Last spacewalk of shuttle era

Spacewalk is scheduled for 8:44 a.m. TuesdaySpace debris no threat to station or shuttle, NASA saysThe crew is delivering supplies and spare partsThe mission is the last of the 30-year space shuttle program

Kennedy Space Center, Florida (CNN) -- Two NASA flight engineers who have been aboard the International Space Station plan to conduct the last spacewalk of the space shuttle era Tuesday, the agency said.

Michael Fossum and Ronald Garan had been at the International Space Station for several weeks before the crew from Atlantis arrived Monday. Members of the Atlantis crew will help choreograph the spacewalk from inside the space station, but only Fossum and Garan are scheduled to venture outside.

The 6.5-hour excursion comes a day after the crew of the space shuttle Atlantis wrapped up a busy day of cargo transfers to the station. Atlantis is the last scheduled flight of any of the U.S. space shuttles.

While on the spacewalk, they will recover a broken pump and stow it in the shuttle's cargo bay, retrieve an experiment from the bay and mount it outside the space station and deploy another experiment, according to NASA.

On Monday, the crews of the International Space Station and space shuttle Atlantis found out they are not in danger from an orbiting piece of debris, the space said.

The agency had been tracking a piece of the COSMOS 375 satellite, saying it could come close to the station.

But the agency said that 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 on 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.