At NASA's Kennedy Space Center in Florida, shuttle Discovery pauses in between Orbiter Processing Facility-3 and the Vehicle Assembly Building (VAB) during a move called "rollover" on September 9th, 2010. Once inside the VAB, the shuttle will be joined to its solid rocket boosters and external fuel tank. Later, Discovery was scheduled to "rollout" to Launch Pad 39A for its launch to the International Space Station on the STS-133 mission. #

The underside of space shuttle Discovery is visible in this image photographed by an Expedition 23 crew member on the International Space Station soon after the shuttle and station began their post-undocking relative separation on April 17th, 2010. Undocking ended a stay of 10 days, 5 hours and 8 minutes.The recognizable feature on Earth below is the south end of Isla de Providencia, about 150 miles off the coast of Nicaragua near 13.3 degrees north latitude 81.4 degrees west longitude. #

Space Shuttle Discovery prepares to touch down at the shuttle landing facility at Kennedy Space Center on April 20, 2010. Discovery's landing attempts at KSC were scrubbed yesterday due to unacceptable weather conditions. #

At NASA's Kennedy Space Center in Florida, shuttle Discovery begins to back out of Orbiter Processing Facility-3 during a move called "rollover" to the nearby Vehicle Assembly Building (VAB). #

This panoramic image of space shuttle Discovery was photographed in Orbiter Processing Facility-3 at NASA's Kennedy Space Center in Florida, as the shuttle was being prepared for "rollover" to the Vehicle Assembly Building in September of 2010. #

In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, STS-133 Mission Specialist Tim Kopra practices with a tool he will use while in space. The astronauts are at Kennedy for the Crew Equipment Interface Test, or CEIT, which provides the crew with hands-on training and observation of shuttle and flight hardware for their mission to the International Space Station. #

NASA astronauts Steve Bowen (foreground) and Alvin Drew, both STS-133 mission specialists, attired in training versions of their Extravehicular Mobility Unit (EMU) spacesuits, are submerged in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center in January of 2010. Divers are in the water to assist Bowen and Drew in their rehearsal, which is intended to help prepare them for work on the exterior of the International Space Station. #

Attired in training versions of their shuttle launch and entry suits, NASA astronauts Steve Lindsey (left), STS-133 commander; Eric Boe (background), pilot; Tim Kopra (right foreground) and Alvin Drew, both mission specialists, participate 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 on January 25th, 2010. #

In the Space Shuttle Main Engine Processing Facility at NASA's Kennedy Space Center in Florida, a suspect turbopump is removed from space shuttle main engine No. 1. The turbopump experienced an issue during torque testing and is being replaced for Discovery's STS-133 mission to the International Space Station. When complete, all three main engines will be transported back to Orbiter Processing Facility-3 and reinstalled. #

At NASA's Kennedy Space Center in Florida, a space shuttle main engine secured on a Hyster forklift is installed in space shuttle Discovery in Orbiter Processing Facility-3. Three main engines, weighing 7,000 pounds each, will be installed for the STS-133 mission to the International Space Station. Engines are inspected and maintained in the nearby Space Shuttle Main Engine Processing Facility before installation. #

While performing touch-and-go landings over the Shuttle Landing Facility runway, STS-133 Commander Steve Lindsey and Pilot Eric Boe enjoyed a perfect sunset over NASA's Kennedy Space Center in Florida. Lindsey and Boe flew two Shuttle Training Aircraft (STA), which are Gulfstream II business jets modified to mimic the shuttle's handling during the final phase of landing. #

At NASA's Kennedy Space Center in Florida, space shuttle Discovery's STS-133 crew members pose for a group photo on the Shuttle Landing Facility runway following their arrival aboard T-38 training jets. From left, are Mission Specialists Nicole Stott, Michael Barratt, Tim Kopra and Alvin Drew, Pilot Eric Boe, and Commander Steve Lindsey. #

At NASA's Kennedy Space Center in Florida, the external fuel tank for space shuttle Discovery's STS-133 mission makes its way from the Launch Complex 39 turn basin to the 525-foot-tall Vehicle Assembly Building. #

A DragonEye proximity sensor developed by Space Exploration Technologies (SpaceX) is installed while space shuttle Discovery is in Orbiter Processing Facility-3 at NASA's Kennedy Space Center in Florida. DragonEye is a Laser Imaging Detection and Ranging (LIDAR) sensor that will be tested on Discovery's docking operation with the International Space Station. Discovery's STS-133 mission, targeted to launch November 1, will be the second demonstration of the sensor, following shuttle Endeavour's STS-127 mission in 2009. The DragonEye sensor will guide SpaceX's Dragon spacecraft as it approaches and berths to the station on future cargo re-supply missions. #

In Orbiter Processing Facility-3 at NASA's Kennedy Space Center in Florida, STS-133 Commander Steve Lindsey familiarizes himself with the layout of the shuttle's cockpit. The astronauts were at Kennedy for the Crew Equipment Interface Test, or CEIT, which provides the crew with hands-on training and observation of shuttle and flight hardware for their mission to the International Space Station. #

During a simulated pad emergency on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-133 Mission Specialists Tim Kopra, left, and Alvin Drew hop in a slidewire basket that would take them to a safe bunker below the pad in an unlikely emergency situation. #

At NASA's Kennedy Space Center in Florida, the STS-133 crew takes a break from a simulated launch countdown to ham it up on the 195-foot level of Launch Pad 39A. From left are, Pilot Eric Boe, Mission Specialist Michael Barratt, Commander Steve Lindsey, and Mission Specialists Tim Kopra, Nicole Stott, and Alvin Drew. #

At NASA's Kennedy Space Center in Florida, workers in the Vehicle Assembly Building begin to secure a large yellow, metal sling to shuttle Discovery for its lift from the transfer aisle into High Bay 3. In the bay, the shuttle will be attached to its external fuel tank and solid rocket boosters. The operation began Sept. 9 and wrapped up early Sept. 10. Later, Discovery will "roll out" to Launch Pad 39A in preparation for its launch to the International Space Station on the STS-133 mission. #

NASA astronauts Michael Barratt and Nicole Stott, both STS-133 mission specialists, participate in an exercise in the systems engineering simulator in the Avionics Systems Laboratory at NASA's Johnson Space Center. The facility includes moving scenes of full-sized International Space Station components over a simulated Earth. #

At NASA's Kennedy Space Center in Florida, a large yellow, metal sling lifts shuttle Discovery from the transfer aisle into High Bay 3 of the Vehicle Assembly Building. In the bay, the shuttle will be attached to its external fuel tank and solid rocket boosters. #

In the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, this panoramic image captures the twin solid rocket boosters and the base of the external fuel tank in place on the mobile launcher platform, awaiting the arrival of space shuttle Discovery. #

Robonaut 2 waits inside the electromagnetic interference chamber at Johnson Space Center following tests that ensure the robot's electronic systems won't cause problems for other important systems at the International Space Station. R2 will be journeying to the space station onboard Discovery during the STS-133 mission. #

Robonaut 2 or R2 for short is now tweeting at twitter.com/AstroRobonaut. With the help of its team, the robot sent its first tweet on July 26, 2010. R2 will be traveling to the International Space Station aboard Discovery as part of the STS-133 mission. #

At NASA's Kennedy Space Center in Florida, space shuttle Discovery begins its nighttime trek, known as "rollout," from the Vehicle Assembly Building to Launch Pad 39A. It will take the shuttle, attached to its external fuel tank, twin solid rocket boosters and mobile launcher platform, about six hours to complete the move atop a crawler-transporter. #

As the sun begins to rise at Launch Pad 39A at NASA's Kennedy Space Center in Florida, the STS-133 crew members are in the pad's White Room preparing to board space shuttle Discovery during the Terminal Countdown Demonstration Test (TCDT). #

Bathed in bright xenon lights, space shuttle Discovery makes its nighttime trip from the Vehicle Assembly Building to Launch Pad 39A at NASA's Kennedy Space Center in Florida. #

On Launch Pad 39A at NASA's Kennedy Space Center in Florida, preparations are under way to reattach the vent line to the ground umbilical carrier plate (GUCP) on space shuttle Discovery's external fuel tank. A hydrogen gas leak at that location during tanking for Discovery's STS-133 mission to the International Space Station caused the launch attempt to be scrubbed November 5. #

The beginning of a total lunar eclipse hovers over the top of space shuttle Discovery as the spacecraft waits to roll back from Launch Pad 39A to the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida. #

Preparations are under way in the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida to examine space shuttle Discovery's external fuel tank. Shown here is the nose of the shuttle, which still is attached to the external tank and solid rocket boosters. Technicians will begin to remove thermal sensors that will give engineers data about the changes the tank went through during the loading and draining of super-cold propellants during a tanking test on December 17. Engineers also will examine 21-foot-long support beams, called stringers, on the outside of the tank's intertank region. Also on the agenda, is to re-apply foam to the outside of the tank. #

Space shuttle Discovery is attached to Launch Pad 39A at NASA's Kennedy Space Center in Florida. Later, the rotating service structure that protects the shuttle from the elements and provides access inside the vehicle will be moved into place. #

Photographers from around the world set up to take photos Wednesday night, February 23, 2011 as the Rotating Service Structure is rolled back from the space shuttle Discovery. #

At NASA's Kennedy Space Center in Florida, space shuttle Discovery is illuminated by bright xenon lights on Launch Pad 39A after the rotating service structure was moved away. #

STS-133 crew members, front row from left, pilot Eric Boe, commander Steve Lindsey, second row, mission specialist Alvin Drew, Steve Bowen, third row from left, Nicole Stott, and Michael Barratt, leave the Operations and Checkout Building at the Kennedy Space Center in Cape Canaveral, Florida, for a trip to the launch pad Thursday, February 24, 2011. The space shuttle Discovery is scheduled to lift off this afternoon on an 11-day mission to the international space station. #

Crew members of the STS-133 space shuttle Discovery gather together on the launchpad at the Kennedy Space Center in Florida before boarding the orbiter for the final space flight in this still image taken from video February 24, 2011. #

Rising on twin columns of fire and creating rolling clouds of smoke and steam, space shuttle Discovery lifts off Launch Pad 39A at NASA's Kennedy Space Center in Florida on a picturesque, warm, late February afternoon. Launch of the STS-133 mission was at 4:53 p.m. EST on February 24. #

The space shuttle Discovery lifts off at Kennedy Space Center in Cape Canaveral, Florida, Thursday, February 24, 2011. Discovery, the world's most traveled spaceship, thundered into orbit for the final time Thursday, heading toward the International Space Station with a crew of six on a journey that marks the beginning of the end of the shuttle era. #

Spectators watch as space shuttle Discovery lifts off from the Kennedy Space Center in Cape Canaveral, Florida, February 24, 2011. Six astronauts are aboard on a mission to the International Space Station. #

Erik Halsteili, of Bellingham, Washington, points out the Space Shuttle Discovery launch to his brother, while dug into the sand on the beach in Cape Canaveral, Florida, Thursday, February 24, 2011. #

Space shuttle Discovery lifts off from the Kennedy Space Center in Cape Canaveral, Florida, February 24, 2011. Discovery carries a crew of six astronauts on a mission to the International Space Station. #

A long range tracking camera shows a close-up view of the space shuttle Discovery en route to space with it's three main engines and two solid rocket boosters firing in this still image taken from video, February 24, 2011. #

Space shuttle Discovery (bottom) continues to orbit as the solid rocket boosters separate from the spacecraft after it lifted off from the Kennedy Space Center in Cape Canaveral, Florida, February 24, 2011. Space shuttle Discovery launched into orbit on its final flight on Thursday for an 11-day mission to the International Space Station. #