If the film The Martian taught us anything, it was that being a lone wolf on another planet is not ideal. Yes, Matt Damon managed to survive for 560 Martian days (sols), but in reality how many people would it take to comfortably sustain a presence on Mars? According to a new mathematical model, the minimum number needed would be 110 individuals.
Jean-Marc Salotti, a Professor at Bordeaux Institut National Polytechnique (INP), wanted to take the assumptions and scenarios that researchers had already discussed about the possibility of settling on another planet to the next level – the quantitative level.
To do so, Salotti first started with the simple statement that, for survival, the working time required to fulfill all necessary needs must be less than the working time capacity of the individuals. Taking into account the productivity of different-aged residents, and allowing time for sleeping, eating, hygiene and resting, the annual working capacity is estimated to be 31.25 percent of the annual living time.
But what fundamental duties must be carried out in this time? Well, Salotti identified five key areas (or domains) for humans to focus on; ecosystem management (ensuring a supply of food and water and maintaining a habitable environment), energy production (to produce electricity and vehicular gas), industry (covers all stages of object manufacturing from mining ores to producing tools), building (construction and maintenance of buildings), and social activities (from raising children to providing entertainment).
As you might imagine, for a smaller group of people the demand in some areas may be less, but the pool of individuals that tasks can be divided between is also diminished. The toss-up of demand and division that survival depends on is encompassed by Salotti in the “sharing factor.”
“If each settler was completely isolated and no sharing was possible, each individual would have to perform all activities,” Salotti wrote in a paper published in Scientific Reports. “[But] a greater number of individuals makes it possible to be more efficient through specialization and to implement other industries allowing the use of more efficient tools.”
For some activities, such as water management, the sharing factor is high as although a lot of effort is required everyone can benefit, whilst for others such as agriculture, the sharing factor is relatively weak, as a larger quantity of food means more work.
Teaming the various sharing factors in each domain with a previously formulated plan for survival on Mars, submitted in a contest run by the Mars Society, Salotti could calculate the minimum number of people needed to fulfill all the requirements of survival whilst not surpassing their 32.5 percent capacity limit. Lo-and-behold, 110 was the magic number.
Obviously, this is not an exact science, and various assumptions were made along the way, but, to Salotti’s knowledge, it was the first quantitative assessment of its kind. “Our method allows simple comparisons, opening the debate for the best strategy for survival and the best place to succeed,” Salotti wrote.
To be fair, Damon probably would have had a better time of it if he were joined by 109 others.