Nasa astronauts begin spacewalk to repair ISS

Spacewalk will be the first of a three-day mission to repair one of the two ammonia cooling systems

(REUTERS)

Astronauts above the International Space Station have begun a series of spacewalks to repair a broken cooling system critical for dispelling heat generated by equipment on the space station.

Nasa ordered the spacewalk on Wednesday following the shutdown one of the station's two ammonia cooling systems, which forced the crew to turn off non-essential equipment and dozens of science experiments.

Station commander cosmonaut Oleg Kotov, Rick Mastracchio, Michael Hopkins, Mikhail Tyurin, Sergey Ryazanaskiy and Japanese astronaut Koichi Wakata are aboard as part of Expedition 38.

American astronauts Rick Mastracchio and Mike Hopkins began their spacewalk at 12pm GMT today. On their website, Nasa said: “Astronauts Rick Mastracchio and Mike Hopkins have unhooked four fluid quick disconnects from the faulty ammonia pump module on the International Space Station’s truss.

“They will continue work to disconnect the old module and begin preparing a spare unit for installation on a follow-on spacewalk.

"In the Russian side of the space station, Commander Oleg Kotov and Sergey Ryazanskiy are preparing for a Dec. 27 pre-planned spacewalk."

The spacewalk is being broadcast live and is expected to take 6.5 hours.

Flight controllers had attempted to fix the problem from the ground, but determined it would be better to find a longer term solution.

The astronauts will undertake another spacewalk on Monday and possibly one on Christmas Day, although Nasa is hoping the third will not be needed. The Christmas Day walk would be the first since 1973 which took place during Skylab, America's first space station.

Spacewalks were temporarily suspended in July when Italian spacewalker Luca Parmitano almost died after water began pouring into his helmet. The suits worn by Mastracchio and Hopkins have been modified with snorkels in case of another leak and absorbent pads to pick up the first signs of excess moisture inside their helmets.