Discovery docks with space station

The space shuttle Discovery successfully docked with the International Space Station Saturday afternoon, on its last visit before being parked at a museum.

The linkup occurred 354 kilometres above Australia.

The shuttle connected to the station at 2:14 p.m. ET. Although Discovery had been running a few minutes behind, it pushed through an optional hold at the 30-foot mark to dock two minutes ahead of schedule.

NASA called it a textbook docking, praising commander Steven Lindsey for piloting the shuttle "almost exactly down the centre line" of the approach to the station.

However, once the shuttle was docked, the process of getting the hatches ready to open was slowed as crews waited for an unexpected oscillating motion between the shuttle and the station to dampen.

In a historic first, four of the five major partners in the station have vessels docked there now. The entire enormous complex, including Discovery, has a mass of 540,000 kilograms, which was set in motion by the extra weight of the shuttle.

Once the motion had stopped, Discovery and the station "hard mated" with a secure connection, and less than a couple of hours later the doors finally swung open. The two skippers shook hands and there were hugs all around.

It was a quick reunion. The astronauts rushed off to see how far they could get Saturday evening with the installation of a platform holding a spare radiator for the station. The giant shelf was carried aboard the shuttle.

'What took you guys so long'

Earlier in the day, as Discovery pulled to within eight kilometres of the station, the space station's commander couldn't resist a little ribbing.

"What took you guys so long?" Scott Kelly asked via ship-to-ship radio.

Discovery should have come and gone last November but was grounded by fuel tank cracks. The shuttle blasted off Thursday with just two seconds to spare, after being held up by a balky ground computer.

"Yeah, I don't know, we kind of waited until like the last two seconds," shuttle commander Steven Lindsey replied. "But it's good to hear your voice, Scott. You guys look great, so we're on our way."

'Friendly robot' joins crew

This is the 13th time Discovery has flown to the space station. On this final voyage, the shuttle is scheduled to spend at least a week at the orbiting outpost. It's carrying a closet-style chamber full of supplies, as well as the first humanoid robot to fly in space. The compartment will be attached permanently to the space station early next week.

Altogether, there are 12 people aboard the linked spacecraft, representing the United States, Russia and Italy.

On Thursday, shortly before Discovery's liftoff from the Kennedy Space Station in Florida, American astronaut Nicole Stott said on Twitter "Go Discovery" and promised "Will try to tweet from space."

Before docking, Discovery performed a slow 360-degree backflip so space station cameras could capture any signs of launch damage. At least four pieces of debris broke off the fuel tank during Thursday's liftoff, and one of the strips of insulating foam struck Discovery's belly.

NASA officials do not believe the shuttle was damaged. That's because the foam loss occurred so late in the launch, preventing a hard impact. As a precaution, every shuttle crew since the 2003 Columbia disaster has had to check thoroughly for possible damage to the thermal shielding, which must be robust for re-entering Earth's atmosphere. The images from the backflip were being downlinked to Earth late Saturday afternoon.

Discovery will be first to retire

Discovery is the first in the fleet to be retired this year. Endeavour and then Atlantis will close out the 30-year shuttle program by midsummer.

Discovery is the oldest of the three and the most travelled, with 230 million kilometres logged over 39 flights and 26 years.

The robot launched aboard Discovery — Robonaut 2 or R2 for short — will remain at the space station, all boxed up for at least another few months. It's an experimental machine that will be tested before attempting simple jobs inside the orbiting complex. The idea is for R2 to eventually serve as an astronaut assistant.

"Let me assure you that I am a friendly robot," Robonaut said in a Twitter update Saturday. It was posted by one of the robot's human colleagues on the ground.