Space shuttle Atlantis and Endeavour are seen on Launch Pads 39A and 39B at NASA's Kennedy Space Center.

Space shuttle Atlantis (left) and space shuttle Endeavour are seen on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding pad 39B 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 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/Dimitri Gerondidakis