HOUSTON — Spacewalking cosmonauts Fyodor Yurchikhin and Alexander Misurkin assisted with the testing of KURS automated docking system hardware and installed cable clamps outside the Russian segment of the International Space Station on June 24 to prepare the six-person orbital outpost for the anticipated arrival of the Nauka Multipurpose Laboratory Module in late 2013.

Scheduled for 6 hr., the excursion lasted 6 hr., 34 min. after beginning at 9:32 a.m. EDT. It marked the third outing so far this year for ISS crews, including an unscheduled NASA spacewalk in May to deal with a U.S. segment cooling system leak. Four more U.S. and Russian spacewalks are planned for July and August to complete external preparations for the arrival of the Russian Nauka MLM, carry out external maintenance tasks and install experiments.

The task list for the June 24 excursion was especially hand-intensive, forcing Yurchikhin and Misurkin to rest frequently toward the end of the outing. They fell more than an hour behind in their work at one point, and Russian ground controllers discussed the possibility of extending the excursion or postponing some lower-priority activities as the outing drew toward a scheduled end shortly after 3:30 p.m. EDT.

Yurchikhin, a veteran of five previous spacewalks, and Misurkin, making his first, initiated their work at the structural interface between the Zarya and Zvezda modules, where they attached data cables for diagnostic tests of the KURS system that is to guide the 44,000-lb. unpiloted MLM to an ISS berthing port currently occupied by the Pirs docking module.

Yurchikhin and Misurkin replaced an aging cooling system flow control valve on Zarya. At nearly 15 years old, Zarya is the station’s oldest module.