Space shuttle Discovery rolled into the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida on Saturday, where the shuttle's external tank and two solid rocket boosters await. Discovery will be lifted to vertical inside the building's 50-story-tall transfer aisle, lowered into a high bay and joined with the tank and boosters atop the mobile launcher platform.

The fully assembled space shuttle will remain in the Vehicle Assembly Building for a week, undergoing final checkouts before rolling out to Launch Pad 39A on May 3.

STS-124 is the second of three flights to deliver the Japan Aerospace Exploration Agency's Kibo laboratory to the International Space Station. Primary payloads are the tour-bus-sized Japanese Experiment Module-Pressurized Module and the lab's robotic arm system.

Mark Kelly will command the seven-member crew, which includes Pilot Ken Ham, Mission Specialists Karen Nyberg, Ron Garan, Mike Fossum, Greg Chamitoff and Japan Aerospace Exploration Agency astronaut Akihiko Hoshide. Chamitoff will replace Expedition 16/17 Flight Engineer Garrett Reisman and remain aboard the station as a member of the Expedition 17 crew.

The crew will visit Kennedy for the three-day Terminal Countdown Demonstration Test, which culminates in a countdown dress rehearsal May 9. Launch is targeted for May 31.