spacetoday.net: Spacewalkers replace ISS coolant pump to resolve leak

Posted: Sun, May 12, 2013, 9:49 AM ET (1349 GMT)
ISS EVA on 2013 May 11 (NASA)

Two NASA astronauts performed an unscheduled spacewalk on Saturday, replacing a coolant pump on the station's truss that appeared to be the source of an ammonia leak detected two days earlier. Chris Cassidy and Tom Marshburn started the five-and-a-half-hour spacewalk at 8:44 am EDT (1244 GMT) to attempt to identify and resolve the ammonia coolant leak first detected by the station's crew on Thursday. The spacewalkers found no obvious source of the leak, but went ahead and replaced the pump controller box on the P6 section of the truss, where the leak occurred. Tests immediately after astronauts installed the new pump showed no sign of a leak, but NASA cautioned that long-term monitoring will be needed to make sure this permanently resolved the leak.