Two astronauts will venture outside the International Space Station today (Aug. 30) as part of the first planned NASA spacewalk in more than a year.
American astronaut Sunita Williams and Japanese spaceflyer Akihiko Hoshide plan to make several repairs and upgrades to the exterior of the orbiting outpost during their 6.5-hour spacewalk. The duo is scheduled to float out of the space station's Quest airlock at 8:15 a.m. EDT (1215 GMT).
Today's excursion will be NASA's first spacewalk since former space station astronauts Mike Fossum and Ron Garan completed maintenance tasks in the vacuum of space in July 2011. Fossum and Garan's spacewalk occurred while four NASA astronauts were visiting the station during the agency's final space shuttle mission.
The primary objectives for Williams and Hoshide will be to replace a faulty power box on the space station's backbone-like truss, install a series of cables, and remove a camera that recently broke on the station's 57-foot-long (17-meters-long) Canadarm 2 robotic arm.
The power box, which is known as a main bus switching unit, helps relay power throughout the orbiting complex.
"It's passing power, but can no longer be switched," Kieth Johnson, lead U.S. spacewalk officer at NASA's Johnson Space Center in Houston, told reporters in a news briefing on Aug. 14. "In order to do future operations, we need to take that box out and put one in that allows us to do that."
After switching out the box with a spare, the defunct unit will be temporarily stored on a cargo platform attached to the exterior of the space station.
Next, Williams will get to work installing cables for a new Russian laboratory module that is expected to launch to the orbiting outpost in 2013, Johnson said. Part of this wiring work will require her to climb inside a section of the station's truss.
Once that is complete, Hoshide will remove the failed camera from the Canadarm 2 robotic arm, and replace it with a new one.
If there is extra time, the spacewalkers may also install a micrometeoroid debris shield over part of an American module, remove a camera located on the exterior of the Japanese Kibo laboratory, and troubleshoot power and data wires on the Russian Zarya module, Johnson added.
Today's excursion will be Williams' fifth spacewalk and Hoshide's first time working in the vacuum of space. The outing is the third this year, but only the second spacewalk of the station's current Expedition 32 mission. Two Russian cosmonauts previously spent nearly six hours working outside the complex on Aug. 20.
The space station's six-person crew includes Russian cosmonauts Gennady Padalka, Yuri Malenchenko and Sergei Revin, Americans Joe Acaba and Sunita Williams, and Japanese astronaut Akihiko Hoshide.
Today's spacewalk will be broadcast live on NASA Television here, beginning at 7 a.m. EDT (1100 GMT): http://www.nasa.gov/ntv