Kennedy Space Center, Florida (CNN) -- Floating 245 miles over the Earth Tuesday, NASA engineers Michael Fossum and Ronald Garan tethered themselves to the International Space Station and paused to absorb the view.
"My goodness, Mike, look down ... absolutely breathtaking," Garan said as they floated over the Yucatan Peninsula. "Welcome back to our other office."
The last spacewalk of the shuttle era began about 40 minutes behind schedule.
Veteran astronaut Stephen Bowen was speaking to the engineers from Houston's Johnson Space Center during the walk, which was scheduled to last just over six hours. The excursion was Fossum's seventh spacewalk and Garan's fourth, according to a NASA statement.
Fossum and Garan had been at the International Space Station for several weeks before the crew from Atlantis arrived Monday on the last shuttle flight of the 30-year-old program. Members of the Atlantis crew helped choreograph the spacewalk from inside the space station, but only Fossum and Garan ventured outside.
While on the spacewalk, the engineers were expected to recover a broken pump and stow it in the shuttle's cargo bay. They also planned to retrieve an experiment from the bay and mount it outside the space station before deploying another experiment, according to NASA.
On Monday, the crews learned they are not in danger from an orbiting piece of debris, the space agency said.
The agency had been tracking a piece of the COSMOS 375 satellite, saying it could come close to the station. But NASA said Mission Control verified that the debris will pass a safe distance from the station and shuttle.
The scrap is one of more than 500,000 pieces of debris tracked in Earth's orbit, according to NASA.
The space agency also announced Monday that Atlantis would stay in space one day more than originally planned.
The shuttle, which was scheduled to land July 20, will now make what NASA called a night landing at the Kennedy Space Center at 5:56 a.m. July 21.
Atlantis lifted off Friday on NASA's final space shuttle mission.
The first shuttle, Columbia, blasted off in April 1981. Since then, space shuttle crews have fixed satellites, performed scientific studies, and ferried materials and people to International Space Station Alpha, a football field-sized construction project in orbit.
In 134 missions, the five space shuttles have ferried 355 astronauts into space.
When Atlantis lands, it will leave the United States with no way to lift humans into space for the first time in decades. NASA will rely on the Russian space agency to ferry U.S. astronauts to orbit.
CNN's Ed Payne contributed to this report.