The space shuttle Atlantis landed in Florida today, capping a 12-day mission to deliver a new module to the International Space Station.
Later this year, Nasa intends to retire the shuttle fleet, which began flying in 1981, after two more flights due to cost and safety concerns.
Nasa plans to fly each of its remaining shuttles, Discovery and Endeavour, once more this year to complete assembly and outfitting of the space station, a $100 billion project of 16 nations that has been under construction for 12 years.
Circling high over the Kennedy Space Centreto burn off speed, commander Ken Ham gently nosed the 100-tonne ship toward a landing strip 5km away from where he and five crew mates blasted off on May 14th to begin Nasa's 132nd shuttle mission.
During a weeklong stay at the station, the Atlantis crew delivered and installed a Russian docking and research laboratory, six huge batteries for the station's solar power system, a spare communications antenna and a work platform for the station's Canadian-built crane.
It was the shuttle's 32nd and final flight. Before being turned over to a museum, Atlantis will be prepared as an emergency rescue ship for the last shuttle crew.
President Barack Obama wants to cancel a follow-on programme to the shuttles to develop rockets and capsules aimed at returning US astronauts to the moon, and instead develop new technologies for travel farther from Earth. The proposal, which is pending before Congress, is controversial.
Nasa is evaluating proposals from museums and science centres wanting to display Atlantis and Endeavour. Discovery, which is scheduled to make its last flight in September, is promised to the Smithsonian Air and Space Museum.
Endeavour, which will carry the $2 billion Alpha Magnetic Spectrometer particle detector to the station, is scheduled to be the programme's finale in November.