The Vehicle Assembly Building stands on the horizon as rain clouds move over the space center soon after Atlantis is revealed.

The Vehicle Assembly Building at NASA's Kennedy Space Center in Florida stands on the horizon as rain clouds move over the space center soon after space shuttle Atlantis is revealed on Launch Pad 39A following the move of the rotating service structure (RSS). The structure provides weather protection and access to the shuttle while it awaits liftoff on the pad. RSS "rollback" marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley and Mission Specialists Sandy Magnus and Rex Walheim, are scheduled to lift off at 11:26 a.m. EDT on July 8 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts to the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Ken Thornsley