The two astronauts assigned to fix the urgent repairs for the International Space Station (ISS) breezed through the first phase, but were forced to delay the second to Christmas Eve.

Rick Mastracchio and Michael Hopkins have been tasked by NASA to perform a multi-day spacewalk to fix an external valve on the ISS. According to the Associated Press, the two removed an ammonia pump with a bad valve on the first day of the spacewalk, when it was originally planned for the second.

The first spacewalk took place Saturday and the second, originally planned for Monday, will have to be delayed to Tuesday, Christmas Eve, because of an issue with a space suit.

"During repressurization of the station's airlock following the spacewalk, a spacesuit configuration issue put the suit Mastracchio was wearing in question for the next excursion," NASA said in a statement. "Both Mastracchio and Hopkins reported dry conditions repeatedly throughout (Saturday's) activities."

A third spacewalk was originally planned for Wednesday, Christmas Day, but on "if-necessary" basis. With the rate Mastracchio and Hopkins worked on the first spacewalk, the third may not be necessary.

According to Reuters, the problem originated on Dec. 11 when the ISS automatically shut down its primary cooling loop because it reached a pre-set temperature limit. Initially, NASA had to assess the severity of the issue and determined the loop needed to be replaced urgently, but was not an immediate threat to the astronauts on board.

Monday's mission was meant to simply disconnect the pump, but Mastracchio and Hopkins were so efficient, they had time to also remove it from its external placement. Tuesday's spacewalk will be to place the spare pump in the place of the old one. If necessary, the third spacewalk will be delayed to Thursday, giving the astronauts Christmas Day off.

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