Two Russian cosmonauts clad in Orlan spacesuits began their second spacewalk within the span of a week when they opened the hatch to the International Space Station's Pirs docking compartment on Thursday (Aug. 22) at 6:34 a.m. CDT (1134 GMT).
During their excursion, which is slated to last about five hours and 40 minutes, Expedition 36 flight engineers Fyodor Yurchikhin and Alexander Misurkin will replace a laser communications experiment with a new platform for a small optical camera system, move a foot restraint and inspect several sites for the origin of a wayward antenna cover observed on Monday.
As the two spacewalkers move out to the first worksite on the Zvezda service module, they will carry a combination EVA workstation and biaxial pointing platform upon which a small optical camera system will be installed during a future spacewalk. After attaching the assembly to a temporary stowage location, Yurchikhin and Misurkin will remove the External Onboard Laser Communications System, which was installed on Zvezda in August 2011 during an Expedition 28 spacewalk.
With the laser communications experiment removed and temporarily stowed with its protective cover, the two spacewalkers will install the camera platform and connect its associated cables.
Once those tasks are complete, Yurchikhin and Misurkin will head out to the aft end of Zvezda to inspect three of the module's six WAL antenna covers. Flight engineer Chris Cassidy observed one of the covers floating away from the station on Monday (Aug. 19), and Russian station officials want to determine its origin and insure that the remaining covers are secure.
The WAL low-gain antennas are used for proximity and rendezvous operations with the European Space Agency's Automated Transfer Vehicle (ATV).
Afterward the two spacewalkers will transfer the communications experiment hardware from its temporary stowage location to the ladder outside the Pirs hatch and split up for the next set of tasks.
As Yurchikhin makes his way to Zvezda's hull to begin the relocation of a foot restraint, he will take a look at the three remaining antenna cover locations on the forward end of that module. Once that is complete, he will remove the foot restraint and install it on the new EVA workstation he and Misurkin set up earlier.
Meanwhile, Misurkin will head over to the Poisk Mini-Research Module-2. There he will use a test kit to collect a particulate sample from under a swath of thermal insulation near the module's hatch. He also will photograph the SKK materials exposure experiment and associated cabling along Poisk.
After Misurkin completes the installation of some gap spanners on the port side of Zvezda, he and Yurchikhin will rejoin to transfer the laser communications experiment hardware and the Poisk test samples into the Pirs airlock.
For the duration of the spacewalk, Cassidy and station commander Pavel Vinogradov will be isolated to the Poisk module and their Soyuz TMA-08M spacecraft, while flight engineers Karen Nyberg of NASA and Luca Parmitano of the European Space Agency will be free to move about the U.S. segment of the complex.
This is the 173rd spacewalk in support of space station assembly and maintenance, the eighth in Yurchikhin's career and the third for Misurkin. Both cosmonauts are wearing blue-striped Orlan spacesuits outfitted with helmet cameras.
Their previous excursion outside the station, a seven hour, 29 minute marathon on Aug. 16 focusing on preparations for the future arrival of the "Nauka" Multipurpose Laboratory Module, was the longest spacewalk in history conducted by a pair of Russian cosmonauts.