CAPE CANAVERAL, United States: 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.
"It's like Christmas morning, opening up a little present here," Mastracchio said as he checked his toolkit.
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.
NASA's only previous Christmas Eve spacewalk occurred in 1999 during a Hubble Space Telescope repair mission.
But NASA's most memorable Christmas Eve was on Dec. 24, 1968. Apollo 8 astronauts read from Genesis, the first book of the Bible, as they orbited the moon on mankind's first lunar flight.
A Moscow-led spacewalk, meanwhile, is set for Friday. Two Russian crew members will install new cameras and fresh experiments outside.