Spacewalkers Set Up, Haul Back Experiments

U.S. astronaut Mike Fincke and Russian cosmonaut Yury Lonchakov are back inside the International Space Station after a spacewalk aimed at setting up and retrieving science experiments outside the outpost.

With the station flying 220 miles above the planet, the core members of Expedition 18 closed the hatch to the Russian Pirs airlock at 1:33 a.m. EST, officially marking the end of the five-hour, 38-minute excursion.

Fincke and Lonchakov made fast work of their first and highest-priority task. They set up a special probe that will measure the electromagnetic potential outside the station, which is thought to be the cause of explosive bolt failures that led to back-to-back ballistic reentries for Soyuz spacecraft in October 2007 and in April.

Installation of the ball-shaped device was ordered up by a Russian investigation commission; data from it is expected to firm up the theory that the electromagnetic potential around the station caused the failure of explosive bolts designed to separate sections of Soyuz spacecraft prior to reentry.

The spacewalkers also retrieved a space science experiment and set up two experiments on a platform attached to the outer hull of the Russian Zvezda Service Module.

One of those experiments -- a Russian plasma physics experiment -- worked just fine. But the second -- a European space exposure experiment -- failed to send back signals to the ground.

The spacewalkers disconnected and reconnected power and data cables to the EXPOSE-R experiment to no avail. No telemetry was received from the experiment, so the spacewalkers disconnected it and brought it back inside the station for further analysis.

The spacewalk started at 7:51 p.m. EST Monday and ended at 1:29 a.m. today. It was the fifth for station skipper Fincke, who performed four spacewalks as a flight engineer during Expedition 9 in 2004. He now has chalked up 21 hours and 23 minutes of spacewalking time.

The excursion was the first spacewalk for Lonchakov.

"Yury, was it beautiful?" asked fellow flight engineer Sandra Magnus, who was inside the station during the spacewalk.

"Yes, it was beautiful," Lonchakov replied. "But we really didn't have time to look around."

"That's no good," Magnus said.

It was the 119th spacewalk performed during the assembly and maintenance of the station since the first two building blocks of the outpost were linked in low Earth orbit 10 years ago this month.

Working in a deadly vacuum, astronauts and cosmonauts have tallied 751 hours and seven minutes of safe spacewalking operations during that time.