Space Shuttle Endeavour's final trek

Ashely Olson, left, poses with her sisters, Alexis, center, and Alyssa in front of the Space Shuttle Endeavour at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif., Thursday, Sept. 20, 2012. Endeavour returned to its California roots after a wistful cross-country journey that paid homage to NASA workers and former Arizona Rep. Gabrielle Giffords and her astronaut husband. (AP Photo/Jae C. Hong)