Nasa has ordered a series of spacewalks to fix a broken cooling line at the International Space Station – including one on Christmas Day.
Station managers will send two American astronauts out on Saturday, Monday and next Wednesday.
“The next week will be busy with space walks so not much tweeting from here,” Nasa astronaut Rick Mastracchio tweeted from space soon after the decision was announced.
The spacewalks are taking priority over the launch of a supply ship from Virginia which has now been delayed until at least mid-January.
Half of the station’s cooling system shut down last Wednesday, forcing the six-man crew to turn off all non-essential equipment, including some science experiments. Because of the valve failure, one of the two cooling lines became too cold.
The space station cooling system, which runs ammonia through the lines, is critical for dispelling heat generated by on-board equipment.
While the astronauts are safe and comfortable, Nasa wants the system back up to full strength in case of another failure that could leave the orbiting outpost even more vulnerable than it is right now.
Flight controllers tried in vain to fix the valve remotely, then came up with a plan to use another valve to regulate the temperature.
Some success was reported, and for a while, engineers thought the space station could limp along with the short-term solution. However the decision has now been taken to make a more permanent fix.
This is the same pump that was replaced by a pair of spacewalking astronauts in 2010. Three spacewalks were needed then.
The station crew includes three Russians and one Japanese, aside from the two Americans.