After more than a year in space, the U.S. Air Force's secretive robotic space plane, the X-37B, is coming down soon.
The space plane now circling Earth is the second spacecraft of its kind built for the Air Force by Boeing’s Phantom Works. What payload the X-37B is carrying is classified, and the mission is being carried out by the Air Force Rapid Capabilities Office.
According to an Air Force fact sheet on the vehicle: "The X-37B Orbital Test Vehicle, or OTV, is a non-operational system that will demonstrate a reliable, reusable, unmanned space test platform for the U.S. Air Force. The objectives of the OTV program include space experimentation, risk reduction and a concept of operations development for reusable space vehicle technologies."