The cost of getting to the Moon is too high to sustain permanent human habitats. People and equipment for small stations can be transported via rockets, but even small habitats are unlikely to be sustainable. The cost of rocket trips from Earth into orbit, not even to the Moon, are just too high. Tens of millions of dollars are spent to put a single human in orbit.

It's the huge gravity well of Earth and the lesser one of the Moon that will keep people off the Moon. Rockets are expensive; most of the weight of a launch goes into fuel and boosters that are completely used up. Payloads are small and the dollar-per-pound cost is enormous. Putting a single human in orbit costs tens of millions of dollars.

Two engineers have an idea for creating a much cheaper approach to beating the gravity wells. Their target is to bring costs down enough to make the Moon a second permanent home for humanity. Trips to Earth orbit have to be cheaper, but that's only a start of their ideas to make life on the Moon sustainable.