FILE - This undated file image provided by the U.S. Air Force shows the X-37B spacecraft. The unmanned Air Force space plane steered itself to a landing early Saturday, June 16, 2012, at a California military base, capping a 15-month clandestine mission. (AP Photo/U.S. Air Force, File)
Air Force's mystery mini-shuttle
A top-secret mini-space shuttle has blasted off from Cape Canaveral. The Air Force launched the unmanned spacecraft Dec. 11 aboard an Atlas V rocket.