Astronaut Jim Voss sets the timer on his camera for a group shot

Mission Control told commander Steven Lindsey and his crew: "It looked like an outstanding landing after an outstanding mission. Well done."

Commander Lindsey replied: "It's great to be home."

During its mission, the crew carried out three spacewalks to install a new $164m airlock on the space station.

Before this, it had only been possible to carry out spacewalks by leaving the station through airlocks of a docked space shuttle.

Now, astronauts living on the space station will be able to work outside the craft even when a shuttle is not there.

New 'front door'

Shuttle programme manager Ron Dittemore said the seven space station construction flights in less than a year had given rise to "a small city in the sky".

"It was just a tremendous feat for all those involved," he said.

"It was a great mission and we accomplished just what we intended to do."

US astronauts Michael Gernhardt and James Reilly made use of the airlock for the first time on Saturday as they floated out into space to hang a high-pressure gas tank on the side of the door.

A total of three spacewalks were required to install the new "front door" or Joint Airlock Module (JAM).

Airlock spec

Material - Aluminium Length - 5.5 metres Diameter - 4 metres Weight - 6,064 kilograms Volume - 34 cubic metres Cost - $164 million, including gas tanks

Its universal fittings mean it will eventually be possible for both American and Russian crew members to use it.

The JAM, which measures four metres (13 feet) across and 5.5 metres (18 feet) in length, was anchored to the ISS with the help of the station's advanced Canadarm2, which was added to the platform in April.

Two Americans and a Russian have been aboard the station since March.

They plan to return to Earth on the next flight, due to be made by the shuttle Discovery next month.