Astronauts aboard the International Space Station are set to go on their second and final spacewalk to repair the station's cooling system on Christmas Eve, according to the Associated Press.

Unless something happens during the spacewalk, astronauts Rick Mastracchio and Michael Hopkins should finish installing a new ammonia pump on Dec. 24, meaning they wouldn't have to go out again for a previously-predicted third spacewalk.

"It's apparent now that we'll be able to get most of our critical objectives done tomorrow (Tuesday)," space station flight director Judd Frieling said during an interview on NASA Television, according to Reuters.

Mastracchio and Hopkins were able to remove the defective pump on Dec. 21. NASA said that everything went so well they decided to jump ahead of schedule and fix the external cooling line that stopped working on Dec. 11.

The second spacewalk would have been today, Dec. 23, but it was pushed a day so that Mastracchio could "swap suits" according to AP.

The astronaut accidentally hit the water switch in the air lock after the spacewalk, and engineers believe that water was able to get into his suit. The suit now has to dry out for around a week before it can be used again, said Frieling, according to AP.

Mastracchio and Hopkins spent Dec. 22 to create a new spacesuit from spare components already on the ISS.

The cooling systems shut down due to an apparent faulty valve inside a pump, located outside the station. Engineers on the ground attempted to avoid the spacewalks, but as of Dec. 16, the cooling system was still down.

NASA delayed a delivery mission from Wallops Island, V.A., because of the spacewalks. That flight was rescheduled for Jan. 7.

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