The U.S. Air Force is developing an Orbital Test Vehicle, based on the design of a NASA X-37 technology demonstrator, to continue full-scale development and on-orbit testing of an unmanned long-duration, reusable space vehicle. The new OTV effort takes advantage of industry and government investments by Air Force, NASA, and the Defence Advanced Research Projects Agency. The Air Force Rapid Capabilities Office will lead the initiative with continued participation of NASA and the Air Force Research Laboratory. Boeing is the prime contractor for the OTV program. Following transfer from NASA to DARPA in October 2004, the X-37 technology demonstrator, the Approach and Landing Test Vehicle, recently completed a series of captive carry and free flight tests from a commercial aircraft. The ALTV validated the X-37 program flight dynamics and extended the flight envelope beyond the earlier low speed/low altitude tests conducted by NASA. The ALTV, in its current configuration, is not capable of space flight.