Generation ships are part of the SF cannon. So what, really, are they? In part one, we defined some of the space requirements to show that a generation ship will be the biggest building ever built by humans. In part two, we will look at the resource constraints needed to design a generation ship.

The main economic function aboard would be supporting the ship itself. For a number of reasons, the ship and its functions will need to be monitored constantly around the clock. Everything related to the ship’s health from monitoring the environmental balance to inspecting the structure for flaws to repair and maintenance would be critical jobs. Service industries, like food production/preparation, entertainment, non-essential medical care, schools, daycares, training programs, funeral services, etc., would be active and vital parts of the economy. In truth, the service economy would be probably be bigger than ship’s health. Depending on the state of artificial intelligence, work functions would free up, and a leisure class could arise. In addition, there will be sick, injured, and dying people who cannot work, and children will need to be cared for and educated. If the ship maintains a twenty-four hour day cycle, ship care would stratify the population into three shifts or require a restructure of the workday.⁷ For a ship to be successful, a robust economy with redundancies would be necessary to keep the small population peaceful. A planned economy would be useful but also dangerous. Some mix of socialism and capitalism would be necessary for the ship to maintain a population able to provide genetic diversity at the end point. Everyone’s basic needs, food, shelter, medical care, would have to be provided, but merit based incentives would help drive later generations, especially those who will never leave the ship. What those incentives are is beyond the guess of this article.

Resource management is what will keep the passengers alive. At the start of the journey, engineers, scientists, and supply chain managers would have to plan for three generations of resources. Once the coffee is gone; there’s no going out for more. Everything required on the journey will have to be stored, grown, or recycled while in flight. Food and oxygen would probably be the least worrisome part of planning. Large gardens strategically located throughout the ship could be designed around both oxygen provisioning and dietary variety. Likely, the average diet would be skewed heavily towards plant based nutrition. Meat requires a larger support system than plant based diets but maybe necessary for health depending on the genetic requirements of the population. Insects and fungus⁸ provide a more efficient protein source based on the farming area required. Frozen animal embryos could be transported along with the passengers for the destination planet, and consumption of meat could resume off ship. Non-biological supplies would require warehouse storage, and these warehouses would need to hold enough supplies for some multiple of the ships lifetime. Basic materials to construct everything on the ship would have to be stored in those warehouses. From electronic components to metal blanks to fuel, the necessary components to keep the ship alive requires its own system of administration. While new coffee could be regrown from the seeds of coffee trees, new iron to patch the ship would not be available unless the ship happened across rogue planets or interstellar asteroids. Given that these things are small compared to the scale of the universe, it’s unlikely that such an encounter would happen. So, the ship would have to pack everything it needed at the start of the ship.

Since resource management is so vital to the mission, storage space for non-renewable resources will be as important a factor as livable space. Even with efficient design and robotic retrieval, storage volume would be huge. The ship will have to pack enough toilet paper⁹ for over a hundred years for thousands of people. It also means that recycling would be a redundancy strategy for the long term. Reusing would be much more effective than consuming a new resource from stores. Loss is going to happen; it’s one of the laws of thermodynamics, but minimizing that amount of loss will push the success rate of the mission higher. It will be critical to recycle and reuse as much as possible in the beginning of the journey because eventually things will wear with no other option but to be replaced. While the material is new and without the miles of usage, recycling will preserve essential resources for the next generation. To ensure success, recycling would not be a strategy to reduce the volume of the ship. Relying on recycling to decrease the amount of needed supplies creates a single supply path and thus a single point of failure. Generation ships would use recycling alongside a large and numerous supply backup.

Filed under resource management will be population control. While our current moral view is to abhor treating humans as resources, the generation ship will not have this luxury due to space and finite consumables. This is a dark area when it comes to planning for a generation ship. Libraries could be filled with the philosophical and religious musings on population control, and the moral implications may be enough to preempt the generation ship project altogether. While keeping a one-to-one birth to death ratio is practically impossible, there will be acceptable limits on both sides of that ratio. The colony cannot afford to get too big, or resources will be consumed too quickly. However, the reverse is true as well, the death rate cannot outstrip the birth rate too much. As stated earlier, there needs to be a minimum population size for genetic diversity and thus survival. At the same time, the essential jobs need to be done, and dipping too far below the population requirements will necessitate people to be forced into job roles instead of choosing them. Population control is an ugly, morally fraught subject that unfortunately will be necessary to ensure a successful mission. The methods for population control on the high side of the growth ratio range from restricted birth rates, i.e. one child per family, to mandatory birth control to age limits and euthanasia. On the other side of the growth ratio, incentivizing child birth will need to be balanced with genetic diversity, which means monitoring, organizing, and controlling family planning efforts. Overpopulation is a much easier problem to address than negative population growth.¹⁰

Population control is also an opportunity to raise the topic of LGBTQ inclusion in the mission. While being LGBTQ is not an acceptable or rational reason for disqualification from the mission, there are people who irrationally want to discriminate against these individuals for that specific reason. But let’s pose the hypothetical that only heterosexual couples are allowed on board the ship. Let’s explore this absurd prejudiced requirement. Since bigots will use reproduction to discriminate, the logical extension of that means that only heterosexual couples capable of AND willing to reproduce would be allowed on board. So, infertile heterosexuals or people who just don’t want kids would be also be excluded despite other qualifications. In addition to screening of the applicant’s personal and professional life, genetic and fertility screening would be needed to produce a passenger list. Divorce is an unpredictable threat as well. What if a couple is married and plans on kids before departure, but on the journey divorces before producing children? That scenario would disqualify them before the journey. How would the requirement address the question of fertile bisexuals; would they be disqualified based on the temptation of forming a new relationship that doesn’t conform to bigoted standards? If reproduction is a requirement, the passenger selection committee would have to consider these questions. If they didn’t, then its clear that reproduction isn’t really the requirement. With in vitro fertilization, reproduction is possible, which, if the true requirement is having children, would remove the restriction of hetero couples only. But for the sake of argument, let’s say these prejudiced planners end up discriminating such that the passenger list is only heterosexual couples who will reproduce. Just as LGBTQ children are born to heterosexual parents today, the same will happen aboard the ship. It’s important to repeat that. Just as LGBTQ children are born to heterosexual parents today, the same will happen aboard the ship. Once on the journey, the children of these couples will represent society, and since LGBTQ is part of society, these individuals will be present. These children will grow up without anyone who understands them or represents them. The problems that arise from this are staggering. Therefore, it’s better to have a diverse crew from the start to deal with the diversity that arises naturally in the human population. The main reason, though, is that LGBTQ people are still people, and a generation ship is about preserving our species. This group deserves equal treatment and the equal right to representation and preservation. Or simply treat all humans as humans.¹¹

Finally the generation ship would be the only home that one or more generations know. It’s possible that arrival at the destination does not mean success. The destination world intended for habitation might not be suitable to human biology for a number of reasons including the ethical dilemma of displacing a native species. Therefore, the generation ship may end up a permanent home for all its passengers. It will be an enclosed planet for the passengers with an even more fragile ecosystem than Earths that just happens to be moving through space from one system to another instead of orbiting a sun. The efforts to plan, design, and build such a habitat would itself take generations. It’s fraught with scientific, economic, and moral points of failure. In the community of science fiction, world building is a topic debated endlessly. A generation ship will be the ultimate exercise in world building.

This essay got a little more in depth than I originally planned, and it got darker and messier than I planned. But that ultimately reflects life. Human endeavors are fraught with both the best and the worse of humanity itself, and generation ships will be no different. Please, let me know what I missed in the comments.

This essay is an introduction to what generation ships are and the staggering scale of the project, and in the next essay, I want to discuss why generation ships are important to the genre of science fiction. What opportunities do generation ships provide storytellers?

Click here for more articles in this series.

7. Based on my anecdotal observation of the average American work ethic, an eight hour shift seems like the most efficient. But I could be wrong. I’m sure many studies would occur before determining the work shift on the ship.

8. See mycoproteins. https://en.wikipedia.org/wiki/Mycoprotein

9. This is just an example to show the length of provisioning with a specific resource. Technology, social mores, and/or recycling could make toilet paper obsolete. Most likely due to limited resources, bidets will probably be used so that the water and waste can be recycled for agriculture.

10. I feel terrible writing this whole section and am unqualified to go any deeper into the details than I already have. It’s a morally problematic area that regardless of the decision to go ahead with the project or not will be debated by both society at large and the passengers for generations. This ignores whether generation ships by themselves are moral. Note that I am not advocating for or condoning population control. It simply seems logical that given confined spaces and finite resources that this will be debated.

11. It’s kind of sad that this paragraph needs to be included, but the internet has exposed me to a dark side of humanity that necessitates it. While some will consider me immoral for writing it, this paragraph deals with humanity as I’ve experienced it.