Endeavour launched into its 25th and final voyage Monday—also the anniversary of the space shuttle's first landing on May 16, 1992. The shuttle flight will be the second-to-last flight for the U.S. space agency's 30-year space shuttle program. Atlantis is set to make the final space shuttle flight in June.
"It's the premier physics experiment; it's probably the most expensive thing ever flown by the space shuttle," Kelly said in a NASA statement. (See a picture of space shuttle Endeavour backlighted by lightning.)
Photograph from NASA/AP
A Space Station Is Born
The first U.S. module of the International Space Station, dubbed the Unity node, is joined to Russia's Zarya module (top) in December 1998, essentially giving birth to the International Space Station.
First launched in May 1992, Endeavour was the fifth and last NASA space shuttle to be built. It was constructed as a replacement for Challenger, following that orbiter's deadly accident in 1986. (See "Five Myths of the Challenger Disaster Debunked.")
Photograph courtesy NASA
Brighter Days for Endeavour
The aurora australis, or southern lights, shimmer beyond Endeavour's vertical fin in a 1994 long-exposure picture. (See more aurora pictures.)
Endeavour was named after the ship commanded by James Cook, the 18th-century British explorer, navigator, and astronomer. The name was chosen through a national competition involving students in U.S. elementary and secondary schools.
NASA astronaut George Zamka, the commander of the February 2010 Endeavour space shuttle mission, peers out of the newly installed cupola—a sort of observation deck—that the shuttle delivered to the International Space Station. (See more pictures of the space station observation deck.)
As the final space shuttle to be built, Endeavour initially featured new and updated hardware not present in the other orbiters, including improved plumbing and electrical connections for longer missions as well as updated flight systems.
"Challenger and Columbia were built first, and they had 1970s technology at best—and in some cases, 1960s technology. With Endeavour being built last, NASA was able to update a lot of that technology," said Roger Launius, a spaceflight historian at the National Air and Space Museum in Washington, D.C.
"It's mostly things like electronics that are behind the panels, not necessarily things that you see when you walk into the spacecraft, but that enable it to perform more effectively and also lighten it a lot."
The Hubble Space Telescope is berthed in Endeavour's payload bay following the satellites's capture by astronauts during Hubble's first servicing mission in 1993.
The mission restored Hubble's image quality to its original specs. Previously, the telescope had been returning blurry images due to a flawed mirror. (See NASA experts' top Hubble Space Telescope pictures.)
Photograph from Time Life Pictures, Getty Images
Clouds of ash billow from the Kliuchevskoi volcano on Russia's Kamchatka Peninsula in this 1994 picture taken by Endeavour astronauts.
As this photo was being taken, other members of the space shuttle crew were taking radar data of the event.
A tray bearing different materials is exposed to unfiltered sunlight and the vacuum of space outside the International Space Station in 2007 during the third Materials International Space Station Experiment, or MISSE-3.
MISSE-3 was left in space for more than a year before being retrieved by Endeavour astronauts.
MISSE-8, the final materials experiment for the space station, will be flown into space as part of Endeavour's final mission.
"Our samples must go into space to prove themselves," Mark Hersam, an engineer at Northwestern University, whose team helped choose the materials to be tested on MISSE-8, told the UPI news service.
"This is the ultimate test. If the materials are resistant to radiation there, they could be used to dramatically improve the technology currently used in space, such as that found in satellites."
Endeavour rides a column of fire and smoke into space in 2001 as an F-15 fighter jet guards the airspace below.
As one of the lighter orbiters in NASA's fleet, Endeavour is often used to ferry the heaviest cargo into space, since the lower combined weight would require less fuel to reach orbit, the National Air and Space Museum's Launius said.
"If you've got a very large, heavy module, you would put it in Endeavour if you could, because it's a lighter vehicle," Launius said.
Photograph by Shaun Withers, U.S. Air Force/AP
All Hands on Deck
In 1992, during Endeavour's first mission, three astronauts hold on to the 4.5-ton Intelsat VI satellite above the space shuttle's payload bay after manually capturing the satellite.
Photograph from NASA
A U.S. Department of Defense "picosatellite" floats above Earth after its release from Endeavour's payload bay in 2009. Endeavour will once again carry some pint-size satellites into space during its last mission.
Called Sprites, the thin, 1-inch-square (2.5-centimeter-square) computer chips will be suspended outside the International Space Station, allowing scientists to test how the chips hold up and transmit data in the harsh conditions of space.
"Their small size allows them to travel like space dust," said Mason Peck, a mechanical and aerospace engineer at Cornell University involved in the Sprites' design.
"Blown by solar winds, they can 'sail' to distant locations without fuel," Peck said in a statement. "We're actually trying to create a new capability and build it from the ground up. ... We want to learn what's the bare minimum we can design for communication from space."
Photograph courtesy NASA
Dominic Gorie and Mark Kelly
NASA astronauts Dominic Gorie (left) and Mark Kelly pose with a U.S. Navy wings patch on the rear flight deck of Endeavour in 2001.
Kelly, who will command Endeavour's final flight, is the husband of U.S. Representative Gabrielle Giffords of Arizona, who survived an assassination attempt in January. Giffords watched Endeavour take off at Kennedy Space Center on Monday.
Photograph courtesy NASA
NASA Night Flight
Endeavour lifts off from Kennedy Space Center's launch pad 39A on November 14, 2008.