CAPE CANAVERAL, Fla. - The "towback" vehicle slowly pulls Space shuttle Discovery from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery rolls to a stop on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Powers

CAPE CANAVERAL, Fla. - Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, checks out the underside of space shuttle Discovery, following its final return from space. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, invited guests, managers and employees gather near the Air Traffic Control Tower at the Shuttle Landing Facility (SLF) to watch shuttle Discovery return from space for the last time. Discovery touched down on Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Discovery's STS-133 crew participates in a post-landing news conference in the Press Site TV Auditorium at NASA's Kennedy Space Center in Florida. From left, are NASA Public Affairs Officer George Diller, STS-133 Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Discovery and crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tom Farrar

CAPE CANAVERAL, Fla. - Space shuttle Discovery casts a shadow in the water beside the towway on its slow trip from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's tail fin clears the hangar door of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - The Convoy Command Vehicle leads space shuttle Discovery and the landing convoy along the towway from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests watch shuttle Discovery return from space for the last time. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- Shuttle Launch Director Mike Leinbach, left, talks to STS-133 Pilot Eric Boe underneath space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Boe and his crew wrapped up a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-133 Mission Specialist Alvin Drew admires space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Drew and his crewmates returned from a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. EST. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, retired NASA astronaut Jon McBride mingles with about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests who are at the Shuttle Landing Facility (SLF) to watch shuttle Discovery return from space for the last time. Discovery touched down on Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Chuck Tintera

CAPE CANAVERAL, Fla. - Space shuttle Discovery appears to be a mirage as it makes its way down Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tony Gray and Tom Farrar

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA managers welcome space shuttle Discovery's STS-133 crew members home to Kennedy Space Center in Florida. In the foreground, Discovery Flow Director Stephanie Stilson hugs STS-133 Pilot Eric Boe. Beside them, Shuttle Launch Director Mike Leinbach congratulates Mission Specialist Alvin Drew on a successful mission. Discovery and its six-member crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, bringing an end to the 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery, pulled by its "towback" vehicle, approaches Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Towering above the processing bays is the 525-foot-tall Vehicle Assembly Building. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Photographers are in position near the towway to capture space shuttle Discovery as it is towed from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery, its drag chute unfurled, appears to be a mirage as it travels down Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tony Gray and Tom Farrar

CAPE CANAVERAL, Fla. - Streams of smoke trail from the main landing gear tires as space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida after 13-days in space, completing the 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Linda Perry

CAPE CANAVERAL, Fla. - Space shuttle Discovery is half in, half out of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-133 crew poses for a photo in front of space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. From left, are Mission Specialists Nicole Stott and Michael Barratt, Pilot Eric Boe, Commander Steve Lindsey, and Mission Specialists Alvin Drew and Steve Bowen. Discovery and crew returned to Earth at 11:57 a.m., completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Streams of smoke trail from the main landing gear tires as space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Chad Baumer

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, greets the STS-133 crew members as they exit the crew transport vehicle after landing aboard space shuttle Discovery. Leading the crew is Commander Steve Lindsey, followed by Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden introduces the STS-133 crew to media representatives waiting on the Shuttle Landing Facility at Kennedy Space Center in Florida to hear statements about space shuttle Discovery's final spaceflight mission. Crew members, from left, are Mission Specialists Nicole Stott and Michael Barratt, Commander Steve Lindsey, Pilot Eric Boe and Mission Specialists Alvin Drew and Steve Bowen. The crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA managers welcome space shuttle Discovery's STS-133 crew members home to Kennedy Space Center in Florida. In the foreground, Shuttle Launch Director Mike Leinbach congratulates STS-133 Commander Steve Lindsey on a successful mission. Discovery and its six-member crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, bringing an end to the 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Chuck Tintera

CAPE CANAVERAL, Fla. -- Employees gather underneath space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. In the foreground, NASA Administrator Charlie Bolden congratulates STS-133 Commander Steve Lindsey on a successful mission. Lindsey and his crew returned from a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. EST. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- On the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-133 Commander Steve Lindsey talks to media representatives about space shuttle Discovery's final spaceflight mission. Mission Specialist Steve Bowen, left, and NASA Administrator Charlie Bolden are behind Lindsey. The STS-133 crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- On the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-133 Commander Steve Lindsey talks to media representatives about space shuttle Discovery's final spaceflight mission. Behind Lindsey, from left, are Mission Specialists Nicole Stott and Michael Barratt, Pilot Eric Boe, and Mission Specialists Alvin Drew and Steve Bowen. The STS-133 crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery glides above Runway 15 before touching down at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Rusty Backer

CAPE CANAVERAL, Fla. -- STS-133 Mission Specialist Michael Barratt admires space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Barratt and his crewmates returned from a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. EST. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- With its drag chute unfurled, space shuttle Discovery rolls down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Chad Baumer

CAPE CANAVERAL, Fla. -- Space shuttle Discovery's main landing gear touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida after 13-days in space, completing the 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Ben Cooper

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden talks to about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests who are at Kennedy Space Center in Florida to watch shuttle Discovery return from space for the last time. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. - Space shuttle Discovery, attached to a purge unit that pumps conditioned air into the shuttle while it is towed, awaits entry into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- The nose gear on space shuttle Discovery descends in anticipation of touch down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Sandra Joseph and Kevin O'Connell

CAPE CANAVERAL, Fla. -- Associate Administrator for Space Operations Bill Gerstenmaier, left, STS-133 Commander Steve Lindsey and Space Shuttle Launch Integration Manager Mike Moses talk about Lindsey's recent 13-day, 5.3-million-mile mission to the International Space Station aboard space shuttle Discovery. The STS-133 crew returned to Earth at 11:57 a.m. on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The STS-133 crew poses for a photo with NASA Fire Rescue personnel in front of space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. From left, are Mission Specialists Nicole Stott and Michael Barratt, Pilot Eric Boe, Commander Steve Lindsey, and Mission Specialists Alvin Drew and Steve Bowen. Discovery and the flight crew returned to Earth at 11:57 a.m., completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Shuttle Launch Director Mike Leinbach and STS-133 Mission Specialist Nicole Stott pose for a photo on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Stott and her crewmates returned from a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - A puff of smoke from space shuttle Discovery's tires follows their contact with Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Sandra Joseph and Kevin O'Connell

CAPE CANAVERAL, Fla. - The Convoy Command Vehicle moves aside while space shuttle Discovery is positioned outside the door of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery is attached to a purge unit that pumps conditioned air into the shuttle while it is towed. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden, right, shows off space shuttle Discovery at Kennedy Space Center in Florida, following its final return from space. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery glides above Runway 15 before touching down at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Chad Baumer

CAPE CANAVERAL, Fla. - Space shuttle Discovery's main landing gear tires are down as the spacecraft approaches Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Linda Perry

CAPE CANAVERAL, Fla. - Vehicles in the landing convoy surround space shuttle Discovery at NASA's Kennedy Space Center in Florida. A purge unit, connected to Discovery's aft end, pumps conditioned air into the shuttle for the slow trip from the Shuttle Landing Facility to Orbiter Processing Facility-2. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery appears to be a mirage as it coasts down Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tony Gray and Tom Farrar

CAPE CANAVERAL, Fla. -- STS-133 Pilot Eric Boe admires space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Boe and his crewmates returned from a 13-day, 5.3-million-mile mission to the International Space Station at 11:57 a.m. EST. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, walks around space shuttle Discovery, following its final return from space. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Terry and Mike Kerley

CAPE CANAVERAL, Fla. - A NASA Fire Rescue Services vehicle drives toward space shuttle Discovery, which touched down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery, attached to a purge unit that pumps conditioned air into the shuttle while it is towed, approaches Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Behind the processing bays is the 525-foot-tall Vehicle Assembly Building. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- On the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, STS-133 Commander Steve Lindsey talks to media representatives about space shuttle Discovery's final spaceflight mission. Behind Lindsey, from left, are Mission Specialists Nicole Stott and Michael Barratt, Pilot Eric Boe, Mission Specialists Alvin Drew and Steve Bowen, and NASA Administrator Charlie Bolden. The STS-133 crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Employees guide space shuttle Discovery into position for entry into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Employees accompany space shuttle Discovery as it is pulled by a "towback" vehicle from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - With its drag chute unfurled, space shuttle Discovery rolls down Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - The nozzles of two orbital maneuvering system pods and three space shuttle main engines protrude from the aft end of space shuttle Discovery as it is pulled by a "towback" vehicle toward Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery enters Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida during a move called "towback." Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery's drag chute deploys on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Powers

CAPE CANAVERAL, Fla. - Space shuttle Discovery's drag chute deploys on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Powers

CAPE CANAVERAL, Fla. -- The landing convoy that will make space shuttle Discovery secure for towing to its processing hangar begins to pull up around the spacecraft following wheelstop on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kenny Allen

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden talks to about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests who are at Kennedy Space Center in Florida to watch shuttle Discovery return from space for the last time. Behind Bolden and to the left is Kennedy's Center Director Bob Cabana. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. - Space shuttle Discovery, attached to a purge unit that pumps conditioned air into the shuttle while it is towed, is reflected in the entranceway to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery is towed into position for entry through the door of Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery is attached to a purge unit that pumps conditioned air into the shuttle while it is towed. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery is connected to its "towback" vehicle, which will slowly pull the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Streams of smoke trail from the main landing gear tires as space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida after 13-days in space, completing the 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Ben Cooper

CAPE CANAVERAL, Fla. - The "towback" vehicle lines up space shuttle Discovery for entry into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery, attached to a purge unit that pumps conditioned air into the shuttle while it is towed, rolls along the towway from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. In the distance at left is the 525-foot-tall Vehicle Assembly Building. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA managers welcome space shuttle Discovery's STS-133 crew members home to Kennedy Space Center in Florida. In the foreground, Shuttle Launch Director Mike Leinbach congratulates STS-133 Commander Steve Lindsey on a successful mission. Discovery and its six-member crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, bringing an end to the 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- With its drag chute unfurled, space shuttle Discovery rolls down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Terry and Mike Kerley

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Director Bob Cabana, left, and NASA Administrator Charlie Bolden talk to about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests who are at the center to watch shuttle Discovery return from space for the last time. Discovery touched down on Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- The news media ask space shuttle Discovery's STS-133 crew members questions during a post-landing news conference in the Press Site TV Auditorium at NASA's Kennedy Space Center in Florida. From left, are NASA Public Affairs Officer George Diller, STS-133 Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Discovery and crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's main landing gear touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida after 13-days in space, completing the 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Linda Perry

CAPE CANAVERAL, Fla. - Space shuttle Discovery slides through the open hangar door into Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden, left, STS-133 Pilot Eric Boe and STS-133 Flight Director Bryan Lunney talk about the recent 13-day, 5.3-million-mile mission to the International Space Station aboard space shuttle Discovery. The STS-133 crew returned to Earth at 11:57 a.m. on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery's drag chute deploys on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tim Powers

CAPE CANAVERAL, Fla. -- Space shuttle Discovery's STS-133 crew participates in a post-landing news conference in the Press Site TV Auditorium at NASA's Kennedy Space Center in Florida. From left, are NASA Public Affairs Officer George Diller, STS-133 Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Discovery and crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m., completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Space shuttle Discovery touches down on Runway 15 at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Tom Farrar

CAPE CANAVERAL, Fla. -- Bill Gerstenmaier, associate administrator for Space Operations, greets the STS-133 crew members as they exit the crew transport vehicle after landing at NASA's Kennedy Space Center in Florida aboard space shuttle Discovery. Leading the crew is Commander Steve Lindsey, followed by Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests watch shuttle Discovery return from space for the last time. Discovery touched down on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- The landing convoy that will make space shuttle Discovery secure for towing to its processing hangar begins to pull up around the spacecraft following wheelstop on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - NASA Kennedy Space Center workers watch as space shuttle Discovery rolls to a stop on Runway 15 at the Shuttle Landing Facility in Florida. Landing was at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. On board are Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Nicole Stott, Michael Barratt, Alvin Drew and Steve Bowen. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Photographers are in position beside the towway to capture space shuttle Discovery and the landing convoy on its slow trip from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end. In the background at left is the 525-foot-tall Vehicle Assembly Building. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, invited guests, managers and employees gather near the Air Traffic Control Tower at the Shuttle Landing Facility (SLF) to watch shuttle Discovery return from space for the last time. Discovery touched down on Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- The crew transport vehicle pulls up to space shuttle Discovery on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. STS-133 Commander Steve Lindsey, Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott will undergo brief medical checks in the crew transport vehicle before they walk around the spacecraft that brought them safely home. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, greets the STS-133 crew members as they exit the crew transport vehicle after landing aboard space shuttle Discovery. Leading the crew is Commander Steve Lindsey, followed by Pilot Eric Boe, and Mission Specialists Alvin Drew, Steve Bowen, Michael Barratt and Nicole Stott. Touchdown on the Shuttle Landing Facility's Runway 15 was at 11:57 a.m. EST, bringing an end to the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden leads the STS-133 crew to media representatives waiting on the Shuttle Landing Facility at Kennedy Space Center in Florida to hear statements about space shuttle Discovery's final spaceflight mission. The STS-133 crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- The landing convoy that will make space shuttle Discovery secure for towing to its processing hangar begins to pull up around the spacecraft following wheelstop on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida. Discovery's final return from space completed the 13-day, 5.3-million-mile STS-133 mission. Main gear touchdown was at 11:57:17 a.m., followed by nose gear touchdown at 11:57:28, and wheelstop at 11:58:14 a.m. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- NASA managers welcome space shuttle Discovery's STS-133 crew members home to Kennedy Space Center in Florida. Discovery and its six-member crew landed on the Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, bringing an end to the 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - Space shuttle Discovery and vehicles in the landing convoy enter the towway at NASA's Kennedy Space Center in Florida. The slow trip from the Shuttle Landing Facility to Orbiter Processing Facility-2 is under way. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. - Space shuttle Discovery's "towback" vehicle slowly pulls the spacecraft from the Shuttle Landing Facility to Orbiter Processing Facility-2 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Discovery's aft end and additional landing convoy vehicles follow closely behind. Discovery touched down on Runway 15 at 11:57 a.m., bringing an end to its 39th and final spaceflight mission, STS-133. Discovery and its six-member STS-133 crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. Inside the processing facility, Discovery will be prepared for future public display. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- NASA Administrator Charlie Bolden escorts the STS-133 crew to media representatives waiting on the Shuttle Landing Facility at Kennedy Space Center in Florida to hear statements about space shuttle Discovery's final spaceflight mission. The STS-133 crew returned to Earth at 11:57 a.m. on Runway 15, completing a 13-day, 5.3-million-mile mission to the International Space Station. STS-133 delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, invited guests, managers and employees gather near the Air Traffic Control Tower at the Shuttle Landing Facility (SLF) to watch shuttle Discovery return from space for the last time. Discovery touched down on Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. -- NASA Kennedy Space Center Director Bob Cabana, left, and NASA Administrator Charlie Bolden talk to about 50 eighth-grade students from McNair Magnet Middle School in Rockledge, Fla., and other invited guests who are at the center to watch shuttle Discovery return from space for the last time. Discovery touched down on Shuttle Landing Facility's Runway 15 at 11:57 a.m. EST, completing the 13-day STS-133 mission to the International Space Station. Discovery and its six-member crew delivered the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. STS-133 was Discovery's 39th and final mission. This was the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA/Jim Grossmann