WASHINGTON : The US space shuttle Endeavour was set to head home to Earth Monday after a record five successful spacewalks and 12 days at the International Space Station where astronauts installed a Japanese lab.

The seven-member crew spent their final hours at the ISS wrapping up transfers of equipment and supplies between Endeavour and the station, and checking out the tools needed for undocking and subsequent activities, officials said.

The Endeavour astronauts bade farewell to the crew who remained aboard the orbiting station, and the hatches between the two craft were closed at 5:49 EDT (2149 GMT), the National Aeronautics and Space Administration (NASA) said.

The undocking is scheduled for 7:56 pm EDT (2356 GMT), when the shuttle embarks on its return to Kennedy Space Center, Florida.

Looking back at the mission during a press conference late Sunday, Endeavour commander Dominic Gorie described it as an all-around success.

"We've done awesome," Gorie said.

"Every spacewalk was a win, every robotic op (operation) was a win. We've got a couple more to go with the undocking and the landing, but we've got a great winning team."

Two astronauts from Endeavour - mission specialists Robert Behnken and Mike Foreman - on Sunday attached a 50-foot sensory boom to the outside of the space station.

ISS flight director Dana Weigel said the spacewalk, often referred to by NASA officials as an EVA, or an extra-vehicular activity, had set a new record.

"This was five EVAs, which was more than we've done on any station mission," Weigel said.

Endeavour launched on March 11. Its mission at the ISS is the longest ever.

The spacewalkers also successfully installed an experiment on the outside of the European Space Agency's laboratory, which the astronauts had failed to complete during the third spacewalk on March 17.

The Endeavour mission's main tasks were to install the first part of the Japanese Kibo lab, which will join similar facilities from the United States, Russia and the EU, whose Columbus lab was delivered to the ISS in February.

"At this moment, the people of Japan are very excited about the module," said Japan Aerospace Exploration Agency astronaut Takao Doi, who is to return to Earth on board Endeavour. "It is going to open up a new era for Japan in the space programme."

He added that it remained to be seen how Japanese culture would adjust to the realities of ISS.

But in the meantime, "we like the food a lot," quipped space station commander Peggy Whitson.

European Space Agency astronaut Leopold Eyharts of France, who is returning to Earth after about two months aboard the ISS, said he was ready for the trip back home.

"I'm trying to exercise regularly, but I'm quite confident because a couple of months is not so much," Eyharts told reporters.

Astronauts also tested new repair techniques for the shuttle's heat shield.

NASA has been testing different in-space repair techniques on the shuttle's protective layer since a crack in Columbia's heat shield caused it to explode while re-entering Earth's atmosphere in 2003, killing its seven-member crew.

Astronauts have also assembled the Canadian-made Dextre robot, which is designed to undertake maintenance operations on the space station that until now required a human touch, and reduce the need for risky spacewalks.

The robot's human-like upper torso swivels at the waist, and its arms were designed with seven joints to provide it with maximum versatility.

Umbilical connectors provide power and data connectivity.

Manipulated by joysticks inside the ISS or from ground control on Earth, the 1.56-tonne Dextre will conduct operations such as replacing small components on the station's exterior.

NASA wants to complete construction of the ISS by 2010, when its three-shuttle fleet is scheduled to be retired. - AFP/ch