Associated Press
This frame grab from NASA-TV shows space shuttle Atlantis docked at the International Space Station on Sunday. Atlantis' current supply visit marks the final shuttle mission by NASA.
A frame grab from NASA-TV shows space shuttle Atlantis performing a pitch maneuver as it closes in for one last docking at the International Space Station on Sunday, July 10, 2011. (AP Photo/NASA)
In this image from NASA television astronauts Mike Fincke, left, and Greg Chamitoff, make their way along the P3 Truss on the International Space Station as they make their way back to the quest airlock wrapping up the fourth spacewalk Friday morning, May 27, 2011. (AP Photo/NASA)
In this March 15, 2011 photo provided by NASA, astronaut Scott Kelly, Expedition 26 commander, right, poses with Robonaut 2, the dexterous humanoid astronaut helper, in the Destiny laboratory of the International Space Station. (AP Photo/NASA)
In this image provided by NASA the space shuttle Discovery is seen from the International Space Station as the two orbital spacecraft accomplish their relative separation on March 7, 2011 after an aggregate of 12 astronauts and cosmonauts worked together for over a week. The area below is the southwestern coast of Morocco in the northern Atlantic. During a post undocking fly-around, the crew members aboard the two spacecraft collected a series of photos of each other's vehicle. Discovery ended its nearly 27-year flying career when it landed Wednesday. (AP Photo/NASA)
In this image provided by NASA the space shuttle Discovery is seen from the International Space Station as the two orbital spacecraft accomplish their relative separation on March 7, 2011 after an aggregate of 12 astronauts and cosmonauts worked together for over a week. The area below is the southwestern coast of Morocco in the northern Atlantic. During a post undocking fly-around, the crew members aboard the two spacecraft collected a series of photos of each other's vehicle. Discovery ended its nearly 27-year flying career when it landed Wednesday. (AP Photo/NASA)
In this image provided by NASA the space shuttle Discovery is seen from the International Space Station as the two orbital spacecraft accomplish their relative separation on March 7, 2011, after an aggregate of 12 astronauts and cosmonauts worked together for over a week. During a post undocking fly-around, the crew members aboard the two spacecraft collected a series of photos of each other's vehicle. Discovery ended its nearly 27-year flying career when it landed Wednesday. (AP Photo/NASA)
In this image provided by NASA the International Space Station is seen from Discovery backdropped against clouds over Earth, as the two orbital spacecraft accomplish their relative separation on March 7, 2011, after an aggregate of 12 astronauts and cosmonauts worked together for over a week. During a post undocking fly-around, the crew members aboard the two spacecraft collected a series of photos of each other's vehicle. Discovery ended its nearly 27-year flying career when it landed Wednesday. (AP Photo/NASA)
This image provided by NASA and photographed Sunday March 6, 2011, by an Expedition 26 crew member on the International Space Station shows Earth's thin line of atmosphere and a gibbous moon. (AP Photo/NASA)
Space shuttle Discovery makes its final landing Wednesday after a mission to the International Space Station, its last flight after nearly 27 years of service. It will become a museum exhibit. (Associated Press)
NASA crews prepare Space Shuttle Discovery for its scheduled launch on Thursday for an 11-day trip to the International Space Station — its 39th mission. No other craft has flown in space as much. (Associated Press)
In this March 3, 2011 photo provided by NASA, astronauts Eric Boe, left, and Scott Kelly move the crate containing Robonaut 2, better known as R2, the first humanoid robot in space, at the International Space Station. The 220-mile-high (354-kilometer-high) unveiling of R2, the first humanoid robot in space, is being moved up at the urging of the president of the United States. Astronaut Catherine Coleman said Friday, March 4, 2011 that she and the 11 other humans aboard the shuttle-station complex want to get R2 out of its packing material as soon as possible. R2, flew to the International Space Station aboard Discovery and will stay behind when the shuttle leaves Monday. (AP Photo/ESA/NASA)