Cosmonauts Pave Vinogradov and Roman Romanenko embarked Friday on a planned six hour spacewalk outside the International Space Station's Russian segment.
The two men plan to install a laser reflecting navigational aid on the station's Zvezda service module to assist with the automated docking of the European Space Agency's ATV-4 re-supply ship, the Albert Einstein. Launch and arrival of the ATV-4 are slated for early June. The worksite was opened Monday with the departure of Russia's Progress 49 supply craft.
The cosmonauts will also install and retrieve external science experiments.
"It's dark outside," said one of the men as the excursion got under way at 10:03 a.m., EDT.
The Russian excursion kicks off a series of eight planned U.S. and Russian spacewalks this year, the most extra-vehicular activity scheduled since the assembly of the station's U. S. segment drew to a close in mid-2011. The U.S.-led ISS mission management team has slowed the pace of spacewalks in the post-assembly period to elevate the priority of scientific research and technology demonstrations aboard the six person orbiting laboratory.
Future outings, in part, will extend external data and solar power cables from the U.S. to the Russian segment to prepare for the anticipated arrival of Russia's Nauka Multipurpose Laboratory Module in December. The work will also involve the decommissioning of the Pirs module, which will be jettisoned to make way for Nauka.
The new Obstanovka experiment, the first task on Thursday's spacewalk, will study plasma waves in the Earth's upper atmosphere. A Biorisk canister the cosmonauts intend to retrieve is part of a study of the effects of bacteria and fungi on spaceflight structures.
Vinogradov, 59, is embarking on his seventh spacewalk.
The excursion is the first for Romanenko, 41, the son of Soviet-era cosmonaut Yuri Romanenko.