The space shuttle Endeavour is seen as strong winds inflate a windsock, Saturday Feb. 6, 2010 at pad 39a of the NASA Kennedy Space Center in Cape Canaveral, Florida. Endeavour and the crew members of the STS-130 mission are set to launch on Sunday at 4:39 a.m. EST. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen as strong winds inflate a windsock, Saturday Feb. 6, 2010 at pad 39a of the NASA Kennedy Space Center in Cape Canaveral, Florida. Endeavour and the crew members of the STS-130 mission are set to launch on Sunday at 4:39 a.m. EST. Photo Credit: (NASA/Bill Ingalls)

Space Shuttle Endeavour paints the still-blue evening sky as it leaves Earth behind on its journey into space on mission STS-118. Liftoff from Launch Pad 39A was on time at 6:36 p.m. EDT. The mission is the 22nd shuttle flight to the International Space Station. It will continue space station construction by delivering a third starboard truss segment, S5, and other payloads such as the SPACEHAB module and the external stowage platform 3. The 11-day mission may be extended to as many as 14 depending on the test of the Station-to-Shuttle Power Transfer System that will allow the docked shuttle to draw electrical power from the station and extend its visits to the orbiting lab.

The space shuttle Endeavour is seen shortly after the rotating service structure is rolled back on Saturday Feb. 6, 2010 at pad 39a of the NASA Kennedy Space Center in Cape Canaveral, Florida. Endeavour and the crew members of the STS-130 mission are set to launch on Sunday at 4:39 a.m. EST. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen after the rotating service structure is rolled back on Saturday Feb. 6, 2010 at pad 39a of the NASA Kennedy Space Center in Cape Canaveral, Florida. Endeavour and the crew members of the STS-130 mission are set to launch on Sunday at 4:39 a.m. EST. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen after the rotating service structure is rolled back on Saturday Feb. 6, 2010 at pad 39a of the NASA Kennedy Space Center in Cape Canaveral, Florida. Endeavour and the crew members of the STS-130 mission are set to launch on Sunday at 4:39 a.m. EST. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen reflected in a puddle of water on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a as a storm passes by prior to the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a as a storm passes by prior to the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

201105150010hq (15 May 2011) --- The space shuttle Endeavour is seen on launch pad 39A after the rollback of the Rotating Service Structure (RSS), May 15, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for May 16 at 8:56 a.m. (EDT). Photo credit: NASA/Bill Ingalls

201105150002hq (15 May 2011) --- The space shuttle Endeavour is seen on launch pad 39A after the rollback of the Rotating Service Structure (RSS), May 15, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for May 16 at 8:56 a.m. (EDT). Photo credit: NASA/Bill Ingalls

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a after the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen on launch pad 39a as a storm passes by prior to the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT. Photo credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. –– Space shuttle Endeavour (left) and space shuttle Atlantis are seen on Launch Pads 39B and 39A, respectively, at NASA's Kennedy Space Center. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010.Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Seen on Launch Pads 39A and 39B at NASA's Kennedy Space Center in Florida are shuttles on both pads. At left is space shuttle Atlantis, poised for the STS-125 mission targeted to launch May 12, and at right is space shuttle Endeavour. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. –– Dawn rises over the Atlantic Ocean behind space shuttle Endeavour on Launch Pad 39B at NASA's Kennedy Space Center in Florida. Surrounding the pad are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour has joined space shuttle Atlantis, which is on pad 39A. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– As dawn begins to brighten the sky over Launch Pad 39B at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is seen bathed in lights from the fixed service structure. Endeavour joins Atlantis, which is on Launch Pad 39A. The towers around the launch pad were erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Launch Pads 39A and 39B at NASA's Kennedy Space Center in Florida are ablaze with lights before dawn, showing shuttles on both pads. At left is space shuttle Atlantis, poised for the STS-125 mission targeted to launch May 12, and at right is space shuttle Endeavour. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following Atlantis' launch. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Chris Rhodes

CAPE CANAVERAL, Fla. –– Early dawn showcases Launch Pads 39A and 39B at NASA's Kennedy Space Center in Florida with shuttles on both pads. At left is space shuttle Atlantis, poised for the STS-125 mission targeted to launch May 12, and at right is space shuttle Endeavour. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following Atlantis' launch. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Chris Rhodes

CAPE CANAVERAL, Fla. –– Under a dawn sky, space shuttle Endeavour is still bathed in light from the fixed service structure. Endeavour joins Atlantis, which is on Launch Pad 39A at NASA's Kennedy Space Center in Florida. The towers around the launch pad were erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– On Launch Pad 39B (left) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour has joined space shuttle Atlantis on Launch Pad 39A (right). This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding pad 39B are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– As dawn begins to brighten the sky over Launch Pad 39B at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is seen bathed in lights from the fixed service structure. Endeavour joins Atlantis, which is on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (left) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (foreground) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (left) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (right) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (left) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. – After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles are poised on two different launch pads. Shuttle Atlantis (foreground) already was on Launch Pad 39A. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Dimitri Gerondidakis

Space shuttle Atlantis (left) and space shuttle Endeavour are seen on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding pad 39B are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Original photo number is KSC-2009-2771.

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis (left) and space shuttle Endeavour are seen on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding the pad are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis (left) and space shuttle Endeavour are seen on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding pad 39B are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis (left) and space shuttle Endeavour are seen on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Surrounding pad 39B are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Dawn breaks over the Atlantic Ocean behind space shuttle Atlantis on Launch Pad 39A at NASA's Kennedy Space Center in Florida. Atlantis is targeted to launch May 12 on its STS-125 mission. Space shuttle Endeavour sits on Launch Pad 39B, probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis atop the mobile launcher platform straddles the flame trench on Launch Pad 39A at NASA's Kennedy Space Center in Florida. It is joined by space shuttle Endeavour on Launch Pad 39B. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– On Launch Pad 39B (left) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour has joined space shuttle Atlantis on Launch Pad 39A. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Early morning light falls on space shuttle Endeavour on Launch Pad 39B at NASA's Kennedy Space Center in Florida. It joins space shuttle Atlantis on Launch Pad 39A. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– On Launch Pad 39B at NASA's Kennedy Space Center in Florida, space shuttle Endeavour has joined space shuttle Atlantis on Launch Pad 39A. In the background is the Atlantic Ocean. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis atop the mobile launcher platform straddles the flame trench on Launch Pad 39A at NASA's Kennedy Space Center in Florida. Behind it is the Atlantic Ocean. Atlantis has been joined by space shuttle Endeavour on Launch Pad 39B. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis atop the mobile launcher platform sits on Launch Pad 39A at NASA's Kennedy Space Center in Florida. At left is the Vehicle Assembly Building. Atlantis has been joined by space shuttle Endeavour on Launch Pad 39B. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– On Launch Pad 39B at NASA's Kennedy Space Center in Florida, space shuttle Endeavour has joined space shuttle Atlantis on Launch Pad 39A. In the background is the Atlantic Ocean. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

The Moon is seen rising behind the Space Shuttle Endeavour (STS-126) on pad 39a Friday, November 14, 2008, at the Kennedy Space Center in Cape Canaveral, Fla. The Shuttle lifted off from launch pad 39A at 7:55 p.m. EST. Photo Credit: (NASA/Bill Ingalls)

The Moon is seen rising behind the Space Shuttle Endeavour (STS-126) on pad 39a Friday, November 14, 2008, at the Kennedy Space Center in Cape Canaveral, Fla. The Shuttle lifted off from launch pad 39A at 7:55 p.m. EST. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour rolls through the gate at Launch Pad 39A. The shuttle earlier moved off Launch Pad 39B starting at 8:28 am. EDT to head for pad 39A. Endeavour completed its move to Launch Pad 39A at 4:37 p.m. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. –– Sunlight spotlights space shuttle Atlantis (left) and space shuttle Endeavour on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Sunlight spotlights space shuttle Atlantis (left) and space shuttle Endeavour on Launch Pads 39A and 39B, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. –– Space shuttle Endeavour (left) and space shuttle Atlantis are seen on Launch Pads 39B and 39A, respectively, at NASA's Kennedy Space Center in Florida. This is probably the final time two shuttles will be on launch pads at the same time with the space shuttle fleet set for retirement in 2010. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. - Palmettos appear to frame space shuttle Endeavour as it rolls toward Launch Pad 39A on NASA's Kennedy Space Center in Florida. The shuttle earlier moved off Launch Pad 39B starting at 8:28 am. EDT and headed for pad 39A. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour rolls toward Launch Pad 39A, at right. The shuttle earlier moved off Launch Pad 39B starting at 8:28 am. EDT to head for pad 39A. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, space shuttle Endeavour nears the end of its 3.4-mile trek from Launch Pad 39B to Launch Pad 39A. First motion of the rollaround from Launch Pad 39B was at 3:16 a.m. EDT, and the shuttle was secured to Launch Pad 39A at 11:42 a.m. EDT. Endeavour was on standby on Pad 39B to be used in the unlikely event that a rescue mission was necessary during space shuttle Atlantis' STS-125 mission to NASA's Hubble Space Telescope. The payload on Endeavour's next mission, STS-127, includes the Japan Aerospace Exploration Agency's Kibo Exposed Facility and the Experiment Logistics Module Exposed Section of the International Space Station. They will be installed on the Kibo laboratory already on the station. Launch of STS-127 is targeted for June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. –– Viewed across the lagoon at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is poised on Launch Pad 39B. Surrounding the pad are the lightning towers erected for NASA's Constellation Program, which will use the pad for Ares rocket launches. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis on Launch Pad 39A is viewed across the lagoon at NASA's Kennedy Space Center in Florida. Atlantis is targeted to launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. –– Space shuttle Atlantis on Launch Pad 39A is viewed across the lagoon at NASA's Kennedy Space Center in Florida. Atlantis is targeted to launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch May 12 on the STS-125 mission to upgrade NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. –– At NASA's Kennedy Space Center in Florida, space shuttles Atlantis (left) and Endeavour (right) are seen on Launch Pad 39A and 39B respectively. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. –– Viewed from the shoreline at NASA's Kennedy Space Center in Florida, space shuttles Atlantis (left) and Endeavour (right) are seen on Launch Pad 39A and 39B respectively. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. –– Viewed across the lagoon at NASA's Kennedy Space Center in Florida, space shuttles Atlantis (right) and Endeavour (background left) are seen on Launch Pad 39A and 39B respectively. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during Atlantis' upcoming mission to upgrade NASA's Hubble Space Telescope. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – Space shuttle Endeavour stands tall and proud on Launch Pad 39B at NASA's Kennedy Space Center in Florida. First motion of Endeavour's rollout from the Vehicle Assembly Building was at 11:57 p.m. EDT April 16. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. – In the Vehicle Assembly Building's High Bay 1 at NASA's Kennedy Space Center in Florida, space shuttle Endeavour is in place for attachment to the external tank and solid rocket boosters on the mobile launcher platform. Endeavour is scheduled to roll out to Launch Pad 39B on April 17. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service the Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch in mid-June. Photo credit: NASA/Troy Cryder

KENNEDY SPACE CENTER, FLA. -- Launch Pad 39A is illuminated as Space Shuttle Endeavour blazes into the sky on mission STS-113. Liftoff from Launch Pad 39A occurred ontime at 7:49:47 p.m. EST. The launch is the 19th for Endeavour, and the 112th flight in the Shuttle program. Mission STS-113 is the 16th assembly flight to the International Space Station, carrying another structure for the Station, the P1 integrated truss. Also onboard are the Expedition 6 crew, who will replace Expedition 5. Endeavour is scheduled to land at KSC after an 11-day journey.

KENNEDY SPACE CENTER, FLA. - Launch Pad 39A is illuminated as Space Shuttle Endeavour blazes into the sky on mission STS-113. Liftoff from Launch Pad 39A occurred ontime at 7:49:47 p.m. EST. The launch is the 19th for Endeavour, and the 112th flight in the Shuttle program. Mission STS-113 is the 16th assembly flight to the International Space Station, carrying another structure for the Station, the P1 integrated truss. Also onboard are the Expedition 6 crew, who will replace Expedition 5. Endeavour is scheduled to land at KSC after an 11-day journey.

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Endeavour is being "rolled around" from Launch Pad 39A to Launch Pad 39B. The rare pad switch was deemed necessary after contamination was discovered in the Payload Changeout Room at pad A. Still to come are the payloads for the upcoming STS-61 mission, the first servicing of the Hubble Telescope

KENNEDY SPACE CENTER, FLA. - All is quiet on Launch Pad 39A where Space Shuttle Endeavour sits prior to launch on mission STS-113 to the International Space Station. [Photo by Scott Andrews]

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, space shuttle Endeavour comes to a stop over the flame trench on Launch Pad 39A. First motion of the 3.4-mile rollaround from Launch Pad 39B was at 3:16 a.m. EDT, and the shuttle was secured to Launch Pad 39A at 11:42 a.m. EDT. Endeavour was on standby on Pad 39B to be used in the unlikely event that a rescue mission was necessary during space shuttle Atlantis' STS-125 mission to NASA's Hubble Space Telescope. The payload on Endeavour's next mission, STS-127, includes the Japan Aerospace Exploration Agency's Kibo Exposed Facility and the Experiment Logistics Module Exposed Section of the International Space Station. They will be installed on the Kibo laboratory already on the station. Launch of STS-127 is targeted for June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, the Atlantic Ocean is backdrop for space shuttle Endeavour as it reaches the hardstand on Launch Pad 39A. First motion of the 3.4-mile rollaround from Launch Pad 39B was at 3:16 a.m. EDT, and the shuttle was secured to Launch Pad 39A at 11:42 a.m. EDT. Endeavour was on standby on Pad 39B to be used in the unlikely event that a rescue mission was necessary during space shuttle Atlantis' STS-125 mission to NASA's Hubble Space Telescope. The payload on Endeavour's next mission, STS-127, includes the Japan Aerospace Exploration Agency's Kibo Exposed Facility and the Experiment Logistics Module Exposed Section of the International Space Station. They will be installed on the Kibo laboratory already on the station. Launch of STS-127 is targeted for June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure around space shuttle Atlantis has been rolled back to enable delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure around space shuttle Atlantis has been rolled back to enable delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure around space shuttle Atlantis has been rolled back to enable delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure around space shuttle Atlantis has been rolled back to enable delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis is in full view after rollback of the rotating service structure. The rollback enables delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis is in full view after rollback of the rotating service structure. The rollback enables delivery and transfer of Atlantis' payload on April 18. After space shuttle Endeavour's rollout to Launch pad 39B at NASA's Kennedy Space Center in Florida this morning, two different shuttles now are poised on two different launch pads in full view. Near the top of the shuttle is the White Room at the end of the orbiter access arm, 147 feet above the pad. When in place against the shuttle, the White Room provides access into the crew compartment on the shuttle. With the space shuttle fleet set for retirement in 2010, this is expected to be the final time two shuttles will be on launch pads at the same time. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission. Atlantis is targeted to launch May 12. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-127 mission to the International Space Station. That flight is targeted for launch June 13. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - After rollout from the Vehicle Assembly Building at NASA's Kennedy Space Center, space shuttle Endeavour is being secured on the launch pad. First motion was at 11:15 p.m. Sept. 18. Endeavour completed the 4.2-mile journey to Launch Pad 39B on Sept. 19 at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. - After rollout from the Vehicle Assembly Building at NASA's Kennedy Space Center, space shuttle Endeavour is being secured on the launch pad. First motion was at 11:15 p.m. Sept. 18. Endeavour completed the 4.2-mile journey to Launch Pad 39B on Sept. 19 at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. - After rollout from the Vehicle Assembly Building at NASA's Kennedy Space Center, space shuttle Endeavour is being secured on the launch pad. First motion was at 11:15 p.m. Sept. 18. Endeavour completed the 4.2-mile journey to Launch Pad 39B on Sept. 19 at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. - Space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - Space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - Space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - With a rainbow serving as a backdrop in the sky, space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - With a rainbow serving as a backdrop in the sky, space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - With a rainbow beginning to appear in the sky, space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - With a rainbow serving as a backdrop in the sky, space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - Space shuttle Atlantis (foreground) sits on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - Clouds serve as a backdrop to frame space shuttle Atlantis (foreground) on Launch Pad A and Endeavour on Launch Pad B at NASA’s Kennedy Space Center in Florida. At the left of each shuttle are the open rotating service structures with the payload changeout rooms revealed. The rotating service structures provide protection for weather and access to the shuttle. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis’ upcoming mission to repair NASA’s Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for its STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. - The lighted crawler-transporter and mobile launcher platform reveal space shuttle Endeavour on top as it rolls out to the launch pad. First motion was at 11:15 p.m. Sept. 18. Endeavour completed the 4.2-mile journey to Launch Pad 39B on Sept. 19 at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Dimitri Gerondidakis

CAPE CANAVERAL, Fla. - After rollout from the Vehicle Assembly Building at NASA's Kennedy Space Center, space shuttle Endeavour is secure on the launch pad. Workers on the pad connect lines on the mobile launcher platform. Endeavour completed the 4.2-mile rollout at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. - After rollout from the Vehicle Assembly Building at NASA's Kennedy Space Center, space shuttle Endeavour is secure on the launch pad. Workers on the pad connect lines on the mobile launcher platform. Endeavour completed the 4.2-mile rollout at 6:59 a.m. EDT. For the first time since July 2001, two shuttles are on the launch pads at the same time at the center. Endeavour will stand by at pad B in the unlikely event that a rescue mission is necessary during space shuttle Atlantis' upcoming mission to repair NASA's Hubble Space Telescope, targeted to launch Oct. 10. After Endeavour is cleared from its duty as a rescue spacecraft, it will be moved to Launch Pad 39A for the STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. Photo credit: NASA/Jim Grossmann

The space shuttle Endeavour is seen at launch pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Florida on Saturday, July 11, 2009. NASA is hopeful that Endeavour will launch with the crew of STS-127 on Sunday. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is framed by a windsock at launch pad 39A at the NASA Kennedy Space Center in Cape Canaveral, Florida on Saturday, July 11, 2009. NASA is hopeful that Endeavour will launch with the crew of STS-127 on Sunday. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen at launch pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Florida on Saturday, July 11, 2009. NASA is hopeful that Endeavour will launch with the crew of STS-127 on Sunday. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen at launch pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Florida on Saturday, July 11, 2009. NASA is hopeful that Endeavour will launch with the crew of STS-127 on Sunday. Photo Credit: (NASA/Bill Ingalls)

The space shuttle Endeavour is seen at launch pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Florida on Saturday, July 11, 2009. NASA is hopeful that Endeavour will launch with the crew of STS-127 on Sunday. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. – Dawn's early light reveals space shuttle Endeavour secure on Launch Pad 39B at NASA's Kennedy Space Center in Florida. First motion of the rollout from the Vehicle Assembly Building was at 11:57 p.m. EDT April 16. Endeavour will be prepared on the pad for liftoff in the unlikely event that a rescue mission is necessary following space shuttle Atlantis' launch on the STS-125 mission to service NASA's Hubble Space Telescope. After Atlantis is cleared to land, Endeavour will move to Launch Pad 39A for its upcoming STS-127 mission to the International Space Station, targeted to launch June 13. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour, atop the mobile launcher platform, comes to rest on Launch Pad 39A after rolling around from launch Pad 39B. The shuttle moved off Launch Pad 39B starting at 8:28 am. EDT and completed its move to Launch Pad 39A at 4:37 p.m. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour comes to rest on Launch Pad 39A after rolling around from launch Pad 39B. The shuttle moved off Launch Pad 39B starting at 8:28 am. EDT and completed its move to Launch Pad 39A at 4:37 p.m. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is hard down on Launch Pad 39A after rolling around from launch Pad 39B. The shuttle moved off Launch Pad 39B starting at 8:28 am. EDT and completed its move to Launch Pad 39A at 4:37 p.m. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - At NASA's Kennedy Space Center in Florida, space shuttle Endeavour, atop the mobile launcher platform, comes to rest on Launch Pad 39A after rolling around from launch Pad 39B. At left are the open rotating service structure and the fixed service structure with the 80-foot-tall lightning mast on top. The shuttle moved off Launch Pad 39B starting at 8:28 am. EDT and completed its move to Launch Pad 39A at 4:37 p.m. Endeavour is targeted to launch Nov. 14 on the STS-126 mission. On this 27th mission to the International Space Station, Endeavour will carry the Lightweight Multi-Purpose Experiment Support Structure Carrier and the Multi-Purpose Logistics Module Leonardo that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, spare hardware and equipment for the regenerative life support system. Photo credit: NASA/Kim Shiflett