Space shuttle Atlantis departed the International Space Station today, leaving behind what one astronaut called a "palace" in space that is 98 per cent finished after 12 years of construction.
The shuttle and six US astronauts are due to land back at the Kennedy Space Center in Florida on Wednesday.
The flight is the final space mission for Atlantis, with sister ships Discovery and Endeavour scheduled for their last missions in September and November.
Nasa is retiring the shuttles for cost and safety issues, and because the heavy transporters are no longer needed once the space station, a $100 billion project involving 16 nations, is complete.
"This place is now a palace," Atlantis astronaut Piers Sellers said on Sunday in a call from space with reporters. "I've had great fun exploring it. It's really magnificent."
Atlantis arrived at the station on May 16th to deliver a new Russian-built docking module and research lab, fresh batteries for a solar power system, a spare communications antenna, a new platform for a robotic crane, science experiments and supplies for the station's six member live-aboard crew.
The module Rassvet (Russian for "dawn") was attached robotically with the station's mechanical arm. The batteries and antenna were installed outside the station during three spacewalks by Atlantis crewmembers.
"We've had a great time together," Atlantis commander Ken Ham said before he and his crewmates bid the station crew goodbye. "We'll see you all on the surface of planet Earth again soon."
On its return to Earth, Atlantis will be prepared for flight as an emergency rescue ship for the final shuttle mission, but is not expected to launch.
Reuters