Space shuttle Endeavour, installed on the mobile launcher platform atop the crawler-transporter, moves out of the Vehicle Assembly Building for rollout to Launch Pad 39B at NASA's Kennedy Space Center in Florida. First motion was at 11:57 p.m. EDT April 16. The 4.2-mile journey is expected to take approximately 7 hours. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller