The three spacewalks, which begin Tuesday, are aimed at installing a bus-sized truss, weighing 16- tonne, which will be used to support a pair of solar arrays and related systems.
If successful, it will double the space laboratory’s ability to produce power from sunlight and ultimately provide a quarter of the power for the completed ISS.
Astronauts Joe Tanner and Heidemarie Stefanyshyn-Piper are scheduled to venture outside the space station on Tuesday for six-and-a-half hours, to prepare the truss for activation and the arrays for unfurling.
Two other astronauts, Dan Burbank and Canadian Steve MacLean, will perform the mission's second space walk Wednesday, with a third space walk planned for Friday.
Mr MacLean has been given the important task of operating the mechanical arm, which will have to manoeuvre the truss to the spot on the station where it will be installed.
Completing the International Space Station is central to US ambitions to fly humans back to the Moon and eventually to Mars, but work on the ISS was held up for nearly four years following the Columbia disaster in 2003 when seven astronauts were killed when the shuttle Columbia disintegrated as it re-entered Earth’s atmosphere.
Atlantis docks
The shuttle Atlantis was the first to the space station since the Columbia disaster. Its 11 day construction mission, Atlantis’s first flight since 2002, is billed as one of the shuttle programs most complex ever.
After completing a tricky backflip to allow the ISS crew to take pictures of the orbiter's underbelly, Atlantis Commander Brent Jett slowly aligned the spacecraft with the docking port and achieved a perfect link-up at about 1048 GMT.
"Houston station, capture confirmed," Jett radioed back to Earth as the spacecraft floated over the Southern Pacific Ocean.
On Monday, after docking, the crew of the Atlantis and the three occupants of the ISS opened the hatch separating their joined spacecraft, completing the first leg of the mission.
US space officials say they couldn't be more pleased with how the mission has gone so far. "It was very spectacular stuff today," said Paul Dye, NASA's lead flight director for the mission.
“The rendezvous this morning was probably just about as perfect as a rendezvous I have ever been part of," he said.
In addition to Mr Jett, the Atlantis crew comprises co-pilot Chris Ferguson and four mission specialists: Daniel Burbank, Heide Stefanyshyn-Piper, Joe Tanner and Steve MacLean of the Canadian Space Agency.
The crew aboard the ISS are Russian Pavel Vinogradov, American Jeffrey Williams and German Thomas Reiter.
NASA plans 15 more shuttle trips to complete the orbiting laboratory by 2010, when the three-shuttle fleet is to be retired.