WASHINGTON, Aug. 16 (Xinhua) -- A pair of U.S. astronauts installed a spare ammonia pump module on the International Space Station on Monday, reviving a disabled cooling system on the station during the third spacewalk in 10 days.
The spacewalk, conducted by Expedition 24 Flight Engineers Doug Wheelock and Tracy Caldwell Dyson, ended at 1:40 p.m. EDT (1740 GMT), NASA said.
The 780-pound spare pump module was removed from an external stowage platform by Wheelock. The module was successfully installed on the S1 Truss after Wheelock attached four bolts and Caldwell Dyson mated five electrical connectors.
Ground controllers confirmed the module was in healthy condition when it began receiving power. After a pressure check and more fluid cable connections, the module was filled with ammonia.
Due to time constraints, ground teams and the crew decided not to attach a power cable extension from Quest to a cable on the Unity module.
Wheelock and Caldwell Dyson were outside during the third repair spacewalk for seven hours, 20 minutes. On Wednesday they were outside during the second spacewalk for seven hours and 26 minutes. The first repair spacewalk took place Aug. 7 and lasted a record eight hours and three minutes.
The space station has been operating with only half its usual cooling capability since an ammonia coolant pump failed on July 31. Science research is on hold and unnecessary equipment is off until the pump can be replaced. The cooling system is crucial for keeping electronics from overheating.