The Archeologist's Guide To Colonizing Other Worlds

Models help scientists understand everything from the particles that make up the universe to massive superstructures of galaxies at the beginning of time. But sometimes they model more mundane, though perhaps even more complex, features - including the course of human civilization. A new paper by Thomas Leppard of the International Archaeological Research Institute and his co-authors, all of whom are also archeologists, propose applying a model of how humans expanded to the different islands across the Pacific Ocean during their early migration to what glean insights into how humanity should manage our colonization of space.

Their paper, which is available in Acta Astronautica, uses island archeology to outline eight different lessons that can impact the success of ongoing space colonization efforts. Considerations for space colonization go beyond just the technical abilities to live on the surface of another world - they have to consider resource availability, genetics, and cultural ties as well.

The authors split the eight lessons into two main categories - physiological factors and biocultural factors. Their first lesson is that distance is important - no surprise there really. Colonization of other islands is most successful when they are close to their source population. This allows help to arrive faster if needed, but also allows the colony’s population to be part of a “metapopulation” with the source population.

Fraser discusses how we could utilize resources on other worlds to enable our colonization of them.

Size also matters when it comes to space exploration. The second lesson is that larger astronomical bodies mean the colony is more likely to be successful. Resources are more abundant and there is typically more diversity in larger areas. However, there is obviously a limit to how large the body can be when talking about space exploration. Pick something too large and you would end up on a gas giant or somewhere with gravity that could crush a person. Not exactly an appealing colonization destination anyway.

Operating in an “archipelagic configuration” where there are plenty of other potential colonies nearby is the third lesson. This allows “evacuation opportunities” in case something goes wrong, and ties together the larger metapopulation more tightly. While it applies to separate colonies on the surfaces of planets and moons, it also would apply to constructed space habitats, though the paper doesn’t go into detail about those.

The final lesson from the first category again has to do with resources, but in this case it deals with their distribution rather than their existence. If resources are too clustered, it can lead to significant wealth inequality, and therefore political instability in a colony. However, that only applies if the colony is separated from the source population completely, such as an interstellar colony would be.

Mars is one of the best colonization candidates, so what we can find there to use?

There has been an ongoing debate amongst space colonization enthusiasts about what the minimum size should be for a first colony. Suggested estimates range from 22 up to 5,000, but the paper suggests as least 1,000 people, though the ideal number would be “as large as possible within technological-ecological limits” as it puts it. This would ensure the long-term genetic viability of the population without significant in-breeding and, ideally, would allow the population itself to be heterogeneous, bringing diverse perspectives and knowledge systems to bear on the problems that will inevitably face every colony.

Maintaining the link to the source population and any other colonies, if at all possible, is the sixth lesson. Ostensibly that would allow for some demographic buffering of small populations, but would also allow for resource exchanges as well as idea flows. This gets harder as the colonies get farther away, and becomes almost impossible, at least in the physical sense, when talking about colonizing other stars. But at the very least information can flow bidirectionally in those cases, maintaining some form of connection back with the source population.

Lesson seven is a little bit counterintuitive - after spending so much time starting to utilize resources and ensuring a stable population for their own colony, successful colonies should continue to send out their own colony ships. This both lessens the chance the first colony would run into a “resource ceiling” but also allows them to build their own populations that they can have cultural exchanges with.

Isaac Arthur discusses interstellar colonization strategies. Credit - Isaac Arthur YouTube Channel

Finally, ecosystem (and in many cases physical system) preservation is the eighth lesson. While many early targets for space colonization might not have any ecosystem whatsoever, our lack of understanding of how the physical systems of a new colony interact with one another could cause an unintentional cascade of consequences that could negatively impact the colony. Trying to maintain the status quo, at least in the beginning, but not just starting to terraform somewhere out of the gate is likely the best way forward.

With all those lessons in mind, the paper calls out some particularly interesting places to colonize. According to the authors, Mars is the most obvious candidate, but the Jovian moons, which are close together and have plenty of resources, would be the second best. For exoplanets, the best candidate current is GJ 1061, which at about 12 light years away is still relatively close, but most importantly it has three planets in or near its habitable zone. Other possibilities include GJ 887 and Barnard’s Star, which is about half the distance and has four planets, but all of them are a little bit too much like Mercury to be “desirable” colonization destination.

Strangely, the paper doesn’t discuss the potential colonization of the Moon, or of any massive fleets of space habitats, each of which could serve as its own little “island”. So while the analogy might be useful, its not perfect, given that in space we can literally make our own “islands in the sky”. That’s something we’ve never done on Earth - and we won’t truly know how well it will work in space until we try.

Learn More:

T. P. Leppard, S. M. Fitzpatrick, & J. A. Holcomb - How to successfully colonize space: Lessons from island archaeology

UT - A Comprehensive Blueprint for the Settlement of Mars

UT - Colonizing the Inner Solar System

UT - A Human Migration to Space is NOT so Inevitable, says New Research