As early as 2040, Musk hopes to have thousands or tens of thousands of people living in a city-like colony on Mars. From there, he hopes to continue to increase the colony’s size until it exceeds one million people, at which point he believes there will be a sufficient number of people to “recreate the entire industrial base,” resulting in a sustainable civilization on Mars.
Elon Musk’s presentation at the 67th International Astronautical Congress in Guadalajara, Mexico, is published in the journal New Space.
In the paper, Musk explores the planetary options for expanding to a space-bearing civilization and describes the advantages Mars offers.
“I think there are really two fundamental paths. History is going to bifurcate along two directions. One path is we stay on Earth forever, and then there will be some eventual extinction event. I do not have an immediate doomsday prophecy, but eventually, history suggests, there will be some doomsday event,” he writes in the article.
“The alternative is to become a space-bearing civilization and a multi-planetary species, which I hope you would agree is the right way to go.”
Musk provides a comprehensive review of a system architecture required for a rocket and spaceship capable of transporting people and supplies to Mars, comparing possible vehicle designs and performance features.
“There has been a lot of great work by NASA and other organizations in the early exploration of Mars and understanding what Mars is like. Where could we land? What is the composition of the atmosphere? Where is there water or ice? We need to go from these early exploration missions to actually building a city,” he writes.
“Using traditional methods, taking an Apollo-style approach, an optimistic cost would be about $10 billion per person. Taking the Apollo program as an example, the cost estimates are somewhere between $100 and $200 billion in current-year dollars, and we sent 12 people to the surface of the Moon, which was an incredible thing — probably one of the greatest achievements of humanity.”
“However, that is a steep price to pay for a ticket. You cannot create a self-sustaining civilization if the ticket price is $10 billion per person. If we can get the cost of moving to Mars to be roughly equivalent to a median house price in the United States, which is around $200,000, then I think the probability of establishing a self-sustaining civilization is very high. I think it would almost certainly occur.”
“Not everyone would want to go. In fact, probably a relatively small number of people from Earth would want to go, but enough would want to go who could afford it for it to happen. People could also get sponsorship. It gets to the point where almost anyone, if they saved up and this was their goal, could buy a ticket and move to Mars — and given that Mars would have a labor shortage for a long time, jobs would not be in short supply.”
A major challenge facing engineers and scientists at present and discussed in the article is the need to improve the cost per ton of transporting materials to Mars by 5 million percent.
“It is a bit tricky because we have to figure out how to improve the cost of trips to Mars by five million percent. This translates to an improvement of approximately four-and-a-half orders of magnitude. This is not easy. It sounds virtually impossible, but there are ways to do it,” Musk writes.
“These are the key elements that are needed in order to achieve the four-and-a-half orders of magnitude improvement. Most of the improvement would come from full reusability — somewhere between two and two-and-a-half orders of magnitude. The other two orders of magnitude would come from refilling in orbit, propellant production on Mars, and choosing the right propellant.”
“To make Mars trips possible on a large enough scale to create a self-sustaining city, full reusability is essential.”
“Full reusability is really the super-hard one. It is very difficult to achieve reusability even for an orbital system, and that challenge becomes substantially greater for a system that has to go to another planet.”
He continues: “it makes sense to load the spaceship into orbit with essentially tanks dry. If it has really big tanks that you use the booster and tanker to refill once in orbit, you can maximize the payload of the spaceship, so when it goes to Mars, you have a very large payload capability.”
“Hence, refilling in orbit is one of the essential elements of this. Without refilling in orbit, you would have roughly a half order of magnitude impact on the cost. What that means is that each order of magnitude is a factor of 10. Therefore, not refilling in orbit would mean roughly a 500% increase in the cost per ticket.”
According to Musk, producing propellant on Mars is obviously also very important.
“Again, if we did not do this, it would have at least a half order of magnitude increase in the cost of a trip. It would be pretty absurd to try to build a city on Mars if your spaceships just stayed on Mars and did not go back to Earth.”
“The threshold for a self-sustaining city on Mars or a civilization would be a million people,” he writes.
“If you can only go every 2 years and if you have 100 people per ship, that is 10,000 trips. Therefore, at least 100 people per trip is the right order of magnitude, and we may end up expanding the crew section and ultimately taking more like 200 or more people per flight in order to reduce the cost per person.”
“However, 10,000 flights is a lot of flights, so ultimately you would really want in the order of 1,000 ships. It would take a while to build up to 1,000 ships. How long it would take to reach that million-person threshold, from the point at which the first ship goes to Mars would probably be somewhere between 20 and 50 total Mars rendezvous — so it would take 40-100 years to achieve a fully self-sustaining civilization on Mars.”
“What about beyond Mars? As we thought about the system and the reason we call it a system– because generally, I do not like calling things ‘systems,’ as everything is a system, including your dog. However, it is actually more than a vehicle. There is obviously the rocket booster, the spaceship, the tanker and the propellant plant, and the in situ propellant production,” Musk writes.
“If you have all four of these elements, you can go anywhere in the Solar System by planet hopping or moon hopping. By establishing a propellant depot on the asteroid belt or on one of the moons of Jupiter, you can make flights from Mars to Jupiter. In fact, even without a propellant depot at Mars, you can do a flyby of Jupiter.”
“However, by establishing a propellant depot, say on Enceladus or Europa, and then establishing another one on Titan, Saturn’s moon, and then perhaps another one further out on Pluto or elsewhere in the Solar System, this system really gives you the freedom to go anywhere you want in the greater Solar System.”
“Therefore, you could travel out to the Kuiper Belt, to the Oort cloud. I would not recommend this for interstellar journeys, but this basic system — provided we have filling stations along the way — means full access to the entire greater Solar System.”
“In my view, publishing this paper provides not only an opportunity for the spacefaring community to read the SpaceX vision in print with all the charts in context, but also serves as a valuable archival reference for future studies and planning,” says Editor-in-Chief Prof. Scott Hubbard, of Stanford University.
“My goal is to make New Space the forum for publication of novel exploration concepts-particularly those that suggest an entrepreneurial path for humans traveling to deep space.”
Elon Musk. 2017. Making Humans a Multi-Planetary Species. New Space 5 (2): 46-61; doi: 10.1089/space.2017.29009.emu
This article is based on text provided by Mary Ann Liebert, Inc.