The US space agency (Nasa) is planning two emergency spacewalks to repair the cooling system on the International Space Station (ISS).
A pump module in the cooling system failed dramatically last week, forcing crew to reduce power on the space station. Astronauts will need a minimum of two spacewalks to remove the failed ammonia pump and replace it with a new one.
he three Russian cosmonauts and three Nasa astronauts aboard the station are not in any danger, the US space agency said in a statement. At the Neutral Buoyancy Laboratory (NBL) in Houston, two astronauts have held dry runs for the spacewalks where they choreographed what would need to be done outside the ISS and worked out how long it might take.
After practising the steps needed to remove and replace the failed unit, Nasa gave the green light to ISS astronauts Doug Wheelock and Tracy Caldwell Dyson to start the first spacewalk on Friday.
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