Space exploration is a magnet for crank science. It’s nearly impossible to talk about something like intersteller propulsion and keep people on the same page as real-world physics and engineering. And it’s even more difficult to talk about far-reaching ideas like colonizing planets without drifting into the realm of science fiction. But here I go anyway.

Consider the famous scenes in 2001, where a NASA official flies to a beautiful space station operated by Pan Am airlines and then on to a Lunar colony. You’re looking at a simulated trillion dollar infrastructure, but why was it built? Who is using it? Who is paying for it? How does it make money? What are people doing on the Moon that is worth all this? These are issues that science fiction simply overlooks.

As in 2001, the analogy is often drawn between the airline industry and a future spaceflight industry. The difference is, on the Earth there are real destinations to fly to. There are countless social and economic reasons to travel from one populated region to another on the Earth. This is not the same as spending billions of dollars to fly to Mars, pick up a rock and return to Earth. For spaceflight to be practical and large-scale, there must be a reason, there must be a destination.

People talk about things like mining helium-3 on the Moon. Both technically and economically that’s nonsense. At present, there is nothing remotely valuable enough to pay for the cost of mining and interplanetary transport. But more importantly, these ideas represents a fundamental misconception about wealth, in the sense defined by Adam Smith. Real estate is valuable because people want to live there and work there. Human activity is the true definition of wealth, and human presence is what makes a destination interesting.

Thus, colonizing space is a bootstrapping problem. it is a problem in economics, not engineering. If Mars had an atmosphere and a population, it would be of incalculable value, and people would pay to travel there and back. But how do reach that point? The technology of cheaper travel and terriforming Mars is fascinating to speculate about. I believe it could be done almost entirely with robotic technology. But that is not what blocks us from proceeding. The real problem is developing a mechanism for funding, when there is a huge return on investment but a turnaround time of centuries. You would have to create a Martian Futures Market that people have genuine confidence in — a serious enterprise that makes steady progress, backed by corporations with proven expertise and probably at least one first-world government.

Maybe you have to engage people’s territorial and competative instincts. Let’s say America declared that it was going to unilaterally colonize Mars and annex it? After the obligatory student protest marches all over the world, I believe other nations might start a competing program! And then it’s hard for anyone to back down. If both programs make enough progress, investors will want them to merge and cooperate eventually. It is just too expensive to duplicate the effort.