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Astronauts perform emergency spacewalk to repair leak Astronauts replace pump on emergency spacewalk
(about 2 hours later)
Two US astronauts are carrying out an emergency spacewalk to fix a leak of ammonia from the International Space Station's cooling system. Two US astronauts have replaced a pump on a spacewalk aimed at fixing a leak of ammonia from the International Space Station's cooling system.
Live video shows Chris Cassidy and Tom Marshburn examining the outside of the craft to search for the escape. Chris Cassidy and Tom Marshburn completed the work an hour ahead of schedule, reporting no further escape.
The crew had spotted particles of ammonia drifting away from the laboratory on Thursday.The crew had spotted particles of ammonia drifting away from the laboratory on Thursday.
It is expected the spacewalk, prepared at record short notice, will last around six and a half hours. Nasa said the crew were not at risk but managers wanted to solve the problem before Mr Marshburn left the station.
He is due to return to Earth early next week along with the space station's Canadian commander Chris Hadfield and Russian cosmonaut Roman Romanenko, after six months in space.
Liquid ammonia is used to extract the heat that builds up in electronic systems, dumping that excess energy to space through an array of radiators.Liquid ammonia is used to extract the heat that builds up in electronic systems, dumping that excess energy to space through an array of radiators.
Nasa says the crew on the ISS are not in any danger. 'No leaks!'
The leak is coming from the station's port side, at the far end of the backbone, or truss, structure that holds one of the laboratory's huge sets of solar arrays. "No leaks! We're bringing Tom & Chris back inside," Mr Hadfield wrote on his Twitter account, some four and a half hours into the spacewalk.
The astronauts will "inspect and possibly replace" a pump controller box in that area of the space station, according to Nasa. The leak was coming from the station's port side, at the far end of the backbone, or truss, structure that holds one of the laboratory's huge sets of solar arrays.
Commander Chris Hadfield reported seeing "a very steady stream of flakes" on Thursday. Mr Hadfield reported seeing "a very steady stream of flakes" on Thursday.
"They were coming out cleanly and repeatedly enough that it looked like it was a point source they were coming from," he added.
It is not the first time that the station's cooling systems have caused problems.It is not the first time that the station's cooling systems have caused problems.
A very small leak was identified in 2007 in the same location, and a spacewalk was organised in 2012 to reconfigure coolant lines and isolate the problem.A very small leak was identified in 2007 in the same location, and a spacewalk was organised in 2012 to reconfigure coolant lines and isolate the problem.
The station currently has a crew of six. Commander Hadfield, a Canadian, is due to leave the platform with American astronaut Tom Marshburn and Russian cosmonaut Roman Romanenko on Monday. While the crew may have been safe, damage to the power system from the leak could affect the station's scientific work.
Cmdr Hadfield had asked mission controllers if the leak might prevent the undocking of his return capsule. They responded that there was no technical reason why it should, but that engineers would update the crew once they understood the issues more fully. The station currently has a crew of six.