The ideal technology for space travel would be simple, robust, reliable, lightweight, and volumetrically efficient. It would have no moving parts, which would make it less likely to break. It would be a passive technology, not requiring any energy from the outside. It would be small. It would be light. An ideal technology for space, says chemical engineer Doug Way, is the membrane. Well, OK, membranes can’t do everything. Membranes won’t boost us into space. And they won’t carry us to Mars. But membranes could solve some of the problems of traveling there. And once we arrive, they could help us get back.