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While many families will gather by gift-laden trees this Christmas, two NASA astronauts will hang out with the unfathomable terrifying vastness of space this year, thanks to urgently needed repair work on the International Space Station.

Here’s why: A faulty valve caused a system used to cool down ISS electronics to stop working, and after NASA realized it couldn’t fix it from Houston, it set out to replace the whole pump, planning for three six-hour spacewalks that began today with the third scheduled for Christmas Day. That very same pump caused problems in 2010 that required three spacewalks.

But why is the issue so urgent that they have to do this on Christmas? Every year, the space station enters a position where it receives more sunlight than usual, which prompts the satellite to do barrel rolls so the sun doesn’t overheat it, and shuts down spacewalks and cargo shipments. This year, that period is from Dec. 30 to Jan. 9, which is soon.

If even thinking about something not working while up in space gives you the cold sweats, you can thank Alfonso Cuaron the spacewalk will feature a saucy extra layer of existential horror: one of the suits that will be worn on the spacewalk sprang a leak in July, nearly drowning the astronaut inside. NASA’s solution: “makeshift snorkels.” Call us old-fashioned, but space tools really should be associated with adjectives like “advanced” or “high-tech,” and never “makeshift.”

Oh, and here’s some bonus degrees of anxiety-causing horror: because the cooling system uses ammonia, it has been leaking ammonia flakes which could in turn find themselves falling on the astronauts while they’re replacing the pipe—and the flakes are toxic.

NASA has said all the right things about having the right equipment and the right talent on board to fix the problem. In the meantime, if all this isn't enough to make you hyperventilate, you can watch a live-stream of the spacewalk here. Meanwhile, former ISS commander Chris Hadfield is live-tweeting during the spacewalk, answering questions from followers about the intricacies of the process.

It will be Rick Mastracchio’s seventh space-walk, and he will take lead with first-timer Michael Hopkins. The spacewalk record is currently held by George Clooney Anatoly Solovyev, who went outside the station 16 times.

This article is from the archive of our partner The Wire.

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