NASA announced on Tuesday that it has approved three spacewalks in an effort to fix a cooling system glitch that had crippled the International Space Station last week.

While experts, including the “Tiger Teams” that are responsible for fixing the most complex problems for NASA, have been working to repair the cooling loop, two of the Expedition 38 crew members are also preparing to venture outside the space station on Dec. 21, 23 and 25.

NASA said that astronauts Rick Mastracchio and Mike Hopkins will remove a pump module that has a failed valve and replace it with an existing spare, which is stored on an external stowage platform. The pump is associated with one of the station's two external cooling loops, which circulate ammonia outside the station to keep both internal and external equipment cool.

According to NASA, the three spacewalks are scheduled to begin Saturday at 5:15 a.m. EST and each of them is scheduled to last six-and-a-half hours. Mastracchio is a veteran of six spacewalks that he conducted during his last two stints on the space station in 2007 and 2010, respectively.


“We have many spare parts on board for both inside and outside the space station, and we train for these situations over and over again,” Mastracchio told in an interview. “So all the procedures and everything are in place to take care of this.”

Although NASA has described the situation aboard the ISS as urgent, the agency has not considered it as an emergency so far, saying that the six-person crew is not currently in any danger, ABC News reported.

“The lights are still on in the station,” Mastracchio said. “Overall, life up here really hasn't changed that much. If anything, it's actually gotten a little slower for us.”

NASA has also postponed the upcoming Orbital Sciences Corp.’s (NYSE:ORB) commercial cargo resupply mission to the space station to proceed with the spacewalks. Orbital Sciences' Cygnus spacecraft is now expected to launch only in January.

NASA expects that the delay of the launch will allow ample time for the station crew to focus on repairing the faulty pump module.