Nasa's Space Shuttle Discovery Begins Final Journey Back To Earth From Space Station

The US space programme's oldest and most travelled shuttle, Discovery, has begun its final trip back to Earth after a near-perfect last mission to the International Space Station. The ageing shuttle has flown more than any other in the fleet during its 27-year career, and will become the first of three to retire as the United States winds down its space shuttle programme.

Astronauts completed an inspection of the shuttle's heat shield and found no problems, said chair of NASA's mission management team Leroy Cain, who heaped praise on the spacecraft's power after 39 missions

Discovery's mission was initially scheduled to last 11 days but was extended to 13 so that astronauts could work on repairs and install a spare room at the orbiting lab

The Italian-built Permanent Multipurpose Module, formerly known as Leonardo, is now on the underside of the lab and adds 21 by 15 feet (6.5 by 4.5 metres) of extra room for storage and experiments

Astronauts also brought the first humanoid robot to the space station, though it spent most of its time wrapped in packing materials and will not become fully operational for some time

During the mission, President Barack Obama called the six Discovery astronauts and their six crewmates who were already aboard the ISS to say he was proud of their cooperation in space

NASA astronaut Eric Boe points a camera through an overhead window on the aft flight deck of Space Shuttle Discovery to photograph the International Space Station after the undocking of the two spacecraft

The Space Shuttle Discovery seen through a window on board the International Space Station after the undocking of the two spacecraft

During the shuttle's mission the crew woke up to a personalised message from actor William Shatner, who played Captain Kirk in the popular Star Trek series. "Space, the final frontier. These have been the voyages of the space shuttle Discovery," said Shatner in a specially recorded introduction to the "Theme from Star Trek," played on the crew's final morning in space

When the shuttle lands, it will have spent a total of 365 days in space over the course of its career, logging about 150 million miles (241 million kilometres)

Space Shuttle Discovery pilot Eric Boe works the controls for the remote manipulator system (RMS) on the aft flight deck of the shuttle

NASA astronaut Michael Barratt watches a water bubble float freely near him on the middeck of Space Shuttle Discovery

NASA's remaining shuttles - Endeavour and Atlantis - are scheduled to make their final flights later in 2011. After that the sole method of transport to and from the ISS will be via Russia's Soyuz space capsules, which can carry three people at a time

Discovery has broken new ground multiple times since it first launched in 1984. It transported the Hubble Space telescope, was the first shuttle to be commanded by a female astronaut and the first to rendezvous with the Russian Mir Space Station

The shuttle was also the first to return to space after two major disasters, the Challenger explosion in 1986 and the Columbia disaster in 2003 when the shuttle broke up on its return toward Earth