We want engines to get us into space and take us to the stars. Of course, as many note, we aren’t quite where we want to be yet. But there is hope. At the moment, spaceship engines can be classed into three categories: rockets, sails, and “other,” and each works in their own, individual way. Rockets work by pushing something out the rear; reaction equaling action, you go in the other direction. With sails, something external pushes. And in the “other” category are things like “space drives” and ramjets.