CAPE CANAVERAL, Fla. – A pair of astronauts ventured out on the first spacewalk of their shuttle mission Thursday to tackle some antenna and cable work at the International Space Station.

The linked shuttle-station was soaring over South America when Michael Foreman and Dr. Robert Satcher Jr. emerged from the hatch.

Satcher, the first orthopedic surgeon in space, was awed by the view 220 miles below. "Beautiful," he murmured. His partner, a veteran spacewalker, couldn't resist poking a little fun.

"Hard to believe, Bobby, I think your feet look bigger from space," Foreman joked.

Two more spacewalks are planned in coming days to perform space station maintenance and get the orbiting outpost ready for the next shuttle visitors.

Atlantis will remain at the space station until Wednesday.

Already, the 12 space travelers have unloaded several tons of pumps, tanks and other big spare parts that came up on Atlantis. They took care of that just hours after the shuttle docked at the station Wednesday.

All the gear should keep the space station operating well past next fall's shuttle retirement.

The shuttle is the only craft large enough to haul these oversize pieces for the space station. That's why NASA is so keen on flying the parts now, long before they're needed.

NASA plans to keep the outpost running until at least 2015.

Five more shuttle missions remain, all devoted to space station work.

Astronaut Nicole Stott, who's winding up a nearly three-month space mission, celebrated her 47th birthday Thursday. She'll have to wait until the shuttle brings her back at the end of next week to blow out her candles. Flames are verboten in orbit.