CAPE CANAVERAL, Fla. -- A NASA helicopter circles space shuttle Atlantis on Launch Pad 39A prior to launch on the STS-135 mission. To the right of the shuttle, the fixed service structure which is normally closed around the shuttle now is open for liftoff. At left of the pad is the 300,000-gallon water tower that provides the water used for sound suppression on the pad during liftoff. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- A NASA helicopter circles space shuttle Atlantis on Launch Pad 39A prior to launch on the STS-135 mission. To the right of the shuttle, the fixed service structure which is normally closed around the shuttle now is open for liftoff. At left of the pad is the 300,000-gallon water tower that provides the water used for sound suppression on the pad during liftoff. 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/Frank Michaux

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at Kennedy Space Center on the STS-135 mission, Friday, July 8, 2011 in Cape Canaveral, Fla. Atlantis launched on the final flight of the shuttle program on a 12-day mission to the International Space Station. The STS-135 crew will deliver the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Dick Clark)

Space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at Kennedy Space Center on the STS-135 mission, Friday, July 8, 2011 in Cape Canaveral, Fla. Atlantis launched on the final flight of the shuttle program on a 12-day mission to the International Space Station. The STS-135 crew will deliver the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Dick Clark)

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, is bathed in xenon lights and takes center stage on Launch Pad 39A at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

Space shuttle Atlantis is seen on launch pad 39a moments after the STS-135 crew arrived for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen on launch pad 39a moments before the STS-135 crew arrives for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen on launch pad 39a moments before the STS-135 crew arrives for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen on launch pad 39a moments after the STS-135 crew arrived for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The STS-135 crew; Chris Ferguson, commander; Doug Hurley, pilot; Rex Walheim and Sandy Magnus, both mission specialists are seen before boarding space shuttle Atlantis at launch pad 39A prior to launch, Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The STS-135 crew; Chris Ferguson, commander; Doug Hurley, pilot; Rex Walheim and Sandy Magnus, both mission specialists are seen before boarding space shuttle Atlantis at launch pad 39A prior to launch, Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen on launch pad 39a moments before the STS-135 crew arrives for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen on launch pad 39a moments after the STS-135 crew arrived for their launch, Friday, July 8, 2011, at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The Astrovan carrying the STS-135 crew; Chris Ferguson, commander, Doug Hurley, pilot, and mission specialists Rex Walheim and Sandy Mangus, arrives at launch pad 39A and space shuttle Atlantis, Friday, July 8, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The Astrovan carrying the STS-135 crew; Chris Ferguson, commander, Doug Hurley, pilot, and mission specialists Rex Walheim and Sandy Mangus, arrives at launch pad 39A and space shuttle Atlantis, Friday, July 8, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is revealed as the rotating service structure (RSS) is rolled back at launch pad 39a on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Atlantis is seen shortly after the rotating service structure (RSS) was rolled back at launch pad 39a, Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The exhaust plume from space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Hiawatha Brown, Heavy Equipment Operator for United Space Alliance (USA), approaches launch pad 39A at the NASA Kennedy Space Center as he drives the Astrovan carrying the STS-135 crew on Friday July 8, 2011 in Cape Canaveral, Fla. The Astrovan is a modified 1983 Airstream and has been in use to carry crews to the launch pads since 1984. A close look at the odometer shows it has a little more than 26,521 miles at the time of this photo. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- T-38 jets and a Shuttle Training Aircraft (STA) sit parked on the tarmac at NASA Kennedy Space Center's Shuttle Landing Facility. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. STS-135 Commander Chris Ferguson and Pilot Doug Hurley practiced landings as part of standard procedure before space shuttle Atlantis' launch to the International Space Station. 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/Frank Michaux

CAPE CANAVERAL, Fla. -- Space shuttle Atlantis, attached to its bright-orange external fuel tank and twin solid rocket boosters, takes center stage on its seaside launch pad at NASA's Kennedy Space Center in Florida in this aerial image taken from a NASA helicopter. 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/Frank Michaux

James Branson of United Space Alliance, far left; Sandra Magnus, STS-135 mission specialist and Rex Walheim, STS-135 mission specialist, far right, are seen in the Astrovan as they ride to launch pad 39A to board space shuttle Atlantis on Friday, July 8, 2011, at the Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

Space Shuttle Atlantis viewed from the Mobil Launch Platform (MLP) during it's final rollout to Launch Pad 39A at Kennedy Space Center, Cape Canaveral, Florida, USA 31 May 2011. Launch of Atlantis on the STS-135 mission to deliver supplies to the International Space Station is currently planned for no earlier than 08 July 2011. The STS-135 mission is planned to last eight days and will be the final flight of the Space Shuttle program.

The Astrovan carrying the STS-135 crew; Chris Furgeson, commander, Doug Hurley, pilot, and mission specialists Rex Walheim and Sandy Mangus, rolls past the Vehicle Assembly Building (VAB) and Launch Control Center (LCC), on its way to launch pad 39a and space shuttle Atlantis, Friday, July 8, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The exhaust plume from space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at the Kennedy Space Center on the STS-135 mission, Friday, July 8, 2011 in Cape Canaveral, Fla. Atlantis launched on the final flight of the shuttle program on a 12-day mission to the International Space Station. The STS-135 crew will deliver the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Dick Clark)

The STS-135 crew; Chris Ferguson, commander; Doug Hurley, pilot;, left, Rex Walheim and Sandy Magnus, both mission specialists are seen before boarding space shuttle Atlantis at launch pad 39A prior to launch, Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

The STS-135 crew; Chris Ferguson, commander; Doug Hurley, pilot; Rex Walheim and Sandy Magnus, both mission specialists stop and pose for photographers before boarding the Astrovan that will take them to launch pad 39A for the launch of the space shuttle Atlantis on Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The STS-135 crew; Chris Ferguson, commander; Doug Hurley, pilot; Rex Walheim and Sandy Magnus, both mission specialists stop and pose for photographers before boarding the Astrovan that will take them to launch pad 39A for the launch of the space shuttle Atlantis on Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The exhaust plume from space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at the Kennedy Space Center on the STS-135 mission, Friday, July 8, 2011 in Cape Canaveral, Fla. Atlantis launched on the final flight of the shuttle program on a 12-day mission to the International Space Station. The STS-135 crew will deliver the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Dick Clark)

Shuttle Atlantis viewed from the Mobil Launch Platform (MLP) departs the Vehicle Assembly Building (VAB) during it's final rollout to Launch Pad 39A at Kennedy Space Center, Cape Canaveral, Florida, USA 31 May 2011. Launch of Atlantis on the STS-135 mission to deliver supplies to the International Space Station is planned for no earlier than 08 July 2011. The STS-135 mission is planned to last eight days and will be the final flight of the Space Shuttle program.

JSC2011-E-050266 (1 June 2011) --- Dawn approaches after space shuttle Atlantis completed its historic final journey to Launch Pad 39A from NASA Kennedy Space Center's Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050265 (1 June 2011) --- Dawn approaches after space shuttle Atlantis completed its historic final journey to Launch Pad 39A from NASA Kennedy Space Center's Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050268 (1 June 2011) --- Sunrise at Launch Pad 39A at NASA's Kennedy Space Center in Florida finds space shuttle Atlantis after completing its historic and final journey from the Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050269 (1 June 2011) --- Sunrise at Launch Pad 39A at NASA's Kennedy Space Center in Florida finds space shuttle Atlantis after completing its historic and final journey from the Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050263 (1 June 2011) --- Space shuttle Atlantis made its historic final journey to Launch Pad 39A after its 3.4 mile trek from NASA Kennedy Space Center's Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050267 (1 June 2011) --- Dawn approaches after space shuttle Atlantis completed its historic final journey to Launch Pad 39A from NASA Kennedy Space Center's Vehicle Assembly Building. Atlantis was secured or "hard down," at its seaside launch pad at 3:29 a.m. (EDT) on June 1, 2011. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

The Astrovan carrying the STS-135 crew; Chris Furgeson, commander, Doug Hurley, pilot, and mission specialists Rex Walheim and Sandy Mangus, rolls toward launch pad 39a and space shuttle Atlantis, Friday, July 8, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

The STS-135 mission specialist Rex Walheim, left, Doug Hurley, pilot; second from left, Sandy Magnus, mission specialist; and Chris Ferguson, commander, right, stop and take a moment to look up at the space shuttle Atlantis prior to boarding at launch pad 39A, Friday, July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

The STS-135 crew, clockwise: Sandra Magnus, mission specialist; Rex Walheim, mission specialist; Chris Ferguson, commander and Doug Hurley, pilot are seen in the Astrovan as they ride to launch pad 39A to board space shuttle Atlantis on Friday, July 8, 2011, at the Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

STS-135 Commander Chris Ferguson, right, talks with NASA Administrator Charles Bolden atop of the Mobile Launch Platform (MLP) as the space shuttle Atlantis (STS-135) rolls out of High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)

JSC2011-E-050245 (1 June 2011) --- Bathed in xenon lights, space shuttle Atlantis embarks on its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050249 (1 June 2011) --- Bathed in xenon lights, space shuttle Atlantis embarks on its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050254 (1 June 2011) --- Bathed in xenon lights, space shuttle Atlantis embarks on its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050253 (1 June 2011) --- Bathed in xenon lights, space shuttle Atlantis embarks on its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

JSC2011-E-050262 (1 June 2011) --- Bathed in xenon lights, space shuttle Atlantis embarks on its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. Photo credit: NASA

NASA Administrator Charles Bolden looks at the space shuttle Atlantis atop of the Mobile Launch Platform (MLP) just prior to rollout of Atlantis (STS-135) from High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden looks at the space shuttle Atlantis atop of the Mobile Launch Platform (MLP) just prior to rollout of Atlantis (STS-135) from High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. -- At Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay doors close around the STS-135 payload for flight. The payload arrived at the pad June 16 for installation into Atlantis and includes the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing satellites and return a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. Atlantis and its crew are scheduled to lift off at 11:26 a.m. EDT July 8. 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/shuttle. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- At Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay doors are closed around the STS-135 payload for flight. The payload arrived at the pad June 16 for installation into Atlantis and includes the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing satellites and return a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. Atlantis and its crew are scheduled to lift off at 11:26 a.m. EDT July 8. 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/shuttle. Photo credit: NASA/Jim Grossmann

The crew of STS-135 is seen as they depart the NASA Kennedy Space Center, Operations and Checkout Building and get into the Astrovan for launch pad 39A, on Friday, July 8, 2011 in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

Crowds are seen out the front window of the Astrovan carrying the STS-135 crew as it departs the NASA Kennedy Space Center, Operations and Checkout Building for launch pad 39A, on Friday, July 8, 2011 in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

STS-135 Tweetup participants are seen outside launch pad 39a and space shuttle Atlantis following the Rotating Service Structure rollback, Thursday, July 7, 2011, at Kennedy Space Center in Cape Canaveral, Fla.About 150 NASA Twitter followers attended the event. The STS-135 mission will be NASA's last space shuttle launch. Photo Credit: (NASA/Paul E. Alers)

CAPE CANAVERAL, Fla. -- STS-135 Commander Chris Ferguson, left, Pilot Doug Hurley, and Mission Specialists Sandy Magnus and Rex Walheim talk to media as their vehicle, space shuttle Atlantis, makes its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. First motion was at 8:42 p.m. EDT. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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. -- STS-135 Commander Chris Ferguson, left, Pilot Doug Hurley, and Mission Specialists Sandy Magnus and Rex Walheim talk to media as their vehicle, space shuttle Atlantis, makes its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. First motion was at 8:42 p.m. EDT. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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 STS-135 crew members talk to media as their vehicle, space shuttle Atlantis, makes its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. First motion was at 8:42 p.m. EDT. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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. -- Accompanying space shuttle Atlantis on its "rollout" to Launch Pad 39A at NASA's Kennedy Space Center in Florida are from left, STS-135 Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim. It will take the crawler-transporter about six hours to carry the shuttle stack to its seaside launch pad. The milestone move, known as "rollout," paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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: Courtesy of Scott Andrews/Canon

CAPE CANAVERAL, Fla. -- The STS-135 crew members talk to media as their vehicle, space shuttle Atlantis, makes its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. First motion was at 8:42 p.m. EDT. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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. -- STS-135 Commander Chris Ferguson, left, Pilot Doug Hurley, and Mission Specialists Sandy Magnus and Rex Walheim talk to media as their vehicle, space shuttle Atlantis, makes its final journey from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. First motion was at 8:42 p.m. EDT. It will take the crawler-transporter about six hours to carry the shuttle, attached to its external fuel tank and solid rocket boosters, to the seaside launch pad. The milestone move paves the way for the launch of the STS-135 mission to the International Space Station, targeted for July 8. 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

Launch pad worker Chris Cassidy lays down grease on the tracks of the rotating service structure (RSS) on launch pad 39a prior to the RSS being rolled back to reveal the space shuttle Atlantis on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Space shuttle Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Launch pad worker Chris Cassidy lays down grease on the tracks of the rotating service structure (RSS) on launch pad 39a prior to the RSS being rolled back to reveal the space shuttle Atlantis on Thursday, July 7, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. Space shuttle Atlantis is set to liftoff Friday, July 8, on the final flight of the shuttle program, STS-135, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Space Shuttle Atlantis (STS-135) is seen atop the Mobile Launch Platform (MLP) during its journey from High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)

Space Shuttle Atlantis (STS-135) is seen atop the Mobile Launch Platform (MLP) during its journey from High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)

Space Shuttle Atlantis (STS-135) is seen atop the Mobile Launch Platform (MLP) as it begins its journey from High Bay 3 in the Vehicle Assembly Building to Launch Pad 39a for its final flight, Tuesday evening, May 31, 2011, at Kennedy Space Center in Cape Canaveral, Fla. The 3.4-mile trek, known as "rollout," will take about seven hours to complete. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. The launch of STS-135 is targeted for July 8. Photo Credit: (NASA/Bill Ingalls)