So you want to colonize Mars, huh? Well, Mars is very far away, and for a colony to function so far from earthly support, things must be thought very carefully. Including how many people it takes to make it work.
A new study sets the minimum number of settlers at 110.
The new study is titled “Minimum Number of Settlers for Survival on Another Planet”. The author is Jean-Marc Salotti, professor at the Bordeaux National Polytechnic Institute. His article is published in Nature: Scientific Reports.
Obviously, there is a lot to think about when it comes to having some kind of sustained presence on another planet. How will people organize themselves? What equipment will they bring? How will they extract resources on site? What kinds of skills are needed?
These questions have been addressed before, of course, and in this report Salotti says that “The use of in the place Different social organizations and resources have been proposed, but there is still a poor understanding of the problem variables. “
This study focuses primarily on one question: How many people will it take? Salotti writes: “I demonstrate here that a mathematical model can be used to determine the minimum number of colonists and the way of life to survive on another planet, using Mars as an example.
Much thought has been given to colonizing Mars. SpaceX says its proposed interplanetary spacecraft could carry 100 people to Mars. Musk has talked about building a fleet of them, so that there is a constant flow of resources to Mars. But is that realistic? “However,” writes Salotti, “this is an optimistic estimate of capacity, the feasibility of reuse remains uncertain, and qualifying the vehicle to land on Mars and relaunch from Mars could be very difficult and take several decades.”
A similar dynamic hangs over other parts of the Mars colony discussion. Many researchers have considered the use of resources in situ, for example. Gases from the atmosphere and minerals from the soil could be extracted. On-site resource extraction could provide organic compounds, iron, and even glass. Even if we grant the feasibility of these ideas, “the complexity of implementation is poorly understood and the number of items that would be left to ship each year would represent a tremendous challenge,” writes Salotti.
The problem of a colony is bafflingly complex.
Salotti worked on a mathematical model that he believes could serve as a good starting point for thinking of a self-sufficient colony. Central to his idea is what he calls the sharing factor, “which allows for a reduction in the time requirements per person if, for example, the activity refers to the construction of an object that can be shared by several people” .
The starting point of the agreement is critical to the rest of the work. What resources will be in place? If there are a lot of technological tools and resources in the beginning, that will affect the rest of the calculations. But somehow, the starting point might not be as critical, for two factors.
The complexity, expense, and feasibility of interplanetary travel are one. And the lifespan of the equipment the settlers start with is another. Each piece of equipment has a useful life.
“For the sake of simplicity,” writes Salotti, “it is assumed here that the initial amount of resources and tools sent from Earth will be quite limited and, consequently, will not have a major impact on survival.” Essentially, building a model based on easy Earth replenishment would not be as helpful.
So, guaranteeing that the initial state of the colony is viable, Salotti goes on to two variables that will have a great effect on survival:
- The availability of local resources. Basically this means water, oxygen and chemical elements. Those resources have to be easy to exploit.
- Production capacity. Think of it as a list of things to produce, as tools, and if enough can be produced in a timely fashion.
What Salotti is working up to here is an equation. Things like resource availability and production capacity are variable in that equation.
But Salotti’s idea always goes back to the concept of the “sharing factor”.
Imagine an isolated individual in a colonization situation on Mars. They would have to do all the tasks themselves. They would have to build and / or maintain their own systems to acquire drinking water, oxygen, and generate energy. There would not be enough time in each day. The burden on one person would be enormous.
But in a larger colony, its technology for things like getting clean water, oxygen, and power generation is used by more people. That creates more demand, but also extends the load. The effort it takes to build and maintain all of those systems now extends to more people. That, in essence, is Salotti’s sharing factor.
It gets better.
As the number of people increases, there is room for further specialization. Imagine a colony of only 10 people. How many of them would need to be able to repair and maintain the drinking water system? Or the oxygen system? Those systems cannot be allowed to fail, so there would be great pressure for a large percentage of those people to operate and understand those systems.
Salotti writes: “If each settler were completely isolated and it was not possible to share, each individual would have to carry out all the activities and the total time requirement would be obtained by a multiplication by the number of individuals”.
But if there are a hundred people, how many people need to understand those systems? Not everyone. That allows others to specialize in something else.
“… more people make it possible to be more efficient through specialization and implement other industries that allow the use of more efficient tools.”
Salotti argues that this sharing factor can be calculated and estimated with different mathematical functions. People interested in math can verify that part of the document for themselves.
There are some limitations and starting points for the sharing factor, of course. “The factor of sharing depends on the needs, the processes, the resources and the environmental conditions, which may be different depending on the planet,” writes Salotti.
This leads us to Salotti’s description of “survival domains”. Salotti describes five domains that must be considered in these calculations:
- ecosystem management
- Energy production
- industry
- buildings
- human factors / social activities
They are mostly self-explanatory, but human factors refer to things like raising and educating children, and a number of cultural activities like sports, games, maybe music.
Now Salotti turns to Mars, the main planet when it comes to this kind of futuristic figure, and the planet Salotti is targeting in his article.
Salotti does not start from scratch when it comes to Mars. There has already been a lot of scientific thinking to build a sustained human presence on that planet. “The specific use of Martian resources for the sustenance of life, agriculture and industrial production has been studied in different workshops and published in reports and books,” explains Salotti.
Obviously, this is a complex problem, and you have to make some assumptions to think about it. For any solution to have merit, those assumptions must be honest. There is no place for science fiction here.
Salottti’s basic assumption is that, for whatever reason, the flow of supplies from Earth has been disrupted and the colony must be maintained. Borrow a scenario from a contest organized by the Mars Society, where participants were asked to define a realistic scenario for establishing Mars.
Basically, the Salotti equation reduces over time. How much time is required for survival vs. how much time is available. For Salotti, the effective number of people needed to balance the equation of time is 110 on Mars. “It is based on the comparison between the working time required to satisfy all survival needs and the working time capacity of individuals,” he writes in the conclusion.
Naturally, work of this nature makes some assumptions, which are detailed in the document. “Obviously, this is a rough estimate with numerous assumptions and uncertainties,” he writes. But that does not diminish its usefulness.
If there will ever be a human colony on Mars, sometime in the future, then we must develop working models to guide our thinking and planning. We have a lot of science fiction chats and flowery ads from people with a lot of followers on Twitter, but that’s not a real job. “As far as we know, however, it is the first quantitative assessment of the minimum number of individuals for survival based on engineering limitations,” says Salotti.
“Our method allows for simple comparisons, opening the debate on the best strategy for survival and the best place to succeed,” he concludes.
Let the debate begin.
