Live in orbit: Spacewalk Preps Under Way

American astronaut Mike Fincke and Russian cosmonaut Yury Lonchakov are in the Pirs airlock of the International Space Station, preparing to head outside the outpost on a spacewalk expected to last six hours and 10 minutes.

Station skipper Fincke will be making his fifth spacewalk; Lonchakov his first. The two aim to set up a science experiment ordered up by a commission that investigated back-to-back ballistic reentries that subjected Soyuz crews to higher than normal gravitational forces.

Working outside the airlock, they'll mount a ball-shaped device that will measure the electrical potential around the station.

The commission found that the electrical potential was the likely cause the failure of bolts designed to separate sections of the Soyuz craft just prior to reentry. Data from the probe will add to the body of knowledge being collected by Russian engineers.

The spacewalkers are getting ready to depressurize the airlock and then head outside the Pirs around 7:15 p.m. EST. You can watch the excursion unfold here in The Flame Trench. Simply click the NASA TV box on the righthand side of the page to launch our NASA TV viewer and live coverage of the spacewalk. And refresh this page for periodic updates.

Fincke is wearing an Orlan suit with a red stripe, and he'll be answering to the radio call sign "EV-2."

Lonchakov is waering a suit with a blue stripe and is "EV-1."