Last week, one of the International Space Station's two coolant loops shut down, forcing the six astronauts on board to turn off all nonessential equipment. Now NASA has ordered a series of three spacewalks to repair the broken line. Two American astronauts — Rick Mastracchio and Michael Hopkins — will be leaving the confines of the ISS on Saturday, Monday, and Christmas Day, to replace a malfunctioning valve.

The timing of the spacewalks means that the scheduled launch of Orbital Sciences' Cygnus mission has been delayed until January 13th at the earliest. Cygnus — a cargo ship carrying supplies to the ISS — was set for this week, the ship using its Antares rocket to blast off from Virginia before docking with the space station. NASA had originally hoped that the valve could "limp along" until after Cygnus' arrival, but decided the best course of action was to fix the issue now in case of additional failures.

NASA has hoped the broken cooling line could 'limp along'

Cygnus' late arrival might delay their Christmas presents, but Mastracchio says the astronauts are "still very comfortable" in the stricken space station, with lighting and sanitation systems still functional. The spacewalks are likely to be less comfortable for veteran Mastracchio and first-timer Hopkins. Earlier this year, astronaut Luca Parmitano told the story of how he almost drowned during such an exercise.

At least the time spent outside the space station will give Mastracchio — a who regularly posts pictures taken from the space station on Twitter — an unobstructed view of our planet on Christmas Day. That should give him the best vantage point for spotting Santa, who the astronaut told the Associated Press he's "always on the lookout for."