Discovery arriving Saturday at space station

Space shuttle Discovery zoomed toward a Saturday afternoon check-in at the International Space Station, its final visit before being parked at a museum.

"Your reservation has been confirmed," Mission Control notified the six shuttle astronauts first thing Saturday morning.

The space station's commander couldn't resist a little ribbing as Discovery pulled to within six miles.

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

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

Discovery - making its final voyage - will 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 will be 12 people aboard the linked spacecraft, representing the United States, Russia and Italy.

Before docking, Discovery will perform a slow 360-degree backflip so space station cameras can 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.

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 traveled, with 143 million miles 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 from the waist up 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.