Two Russian cosmonauts spent more than five hours outside the international space station Wednesday, laying cable and installing protective panels to guard against space debris.
The walk lasted five hours and 37 minutes, about 15 minutes faster than planned.
Fyodor Yurchikhin and Oleg Kotov strung Ethernet cable along the space station’s Russian Zarya module, part of a project to establish a local-area network that would allow the American section of the orbiting lab to exert command over the Russian section in case of systems failure in the latter.
They also placed containers on the outside of the station for a Russian “bio-risk” experiment that is aimed at studying the effect of space orbit on various organisms.
Both tasks were completed relatively quickly — despite some wrestling with the bulky cable — and the hardest work came last with the installation of a dozen aluminum panels on the Russian section of the station to protect against space debris.
As the two Russians worked outside in their second spacewalk in a week, American astronaut Sunita Williams remained inside. Video from the station showed her working on other tasks.
Because of the angle of orbit of the station, the sun was shining on the cosmonauts for almost all of their spacewalk, and that prompted some mild complaints.
“The sun is not on our side today. It’s kind of hot,” one of the cosmonauts was heard saying on the video feed.
Wednesday’s installation of the inch-thick (2.5-centimeter-thick) panels followed the attachment of five others last week.
Engineers on the ground are able to monitor by radar the largest pieces of space debris — objects larger than a softball — and adjust the station’s position accordingly. The panels are designed to protect against smaller objects.
“The consequence of small particles is not so great,” Kirk Shireman, NASA’s deputy program manager for the space station, said last week. “Then there are the midrange particles. Those are the ones we worry about.”
An independent safety task force in February said that there was a 9 percent risk the space station, once completed in 2010, could be hit with space debris severe enough to cause the loss of the outpost or crew members. The risk was reduced to 5 percent with the installation of protective panels on Russian portions of the space station.
Sections of the space station built by NASA and the Japanese and European space agencies were protected sufficiently against space debris, the task force said.
In the course of Wednesday’s work, the cosmonauts noted at least one sign of debris or meteorite damage to the Russian section, an indentation that one of them said “looks like a bullet hole.”
They also inspected what they initially thought were ice crystals on the station’s exterior but then determined were paint flecks coming from one of the hand railings.
Amid the work, they still had the opportunity to marvel at where they were.
“Everything is so beautiful down there,” one of them commented about Earth, some 220 miles (350 kilometers) below.