NASA has ordered up a series of urgent spacewalks to fix a broken cooling line at the International Space Station, a massive repair job that could stretch to Christmas Day.
Station managers decided on Tuesday to send two US astronauts out as soon as possible to replace a pump with a bad valve. The task will require two or possibly three spacewalks on Saturday, Monday and Wednesday next week, which is Christmas Day.
“The next week will be busy with space walks so not much tweeting from here,” NASA astronaut Rick Mastracchio said from space via Twitter 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 the middle of next month.
US-led spacewalks have been on hold since July, when an Italian astronaut almost drowned because water leaked into his helmet.
The US space agency hopes to wrap up the pump swap in two spacewalks and not have to do a third on Christmas Day.
Astronauts have ventured outside of their spaceship on Dec. 25 only once, in 1973, at Skylab, the US’ first space station. Shuttle astronauts finished a series of spacewalks on the Hubble Space Telescope on Christmas Eve in 1999.
Half of the International Space Station’s cooling system shut down on Wednesday last week, 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 cooling system, which runs ammonia through the lines, is critical for dispelling the 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 this short-term solution. However, managers on Tuesday opted to conduct the spacewalks.