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