Space shuttle Discovery rolls out of the Vehicle Assembly Building and heads toward Launch Pad 39A at NASA's Kennedy Space Center.

Space shuttle Discovery slowly rolls out of the Vehicle Assembly Building and heads toward Launch Pad 39A at NASA's Kennedy Space Center in Florida. The slow trek, known as "rollout," will take the shuttle, attached to its external fuel tank, twin solid rocket boosters and mobile launcher platform atop a crawler-transporter, about seven hours to complete. This is the second time Discovery has rolled out to the pad for the STS-133 mission, and comes after a thorough check and modifications to the shuttle's external tank.

Targeted to liftoff Feb. 24, Discovery will take the Permanent Multipurpose Module (PMM) packed with supplies and critical spare parts, as well as Robonaut 2 (R2) to the International Space Station. For more information on STS-133, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jim Grossmann