Endeavour was the last space shuttle to join NASA's fleet: It was built to replace the shuttle Challenger, which was lost in an explosion shortly after launch in 1986. This view shows Endeavour perched atop a modified Boeing 747 on May 2, 1991, beginning the ferry flight from Palmdale, Calif. - where the shuttle was built - to Kennedy Space Center in Florida.
Endeavour lifts off from Launch Pad 39B at NASA's Kennedy Space Center on May 7, 1992, beginning its first mission. The STS-49 mission's primary task was the repair of the Intelsat VI telecommunications satellite. Endeavour was the only shuttle to make its maiden flight from Pad 39B.
Endeavour astronauts Richard Hieb, Thomas Akers and Pierre Thuot hold onto the 4.5-ton Intelsat VI satellite after making a six-handed "capture" on May 13, 1992. The satellite failed to rise above low Earth orbit when it was launched in 1990. During Endeavour's maiden mission, astronauts retrieved the satellite, attached it to a new upper-stage booster and relaunched it to its intended geosynchronous orbit. This mission marked the first time that three people from the same spacecraft walked in space at the same time.
Endeavour astronauts Jan Davis, left, and Mae Jemison prepare to deploy the lower body negative pressure apparatus on Sept. 15, 1992. Scientific research was the main focus of this Spacelab-J mission, also known as STS-47. The mission's crew included the first African-American woman to fly in space (Mae Jemison) and the only husband-and-wife team to go into space together (Jan Davis and Mark Lee).
Astronauts flew on Endeavour to take on the first Hubble servicing mission in December 1993. In this picture, spacewalkers Story Musgrave and Jeffrey Hoffman perform an orbital ballet. The coastline of western Australia is visible below. The complex and highly successful repair mission allowed Hubble, which was launched with a defective mirror, to see into the universe with unprecedented clarity.
Endeavour spacewalker Jim Newman holds onto the International Space Station's Unity connecting module as he removes covers and works on connecting cables on Dec. 7, 1998. The STS-88 flight marked the shuttle fleet's first space station assembly mission.
Eliot J. Schechter / Getty Images
The shuttle Endeavour sits on its launch pad at Kennedy Space Center in Florida on July 11, 2007. "Endeavor" is spelled incorrectly on the banner. The shuttle was named after the HMS Endeavour, the British sailing ship that carried Captain James Cook on his first voyage of discovery from 1768 to 1771. That's why Endeavour reflects the British spelling of the word.
During the first spacewalk of the STS-118 mission, on Aug. 11, 2007, astronaut Rick Mastracchio and Canada's Dave Williams (out of frame) attach a new segment of the International Space Station's truss and retract a collapsible radiator.
The crew members of Endeavour's STS-118 crew pose for their official portrait on Aug. 8, 2007. From left are Rick Mastracchio, Barbara Morgan, pilot Charles Hobaugh, mission commander Scott Kelly, Tracy Caldwell, Canadian astronaut Dave Williams and Alvin Drew. During this flight, Morgan became the first educator astronaut to go into orbit. In 1986, she was the backup for Christa McAuliffe, the New Hampshire teacher who died in the Challenger explosion.
Endeavour spacewalker Rick Mastracchio relocates communications equipment on the International Space Station during an outing on Aug. 15, 2007.
NASA via AP
Tiles on the underside of the space shuttle Endeavour show evidence of damage in a photo taken on Aug. 12, 2007, using the shuttle's robotic arm and a camera-tipped extension boom. The close-up imagery helped mission managers determine that the gouge would pose no threat during Endeavour's atmospheric re-entry.
Crew members aboard the shuttle Endeavour captured this picture of Hurricane Dean's eye in the Caribbean on Aug. 18, 2007. The STS-118 mission ended on Aug. 21, one day earlier than planned, to avoid potential complications due to the storm. Forecasters worried that Hurricane Dean could have swept over Houston around the time of landing - but in the end, the storm took a different course.
Bill Ingalls / NASA
NASA Administrator Michael Griffin watches the liftoff of the space shuttle Endeavour from the Launch Control Center at NASA's Kennedy Space Center on Nov. 14, 2008. The STS-126 mission delivered two spare bedrooms as well as a second kitchen and bathroom to the International Space Station.
Tim Jacobs / NASA
Workers perform repairs on the shuttle Endeavour's external fuel tank at the Kennedy Space Center launch pad on June 14, 2009. The launch team detected a leak of hydrogen fuel from the tank, forcing a delay in Endeavour's STS-127 launch. The mission's main task was the delivery of the final segment of Japan's Kibo laboratory to the International Space Station.
Gene Blevins / Zuma Press
A giant bolt of lightning hits Endeavour's Florida launch pad on July 10, 2009. Technical problems and severe weather forced five delays in Endeavour's STS-127 launch.
The space shuttle Endeavour rises from Kennedy Space Center's Launch Pad 39A on July 15, 2009, on the STS-127 mission's sixth launch attempt.
The space shuttle Endeavour is photographed from the International Space Station soon after its departure on July 28, 2009. A Soyuz spacecraft docked at the station is visible in the foreground.
The shuttle Endeavour is silhouetted against different layers of the sunlit atmosphere during its approach to the International Space Station on Feb. 9, 2010. The primary payloads for Endeavour's STS-130 mission were the Tranquility module and the Cupola observation deck and control station.
Astronaut George Zamka, Endeavour's commander for the STS-130 mission, peeks out a window of the International Space Station's newly installed Cupola observation deck on Feb. 19, 2010. The Cupola provides an unparalleled view of Earth below.
John Raoux / AP
The external fuel tank for Endeavour's final mission, STS-134, is transported to the Vehicle Assembly Building at the Kennedy Space Center in Florida on July 14, 2010. STS-134's main payload is the $2 billion Alpha Magnetic Spectrometer, an international physics experiment.
NASA via Getty Images
The space shuttle Endeavour is lowered into place for attachment to its external fuel tank and solid rocket boosters in the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida on March 1, 2011.
Roberto Gonzalez / Getty Images
The sun rises as photographers gather on a hill to take pictures shortly after the shuttle Endeavour's arrival at Kennedy Space Center's Launch Pad 39A on March 11, 2011.
Craig Rubadoux / Daytona Beach News-Journal via AP
Photographers track the space shuttle Endeavour's ascent as it pierces the clouds and disappears after launch from NASA's Kennedy Space Center in Florida on May 16.
Scott Audette / Reuters
Spectators react as the space shuttle Endeavour lifts off from NASA's Kennedy Space Center in Florida on May 16. Hundreds of thousands of people watched the start of the next-to-last space shuttle flight.
Stefanie Gordon / for msnbc.com
Stefanie Gordon captured this remarkable picture of the space shuttle Endeavour rising above Florida's cloud cover on May 16 while she was on a commercial flight from New York to Palm Beach, Fla.
Nasa T.V. via EPA
NASA astronaut Greg Chamitoff holds a handrail during the fourth and last spacewalk conducted by the shuttle Endeavour's crew at the International Space Station on May 27. Chamitoff and astronaut Michael Fincke (visible in the reflections from Chamitoff's helmet visor) transferred an inspection boom system, completing U.S. assembly of the station. The May 27 outing marked the last scheduled spacewalk to be conducted by a space shuttle crew.
NASA via Reuters
Backdropped by a nighttime view of Earth and the starry sky, the space shuttle Endeavour is seen docked to the International Space Station on May 28.
Joe Skipper / Reuters
The space shuttle Endeavour lands for the last time at NASA's Kennedy Space Center in Florida on June 1, 2011. The touchdown capped Endeavour's 16-day mission to deliver a $2 billion science experiment to the International Space Station on NASA's next-to-last shuttle flight.
A NASA poster pays tribute to Endeavour and its space missions over the past two decades. The shuttle is shown rising to orbit, with patches for each of its missions laid out in a spiral. The HMS Endeavour, which inspired the spaceship's name, is shown at lower right. At upper left, pictures of Endeavour are framed in the windows of the Cupola. The background image depicts the nebula NGC 602 as seen by the Hubble Space Telescope, which was first serviced by Endeavour in 1993.