CAPE CANAVERAL, Fla. – NASA's most traveled space shuttle, Discovery, was fueled Thursday for its final voyage after nearly three decades of service.

The six astronauts for the space station delivery mission headed to the launch pad in early afternoon, waving and smiling to the massive picture-taking crowd at crew quarters. Once at the pad, they paused at the base of the pad to gaze up at Discovery and embraced in a group hug, before getting on board.

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The crew never made it this far before; November's launch attempt ended midway through fueling.

Launch director Mike Leinbach said everything finally seemed to be coming together. Even the weather was looking up: the forecast improved to 90 percent "go" for the 4:50 p.m. liftoff.

"I think the weather's going to be good," Leinbach said Thursday morning. "It's a machine so you never know until the final seconds on the clock if all pieces of the machine are going to behave. But right now, it feels good."

This time, no hydrogen gas seeped out during fueling. NASA also was confident no cracks would develop in the external fuel tank; final checks uncovered nothing serious, although pictures still were being analyzed. Both problems cropped up during the initial countdown in November, and the repairs took almost four months. The cracks in the midsection of the tank, which holds instruments but no fuel, could have been dangerous.

Discovery will head to the International Space Station with the crew, as well as a load of supplies and a humanoid robot.

This will be the 39th flight for Discovery, set to become the first of the three surviving space shuttles to be retired this year and sent to a museum. It has since logged 143 million miles since its first flight in 1984.

Atlantis is set to soar in April and Endeavour at the end of June.