Inside Elon Musk's Mars Math

“I do in fact know that this sounds crazy,” Elon Musk tweeted this week. “But if humanity wishes to become a multi-planet species, then we must figure out how to move millions of people to Mars.”

Like any big, bold idea, Musk’s plan for colonizing Mars strikes you at first glance as indeed crazy, and it also probably makes your head spin a bit. How on earth, you are probably wondering, could we possibly do that? But let’s suspend disbelief for a moment and assume Musk is able to build a reusable rocket that can efficiently shuttle colonists to the Red Planet. The question is: what then?

Musk, who told Bloomberg “I want to die on Mars,” is concerned with the question of how to make a Mars colony self-sustaining. That would require 80,000 volunteers, Musk said in a recent speech to the Royal Aeronautical Society. Then Musk qualified that number on Twitter. We will need 80,000 volunteer colonists per year, he argued, in order to eventually reach a population in the millions.

What’s the Big Idea?

Musk is throwing out a bunch of numbers here, but they are not as random as they may seem. In order for his project to be economically feasible, the cost of space travel will have to be drastically reduced. So here’s what needs to happen. An initial group of 10 colonists will need to pay $500,000 a pop for the one-way trip to Mars. As the colony becomes increasingly self-sustainable — and fewer resources need to be transported from Earth — that will free up more space for additional human cargo. Transporting more and more paying customers, and relying on a “rapid and reusable” rocket, is key to Musk’s price improvement strategy.

Of course, there are many unknowns about the human capacity to live, and flourish, in space, so the question of how to create a stable population on Mars is enormously complex. For instance, will fertility and mortality rates be similar to what they are on Earth?

We need to answer these questions before we can truly determine whether Musk’s model is ultimately sustainable. After all, what does it take for a colony to succeed?

One useful analogy we can look to is the growth of colonial America. The most dramatic jump in population occurred between 1630 — when Puritan emigration from England began — and 1650. During that period the population rose from 4,600 to 50,400. The decades that followed produced fairly steady growth, with the population eventually breaking the one million threshold somewhere around 1750.

In other words, it took over one hundred years for the colonial population to reach the same target that Musk hopes to hit in 12.5 years.

What’s the Significance?

In case you still think this is all just crazy talk, it is important to realize that Musk — an enormously successful entrepreneur who has created four of the most innovative companies in America — is simply following the mission statement of one of his companies, SpaceX, which is to make humans a multi-planetary species.

As Musk tells Big Think, is analytically minded, first and foremost:

I think it is important to apply critical thinking…and in my critical thinking I’m interested in considering whether you have the right axioms, and the axioms are necessarily related to the conclusions that really follow. It’s not too complicated, but most people don’t actually do that.

And then I also try to reason from first principles, which is a good framework that is used in physics where you try to reason outward from things that are considered fundamental truths. And to vet any theory or idea you have against those fundamental truths to make sure you’re not violating them. These are, I think quite elementary things, but yet, very few people do them. I think it’s a good idea to use those mental constructs.

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