CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) slowly rolls away revealing space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) begins to roll away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) slowly rolls away revealing space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) slowly rolls away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) begins to roll away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers monitor the progress of the rotating service structure (RSS) as it rolls away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) slowly rolls away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers monitor the progress of the rotating service structure (RSS) as it rolls away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure (RSS) slowly rolls away revealing space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to roll the rotating service structure (RSS) away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- On a cloudy and overcast day on Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers monitor the progress of the rotating service structure (RSS) as it rolls away from space shuttle Atlantis. The RSS provides weather protection and access to the shuttle while it awaits liftoff. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- A worker in a control booth on Launch Pad 39A at NASA's Kennedy Space Center in Florida monitors the progress of the rotating service structure (RSS) as it is rolled back revealing space shuttle Atlantis. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Employees check out space shuttle Atlantis after it was uncovered on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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. In front of the pad a banner proclaims the sentiments of Kennedy's work force. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- A worker in the control booth on Launch Pad 39A at NASA's Kennedy Space Center in Florida monitors the progress of the rotating service structure (RSS) as it is rolled back revealing space shuttle Atlantis. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- A worker in the control booth on Launch Pad 39A at NASA's Kennedy Space Center in Florida monitor's the progress of the rotating service structure (RSS) as it is rolled back revealing space shuttle Atlantis. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- A worker in the control booth on Launch Pad 39A at NASA's Kennedy Space Center in Florida monitors the progress of the rotating service structure (RSS) as it is rolled back revealing space shuttle Atlantis. 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Flags wave briskly at Launch Pad 39A at NASA's Kennedy Space Center in Florida as space shuttle Atlantis is revealed 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Flags wave briskly at Launch Pad 39A at NASA's Kennedy Space Center in Florida as space shuttle Atlantis is revealed 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/Troy Cryder

CAPE CANAVERAL, Fla. -- Workers check out space shuttle Atlantis after it was uncovered on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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/Troy Cryder

CAPE CANAVERAL, Fla. -- CAPE CANAVERAL, Fla. - Space shuttle Atlantis soars above its billowing exhaust from Launch Pad 39A at NASA's Kennedy Space Center in Florida on its STS-135 mission to the International Space Station. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Kenny Allen

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- At Launch Pad 39A at NASA's Kennedy Space Center in Florida space shuttle Atlantis is reflected in a pond near the pad after the retraction of the rotating service structure (RSS). The structure provides weather protection and access to the shuttle while it awaits liftoff on the pad. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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. The tower at left is used for safely burning off any excess hydrogen while the shuttle is on the pad prior to launch. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis awaits liftoff from Launch Pad 39A at NASA's Kennedy Space Center in Florida on its STS-135 mission to the International Space Station. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/Kenny Allen

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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. The tower at left is used for safely burning off any excess hydrogen while the shuttle is on the pad prior to launch. To the right of the pad is the 300,000-gallon water tower that provides the water used for sound suppression on the pad during liftoff. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis soars from Launch Pad 39A at NASA's Kennedy Space Center in Florida on its STS-135 mission to the International Space Station. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Kenny Allen

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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. To the right of the pad is the 300,000-gallon water tower that provides the water used for sound suppression on the pad during liftoff. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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. The tower at left is used for safely burning off any excess hydrogen while the shuttle is on the pad prior to launch. To the right of the pad is the 300,000-gallon water tower that provides the water used for sound suppression on the pad during liftoff. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- At Launch Pad 39A at NASA's Kennedy Space Center in Florida space shuttle Atlantis is reflected in a pond near the pad after the retraction of the rotating service structure (RSS). The structure provides weather protection and access to the shuttle while it awaits liftoff on the pad. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

Cape Canaveral, Fla. – Shortly after launch, members of the news media continue the coverage of space shuttle Atlantis on the STS-135 mission to the International Space Station. Working from the NASA News Center at Kennedy Space Center, news media from television, World Wide Web and newspaper outlets from around the world relayed the launch and mission details for the final flight of the Space Shuttle Program. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Jim Grossmann

Cape Canaveral, Fla. - Space shuttle Atlantis soars into a layer of thin clouds at NASA's Kennedy Space Center in Florida moments after lifting off on the STS-135 mission to the International Space Station. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Jim Grossmann Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis soars from Launch Pad 39A at NASA's Kennedy Space Center in Florida on its STS-135 mission to the International Space Station. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Kenny Allen

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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 retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis completes its roll program moments after liftoff from Launch Pad 39A at NASA's Kennedy Space Center in Florida on its STS-135 mission to the International Space Station. The roll maneuver puts the shuttle in the proper orientation as it heads into space. Atlantis with its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, lifted off at 11:29 a.m. EDT on July 8, 2011 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for 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 is 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/ Kenny Allen

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida bathed in xenon lights 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. The tower at left is used for safely burning off any excess hydrogen while the shuttle is on the pad prior to launch. RSS retract marks a major milestone in Atlantis' STS-135 mission countdown. Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim will 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 for 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 is 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: Jim Grossmann

STS135-S-151 (8 July 2011) --- Space shuttle Atlantis is pictured on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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. Liftoff was at 11:29 a.m. (EDT) on July 8, 2011. Onboard are NASA astronauts Chris Ferguson, commander; Doug Hurley, pilot; Sandy Magnus and Rex Walheim, both mission specialists. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the space station. Atlantis also carries 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. Photo credit: NASA

STS135-S-152 (8 July 2011) --- Space shuttle Atlantis is pictured on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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. Liftoff was at 11:29 a.m. (EDT) on July 8, 2011. Onboard are NASA astronauts Chris Ferguson, commander; Doug Hurley, pilot; Sandy Magnus and Rex Walheim, both mission specialists. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the space station. Atlantis also carries 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. Photo credit: NASA

STS135-S-150 (8 July 2011) --- Space shuttle Atlantis is pictured on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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. Liftoff was at 11:29 a.m. (EDT) on July 8, 2011. Onboard are NASA astronauts Chris Ferguson, commander; Doug Hurley, pilot; Sandy Magnus and Rex Walheim, both mission specialists. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the space station. Atlantis also carries 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. Photo credit: NASA

CAPE CANAVERAL, Fla. – Photographers Stan Hernda of AFP News, left, and Scott Andrews of Canon record space shuttle Atlantis as it is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla.-- 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- The crew compartment of space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. – Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. – Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla.-- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is revealed on Launch Pad 39A at NASA's Kennedy Space Center in Florida 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