CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician is preparing to work on replacing some of space shuttle Atlantis' heat shield tiles. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician is replacing a heat shield tile under space shuttle Atlantis. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician closely inspects a heat shield tile for space shuttle Atlantis before securing it into position. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician places a heat shield tile into position under space shuttle Atlantis. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician is ready to work on replacing some of space shuttle Atlantis' heat shield tiles. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician inspects the area on space shuttle Atlantis' underside before a heat shield tile is installed. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician applies a bonding agent to an area on space shuttle Atlantis' underside where a heat shield tile will be installed. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician secures a newly installed heat shield tile in place under space shuttle Atlantis with a pressure fitting to ensure a tight bond. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician installs a gap filler in the area on space shuttle Atlantis' underside before a heat shield tile is installed. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician takes a measurement of the surface in the area on space shuttle Atlantis' underside where a heat shield tile will be installed. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician prepares the surface under space shuttle Atlantis before installing a heat shield tile. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician has secured a newly installed heat shield tile in place under space shuttle Atlantis with a pressure fitting to ensure a tight bond. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician prepares the surface under space shuttle Atlantis before installing a heat shield tile. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician has secured a newly installed heat shield tile in place under space shuttle Atlantis with a pressure fitting to ensure a tight bond. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician secures a newly installed heat shield tile in place under space shuttle Atlantis with a pressure fitting to ensure a tight bond. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician secures a newly installed heat shield tile in place under space shuttle Atlantis. The tiles are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, a thermal protection system technician applies a bonding agent to an area on space shuttle Atlantis' underside where a heat shield tile will be installed. The tiles are part of the Orbiter Thermal Protection System that protects the shuttle against temperatures as high as 3,000 degrees Fahrenheit, which are produced during descent for landing. Atlantis is being prepared for the STS-135 mission, which will carry the Raffaello multi-purpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last flight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

NASA astronaut Chris Ferguson, STS-135 commander, examines the thermal tiles of the orbiter after the space shuttle Atlantis landed at the Kennedy Space Center in Florida completing STS-135, the final mission of the NASA shuttle program, on Thursday, July 21, 2011. ( NASA Photo / Houston Chronicle, Smiley N. Pool )

CAPE CANAVERAL, Fla. -- A United Space Alliance technician examines one of shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. The tile went through a pull test, which measured the force it took to pull it off of the shuttle in order to make sure the bond between the two is strong enough to withstand the force of launch and landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- United Space Alliance technicians gear up for a pull test of shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. The pull test measures the force it takes to pull a tile off of the shuttle in order to make sure the bond between the two is strong enough to withstand the force of launch and landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- United Space Alliance technicians perform a pull test on shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. The pull test measures the force it takes to pull a tile off of the shuttle in order to make sure the bond between the two is strong enough to withstand the force of launch and landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- United Space Alliance technicians perform a pull test on shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. The pull test measures the force it takes to pull a tile off of the shuttle in order to make sure the bond between the two is strong enough to withstand the force of launch and landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- STS-135 Commander Chris Ferguson talks with United Space Alliance tile technician Terry White, left, and NASA Kennedy Space Center Director Bob Cabana, right, in Orbiter Processing Facility-1 during shuttle Atlantis' final planned move to the Vehicle Assembly Building. The move called "rollover" is a major milestone in processing for the STS-135 mission to the International Space Station. Inside the VAB, the shuttle will be attached to its external fuel tank and solid rocket boosters. Ferguson, along with Pilot Doug Hurley and Mission Specialists Rex Walheim and Sandra Magnus are targeted to launch in early July, taking with them the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing spacecraft and return a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Jack Pfaller

NASA Kennedy Space center Director Robert Cabana talks with members of the shuttle tile team which are wearing flowered shirts together at the Shuttle Landing Facility (SLF) runway at NASA Kennedy Space Center shortly after the space shuttle Atlantis (STS-135) landed, completing its 13-day mission to the International Space Station (ISS) and the final flight of the Space Shuttle Program, early Thursday morning, July 21, 2011, in Cape Canaveral, Fla. Overall, Atlantis spent 307 days in space and traveled nearly 126 million miles during its 33 flights. Atlantis, the fourth orbiter built, launched on its first mission on Oct. 3, 1985. Photo Credit: (NASA/Bill Ingalls)