Atlantis heads off on what could be its final mission

Space shuttle Atlantis blasted off into a blue Florida sky on Friday on a swansong flight after 25 years of service.

Carrying six astronauts, the orbiter is racing toward a rendezvous with the International Space Station.

"Have a little fun out there," said NASA Shuttle Launch Director Mike Leinbach shortly before launch.

Atlantis commander Ken Ham answered: "Thousands of folks out there have taken care of this bird for a long time."

Tens of thousands of spectators crowded Space Coast beaches and causeways to catch a glimpse of this historic flight from Kennedy Space Center. Only two shuttle missions are still on the books before NASA retires the fleet later this year.

Kennedy Space Center saw a hubbub of VIP's for Atlantis' final voyage, including Defense Secretary Robert Gates, Apollo 11 astronaut Buzz Aldrin and David Letterman, host of the CBS "Late Show."

"This is the third to last shuttle launch so I feel like I want them to be able to say, 'Where were you when it went off? I was here,''" said Brian Dedischew, 34, of Michigan, who brought his 7- and 5-year-old sons to Kennedy Space Center Visitor Complex to watch Atlantis lift off.

The only hiccup during the countdown was the discovery of a missing ball bearing inside the orbiter's payload bay. Engineers studied whether it could present a problem, but ultimately cleared the shuttle for launch.

Atlantis is hauling up a keg-shaped Russian module that will serve as a fourth station docking port for visiting Soyuz crew transports and Progress space freighters.

Three spacewalks are planned to set spare parts on stowage platforms outside the station and replace six batteries that have powered the outpost since late 2000. Landing is scheduled for May 26.

After returning, Atlantis will be prepared to launch on a rescue mission if astronauts run into trouble on NASA's last planned shuttle flight, now set to fly in late November.

Some inside NASA are pushing for extra money to give Atlantis one extra flight even if it's not needed for a rescue mission, but that's far from a sure thing. It would cost $800 million and pose some safety risks because NASA would not have a rescue vehicle ready if Atlantis then got into trouble.