Generation ships

Previously we discussed both embryo space colonization as well sleeper ships as possible methods of interstellar space colonization. Our conclusion was that neither method could be considered as a serious option for colonizing other stellar systems, though we were a little bit more optimistic about sleeper ships than about embryo space colonization.

Unfortunately space colonization is often conflated with interstellar travel, and space colonization is subsequently rejected as unfeasible, at least at this moment. Space colonization is, however, the process of establishing permanent human settlements outside the Earth, including colonies within our very own Solar System. Given the infeasiblilty of practical interstellar travel, current space colonization efforts should focus on establishing space settlements in our own Solar System.

Besides interstellar travel being unfeasible, there’s also no need for interstellar colonization since the Solar System contains enough resources for a large expansion of humanity. According to John S. Lewis the Asteroid belt alone contains enough resources to sustain ten quadrillion people (1), and there are much more resources outside the Asteroid belt.

Does this mean that Republic of Lagrangia is opposed to interstellar colonization? No, but given the current state of affairs interstellar colonization should not have our primary attention. Instead we should concentrate our efforts on the creation of space habitats. Once properly designed, build and maintained, those habitats can last for centuries. And an important additional benefit of space habitats is that, unlike planetary or lunar colonies, they can be moved.

And because of this property, space habitats are indistinguishable from generation ships. A generation ship is a space ship on which many generation can live, and they are a common trope in science fiction. Usually generation ships are proposed as a method of interstellar travel at low (i.e. subluminal) velocities, and consequently the crew which arrives at the ship’s destination is not the same as which left our Solar system, but are instead the descendants of the original crew.

If we are really eager to make a distinction between space habitats and generation ships, we have to find it in the purpose for which these structures are build. Space habitats are build just with the purpose of providing living space for people, whilst generation ships are build the intent to reach a certain (interstellar) destination.

That these two “purposes” aren’t mutually exclusive, is demonstrated by the following example. Suppose that at a certain moment a space habitat has been built in the Asteroid belt, but for various reasons the inhabitants decide to move the habit towards the outskirts of our Solar System at some point. But after some period of time, they decide to move another little bit further. If such decisions are repeated over time, the space habitat will move further away from its original destination and might at some point in the future even leave the Solar System completely.

Basically this is the model of how interstellar colonization will and should happen, each generation of colonists will decide whether they will stay were they are, or if they will go to somewhere else. But first we should settle our own Solar system.

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2 thoughts on “Generation ships”

  1. But after some period of time, they decide to move another little bit further. If such decisions are repeated over time, the space habitat will move further away from its original destination and might at some point in the future even leave the Solar System completely.

    The thing is, isn’t there a bit of an “event horizon,” so to speak, once you get far enough out? I mean that it’s feasible to move “a little bit farther” within the Solar System, but once you get past Pluto (or whatever the farthest body is), you have to go all-out and jump to another solar system entirely. If you move a little bit beyond the Asteroid Belt, you can get to Jupiter, and a little bit beyond that to Saturn, and so on. But if you move “a little bit” beyond the edge of the solar system, there’s nowhere to go and nothing there. At that point, you have to be prepared to head straight to the next closest solar system.

    1. The thing is, isn’t there a bit of an “event horizon,” so to speak, once you get far enough out?

      Yes, you make an important observation here. Once you leave the Solar System, there’s indeed a drop in the amount of resources out there. However, the greater the distance from the Sun becomes, the lesser the resource density of the Solar System becomes. Further there are resources in interstellar space.

      More importantly if a space habitat is able to run a steady-state closed economy, i.e. a fixed population and efficient recycling of material resources, it could cover the distance to the next Solar System. As long as a Space habitat stays in the Solar System, it’s able to accumulate the required resources. The greatest challenge for a space habitat in interstellar space is to obtain the needed energy to run society. However, they could solve this by collecting samples of traces of interstellar hydrogen and helium for nuclear fusion.

      but once you get past Pluto (or whatever the farthest body is)

      Pluto is now believed by planetary scientists part of a group trans-Neptunian objects or TNOs, called the Kuiper belt, wichh is believed to stretch from 30 to 50 astronomical units from the Sun, with outliers to 100 AU. (Pluto is located between 30 and 49 AU.) Beyond the Kuiper belt, the Solar System is believed to contain an other belt of resources (mainly in the form of comets), the famous Oort cloud. This is located at approximately 50,000 AU away from the Sun, or 1 light-year away. And this is generally considered to be the out-most boundary of the Solar System, though some argue it’s actually outside the Solar System.

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