ROUGH CUT - NO REPORTER NARRATION<br/> <br />An unmanned Atlas 5 rocket carrying a small robotic space shuttle lifted off from Cape Canaveral Air Force Station in Florida on Tuesday (December 11) for the third flight in a classified military test program.<br/> <br />The 196-foot (60-meter) rocket blasted off at 1:03 p.m. ET (1603 GMT) carrying the military's original X-37B experimental space plane, also known as an Orbital Test Vehicle, or OTV.<br/> <br />The unmanned, reusable space shuttle, one of two operated by the U.S. Air Force, spent 224 days circling Earth during its debut mission in 2010. A sister ship blasted off in 2011 and landed itself after 469 days in space, completing the second orbital test flight.<br/> <br />The military is not saying how long the third X-37B mission will last, nor what the vehicle will be doing in orbit.
