CAPE CANAVERAL, USA - THE US shuttle Discovery touched down in Florida on Saturday, capping a successful 14-day mission to deliver and open Japan's first space laboratory at the International Space Station.

Under a sunny sky, the orbiter carrying seven astronauts landed right on time at 11.15am (11.15pm Singapore time) at the Kennedy Space Center in Cape Canaveral after gliding over Mexico's Yucatan peninsula as it plunged toward Earth.

'Beautiful landing Mark and congratulations on a great mission,' a mission control official told Discovery commander Mark Kelly.

After travelling 217 orbits and 9.2 million kilometres around Earth, Discovery plunged towards the planet at more than 20 times the speed of sound before slowing down for its landing.

A double sonic boom signaled the shuttle's imminent arrival. Three minutes before landing, Mr Kelly took the shuttle off auto-pilot and steered it towards Kennedy's landing strip number 15.

Nasa had given the shuttle the green light to wrap up its two-week journey and return to Earth after it determined that the loss of a small clip from its rudder posed no risk during landing.

The agency has kept a close eye on the shuttle's protective thermal layer since a crack in Columbia's heat shield caused the orbiter to explode as it re-entered Earth's atmosphere in February 2003, killing its seven astronauts.

Discovery undocked from the ISS on Wednesday about 344km above the South Pacific east of Australia.

The shuttle's main task was to deliver, open and outfit the 11.2m long, 4.4m wide main module of the Japanese Kibo laboratory, which became the station's biggest facility.

Kibo - which means 'Hope' in Japanese - represents Japan's and Asia's first major contribution to the orbiting international station, which already has modules from the United States, Russia and the European Space Agency.

Shuttle Endeavour had already brought the bus-sized lab's storage room in March.

The third and final part of the lab - an outdoor facility that will allow experiments to be exposed to the effects of space - will be delivered next year.

When completed, Kibo will allow astronauts to carry out experiments in medicine, biology and biotechnology, material production and communications, both in a pressurised environment and completely exposed to space.

'I can't think of a mission really that's been better than this one,' said Mr Bill Gerstenmaier, Nasa's associate administrator of space operations.

'We're starting to break that tie to planet Earth and get out and do what exploration is,' he said.

The Discovery mission also included three spacewalks.

In addition, Discovery brought a new crew member to the ISS, Mr Greg Chamitoff, who replaced fellow American astronaut Garrett Reisman.

Mr Reisman returned to Earth after a three-month stint at the outpost, and told Nasa TV on Friday that he was primarily looking forward to 'being back home, sleeping in my own bed - and using my own toilet.' The only toilet at the International Space Station began to fail just before Discovery's launch, and spare parts were sent up on the shuttle to repair it.

Nasa hopes to complete construction of the space station by 2010, viewing it as a central part of space exploration ambitions because it allows scientists to study the effects of microgravity on humans.