The Boeing-built X-37B, the US military's unmanned robotic space shuttle, is shown in this handout photo at Vandenberg Air Force Base, California June 16, 2012, after completing a secretive 15-month test flight. [Photo/Agencies]
The US military's unmanned X-37B robotic space shuttle lands after returning from orbit, from a secretive 15-month test flight, in California in this still image taken from infrared video shot on June 16, 2012. [Photo/Agencies]