The US space shuttle Discovery has docked with the International Space Station for a final time before it retires, carrying a new module and a robot to the orbiting research lab.

NASA's oldest and most heavily travelled shuttle linked up with the ISS at 2:14pm (US time) as the space outpost was 350 kilometres over Western Australia, mission control in Houston said.

Discovery arrived in spectacular fashion, with Commander Steve Lindsey executing a "rendezvous pitch manoeuvre," a one-degree-per-second rotational backflip, before docking.

The ISS is a crowded place these days, with space vehicles and labs from every nation involved in the international research station currently docked there.

"This is the first time all visiting vehicles have something represented," mission control in Houston said, noting that the floating ISS currently weighs a whopping 540,000 kilograms.

Japan's HTV vehicle, Russia's Progress and Soyuz craft, the Canadian Dexter robot and the European ATV-2 robot freighter are all there, NASA said.

Discovery launched on Thursday from Kennedy Space Centre in Florida, carrying an all-American crew of six astronauts. The lift-off drew thousands of onlookers eager to catch a glimpse of one of the last three shuttle launches.

The US space shuttle program will end later this year, after Endeavour launches in April followed by Atlantis in June, leaving Russia's space capsules as the sole method of transport for astronauts heading to the ISS.

The Discovery crew is there to deliver the Permanent Multipurpose Module, with extra storage space and an area for experiments, as well as some spare parts and the Express Logistic Carrier, an external platform for large equipment.

The shuttle has also brought the first humanoid robot to the ISS. The Robonaut 2, or R2, is a joint project of General Motors and NASA and will stay behind as a permanent resident of the space station when the shuttle leaves.

When Discovery wraps up its tour, the oldest surviving shuttle will have flown more missions than any of its cohorts and transported 180 people into space, including the first female shuttle commander and the first African-American spacewalker.

Discovery has broken new ground multiple times since it first launched in 1984. It has transported the Hubble Space telescope, was the first to rendezvous with the Russian Mir Space Station, and delivered part of the Japanese Kibo lab to the ISS.

Discovery has circled the globe more than 5,600 times and logged 230 million kilometres over its 352 days in space.

It was also the first shuttle 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.

The end of the shuttle program will create a gaping hole in the US space program during a period of belt-tightening and budget freezes, and will leave Russia's space capsules as the sole transit option to the ISS.

- AFP