The flight will be the last for Discovery, the first of three shuttles NASA plans to retire this year [Reuters]

Space shuttle Discovery, NASA's most heavily travelled spacecraft, has arrived at the International Space Station after blasting off from the US state of Florida last week on its final mission.

"What took you guys so long?" asked Scott Kelly,  the space station's commander on Saturday.

Discovery should have come and gone last November, but was grounded by fuel tank cracks.

The shuttle blasted off on Thursday carrying six astronauts and a load of supplies, spare parts and a robot for the International Space Station.

The launch was the 133rd for the 30-year-old shuttle programme, with up to two flights remaining before the three-ship fleet is retired later this year.

'Humanoid robot'

Discovery made 39 of those flights, including both return-to-flight missions following the fatal Challenger and Columbia accidents.

The shuttle carries a storage room, a spare parts platform and a prototype humanoid robot for the space station, a $100bn project of 16 nations nearing completion after more than a decade of construction 354km above the Earth.

Discovery, flying on its final voyage, will spend at least a week at the orbiting outpost.

Along with the robot, it carries a closet-style chamber full of supplies. 

There are 12 people aboard the joint space station, representing the United States, Russia and Italy.

And in a historic first, four of the five major partners have vessels docked there right now, including cargo ships from Japan and Europe.

The entire conglomeration has a mass of 540,000kg, including the shuttle.

The shuttles are being retired due to high operational costs and to free up money to develop new vehicles capable of travelling beyond the space station's orbit.

Source: Agencies