CAPE CANAVERAL, Fla. – The rotating service structure is closed around space shuttle Endeavour on Launch Pad 39A at NASA's Kennedy Space Center in Florida after its launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – Space Shuttle Endeavour is still on launch Pad 39A at NASA's Kennedy Space Center in Florida after the launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – The rotating service structure is closed around space shuttle Endeavour on Launch Pad 39A at NASA's Kennedy Space Center in Florida after its launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – A closeup of NASA's Lunar Reconnaissance Orbiter, or LRO, and NASA's Lunar Crater Observation and Sensing Satellite, known as LCROSS, ready for liftoff on an Atlas V/Centaur rocket from Launch Pad 41 at Cape Canaveral Air Force Station in Florida. LRO and LCROSS are the first missions in NASA's plan to return humans to the moon and begin establishing a lunar outpost by 2020. The LRO also includes seven instruments that will help NASA characterize the moon's surface: DIVINER, LAMP, LEND, LOLA , CRATER, Mini-RF and LROC. Launch is scheduled for 5:12 p.m. EDT June 18. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – Photographer Joel Powell, with Spaceflight Magazine, captures a closeup of NASA's Lunar Reconnaissance Orbiter, or LRO, and NASA's Lunar Crater Observation and Sensing Satellite, known as LCROSS, atop the Atlas V/Centaur rocket on Launch Pad 41 at Cape Canaveral Air Force Station in Florida. Around the pad are the lightning towers. LRO and LCROSS are the first missions in NASA's plan to return humans to the moon and begin establishing a lunar outpost by 2020. The LRO also includes seven instruments that will help NASA characterize the moon's surface: DIVINER, LAMP, LEND, LOLA , CRATER, Mini-RF and LROC. Launch is scheduled for 5:12 p.m. EDT June 18. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – The rotating service structure is closed around space shuttle Endeavour on Launch Pad 39A at NASA's Kennedy Space Center in Florida after its launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. At right in the background is Launch Pad 39B, surrounded by lightning towers, which will be used for the Constellation Program. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – Space Shuttle Endeavour (center) is still on launch Pad 39A midday after the launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate, the same cause for the June 13 delay. On the left is Launch Pad 39B, surrounded by lightning towers, which will be used for the Constellation Program. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. – NASA's Lunar Reconnaissance Orbiter, or LRO, and NASA's Lunar Crater Observation and Sensing Satellite, known as LCROSS, stand ready for liftoff on an Atlas V/Centaur rocket from Launch Pad 41 at Cape Canaveral Air Force Station in Florida. LRO and LCROSS are the first missions in NASA's plan to return humans to the moon and begin establishing a lunar outpost by 2020. The LRO also includes seven instruments that will help NASA characterize the moon's surface: DIVINER, LAMP, LEND, LOLA , CRATER, Mini-RF and LROC. Launch is scheduled for 5:12 p.m. EDT June 18. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – NASA's Lunar Reconnaissance Orbiter, or LRO, and NASA's Lunar Crater Observation and Sensing Satellite, known as LCROSS, stand ready for liftoff on an Atlas V/Centaur rocket from Launch Pad 41 at Cape Canaveral Air Force Station in Florida. At left is one of the lightning towers that surround the pad. LRO and LCROSS are the first missions in NASA's plan to return humans to the moon and begin establishing a lunar outpost by 2020. The LRO also includes seven instruments that will help NASA characterize the moon's surface: DIVINER, LAMP, LEND, LOLA , CRATER, Mini-RF and LROC. Launch is scheduled for 5:12 p.m. EDT June 18. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – The rotating service structure is closed around space shuttle Endeavour on Launch Pad 39A at NASA's Kennedy Space Center in Florida after its launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Ken Thornsley

CAPE CANAVERAL, Fla. – The rotating service structure is closed around space shuttle Endeavour on Launch Pad 39A at NASA's Kennedy Space Center in Florida after its launch for the STS-127 mission was scrubbed at 1:55 a.m. EDT June 17 due to a gaseous hydrogen leak at the Ground Umbilical Carrier Plate. Endeavour’s next launch attempt for the mission is targeted for July 11 at 7:39 p.m. EDT. Photo credit: NASA/Ken Thornsley

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

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the rotating service structure around space shuttle Atlantis begins to open 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. 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 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 (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