How Many People Do We Need To Live Among The Stars?

By Joelle Renstrom | Published

interstellar travelThis isn’t a “how many people would it take to screw in a lightbulb” type of riddle. Provided we can figure out interstellar travel, the next question is how many people we’d need to put on spacecrafts to begin to populate whatever new world we find. Different scenarios have different timeframes. Maybe it will only take roughly one human lifetime to get to, say, Proxima Centauri, which is over 4 light years away. Or maybe it we’re talking about a couple of lifetimes, which would affect the numbers of humans we’d need on board. It’s a question with so many variables that it sounds impossible to calculate, but if science has taught us anything, it’s that everything is calculable. Whether the numbers are correct is another question, and it seems like the initial calculations significantly underestimate how many people we need to colonize another star system.

starship calculationOver a decade ago, a University of Florida anthropology professor tackled this question. He set aside the question of how exactly we would get there, and focused more on how to sustain human life on the journey, as well as on our new home. He tried to factor in the necessary number of suitable mates that would allow for procreation without inbreeding (anything beyond second cousins is fair game). He used a computer model to deduce that 150-180 people would be sufficient, even if the journey took upward of 2,000 years, or over 60 generations. The number he arrived at also happen to be the outer limit of most hunter-gather societies.

starship calculationA new study conducted by Cameron Smith, an anthropologist from Portland State University, challenges the earlier estimates. Using MATLAB simulations for a range of different population sizes and timeframes, Smith calculated that at least 10,000 people would have to make the journey, and that a number closer to 40,000 would be even better when you consider the possibility, if not the inevitability, of death along the way. The bigger and more diverse the group, the more likely they will be able to live through such a journey. A group involved with the 100 Year Starship project, commissioned the work. The DARPA-funded initiative wants to lay the foundation for interstellar travel within the next century.

I wonder what such a project could learn from Mars One, regardless of how it turns out.