NASA astronauts work on repairs for the International Space Station on Dec. 24, 2013.
CAPE CANAVERAL, Florida (AP) - Two space station astronauts have floated outside on Christmas Eve in hopes of finishing urgent cooling system repairs.
It's only the second Christmas Eve spacewalk in NASA history. The first was 14 years ago. And it's the second spacewalk in four days for U.S. astronauts Rick Mastracchio and Michael Hopkins.
Mastracchio and Hopkins removed a faulty ammonia pump at the International Space Station during Saturday's outing. On Tuesday, they'll work to install a new pump 260 miles (418 kilometers) above the planet.
The external cooling line - one of two - shut down Dec. 11. The six-man crew had to turn off all nonessential equipment, including experiments.