The Age of Discovery Comes to an End

Having put in 26 loyal years, Discovery is on its final planned mission, as NASA winds down its shuttle program. In the mission, named STS-133, astronauts will bring a new module to the space station -- and a new robot astronaut. (NASA / Tony Gray)

<b>Sunlight</b> Backdropped by a cloud-covered part of Earth, space shuttle Discovery is featured in this image photographed by an Expedition 26 crew member as the shuttle approaches the International Space Station during STS-133 rendezvous and docking operations. (NASA)

<b>Flight Day 7</b> Anchored to a Canadarm2 mobile foot restraint, STS-133 Mission Specialist Steve Bowen participates in the mission's second spacewalk as construction and maintenance continue on the International Space Station. Over the course of six hours and 14 minutes, Bowen and Mission Specialist Alvin Drew tackled a variety of tasks, including venting into space some remaining ammonia from a failed pump module they moved during the mission's first spacewalk. (NASA)

<b>Anchored</b> Anchored to a Canadarm2 mobile foot restraint, NASA astronaut Steve Bowen participates in the STS-133 mission's second spacewalk as construction and maintenance continue on the International Space Station. During the six-hour, 14-minute spacewalk, Bowen and fellow astronaut Alvin Drew tackled a variety of tasks, including venting into space some remaining ammonia from a failed pump module they moved during the mission's first spacewalk.   (NASA)

<b>Flight Day 8</b> Expedition 26 and STS-133 crew members share a meal in the Unity node of the International Space Station while space shuttle Discovery remains docked with the station. Pictured from the left are NASA astronauts Steve Bowen, Nicole Stott, both STS-133 mission specialists; Steve Lindsey, STS-133 commander; European Space Agency astronaut Paolo Nespoli, Expedition 26 flight engineer; and NASA astronaut Michael Barratt, STS-133 mission specialist. (NASA)

<b>Flight Day 3</b> The docked space shuttle Discovery and the Canadian-built Dextre, also known as the Special Purpose Dextrous Manipulator, are photographed by an STS-133 crew member on the International Space Station. The blackness of space and Earth's horizon provide the backdrop. (NASA)

Feb. 24: Space shuttle Discovery lifts off from Pad 39A at the Kennedy Space Center in Cape Canaveral, Fla. Discovery on its last mission, will carry the Leonardo Permanent Multipurpose Module, or PMM, to the International Space Station. (AP) (AP)

Feb. 24: Space shuttle Discovery lifts off from Kennedy Space Center in Cape Canaveral, Fla. Discovery is on an 11-day mission to the international space station. (AP) (AP)

Feb. 24: Space shuttle Discovery lifts off from Pad 39A at the Kennedy Space Center in Cape Canaveral, Fla. (AP) (AP)

Feb. 24: Space shuttle Discovery lifts off from Pad 39A at the Kennedy Space Center in Cape Canaveral, Fla. (AP)

At NASA's Kennedy Space Center in Florida, space shuttle Discovery's STS-133 pose for a photo on the Shuttle Landing Facility runway after arriving in T-38 jets. From left, are Mission Specialists Nicole Stott, Michael Barratt, Steve Bowen and Alvin Drew, Pilot Eric Boe, and Commander Steve Lindsey. (NASA/Kim Shiflett)

Space shuttle Discovery arrives at Launch Pad 39A from the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. It took the shuttle, attached to its external fuel tank, twin solid rocket boosters and mobile launcher platform, about seven hours to complete the move atop a crawler-transporter. This is the second time Discovery has rolled out to the pad for the STS-133 mission, and comes after a thorough check and modifications to the shuttle's external tank. (NASA/Kim Shiflett)

Xenon lights illuminate space shuttle Discovery and create a mirror image in the Turn Basin at NASA's Kennedy Space Center in Florida as the space vehicle rolls out to Launch Pad 39A from the Vehicle Assembly Building. (NASA/Kim Shiflett)

Construction of Discovery began in 1982. The vehicle would go on to become NASA's most prolific space shuttle. (NASA)

Discovery launched from Kennedy Space Center, August 30, 1984, for its first mission: STS-41-D. This made it the third operational orbiter for the U.S. space agency. (NASA)

Discovery docked at the International Space Station during STS-131. Mexico, Baja California, and the Gulf of California (Sea of Cortez) can be seen below as the Earth sits in the background. (NASA)

The Space Shuttle Discovery approaches the International Space Station for docking -- but before the link-up could occur, the orbiter "posed" for a thorough series of inspection photos, including performing the "Rendezvous pitch maneuver." (NASA)

Discovery has flown 38 flights, completed 5,247 orbits, and has spent 322 days in orbit. Discovery is the orbiter fleet leader, having flown more flights than both Atlantis and Endeavor and is the oldest orbiter in service. (Source: Wikipedia)

Smoke trails from the landing gear tires as Space Shuttle Discovery touches down at Edwards Air Force Base at the conclusion of STS-128. (NASA / Jim Ross)

Discovery streaks across the Florida sky during a rare night launch in 2006. (AP)

Buzz Lightyear returned from the International Space Station in September of 2009. NASA and Disney teamed up in 2008 to put the "Toy Story" figurine into orbit via a flight on the shuttle Discovery.  (NASA)

Space Shuttle Discovery sits atop launch pad 39A at the Kennedy Space Center in the early morning hours before mission STS-119, on March 11, 2009. (NASA / Bill Inglais)

Like many of us, Space Shuttle Discovery often travels via Boeing 747. This one, however, is a specially modified 747 that NASA crafted to carry the space shuttle on its back. (NASA / Jim Ross)

Discovery makes its way towards the Kennedy Space Center's Vehicle Assembly Building, where operators will hoist it up with a metal sling as the crew connects it into place atop the booster rockets -- leaving the combined unit in a familiar, launch-day shape. (Jen Scheer)

With the Countdown Clock in the foreground, Space Shuttle Discovery lifts off. (AP)

NASA mission specialist Clayton Anderson participates in the third and final session of extravehicular activity on mission STS-131. Anderson's goal: routine maintenance on the International Space Station. (NASA)

Attired in training versions of their shuttle launch and entry suits, the STS-133 crew prepare for Discovery's final flight in a simulation exercise in the motion-base shuttle mission simulator in the Jake Garn Simulation and Training Facility at NASA's Johnson Space Center. (NASA / JSC James Blair)

Discovery rolls to the pad for its final planned mission to the International Space Station. (NASA / Tom Moler)