A space elevator is a fairly simple concept. It would be made of an ultra-strong metal ribbon that stretches from a mobile base in the ocean at the Earth's equator, up thousands of miles into space, attaching at its other end to an "anchor" in geostationary orbit. Robotic climbers rush up the ribbons, pulling cars full of their cargo—human or otherwise. Because the space elevator pulls cargo out of our gravity well, rather than pushing it using combustion, it would save a lot of energy and be capable of bringing far more materials offworld quickly.