though the spacewalkers are "inch-worming" along the truss, except that one person is always holding a 375-pound battery.