CAPE CANAVERAL, Fla. - Inside space shuttle Atlantis' crew compartment, a United Space Alliance employee works through an extensive checklist to 'safe' the vehicle for towback from the Shuttle Landing Facility runway to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. After every shuttle landing, about 150 trained workers assist the crew out and then make the vehicle safe for towing atop a large diesel-driven tractor. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. Inside the processing facility, Atlantis will be prepared for the unlikely event it is needed as a rescue spacecraft for the final planned shuttle flight, Endeavour's STS-134 mission. For more information, visit www.nasa.gov_shuttle. Photo credit: NASA_Troy Cryder

CAPE CANAVERAL, Fla. - Inside space shuttle Atlantis' crew compartment, a United Space Alliance employee begins to power down the vehicle for towback from the Shuttle Landing Facility runway to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. After every shuttle landing, about 150 trained workers assist the crew out and then make the vehicle safe for towing atop a large diesel-driven tractor. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. Inside the processing facility, Atlantis will be prepared for the unlikely event it is needed as a rescue spacecraft for the final planned shuttle flight, Endeavour's STS-134 mission. For more information, visit www.nasa.gov_shuttle. Photo credit: NASA_Troy Cryder

CAPE CANAVERAL, Fla. - Inside space shuttle Atlantis' crew compartment, a United Space Alliance employee closes the vehicle's hatch for towback from the Shuttle Landing Facility runway to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. After every shuttle landing, about 150 trained workers assist the crew out and then make the vehicle safe for towing atop a large diesel-driven tractor. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. Inside the processing facility, Atlantis will be prepared for the unlikely event it is needed as a rescue spacecraft for the final planned shuttle flight, Endeavour's STS-134 mission. For more information, visit www.nasa.gov_shuttle. Photo credit: NASA_Troy Cryder

CAPE CANAVERAL, Fla. -- A towback technician is seen through the cockpit windows of space shuttle Atlantis as he safes the vehicle on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Atlantis' final landing was the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. – Space shuttle Discovery rolls toward Orbiter Processing Facility 3 at NASA's Kennedy Space Center in Florida. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, workers look on as space shuttle Atlantis enters Orbiter Processing Facility-1, where it will be processed for the unlikely event it is needed as a rescue spacecraft for the final shuttle flight, Endeavour's STS-143 mission. Atlantis touched down on the Shuttle Landing Facility's Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. – Space shuttle Discovery is towed into Orbiter Processing Facility 3 at NASA's Kennedy Space Center in Florida. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. – Surrounding lights cast a glow as space shuttle Discovery is towed to Orbiter Processing Facility 3 at NASA's Kennedy Space Center in Florida. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. – After sunset, space shuttle Discovery is towed from the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida to Orbiter Processing Facility 3. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. - From inside space shuttle Atlantis' crew compartment, NASA Kennedy Space Center workers are seen awaiting the vehicle's arrival to Orbiter Processing Facility-1. Atlantis is making its slow trek atop a large diesel-driven tractor to the processing facility, after being safed by about 150 trained workers on the Shuttle Landing Facility runway. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. Inside the processing facility, Atlantis will be prepared for the unlikely event it is needed as a rescue spacecraft for the final planned shuttle flight, Endeavour's STS-134 mission. For more information, visit www.nasa.gov_shuttle. Photo credit: NASA_Troy Cryder

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis enters Orbiter Processing Facility-1, where it will be processed for the unlikely event it is needed as a rescue spacecraft for the final shuttle flight, Endeavour's STS-143 mission. Atlantis touched down on the Shuttle Landing Facility's Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. –Space shuttle Discovery arrives inside Orbiter Processing Facility 3 at NASA's Kennedy Space Center in Florida. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Atlantis makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-1. Atlantis touched down on Runway 33 after 12 days in space, completing the 4.8-million mile STS-132 mission to the International Space Station. The six-member STS-132 crew carried the Russian-built Mini Research Module-1 to the space station. STS-132 is the 34th shuttle mission to the station, the 132nd shuttle mission overall and the last planned flight for Atlantis. For information on the STS-132 mission and crew, visit www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts132_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. – Space shuttle Discovery is silhouetted against a fading sunset sky at NASA's Kennedy Space Center in Florida as it is towed to Orbiter Processing Facility 3. Discovery landed at 3:13:17 p.m. EDT after completing a 13-day journey of more than 5.3 million miles on the STS-119 mission. The mission was the 28th flight to the station, the 36th flight of Discovery and the 125th in the Space Shuttle Program, as well as the 70th landing at Kennedy. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. - The "towback" vehicle slowly pulls Space shuttle Discovery from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Employees accompany space shuttle Discovery as it is pulled by a "towback" vehicle from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery enters Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida during a move called "towback." Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - The "towback" vehicle lines up space shuttle Discovery for entry into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - A "towback" vehicle slowly pulls space shuttle Discovery through the open door of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. There to welcome Atlantis home are thousands of workers who have processed, launched and landed the shuttles for more than three decades. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Media photograph space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Media photograph space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers prepare space shuttle Atlantis for its trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- In front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida the STS-135 crew members express their gratitude to the thousands of workers who have processed, launched and landed the space shuttles for more than three decades during an employee appreciation event. Seen here is Commander Chris Ferguson shaking the hand of Kennedy Space Center Director Bob Cabana. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members pause for a photograph in front of space shuttle Atlantis after an employee appreciation event held at Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Commander Chris Ferguson (left), Mission Specialist Sandy Magnus, Pilot Doug Hurley and Mission Specialist Rex Walheim. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the landing convoy vehicles accompany space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility to an orbiter processing facility. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- It is time for reflection at NASA's Kennedy Space Center in Florida as employees accompany space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility to an orbiter processing facility. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Thousands of workers who have processed, launched and landed space shuttles for more than three decades, gather for an employee appreciation event in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members express their gratitude to the thousands of workers who have processed, launched and landed the space shuttles for more than three decades during an employee appreciation event held in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Mission Specialists Sandy Magnus and Rex Walheim, Commander Chris Ferguson and Pilot Doug Hurley. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers prepare space shuttle Atlantis for its trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis and its employee entourage saunter along the towway from the Shuttle Landing Facility to the Orbiter Processing Facility at NASA's Kennedy Space Center in Florida. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members stop for a photograph after an employee appreciation event held in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Mission Specialists Rex Walheim (left) and Sandy Magnus, Commander Chris Ferguson and Pilot Doug Hurley. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Media photograph space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, NASA Administrator Charles Bolden, left, and Kennedy Space Center Director Bob Cabana join Kennedy employees in the Pledge of Allegiance at an employee appreciation event for the thousands of workers who have processed, launched and landed America's space shuttles for more than three decades. Following the successful STS-135 mission, space shuttle Atlantis was parked at the celebration site for photo opportunities. STS-135 secured the space shuttle fleet's place in history and brought a close to NASA's Space Shuttle Program. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members express their gratitude with a banner dedicated to the thousands of workers who have processed, launched and landed the space shuttles for more than three decades during an employee appreciation event held in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Mission Specialists Rex Walheim and Sandy Magnus, Commander Chris Ferguson and Pilot Doug Hurley. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Thousands of workers who have processed, launched and landed space shuttles for more than three decades, gather in front of space shuttle Atlantis after an employee appreciation event at Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Thousands of workers who have processed, launched and landed space shuttles for more than three decades, gather for an employee appreciation event in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is reflected in the water along the towway from the Shuttle Landing Facility to the Orbiter Processing Facility at NASA's Kennedy Space Center in Florida. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Thousands of workers who have processed, launched and landed space shuttles for more than three decades, gather for an employee appreciation event in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Employees accompany space shuttle Atlantis as it is slowly towed from the Shuttle Landing Facility to an orbiter processing facility at NASA's Kennedy Space Center in Florida. Looming in the background is the 525-foot-tall Vehicle Assembly Building. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, the landing convoy vehicles line up to accompany space shuttle Atlantis from the Shuttle Landing Facility to an orbiter processing facility. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members express their gratitude to the thousands of workers who have processed, launched and landed the space shuttles for more than three decades during an employee appreciation event held in front of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Mission Specialists Sandy Magnus and Rex Walheim, Commander Chris Ferguson and Pilot Doug Hurley. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers prepare space shuttle Atlantis for its trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Workers accompany space shuttle Atlantis as it makes its slow trek from the Shuttle Landing Facility to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-135 crew members pause for a photograph in front of space shuttle Atlantis after an employee appreciation event held at Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Seen here are Commander Chris Ferguson (left), Mission Specialist Sandy Magnus, Pilot Doug Hurley and Mission Specialist Rex Walheim. Atlantis' final return to Earth occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, NASA Administrator Charles Bolden thanks the Kennedy work force for their dedication at an employee appreciation event for the thousands of workers who have processed, launched and landed America's space shuttles for more than three decades. Following the successful STS-135 mission, space shuttle Atlantis was parked at the celebration site for photo opportunities. STS-135 secured the space shuttle fleet's place in history and brought a close to NASA's Space Shuttle Program. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Employees admire space shuttle Atlantis as the landing convoy crew makes the vehicle safe for towing to Orbiter Processing Facility-2. Atlantis' final return to Earth on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis is slowly towed from the Shuttle Landing Facility runway to Orbiter Processing Facility-2 for the last time. Atlantis' final return to Earth on Runway 15 at NASA's Kennedy Space Center in Florida occurred at 5:57 a.m. EDT July 21, 2011. Securing the space shuttle fleet's place in history, Atlantis marks the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Atlantis and its crew delivered to the International Space Station the Raffaello multi-purpose logistics module packed with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 is the 33rd and final flight for Atlantis and the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery, pulled by its "towback" vehicle, approaches Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Towering above the processing bays is the 525-foot-tall Vehicle Assembly Building. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - The nozzles of two orbital maneuvering system pods and three space shuttle main engines protrude from the aft end of space shuttle Discovery as it is pulled by a "towback" vehicle toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery is connected to its "towback" vehicle, which will slowly pull the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end and additional landing convoy vehicles follow closely behind. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered 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. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Workers accompany shuttle Endeavour as a "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Workers accompany shuttle Endeavour as a "towback" vehicle slowly pulls it into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Slowly and carefully, a "towback" vehicle pulls space shuttle Atlantis into the empty bay of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, media photograph space shuttle Endeavour as a "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- With the assistance of a "towback" vehicle, space shuttle Atlantis inches its way into the empty bay of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls space shuttle Atlantis toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Atlantis' aft end. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls space shuttle Atlantis toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Atlantis' aft end. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls space shuttle Atlantis toward the empty bay of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Atlantis' aft end. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls space shuttle Atlantis toward the open door of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Atlantis' aft end. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls space shuttle Atlantis toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Atlantis' aft end. Once inside the processing facility, Atlantis will be prepared for future public display at Kennedy's Visitor Complex. Atlantis' final return from space at 5:57 a.m. EDT concluded the STS-135 mission, secured the space shuttle fleet's place in history and brought a close to America's Space Shuttle Program. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m. On board were STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered the Raffaello multi-purpose logistics module filled with more than 9,400 pounds of spare parts, equipment and supplies that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles, and also the final mission of the Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett