Two astronauts aboard the International Space Station conducted a hastily arranged spacewalk on Saturday to look for the source of a leak that had forced the shutdown of one of the eight power systems that provide electricity to the orbiting laboratory.
The astronauts, Tom Marshburn and Chris Cassidy, both American, spent 5 ½ hours outside the space station. They were unable to locate the source of the leak, but did install a new pump, which appeared to solve the problem.
On Thursday, astronauts had spotted frozen flakes emanating from one of the station’s trusses. Engineers concluded the source of the leaks was a pump that pushes ammonia coolant to regulate temperatures on one of the eight solar arrays, which provide electricity. Nasa officials said if a problem developed with a second cooling loop, the station might have had to cut back on its power consumption, limiting experiments.
In less than 48 hours, plans for the the repairs were put together. At 8.44 am Eastern time on Saturday, Marshburn and Cassidy started the spacewalk. On reaching the site of the suspected leak, they were un able to spot evidence of it.
The duo then installed a new pump to fix the problem — for now. Marshburn and Cassidy did take a moment to admire the view. “Did you see the moon?” Marshburn asked. “I did, oh my God!” Cassidy replied. “Burn that in your memory!”
Source : http://timesofindia.indiatimes.com/home/science/Astronauts-replace-pump-to-plug-ISS-ammonia-leak/articleshow/20022897.cms