** FILE ** In this file image provided by NASA, this is the STS-48 onboard photo of the Upper Atmosphere Research Satellite (UARS) in the grasp of the RMS (Remote Manipulator System) during deployment, from the shuttle in September 1991. (AP Photo/NASA)
NASA VIA ASSOCIATED PRESS
This image of the moon taken by NASA's Lunar Reconnaissance Orbiter shows tracks left by astronauts, as well as ruts left by a moon buggy on the 1972 Apollo 17 mission. The pictures were taken from 13 to 15 miles up and show the landing sites for Apollo 12, 14 and 17.
NASA VIA ASSOCIATED PRESS
This image provided Thursday by NASA shows the Mars rover Opportunity using its camera to take a photograph showing the rover's arm extended toward a light-toned rock, "Tisdale 2," during the rover's 2,695th day on the planet.
This computer-generated graphic provided by NASA shows images of objects in Earth orbit that are currently being tracked. Space junk has made such a mess of Earth's orbit that experts say it may need to be cleaned up. (Associated Press/NASA)
Zoe Bentley, a 14-year-old "unschooler," visits the Mars Yard at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Zoe's parents allow her to explore what she likes rather than take part in a traditional educational system.
A date to go scuba diving with former NASA astronaut and famed moon walker Buzz Aldrin is up for bid in an online auction organized by astronauts to raise money for student science scholarships. (Astronaut Scholarship Foundation)
An image provided by NASA shows Hurricane Irene as photographed from onboard the International Space Station at 3:14 p.m. EDT on Aug. 24, 20ll. The image, captured with a 38 mm lens, reveals the eye of the storm at center of the frame. (AP Photo/NASA)
The Dawn spacecraft launched by NASA took this photo of the pockmarked surface of the asteroid Vesta from 9,500 miles away. The data gathered by the craft over the next year should help future manned missions.
**FILE** In this photo from May 27, 2011, made available by NASA, technicians at Astrotech's payload processing facility in Titusville, Fla., stow solar array #2 against the body of NASA's Juno spacecraft. (Associated Press/NASA)
Atlantis is towed to the Orbitor Processing facility as hundreds of NASA employees gather at the Kennedy Space Center at Cape Canaveral, Fla., on Thursday. The landing of Atlantis marks the end of the 30-year program. (Associated Press)
NASA employees sign a banner at the Kennedy Space Center at Cape Canaveral, Fla., on Thursday, July 21, 2011. The landing of the space shuttle Atlantis marks the end of NASA's 30-year shuttle program. (AP Photo/Dr. Scott M. Lieberman)
Space shuttle Atlantis is towed to the Orbitor Processing Facility for decommissioning as hundreds of NASA employees gather at the Kennedy Space Center at Cape Canaveral, Fla., on Thursday, July 21, 2011. The landing of the spacecraft marks the end of NASA's 30-year shuttle program. (AP Photo/Terry Renna)
NASA Administrator Charles Bolden (right) and pilot Doug Hurley speak while walking under space shuttle Atlantis after it landed at the Kennedy Space Center at Cape Canaveral, Fla., on Thursday, July 21, 2011. The landing of the spacecraft marks the end of NASA's 30-year shuttle program. (AP Photo/Scott Audette, Pool)
This image provided by NASA shows a view of Space Shuttle Atlantis while still docked with the International Space Station taken by crew member Mike Fossum aboard the station Monday. The robotic arm on the shuttle appears to be saluting "goodbye." Earth's airglow is seen as a thin line above Earth's horizon.