Station managers decided Tuesday to send two American astronauts out as soon as possible to replace a pump with a bad valve. It's a major job that will require three spacewalks — Saturday, Monday and next Wednesday on Christmas Day.
"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. The commercial delivery had been scheduled for this week, but is now 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 nonessential 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.
