crew safety. Other program components Other components of the OSP program were the X-37 and the DART. The X-37 vehicle was designed to flight test advancing technologies to reduce the risk of future reusable launch vehicle systems, including the Orbital Space Plane. The Demonstration for Autonomous Rendezvous Technology or DART, was another flight demonstrator vehicle designed to test technologies required to locate and rendezvous with other spacecraft. Using onboard guidance sensors, DART would have performed a series of maneuvers around a retired satellite. However, after a successful launch, unknown problems with the guidance system caused the vehicle to run out of thruster fuel prematurely, ending the mission before all objectives could be carried out. In 2010, Orbital Sciences Corporation reused some work done under OSP program contracts for its Prometheus spacecraft proposal to NASA under phase 2 of the Commercial Crew Development program. See also Hermes Dream Chaser References Spaceplanes Crewed spacecraft NASA vehicles NASA programs Proposed spacecraft