Space Shuttle Atlantis lands at the Kennedy Space Center July 21, 2011 in Cape Canaveral, Florida. The landing brings to a close the 30-year era of the space shuttle program that began in 1981, and has included 135 missions. (Photo by Bill Ingalls/NASA via Getty Images)

NASA workers pose in front of the Space Shuttle Atlantis after it landed at Kennedy Space Center July 21, 2011 in Cape Canaveral, Florida. (Photo by Win McNamee/Getty Images)

Space shuttle Atlantis is rolled over to the Obiter Processing Facility shortly after landing at NASA's Kennedy Space Center Shuttle Landing Facility July 21, 2011 in Cape Canaveral, Florida. (Photo by Bill Ingalls/NASA via Getty Images)

Space Shuttle Atlantis is towed at Kennedy Space Center July 21, 2011 in Cape Canaveral, Florida. (Photo by Joe Raedle/Getty Images)