_and_Endeavour_(STS-400)_on_launch_pads.jpg)
Space Shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA's Kennedy Space Center in Florida in 2008. Endeavour stood by at pad B in case a rescue mission was necessary during Atlantis' mission to repair NASA's Hubble Space Telescope. At the left of each shuttle are the open rotating service structures, with the payload changeout rooms visible. These structures provided weather protection and access to the shuttle.Photo: NASA/Troy Cryder