Mass driver

Mass driver (or space gun) is a proposed non-rocket launch mechanism, which uses a continuous track to accelerate cargo to orbital speeds. Any method of propulsion is suitable as long as the track can support the required speed, for example coilguns, railguns or magnetic levitation. On airless planets and moons, mass drivers can be built directly on the surface. On planets with atmosphere, the track (or at least its exit) needs to be raised above the atmosphere, for example with a launch loop or an orbital ring.