An astronaut and a cosmonaut successfully performed a series of tasks outside the station.
The crew of the International Space Station spent more than five hours outside their ship beginning Monday night, completing installation of an electromagnetic energy probe and performing other experiments that didn't wrap up until 1:29 a.m. Eastern time Tuesday.
The tasks marked the fifth spacewalk for commander Mike Fincke and the first for flight engineer Yuri Lonchakov.
The astronaut and the cosmonaut, wearing Russian Orlan spacesuits, worked together to install an electromagnetic measuring device known as a Langmuir probe on the space station's Pirs docking compartment. The device could prove useful in measuring the effects of electromagnetic fields on pyrotechnical separation bolts.
Those bolts may have failed during Expeditions 15 and 16 of the Russian Soyuz spacecraft, leading to a ballistic, or steeper-than-normal, re-entry of the craft into the Earth's atmosphere.
Fincke and Lonchakov also installed what NASA is calling "the Impulse experiment," under which disturbances in the ionosphere surrounding the space station are measured. The spacewalkers successfully installed the experiment, but only after dealing with some uncooperative cable connectors.
NASA said mission specialists on Earth were unable to receive telemetry data from Impulse and decided to shut it down.
Fincke and Lonchakov then returned to Pirs, re-entered the airlock, and closed the hatch. In total, they spent five hours and 38 minutes outside the space station.
The space station, an international project funded by 16 nations, has been under construction for more than a decade at a cost of $100 billion. Ultimately, NASA plans to expand the size of the station's crew from three members to six.