File:STS135 crew pose in front of Atlantis on rollover day.jpg

English: STS-135 Commander Chris Ferguson (left), Mission Specialists Sandra Magnus and Rex Walheim, and Pilot Doug Hurley pause for a photo while watching shuttle Atlantis' rollover from Orbiter Processing Facility-1 to the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida. The move called "rollover" is a major milestone in processing for the STS-135 mission to the International Space Station. Inside the VAB, the shuttle will be attached to its external fuel tank and solid rocket boosters. Commander Chris Ferguson, Pilot Doug Hurley and Mission Specialists Sandra Magnus and Rex Walheim are expected to launch in mid July, taking with them the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing spacecraft and return 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.