Space shuttle Endeavour moves through a high bay door of the Vehicle Assembly Building to begin its journey to Launch Pad 39A.

Space shuttle Endeavour moves through a high bay door of the Vehicle Assembly Building to begin its nighttime journey to Launch Pad 39A at NASA's Kennedy Space Center in Florida.

Riding atop a crawler-transporter attached to its external fuel tank and solid rocket boosters, Endeavour's 3.4-mile trek, known as "rollout," began at 7:56 p.m. EST and will take about seven hours to complete. This is the final scheduled rollout for Endeavour. Endeavour and its six-member crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank, additional spare parts for the Dextre robotic helper and micrometeoroid debris shields to the International Space Station on the shuttle's final spaceflight, STS-134. Launch is targeted for 7:48 p.m. EDT April 19. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Terry Zaperach