This vehicle has the potential to become the United States' first operational military spaceplane, after the cancellation of Dyna-Soar in 1963. It is expected to operate in a velocity range of up to Mach 25 on reentry. Among the technologies to be demonstrated with the X-37 are improved thermal protection systems, avionics, the autonomous guidance system, and an advanced airframe. The on-board engine is the Rocketdyne AR-2/3, which is fueled by hydrogen peroxide and JP-8.