Cosmonauts deploy and activate relocated radiator

Sergey Prokopyev and Dmitry Petelin successfully deployed the heat exchanger during their 5 hour and 14 minute extravehicular activity (EVA) on Friday (May 12).

After opening the airlock hatch on the Poisk module at 11:47 a.m. EDT (1547 GMT) and exiting the station, Prokopyev and Petelin made their way to the Nauka module to remove the remaining restraints holding the radiator closed. As the bolts were loosened, the radiator began to unfold to its full length.

With the hardware in place, the two spacewalkers set about opening the first set of valves to begin loading the radiator with coolant fluid, a process that in total was estimated to take about two hours.

While waiting for the coolant to flow into the radiator, Prokopyev and Petelin installed two gap spanners on the European Robotic Arm (ERA). The manipulator was earlier used to transfer the radiator and airlock from Rassvet to Nauka during spacewalks on April 18 and May 3.

The two cosmonauts also completed a few "get-ahead" tasks for future spacewalks, installing a pair of handrails connecting the Nauka laboratory to the Prichal docking node.

Prokopyev and Petelin then opened a second set of valves to complete the coolant loading for the radiator. With no leaks reported, Russian flight controllers were able to confirm the radiator had been successfully integrated into Nauka's thermal control system.

The spacewalkers then began cleaning up their work area to return inside, having completed all of the tasks set out for them about an hour ahead of what had been planned. After jettisoning towels used to wipe down their spacesuits of an errant coolant, Prokopyev and Petelin ended their spacewalk at 5:01 p.m. EDT (2101 GMT).

With Friday's EVA, Prokopyev, now has has spent 42 hours and 16 minutes on six spacewalks. Petelin has now completed four outings, logging 26 hours and 45 minutes outside the station.

The spacewalk was the sixth for the year and 263rd dedicated to assembly and maintenance of the International Space Station.