Viewed at NASA's Kennedy Space Center in Florida shuttle Endeavour is poised on Launch Pad 39B.

Viewed across the lagoon at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is poised on Launch Pad 39B. Surrounding the pad are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch May 12 on the STS-125 mission to upgrade 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