Working 230 miles above Earth at a speed of 16,000 miles per hour, the astronauts carried out a number of tasks including attaching two cranes to the outside of the station that will allow future crews to move cargo.

Tamara Jernigan and Daniel Barry were outside of the shuttle for seven hours 55 minutes - the second longest space walk ever made from the space shuttle.

At the end of the walk it seemed they were reluctant to go back inside.

Space suits

Discovery is the first vehicle to dock with the orbting space station

"You can't be telling me we're almost done?" said Barry as the space walk, known as an EVA in Nasa-speak, came to and end.

"Wow. It feels like we just walked outside."

The bulky space suits - known as extravehicular mobility units, or EMUs - were kept low on pressure during the EVA to make them more manoeuvrable.

During the walk Barry exchanged greetings with his wife on the ground and thanked her for letting him spend their wedding anniversary high above the earth.

Supply delivery

Earlier the two "skywalkers" were woken by the theme music from Star Wars piped up from Mission Control in Houston.

In the next stage of equipping the International Space Station (ISS) two other astronauts, a Canadian and a Russian, will enter the station to deliver two tons of supplies, ranging from spare parts and computers to rubbish bags and signs pointing to the emergency exit.

Food, water and clothing for the stations first inhabitants will also be stored on board.

Alva McNicol reports: "The two astronauts have a long list of chores they must complete"

These are for the future inhabitants - two Russian and an American - who are due to arrive aboard a Russian Soyuz craft in March next year.

Nasa officials say the ISS construction programme is the first truly international space mission with bringing together the US, Russia, Japan, Canada and Brazil with the 11 members of the European Space Agency.

The crew is also scheduled to test a number of new UCDs (urine collection devices) for astronauts of both sexes as a back up to the shuttle's toilet system.

Nasa says the UCDs will be tested in microgravity for fit, leakage, hygiene and ease of use, with a view to designing and evaluating improvements to "the male interface" attachment.

Construction site

Daniel Barry spent his wedding annversary building the new space station

The current mission, STS-96, is the first construction activity on the ISS since the first two pieces were launched late last year.

On Saturday Discovery made history becoming the first space vehicle to dock with the orbiting space station.

It is currently made up of two components - The Russian-built Zarya launched first, and the American-built Unity module.

The station is orbiting 400km above earth

Space walking is considered to be one of the most dangerous activities in the programme, after launches and landing. Nasa says another 42 space walks will be required for the assembly phase of the $60bn station - completion is due in 2005.

The astronauts also installed a number of tool kits and foot holds - designed to fit both American and Russian space boots - in preparation for future construction missions.