NASA has ordered a series of emergency spacewalks to carry out repairs on a broken cooling line at the International Space Station (ISS).
Three spacewalks by two astronauts are needed to replace a faulty pump module on the station's cooling system - the first of which is planned for Saturday, NASA said.
NASA astronauts Rick Mastracchio and Mike Hopkins will remove a pump module that has a failed valve.
They will replace it with an existing spare that is stored on an external stowage platform, the space agency said.
The pump is associated with one of the station's two external cooling loops, which circulate ammonia outside the station to keep both internal and external equipment cool.
Each of the three spacewalks is scheduled to last six and a half hours, NASA said.
NASA managers are postponing the upcoming Orbital Sciences commercial cargo resupply mission to the ISS to proceed with a series of spacewalks to replace the faulty pump module on the space station.
Orbital Sciences' Cygnus spacecraft, atop its Antares rocket, now will launch no earlier than mid-January, NASA said.
The postponement of the Antares launch will allow ample time for the station crew to focus on repairing the faulty pump module that stopped working properly on December 11.
NASA currently plans for two Expedition 38 astronauts to venture outside the space station on December 21, 23 and 25.
