CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers prepare to drive the truck that moves the rotating service structure, or RSS. The RSS will be moved around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

Workers on Launch Pad 39A get ready to begin the movement of the rotating service structure above them. The RSS has not been rotated for more than a year during the maintenance and upgrades on the pad. Some of the work included sandblasting the structure to remove rust and repainting. In addition, the RSS was jacked up and a new upper-bearing race assembly installed where the RSS pivots against the fixed service structure and a half-inch steel plate added. Pad 39A is being made ready for its first launch in four years, the upcoming STS-117 on March 15.

The rotating service structure on Launch Pad 39A has moved for the first time in more than a year due to maintenance and upgrades on the pad. Some of the work included sandblasting the structure to remove rust and repainting. In addition, the RSS was jacked up and a new upper-bearing race assembly installed where the RSS pivots against the fixed service structure and a half-inch steel plate added. Pad 39A is being made ready for its first launch in four years, the upcoming STS-117 on March 15.

The rotating service structure on Launch Pad 39A is being moved for the first time in more than a year due to maintenance and upgrades on the pad. Some of the work included sandblasting the structure to remove rust and repainting. In addition, the RSS was jacked up and a new upper-bearing race assembly installed where the RSS pivots against the fixed service structure and a half-inch steel plate added. Pad 39A is being made ready for its first launch in four years, the upcoming STS-117 on March 15.

The rotating service structure on Launch Pad 39A is being moved for the first time in more than a year due to maintenance and upgrades on the pad. Some of the work included sandblasting the structure to remove rust and repainting. In addition, the RSS was jacked up and a new upper-bearing race assembly installed where the RSS pivots against the fixed service structure and a half-inch steel plate added. Pad 39A is being made ready for its first launch in four years, the upcoming STS-117 on March 15.

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers keep watch as the rotating service structure, or RSS, is moved to enclose space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers begin closing the rotating service structure, or RSS, around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, workers talk to the driver of the rotating service structure, or RSS, before it is moved around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

The rotating service structure on Launch Pad 39A has been fully opened for the first time in more than a year due to maintenance and upgrades on the pad. Some of the work included sandblasting the structure to remove rust and repainting. In addition, the RSS was jacked up and a new upper-bearing race assembly installed where the RSS pivots against the fixed service structure and a half-inch steel plate added. Pad 39A is being made ready for its first launch in four years, the upcoming STS-117 on March 15. Photo credit: NASA/George Shelton

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure has been moved into place around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

CAPE CANAVERAL, Fla. – Viewed from the side of Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure has been moved into place around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, a worker prepares the rail for the closing of the rotating service structure around space shuttle Endeavour. The RSS provides protected access to the shuttle for changeout and servicing of payloads at the pad. The structure is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad's flame trench. The RSS rotates through 120 degrees (one-third of a circle) on a radius of 160 feet. Support for the outer end of the bridge is provided by two eight-wheel, motor-driven trucks that move along circular twin rails installed flush with the pad surface. The track crosses the flame trench on a permanent bridge. Endeavour is targeted to launch June 13 on its STS-127 mission to the International Space Station. Photo credit: NASA/Tim Jacobs

CAPE CANAVERAL, Fla. – Viewed across the Indian River Lagoon, space shuttle Endeavour waits for launch after rollback of the rotating service structure, or RSS, at left. First motion of the RSS was at 10:15 a.m. EDT. At far right is the tank that holds 300,000 gallons of water used for sound suppression during liftoff. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – Framed by branches across the Indian River Lagoon, space shuttle Endeavour waits for launch after rollback of the rotating service structure, or RSS, at left. First motion of the RSS was at 10:15 a.m. EDT. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After rollback of the rotating service structure, or RSS, on Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour waits for launch. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery in full launch configuration is revealed after the Rotating Service Structure (RSS) is rotated back at Launch Pad 39B at NASA Kennedy Space Center. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery in full launch configuration is revealed after the Rotating Service Structure (RSS) is rotated back at Launch Pad 39B at NASA Kennedy Space Center. The gaseous oxygen vent arm (beanie cap) has been extended to the top of the External Tank. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery in full launch configuration is revealed after the Rotating Service Structure (RSS) is rotated back at Launch Pad 39B at NASA Kennedy Space Center. At the top of the Fixed Service Structure is the 80-foot-tall lightning mast. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery in full launch configuration is revealed after the Rotating Service Structure (RSS) is rotated back at Launch Pad 39B at NASA Kennedy Space Center. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery in full launch configuration is revealed after the Rotating Service Structure (RSS) is rotated back at Launch Pad 39B at NASA Kennedy Space Center. The gaseous oxygen vent arm (beanie cap) has been extended to the top of the External Tank and the orbiter access arm is extended to Discovery’s hatch. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

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. – The open rotating service structure, or RSS (left), on Launch Pad 39A at NASA's Kennedy Space Center in Florida reveals space shuttle Endeavour poised for launch. The RSS was rotated to its open position in preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. First motion was at 10:39 a.m. EDT and completed at 11:18 a.m. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Jim Grossmann

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. – After rollback of the rotating service structure, or RSS, on Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is revealed. The shuttle sits on the mobile launcher platform, which straddles the flame trench below. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. Above the external tank is the "beanie cap," the oxygen vent hood that is designed to vent gaseous oxygen vapors away from the shuttle. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After rollback of the rotating service structure, or RSS, on Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is closer to launch. Against Endeavour's cockpit is seen the White Room at the end of the orbiter access arm. The White Room provides the astronauts entry into the shuttle. Endeavour sits on the mobile launcher platform, which straddles the flame trench below. On either side of the engine nozzles are the tail masts, which provide several umbilical connections to the orbiter, including a liquid-oxygen line through one and a liquid-hydrogen line through another. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After rollback of the rotating service structure, or RSS, on Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is revealed. The shuttle sits on the mobile launcher platform, which straddles the flame trench below. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. Above the external tank is the "beanie cap," the oxygen vent hood that is designed to vent gaseous oxygen vapors away from the shuttle. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

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. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, technicians in the control booth get ready to roll the rotating service structure, or RSS, above them away from space shuttle Endeavour. First motion was at 10:39 a.m. EDT. The rollback is in preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, technicians in the control booth roll the rotating service structure, or RSS, away from space shuttle Endeavour. First motion was at 10:39 a.m. EDT. The rollback is in preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/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 "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. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/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/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. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is revealed after the rollback of the rotating service structure, or RSS. In the foreground is the flame trench, which the mobile launcher platform straddles. On top of the external fuel tank is the oxygen vent hood, called the "beanie cap," which is designed to vent gaseous oxygen vapors away from the shuttle. The rollback is preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. First motion was at 10:39 a.m. EDT and completed at 11:18 a.m. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/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 "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. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/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/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. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the oxygen vent hood, called the "beanie cap," is positioned above the external fuel tank of space shuttle Endeavour following the rollback of the rotating service structure, or RSS, at left. The beanie cap is designed to vent gaseous oxygen vapors away from the shuttle. The rollback is preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. First motion was at 10:39 a.m. EDT and completed at 11:18 a.m. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Ken Thornsley

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. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/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/Troy Cryder

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure (RSS) was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 11:52 p.m. EDT on April 28. The move was scheduled to begin at 7 p.m., but storms over Kennedy delayed pad operations for a few hours. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/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/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. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is revealed after the rollback of the rotating service structure, or RSS. On the left of Endeavour is the White Room, at the end of the orbiter access arm. The White Room provides entry into the shuttle for the astronauts. The rollback is preparation for Endeavour's liftoff June 13 on the STS-127 mission with a crew of seven. First motion was at 10:39 a.m. EDT and completed at 11:18 a.m. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. It is supported by a rotating bridge that pivots on a vertical axis on the west side of the pad's flame trench. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Jim Grossmann

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

KENNEDY SPACE CENTER, FLA. - Flags are flying on Launch Pad 39B at NASA Kennedy Space Center as Space Shuttle Discovery is ready on the pad for launch after rollback of the Rotating Service Structure. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - A worker on Launch Pad 39B at NASA Kennedy Space Center walks alongside the track of the Rotating Service Structure as it begins rolling back from its position around Space Shuttle Discovery. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - A worker on Launch Pad 39B at NASA Kennedy Space Center sits in the control cab of the Rotating Service Structure as it begins rolling back from its position around Space Shuttle Discovery. Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Flags are flying on Launch Pad 39B at NASA Kennedy Space Center as Space Shuttle Discovery is ready on the pad for launch after rollback of the Rotating Service Structure. Visible above the External Tank is the gaseous oxygen vent arm (beanie cap). Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

KENNEDY SPACE CENTER, FLA. - Flags are flying on Launch Pad 39B at NASA Kennedy Space Center as Space Shuttle Discovery is ready on the pad for launch after rollback of the Rotating Service Structure. Visible above the External Tank is the gaseous oxygen vent arm (beanie cap). Rollback of the RSS is a major preflight milestone, typically occurring during the T-11-hour hold on L-1 (the day before launch). Discovery is scheduled to lift off on the historic Return to Flight mission STS-114 at 10:39 a.m. EDT July 26 with a crew of seven. On the mission to the International Space Station the crew will perform inspections on orbit for the first time of all of the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wings and the Thermal Protection System tiles using the new Canadian-built Orbiter Boom Sensor System and the data from 176 impact and temperature sensors. Mission Specialists will also practice repair techniques on RCC and tile samples during a spacewalk in the payload bay. During two additional spacewalks, the crew will install the External Stowage Platform-2, equipped with spare part assemblies, and a replacement Control Moment Gyroscope contained in the Lightweight Multi-Purpose Experiment Support Structure.

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, technicians in the control booth (lower left) begin to roll away the rotating service structure, or RSS, from space shuttle Endeavour. First motion was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the orbiter access arm and White Room are extended toward space shuttle Discovery after rollback of the rotating service structure. The White Room provides crew access into the shuttle. The rollback is in preparation for Discovery's liftoff on the STS-119 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The mission is the 28th to the International Space Station and the 125th space shuttle flight. Discovery will deliver the final pair of power-generating solar array wings and the S6 truss segment. Installation of S6 will signal the station's readiness to house a six-member crew for conducting increased science. Liftoff of Discovery is scheduled for 9:20 p.m. EDT on March 11. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Discovery is revealed after the rotating service structure has been rolled back. The rollback is in preparation for Discovery's liftoff on the STS-119 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The mission is the 28th to the International Space Station and the 125th space shuttle flight. Discovery will deliver the final pair of power-generating solar array wings and the S6 truss segment. Installation of S6 will signal the station's readiness to house a six-member crew for conducting increased science. Liftoff of Discovery is scheduled for 9:20 p.m. EDT on March 11. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure, or RSS, at left is rolled away from space shuttle Endeavour. First motion was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After rollback of the rotating service structure, or RSS, on Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is closer to launch. Above the external tank is the "beanie cap," the oxygen vent hood that is designed to vent gaseous oxygen vapors away from the shuttle. At center against Endeavour's cockpit is seen the White Room at the end of the orbiter access arm. The White Room provides the astronauts entry into the shuttle. Endeavour sits on the mobile launcher platform, which straddles the flame trench below. On either side of the engine nozzles are the tail masts, which provide several umbilical connections to the orbiter, including a liquid-oxygen line through one and a liquid-hydrogen line through another. First motion of the RSS was at 10:15 a.m. EDT. The rollback is in preparation for Endeavour's liftoff on the STS-127 mission with a crew of seven. This is the second launch attempt for Endeavour after the June 13 launch was scrubbed due to a hydrogen leak at the Ground Umbilical Carrier Plate during tanking June 12. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. The mission is the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the space station. Endeavour's launch is scheduled for June 17 at 5:40 a.m. EDT. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the rotating service structure on Launch Pad 39A begins to move away from space shuttle Discovery, which is illuminated by bright xenon lights. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Discovery is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the rotating service structure on Launch Pad 39A begins to move away from space shuttle Discovery. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. From here, cameras will catch the shuttle lift off amidst the space center's pristine wildlife refuge. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the orbiter access arm and White Room are extended toward space shuttle Discovery after rollback of the rotating service structure. The White Room provides crew access into the shuttle. Above the external tank is the oxygen vent hood, called the "beanie cap." The rollback is in preparation for Discovery's liftoff on the STS-119 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The mission is the 28th to the International Space Station and the 125th space shuttle flight. Discovery will deliver the final pair of power-generating solar array wings and the S6 truss segment. Installation of S6 will signal the station's readiness to house a six-member crew for conducting increased science. Liftoff of Discovery is scheduled for 9:20 p.m. EDT on March 11. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Discovery is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the rotating service structure on Launch Pad 39A begins to move away from space shuttle Discovery. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. From here, cameras will catch the shuttle lift off amidst the space center's pristine wildlife refuge. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the orbiter access arm and White Room are extended toward space shuttle Discovery after rollback of the rotating service structure. Above the external tank is the oxygen vent hood, called the "beanie cap." The rollback is in preparation for Discovery's liftoff on the STS-119 mission with a crew of seven. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. The mission is the 28th to the International Space Station and the 125th space shuttle flight. Discovery will deliver the final pair of power-generating solar array wings and the S6 truss segment. Installation of S6 will signal the station's readiness to house a six-member crew for conducting increased science. Liftoff of Discovery is scheduled for 9:20 p.m. EDT on March 11. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Discovery is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure was moved away. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the rotating service structure on Launch Pad 39A begins to move away from space shuttle Discovery, which is illuminated by bright xenon lights. The structure provides weather protection and access to the shuttle while it awaits lift off on the pad. RSS "rollback," as it's called, began at 8:02 p.m. EST on Feb. 23 and wrapped up at 8:37 p.m. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Discovery, which will fly its 39th mission, is scheduled to be retired following STS-133. This will be the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Jack Pfaller