Feb 22, 2007, 12:43 GMT
Moscow - US astronaut Michael Lopez-Alegria and his Russian colleague Mikhail Tyurin on Thursday started their spacewalk with a half-hour delay.
Preparations for leaving the Russian 'Pirs' segment of the International Space Station (ISS) had dragged on for longer than planned, a Russian space control centre spokesperson said.
The spacewalk started at 1027 GMT and was due to take around six hours.
The astronauts were planning to repair an antenna which did not detract automatically when docking the Russian spacecraft in autumn 2006.
The unmanned spacecraft is to be filled with waste from the ISS and burn up upon reentry into the Earth's atmosphere.
The third member of the ISS's 14th permanent crew, Sunita Williams, was to control her colleagues' mission with a video camera on board the ISS.
US astronaut Michael Lopez-Alegria is set to break another space record, becoming the first US astronaut to complete 10 spacewalks.
The 48-year-old current commander of the ISS is to break the record for the most spacewalks, currently held by Jerry Ross.
He broke the record for the most time on spacewalks - 61 hours and 22 minutes - on February 8.
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