( dpa ) - US astronauts Peggy Whitson and Dan Tani climbed out the hatch of the International Space Station on Wednesday to replace the motor of one of its solar wings.
The spacewalk, which began at 9.56 GMT, was expected to last approximately 6.5 hours, according to a NASA statement.
The open space manoeuvre was led by veteran spacewalker Whitson to replace the motor that powers the solar panel's tracking of the sun and which was found to be faulty in December.
The two astronauts will also inspect a solar rotary joint that was seen to be cluttered with debris during previous inspections, preventing the wings' optimal gathering of solar rays.
Russian cosmonaut Yuri Malashenko was to remain in the space station to provide support to the US astronauts.
The International Space Station was initiated 10 years ago with the signing of an intergovernmental agreement in 1998 for space exploration.