An faint profile outline of the space shuttle Endeavour is seen projected in the sky as powerful xenon lights illuminate launch pad 39a shortly after the rollback of the Rotating Service Structure (RSS) from Endeavour, 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)

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)

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

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)

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 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)

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 STS-134 astronauts from left, European Space Agency's Roberto Vittori, Gregory H. Johnson, pilot; Mark Kelly, commander; Michael Fincke, Greg Chamitoff, and Andrew Feustel all mission specialists, pose for a group photograph shortly after landing onboard the space shuttle Endeavour at the Shuttle Landing Facility (SLF) at Kennedy Space Center, Wednesday, June 1, 2011, in Cape Canaveral, Fla. Endeavour, completing a 16-day mission to outfit the International Space Station, spent 299 days in space and traveled more than 122.8 million miles during its 25 flights. It launched on its first mission on May 7, 1992. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, STS-134 Pilot Gregory H. Johnson and Mission Specialist Roberto Vittori with the European Space Agency accompany space shuttle Endeavour's move, or "rollover," to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final and upcoming STS-134 mission. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Mission Specialist Andrew Feustel, seen here, last flew to NASA's Hubble Space Telescope in 2009. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

STS-134 mission Commander Mark Kelly is seen preparing to enter space shuttle Endeavour on a monitor in Firing Room Four of the Launch Control Center (LCC), Monday, May 16, 2011, at the 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. Photo Credit: (NASA/Bill Ingalls)

The press site at the NASA Kennedy Space Center is seen as the sun rises a few hours prior to the launch of the space shuttle Endeavour with the STS-134 crew, Monday, May 16, 2011, 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. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. -- An interactive docking simulator developed by Lockheed Martin gave STS-134 launch guests at NASA's Kennedy Space Center in Florida the opportunity to fly a realistic docking maneuver with the International Space Station. The center screen provides the forward view to the docking target while the white T-shaped handle is used for translation corrections during the maneuver. The Sensor Test for Orion Relnav Risk Mitigation, or STORRM, flight test planned for space shuttle Endeavour's STS-134 mission will mature the sensor technologies to make these docking operations easier and safer for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, employees hold up a banner to commemorate space shuttle Endeavour's STS-134 mission as it is transported from Orbiter Processing Facility-2 to the Vehicle Assembly Building. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, employees gather to hold up a banner to commemorate space shuttle Endeavour's STS-134 mission, as it is moved from Orbiter Processing Facility-2 to the Vehicle Assembly Building. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, employees hold up a banner to commemorate space shuttle Endeavour's STS-134 mission as it is transported from Orbiter Processing Facility-2 to the Vehicle Assembly Building. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- Howard Hu, manager for the Orion System Performance and Analysis Office at NASA's Johnson Space Center, provides an overview of the Sensor Test for Orion Relnav Risk Mitigation, or STORRM, flight test that space shuttle Endeavour will perform on the last on-orbit day of the STS-134 mission. The overview took place at NASA's Kennedy Space Center in Florida where Endeavour is awaiting liftoff. During the mission, Endeavour will fly a dedicated maneuver to simulate an Orion rendezvous trajectory, while two Orion sensors collect visual- and laser-based relative navigation data. This will provide an unprecedented in-flight test opportunity for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Pilot Greg H. Johnson, seen here, last piloted space shuttle Endeavour during its STS-123 mission in 2008. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Commander Mark Kelly, seen here, last commanded space shuttle Discovery during its STS-124 mission in 2008. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, media gather outside of Orbiter Processing Facility-2 to photograph space shuttle Endeavour's move, or "rollover," to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final and upcoming STS-134 mission. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Mission Specialists Andrew Feustel (left), European Space Agency astronaut Roberto Vittori and Michael Fincke are photographed after their arrival. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour approaches the Vehicle Assembly Building, or VAB, on its move from Orbiter Processing Facility-2 where it was processed for its final mission, STS-134. In the VAB, Endeavour will be lifted into a high bay where it will be joined to its external fuel tank and solid rocket boosters. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, enters the Canister Rotation Facility from the Space Station Processing Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Mission Specialist Greg Chamitoff is photographed as he speaks to media. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour approaches the Vehicle Assembly Building, or VAB, on its move from Orbiter Processing Facility-2 where it was processed for its final and upcoming STS-134 mission. In the VAB, Endeavour will be lifted into a high bay where it will be joined to its external fuel tank and solid rocket boosters. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Pilot Greg H. Johnson is photographed after his arrival. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, is in the Canister Rotation Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, enters the Canister Rotation Facility from the Space Station Processing Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, media gather outside of Orbiter Processing Facility-2 to photograph space shuttle Endeavour's move, or "rollover," to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final and upcoming STS-134 mission. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Shuttle Landing Facility in Florida, STS-134 Mission Specialist Greg Chamitoff disembarks from his T-38 jet. The STS-134 crew members landed at 12:52 p.m. EDT to get ready for shuttle Endeavour's launch to the International Space Station scheduled for Friday, April 29 at 3:47 p.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- This panoramic image shows space shuttle Endeavour in the transfer aisle of the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida, where workers have attached an overhead crane to the spacecraft. The crane will lift Endeavour into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, media photograph space shuttle Endeavour's move, or "rollover," to the Vehicle Assembly Building (VAB) from Orbiter Processing Facility-2. In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final and upcoming STS-134 mission. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour approaches the Vehicle Assembly Building, or VAB, on its move from Orbiter Processing Facility-2 where it was processed for its final mission, STS-134. In the VAB, Endeavour will be lifted into a high bay where it will be joined to its external fuel tank and solid rocket boosters. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Commander Mark Kelly is photographed as he speaks to media. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Shuttle Landing Facility in Florida, STS-134 crew members, Pilot Greg H. Johnson and European Space Agency astronaut Roberto Vittori greet each other upon arrival. The STS-134 crew landed at 12:52 p.m. EDT to prepare for shuttle Endeavour's launch to the International Space Station scheduled for Friday April 29 at 3:47 p.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, space shuttle Endeavour is secured to a transporter for its move, or "rollover" from Orbiter Processing Facility-2 to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, European Space Agency astronaut Roberto Vittori, STS-134 Mission Specialist, is photographed after his arrival. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Mission Specialist Greg Chamitoff is photographed as he speaks to media while Commander Mark Kelly (left) and Mission Specialist Andrew Fuestel look on. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, is in the Canister Rotation Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, workers accompany space shuttle Endeavour as it is being transported from Orbiter Processing Facility-2 to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, is in the Canister Rotation Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, enters the Canister Rotation Facility from the Space Station Processing Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour is stationed in the transfer aisle of the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Shuttle Landing Facility in Florida, STS-134 Mission Specialist Andrew Feustel disembarks from his T-38 jet. The STS-134 crew members landed at 12:52 p.m. EDT to get ready for shuttle Endeavour's launch to the International Space Station scheduled for Friday, April 29 at 3:47 p.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, space shuttle Endeavour enters the transfer aisle of the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-134 Pilot Greg H. Johnson is photographed as he speaks to media. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, is moved from the Space Station Processing Facility to the Canister Rotation Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- A canister, carrying the Alpha Magnetic Spectrometer-2 AMS and Express Logistics Carrier-3 for space shuttle Endeavour's STS-134 mission, is moved from the Space Station Processing Facility to the Canister Rotation Facility at NASA's Kennedy Space Center in Florida. There, the canister that protects the space-bound payload will be rotated from a horizontal to vertical position so that it can be installed into Endeavour's payload bay. AMS is a particle physics detector, designed to operate as an external experiment on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for dark matter. AMS-2 will fly to the station aboard Endeavour's STS-134 mission targeted to launch April 19 at 7:48 p.m. EDT. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Shuttle Landing Facility in Florida, STS-134 Commander Mark Kelly (right) and Pilot Greg H. Johnson disembark from the Shuttle Training Aircraft. The STS-134 crew members landed at about 9 a.m. EDT to get ready for space shuttle Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, media gather outside of Orbiter Processing Facility-2 to photograph space shuttle Endeavour's move, or "rollover," to the Vehicle Assembly Building (VAB). In the VAB, Endeavour will be lifted into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final and upcoming STS-134 mission. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, spare parts, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA

CAPE CANAVERAL, Fla. -- At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, European Space Agency astronaut Roberto Vittori, STS-134 Mission Specialist, is photographed after his arrival. The STS-134 crew members landed at about 9 a.m. EDT for final preparations for Endeavour's liftoff to the International Space Station scheduled for Monday, May 16 at 8:56 a.m. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

NASA Kennedy Space Center Assistant Launch Director Pete Nickolenko monitors the countdown to the launch of the space shuttle Endeavour (STS-134) from Firing Room Four of the Launch Control Center (LCC), Monday May 16, 2011, at the 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. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Space Operations William Gerstenmaier points to one the monitors in Firing Room Four of the Launch Control Center (LCC) as NASA Administrator Charles Bolden, right, and other NASA managers look on during the launch of the space shuttle Endeavour (STS-134), Monday, May 16, 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. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Space Operations William Gerstenmaier monitors the countdown to the launch of the space shuttle Endeavour (STS-134) from Firing Room Four of the Launch Control Center (LCC), Monday, May 16, 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. Photo Credit: (NASA/Bill Ingalls)

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Mission Specialist Greg Chamitoff, seen here, last served as flight engineer and science officer aboard the International Space Station in 2008. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, Mallory Jennings and Heather Paul, aerospace engineers with Johnson Space Center's Spacesuit Life Support, perform a spacesuit demonstration during the STS-134 Tweetup event. About 150 people from 43 states, Washington, D.C., and half a dozen countries are participating in the event. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Mission Specialist Michael Fincke, seen here, last served as a member of the Expedition 18 crew of the International Space Station in 2009. This will be Fincke's first flight aboard a space shuttle. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour's six STS-134 astronauts, dressed in their orange launch-and-entry suits, wave to news media and other spectators before hopping aboard the Astrovan parked in front of the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. The modified Airstream recreational vehicle has transported astronauts to their spacecraft since 1984. From left, are Mission Specialists Greg Chamitoff, Andrew Feustel, Roberto Vittori with the European Space Agency and Michael Fincke, Pilot Greg H. Johnson and Commander Mark Kelly. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- In the Operations and Checkout Building (O&C) at NASA's Kennedy Space Center in Florida, space shuttle Endeavour's STS-134 astronauts put on their launch-and-entry suits and check the fit of their helmets and gloves before heading to the Astrovan for the ride to Launch Pad 39A. Mission Specialist Roberto Vittori with the European Space Agency, seen here, will be making his third trip to the International Space Station. His first mission was in 2002 and second in 2005, both of which were launched aboard a Russian Soyuz spacecraft. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, Mallory Jennings, left, and Heather Paul, aerospace engineers with Johnson Space Center's Spacesuit Life Support, perform a spacesuit demonstration during the STS-134 Tweetup event. About 150 people from 43 states, Washington, D.C., and half a dozen countries are participating in the event. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A model of the Sensor Test for Orion Relnav Risk Mitigation, or STORRM, is displayed at NASA's Kennedy Space Center in Florida. Seen here, is the International Space Station docking target and STORMM sensor enclosure assembly. A flight test of STORRM will be performed on STS-134 on the last on-orbit day of the mission, when space shuttle Endeavour will fly a dedicated maneuver to simulate an Orion rendezvous trajectory. Throughout the maneuver, two Orion sensors will collect visual- and laser-based relative navigation data. This will provide an unprecedented in-flight test opportunity for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, Mallory Jennings, left, and Heather Paul, aerospace engineers with Johnson Space Center's Spacesuit Life Support, perform a spacesuit demonstration during the STS-134 Tweetup event. About 150 people from 43 states, Washington, D.C., and half a dozen countries are participating in the event. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour's six STS-134 astronauts, dressed in their orange launch-and-entry suits, wave to news media and other spectators as they walk toward the Astrovan parked in front of the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. The modified Airstream recreational vehicle has transported astronauts to their spacecraft since 1984. Leading the way are Commander Mark Kelly, right, and Pilot Greg H. Johnson. Behind Kelly are crewmates Michael Fincke and Andrew Feustel. Behind Johnson are crewmates Roberto Vittori with the European Space Agency and Greg Chamitoff. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, Mallory Jennings and Heather Paul, aerospace engineers with Johnson Space Center's Spacesuit Life Support, perform a spacesuit demonstration during the STS-134 Tweetup event. About 150 people from 43 states, Washington, D.C., and half a dozen countries are participating in the event. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour's six STS-134 astronauts, dressed in their orange launch-and-entry suits, wave to news media and other spectators as they walk toward the Astrovan parked in front of the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. The modified Airstream recreational vehicle has transported astronauts to their spacecraft since 1984. Leading the way is Commander Mark Kelly, followed by crewmates Greg H. Johnson, Michael Fincke, Andrew Feustel, Roberto Vittori with the European Space Agency and Greg Chamitoff. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- About 150 people from 43 states, Washington, D.C., and half a dozen countries participate in the STS-134 Tweetup event at NASA's Kennedy Space Center in Florida. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Heather Hinkel, principal investigator for the Sensor Test for Orion Relnav Risk Mitigation, or STORRM, Project at NASA's Johnson Space Center, provides an overview of the flight test that space shuttle Endeavour will perform on the last on-orbit day of the STS-134 mission. The overview took place at NASA's Kennedy Space Center in Florida where Endeavour is awaiting liftoff. During the mission, Endeavour will fly a dedicated maneuver to simulate an Orion rendezvous trajectory, while two Orion sensors collect visual- and laser-based relative navigation data. This will provide an unprecedented in-flight test opportunity for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- Heather Hinkel, principal investigator for the Sensor Test for Orion Relnav Risk Mitigation, or STORRM, Project at NASA's Johnson Space Center, provides an overview of the flight test that space shuttle Endeavour will perform on the last on-orbit day of the STS-134 mission. The overview took place at NASA's Kennedy Space Center in Florida where Endeavour is awaiting liftoff. During the mission, Endeavour will fly a dedicated maneuver to simulate an Orion rendezvous trajectory, while two Orion sensors collect visual- and laser-based relative navigation data. This will provide an unprecedented in-flight test opportunity for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- Frank Novak, project manager for the Sensor Test for Orion Relnav Risk Mitigation, or STORRM, at NASA's Langley Research Center in Hampton, Va., provides an overview of the flight test that space shuttle Endeavour will perform on the last on-orbit day of the STS-134 mission. The overview took place at NASA's Kennedy Space Center in Florida where Endeavour is awaiting liftoff. During the mission, Endeavour will fly a dedicated maneuver to simulate an Orion rendezvous trajectory, while two Orion sensors collect visual- and laser-based relative navigation data. This will provide an unprecedented in-flight test opportunity for America's next-generation exploration spacecraft. STS-134 also will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, this image shows the rear of space shuttle Endeavour and it covered three main engines as a worker attaches an overhead crane. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, this image shows the rear of space shuttle Endeavour and it covered three main engines as a worker attaches an overhead crane. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, workers attach an overhead crane to the rear of space shuttle Endeavour. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, a worker attaches an overhead crane to space shuttle Endeavour. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, workers attach an overhead crane to space shuttle Endeavour. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. -- In the transfer aisle of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, a worker attaches an overhead crane to space shuttle Endeavour. The crane will lift the spacecraft into a high bay where it will be attached to its external fuel tank and solid rocket boosters for its final mission, STS-134. Endeavour and its STS-134 crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer, a high-pressure gas tank, additional spare parts for Dextre and micrometeoroid debris shields to the International Space Station. Launch is targeted for April 19 at 7:48 p.m. EDT. For more information visit, http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Frankie Martin

CAPE CANAVERAL, Fla. - Inside Orbiter Processing Facility-2 at Kennedy Space Center in Florida, a crane is used to lift the Orbiter Boom Sensor System, or OBSS, from the payload bay of space shuttle Endeavour. The OBSS will be transported to the Vehicle Assembly Building for refurbishment. After refurbishment, the boom will be reinstalled in Endeavour for use during the STS-134 mission, currently targeted for launch in July. Photo credit: NASA_Jim Grossmann

CAPE CANAVERAL, Fla. - Inside Orbiter Processing Facility-2 at Kennedy Space Center in Florida, technicians begin to detach the Orbiter Boom Sensor System, or OBSS, from the payload bay of space shuttle Endeavour. The OBSS will be transported to the Vehicle Assembly Building for refurbishment. After refurbishment, the boom will be reinstalled in Endeavour for use during the STS-134 mission, currently targeted for launch in July. Photo credit: NASA_Jim Grossmann

CAPE CANAVERAL, Fla. - Inside Orbiter Processing Facility-2 at Kennedy Space Center in Florida, technicians detach the Orbiter Boom Sensor System, or OBSS, from the payload bay of space shuttle Endeavour. The OBSS will be transported to the Vehicle Assembly Building for refurbishment. After refurbishment, the boom will be reinstalled in Endeavour for use during the STS-134 mission, currently targeted for launch in July. Photo credit: NASA_Jim Grossmann

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Launch Pad 39A, the Load Control Assembly-2 (LCA-2) has been replaced inside of space shuttle Endeavour. Located in Endeavour's aft avionics bay 5, the LCA-2, which distributes power to nine shuttle systems, is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail April 29 during the first launch attempt for the STS-134 mission and has been replaced. Systems will be retested before the launch is rescheduled. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. The mission also will be the final spaceflight for Endeavour. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Launch Pad 39A, the Load Control Assembly-2 (LCA-2) has been replaced inside of space shuttle Endeavour. Located in Endeavour's aft avionics bay 5, the LCA-2, which distributes power to nine shuttle systems, is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail April 29 during the first launch attempt for the STS-134 mission and has been replaced. Systems will be retested before the launch is rescheduled. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. The mission also will be the final spaceflight for Endeavour. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. -- At NASA Kennedy Space Center's Launch Pad 39A, the Load Control Assembly-2 (LCA-2) has been replaced inside of space shuttle Endeavour. Located in Endeavour's aft avionics bay 5, the LCA-2, which distributes power to nine shuttle systems, is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail April 29 during the first launch attempt for the STS-134 mission and has been replaced. Systems will be retested before the launch is rescheduled. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. The mission also will be the final spaceflight for Endeavour. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. – STS-134 pilot Greg Johnson speaks to guests about the final mission of the space shuttle Endeavour at the Visitor Complex of NASA's Kennedy Space Center in Florida. STS-134 commander Mark Kelly, pilot Greg Johnson and Mission Specialists Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori lifted off May 16, 2011 aboard space shuttle Endeavour. During the nearly 16-day STS-134 mission, Endeavour delivered to the International Space Station the Alpha Magnetic Spectrometer and spare parts, including two S-band communications antennas and a high-pressure gas tank. This was the 36th shuttle mission to the station and Endeavour's 25th and final flight. For more information, visit: www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/main/index.html Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – STS-134 mission specialist Gregory Chamitoff speaks to guests about the final mission of the space shuttle Endeavour at the Visitor Complex of NASA's Kennedy Space Center in Florida. STS-134 commander Mark Kelly, pilot Greg Johnson and Mission Specialists Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori lifted off May 16, 2011 aboard space shuttle Endeavour. During the nearly 16-day STS-134 mission, Endeavour delivered to the International Space Station the Alpha Magnetic Spectrometer and spare parts, including two S-band communications antennas and a high-pressure gas tank. This was the 36th shuttle mission to the station and Endeavour's 25th and final flight. For more information, visit: www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/main/index.html Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – STS-134 mission specialist Michael Fincke speaks to guests about the final mission of the space shuttle Endeavour at the Visitor Complex of NASA's Kennedy Space Center in Florida. STS-134 commander Mark Kelly, pilot Greg Johnson and Mission Specialists Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori lifted off May 16, 2011 aboard space shuttle Endeavour. During the nearly 16-day STS-134 mission, Endeavour delivered to the International Space Station the Alpha Magnetic Spectrometer and spare parts, including two S-band communications antennas and a high-pressure gas tank. This was the 36th shuttle mission to the station and Endeavour's 25th and final flight. For more information, visit: www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/main/index.html Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – STS-134 mission specialist Andrew Feustel speaks to guests about the final mission of the space shuttle Endeavour at the Visitor Complex of NASA's Kennedy Space Center in Florida. STS-134 commander Mark Kelly, pilot Greg Johnson and Mission Specialists Michael Fincke, Gregory Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori lifted off May 16, 2011 aboard space shuttle Endeavour. During the nearly 16-day STS-134 mission, Endeavour delivered to the International Space Station the Alpha Magnetic Spectrometer and spare parts, including two S-band communications antennas and a high-pressure gas tank. This was the 36th shuttle mission to the station and Endeavour's 25th and final flight. For more information, visit: www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/main/index.html Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour rises through clouds of smoke and steam from Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight, the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Sandra Joseph and Kevin O'Connell

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour rises on twin columns of flame from Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight, the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Tony Gray and Tom Farrar

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour roars through clouds of smoke and steam from Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kenny Allen

CAPE CANAVERAL, Fla. -- A cloud of steam and smoke emerge as space shuttle Endeavour's main engines ignite for liftoff at Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight, the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Sandra Joseph and Kevin O'Connell

CAPE CANAVERAL, Fla. -- During the L-1 prelaunch news briefing in the Press Site auditorium at NASA's Kennedy Space Center in Florida, STS-134 Payload Mission Manager Joe Delai speaks to media about the processing and readiness of space shuttle Endeavour's payload for flight. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Launch is scheduled for April 29 at 3:47 p.m. EDT. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- In the Press Site auditorium at NASA's Kennedy Space Center in Florida, NASA Test Director Jeff Spaulding speaks to media about preparations for space shuttle Endeavour's launch on the STS-134 mission. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Launch is scheduled for April 29 at 3:47 p.m. EDT. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov_mission_pages_shuttle_shuttlemissions_sts134_index.html. Photo credit: NASA_Jack Pfaller

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour's main engines are ignited for liftoff at Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight, the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Tony Gray and Tom Farrar

CAPE CANAVERAL, Fla. -- Space shuttle Endeavour soars toward orbit after lifting off from Launch Pad 39A at NASA's Kennedy Space Center in Florida. Endeavour began its final flight, the STS-134 mission to the International Space Station, at 8:56 a.m. EDT on May 16. Endeavour and its six-member crew will deliver the Alpha Magnetic Spectrometer-2 (AMS), Express Logistics Carrier-3, a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the space station. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Rusty Backer and Mike Gayle