Launch Pads 39A and 39B at NASA's Kennedy Space Center in Florida are ablaze with lights before dawn.

Launch Pads 39A and 39B at NASA's Kennedy Space Center in Florida are ablaze with lights before dawn, showing shuttles on both pads. At left is space shuttle Atlantis, poised for the STS-125 mission targeted to launch May 12, and at right is space shuttle Endeavour. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following Atlantis' launch. 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/Chris Rhodes