(AP)—Two astronauts—an American and Japanese—are taking a spacewalk to replace failed equipment at the International Space Station.
Sunita Williams and Akihiko Hoshide expect to spend six hours plugging in a new power-switching unit, hooking up power cables and replacing a bad camera on the space station's big robotic arm.
It's the second spacewalk in less than two weeks. On Aug. 20, two Russians worked outside the orbiting lab.
It's no longer common for astronauts to step into the vacuum of space. That's because after almost 14 years, the space station is virtually complete and running well.
Explore further: NASA puts off space station repair until Friday