Things Authors Forget When Writing About Generation Ships
Space! The next adventure! The final frontier! A cool excuse for you to make your characterâs hair get all floaty!
And if thereâs one thing spacefarers all love, itâs generation ships. Generation ships (sometimes known as sleeper ships) are vessels that can carry hundreds to thousands of people at slower than light speeds. If faster than light (FTL) travel doesnât exist in your story, then this is the only way humans will be able to colonize distant star systems. A man boards; his great-great-great grandchild exits on an alien world.
For more about what generation ships are, see TvTropes.Â
Before everyone sets sail (or flees Earth, depending on the circumstances), youâll want to take into account a few things about the biological and psychological nature of having, quite literally, a âcity in a bottle.â Below are a list of things to consider, or, more honestly, âEverything that Could Go Wrong on a Generation Shipâ:
Population control. This one is obvious: a generation ship can only support so many people for so much time. Â A strict system may have to be in placeâperhaps a two child policyâto make sure that the population doesnât change significantly over time.
Genetic drift and the bottleneck effect. In small populations, the overall genetic makeup of the population will change more rapidly than in large populations. This is due to pure chance, not natural selection or mutation, and is called genetic drift. Combine this with the bottleneck effect (when a population has very low genetic diversity after experiencing a period when the population was extremely small) and after a few generations, you might have a population with a very different, but far less diverse, genetic makeup than those who originally boarded the ship. For example, maybe the original passengers were of a variety of different heights and with histories of different genetic diseases (or no history of genetic disease), but within a few generations, all of them are average height and there is an alarmingly high proportion of people with Cystic Fibrosis. Thus the overall genetic makeup of the population has changed significantly (from low proportion of CF --> high proportion of CF), and there is little genetic diversity (many heights --> all one height). For more about both of these concepts, you can read here. Without serious genetic engineering and intervention, this is likely to happen on a generation ship.
Infectious diseases. In part because of the loss of genetic diversity, and also in part because of the closed, sealed space everyone is in, the spread of infectious diseases will become a lot more serious. Even in the ship, bacteria and other pathogens will exist. Worse, they too are subject to genetic drift, and so changes in microbial genetics could rapidly create new strains of bacteria. The wrong strain doesnât even need to kill all of the population. Killing just 25% might be enough to make it impossible to have enough people to keep up with food production, ship maintenance, and ship navigation. The rest of the population might just slowly die off as their means of survival disappears.
Self-reliance. The ship must be able to be self-sustaining, as it will be impossible to get any help once itâs far from Earth. This not only means ship maintenance must be able to be conducted on the ship, but also food and water production (where do they get the water? Do they mine icy comets for it? Do they produce it with chemical reactions?), finding fuel sources for electricity (nuclear power? What happens in the case of a nuclear accident? Solar can work, but only if theyâre near a star system), etc. All items must be able to be made on the ship, as anything brought onboard with the original passengers wonât last hundreds of years. If youâre writing a generation ship story, take a few days to analyze every object you use in your life, figure out roughly how it is made, and determine if thatâs sustainable on a generation ship with few people and few resources. Fabric? Itâll probably all be synthetic materials, unless your ship has cotton fields or sheep. Plastic? Itâs made from crude oil, which you probably wonât find in space.
Ethical concerns. This may be one of the biggest issues youâll run into with a generation ship. Sure, the people boarding the ship get the excitement of setting sail to a new world, and the people exiting get to sink their feet into alien soil⊠but what about the generations in between? How do they find meaning in their lives, knowing that they can never be more than the ship? Exaggerating the importance of the ship may be one way. Youâre not just there because youâre a collection of genes chosen to further the human race. You were chosen by divinity, ordained by the stars. Maybe you were destined to set an example for future generations of humans so that humanity can rise to its true moral status, or maybe youâre there to devote your life to the purification of the human race, and your whole life revolves around genetically engineering a âbetterâ human species. For the middle generations, dealing with the futility of life onboard can quickly result in the rise of religious cults, eugenics, and other forms of extremism in order to make sense of their lives. Humanity may be very different when they get off the ship.
These are just some of the many things that can become problems in a sealed metal space box. The populationâs genetic makeup could drift to extremes, infectious diseases could also drift to extremes and kill everybody, common luxuries and even basic staples of civilization that we take for granted will not exist, and even if everybody survives, the middle generations could steer the ship towards extremism.
And thatâs not even going into if your ship includes cryogenically frozen humans, which weâll talk about later!










