The orbiter Discovery sitting on an orbiter transporter rolls to NASA's Vehicle Assembly Building VAB.

Accompanied by Center employees, the orbiter Discovery, sitting on an orbiter transporter, rolls to NASA's Vehicle Assembly Building (VAB). The rollover marks the start of the journey to the launch pad and, ultimately, launch. Once inside the VAB, Discovery will be raised to vertical and lifted up and over into high bay 3 for stacking with its redesigned external tank and twin solid rocket boosters. The rollout of Space Shuttle Discovery to Launch Pad 39B is expected in approximately a week. Launch of Discovery on mission STS-121 is scheduled to take place in a window extending July 1 to July 19. Photo credit: NASA/Jack Pfaller