(NASA/CNN) - Imagine spending Christmas Eve more than 200 miles above the Earth.
Two American astronauts celebrated a Christmas Eve success after completing a mission to replace a malfunctioning pump on the International Space Station during an emergency spacewalk Tuesday.
Two weeks ago a valve got stuck, jeopardizing the space station's cooling system.
The pump, which removes heat created by the station's equipment, is critical to the space station, so it flies with a backup. The faulty one was shut down, along with some station activities.
On Saturday, Rick Mastracchio and Mike Hopkins took the first spacewalk of their repair mission, lasting more than five hours, to remove the defective pump.
Scary as it seems to the average person, Astronaut Mike Massamino said not to worry.
"You have a person on the ground actually talking to the astronauts in space, walking them through the procedure. And you have the control team on the ground in Houston. Everyone in the control center, the instructors, the flight controllers, everyone. It's a gigantic team to help do the spacewalk the right away," he said.
The American space duo planned to continue the work on Monday, but there was another problem, this time with Mastracchio's space suit.
So NASA pushed the second walk back a day, making this only the second Christmas Eve spacewalk in history.
The first was a multi-day mission in 1999 to repair the Hubble Space Telescope.
"We're well-trained, and this really is an extraordinary experience for the astronauts to be getting a chance to do this," Mastracchio said.