SPACE NAZIS BECAUSE SPACE NAZIS

I dunno why it took 7 weeks to appear on arXiv after acceptance, but it did. A longer blog post replete with OH GOD SO MANY NAZI REFERENCES is available here. This is the "short and to the point" version.

This project is the result of the twisted mind of my former housemate. He found that there were competing claims for the minimum population you could use to start an interstellar colony. One said you'd need only about 150 people, the other said it was more like 14,000. Quite a disparity !

Surprisingly, there doesn't seem to be much in the literature about minimum viable population size (perhaps there is and we as astronomers simply aren't aware of it). So Frederic decided to write his own numerical, agent-based code based on available medical data. Virtual people, called agents, have various parameters - age, gender, fertility, etc., which can be tracked and altered within the simulation. The crucial bit is that the ancestry of the agents is also monitored. That means that the amount of inbreeding aboard ship can be both tracked and controlled.

The first paper examined the earlier claims, which both (somewhat arbitrarily) dealt with a 200 year-long voyage. Both of them succeed in still having a population unlucky survivors aboard by the end of the simulation, but neither are doing very well. The smaller crew would be on the verge of extinction, and though the larger ship is doing okay, there's a worrying level of inbreeding. The main problem seems not to be the population size so much as it was the arbitrary and fixed rules for procreation, especially the restriction that only those aged 35-40 were allowed to breed. Perfectly healthy people were forbidden from breeding, and the strict two children per couple policy was found to be counter-productive. It prevents overpopulation, but it's much too aggressive.

The second paper attempted to redress the wrongs and find a better value for the minimum population required. By allowing the rules to be more flexible, e.g. 3 children per couple when the population becomes too low, and widening the allowed breeding age range, and trying hundreds of simulations with different starting populations, the minimum number of crew was found to be 98 (with any inbreeding forbidden). With that many inhabitants or more, the missions always succeed even accounting for random variations : they reach a stable population level of ~500 indefinitely. Strictly speaking it didn't establish the minimum stable population level, but it's clearly somewhere between 100 and 500.

It's technically possible to have a successful mission with as few as 32 occupants. But to guarantee success would require an incredibly strict breeding program, hence the Naziism. And with breeding ages of 32-40, we have a population of Nazi milfs.

In this third paper we estimate how much food the crew would need, since they'd have to grow their own rather than taking stores. This accounts for the height, weight, and activity levels of the crew, which vary (again with random variations) over their lifetimes. We found they'd need about half a square kilometre of farmland, so the size of the spaceship is comparable to a skyscraper. It doesn't really matter if the crew were all couch potatoes or Olympian athletes either. And this included a healthy, balanced diet with plenty of room for the animals... so yeah, space Nazi farmer milfs with cows. Seriously.

In a future paper we may attempt to estimate the water requirements, and possibly how the farmland would be affected by the recycling efficiency. Ultimately we'd like to establish the minimum mass of a colony ship, though we're under no illusions about the complexity of the task. Per ardua ad astra, and all that,
https://arxiv.org/abs/1901.09542