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 .
NEW : Engineers Mike Fossum and Ronald Garan begin excursion . The crew of the International Space Station (ISS) has been busy preparing for a spacewalk on Friday to replace one of two faulty solar arrays that failed during last week's launch from Kazakhstan. : Garan : ` ` Welcome back to our other office '' The Atlantis crew is delivering supplies and spare parts . The mission is the last of the 30-year space shuttle program .