Tag Archives: interstellar space travel

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.

Sleeper ships

A few weeks ago we discussed the desirability of embryo space colonization as mean for establishing interstellar space travel. In that post we argued such program would not have any purpose for this and the next few generations, and its only reasonable aim is to ensure the continuation of our species in the event that human life in our Solar System would become impossible.

Another popular suggestion for interstellar travel, and possibly colonization, is the use of so-called sleeper ships. In such ship the passengers are kept in suspended animation, a kind of artificial hibernation. Suspended animation should be distinguished from cryonics, the supposed science of freezing human corpses in the hope that future generations will be able to revive them. Though both concepts are often confused, the primary difference between those two are that in the former process the body’s metabolism is slowed down, but not terminated. In the latter process there’s no whatsoever metabolism present.

There are several technological issues with sleeper ships which has to be resolved before such ship could be launched. With the current state of affairs humans and other animals can be held into suspended animation for several hours or in some cases even days. Since interstellar space travel might take several decades to several thousands years, huge improvements in this field of science need to be made.

A related issue is that slowing down one’s metabolism might extend one’s life, but not necessarily long enough to arrive at the desired destination. And further even a suspended animated body still requires life support, which needs to last for many hundreds of years because repairs are not possible during the trip.

By travelling at relativistic speeds, one could take advantage of time dilation, the phenomenon that time will run slower if you are travelling faster. An interstellar journey might look from the perspective of an Earth bound observer a 1,000 years, but (depending on the actual speed) might be only a few decades for the passengers. This has clear benefits for the designers of the ship’s life support system, they only have to make sure their product will last for several decades instead of a 1,000 years.

Like embryo space colonization one should ask what purpose sending sleeper ships to distant star systems would serve, assuming the technical issues can be solved. Since an interstellar mission might take several centuries from our terrestrial perspective, current generations and those following immediately after us may not receive any benefit from such mission. And possibly humanity might not even exists in this part of the universe by then.

Therefore the main reason for the use of sleeper ships is for the sake of the passengers, as they are the only ones who will live long enough to witness the completion of the journey. But as a formal objective of public policy of interstellar space colonization, does not make much sense, unless we use it to transport all of humanity to an interstellar destination, or at least of all humans who are willing to emigrate to such destination.

Of course groups of selfish people might decide that they want to board a sleeper ship, maybe are these the same people as preppers, who will do anything to survive upcoming disasters. But these people shouldn’t count on public funding for their emigration plans. However, these are also the people for who sleeper ships are actually a solution.

Sleeper ships are currently not feasible, and offer also no clear benefits for the majority of currently living humans. The colonization of our own Solar System is feasible within a few decades from now, and can produce benefits for those who will remain on Earth. As a method of interstellar space colonization it’s only of interest for a small number of people.

Embryo space colonization

Republic of Lagrangia endorses the colonization of our own Solar System, and of the Lagrange points of the Sun-Earth system in particular, before any attempt is to be made at colonizing other stellar system. Despite decades of scientific research, currently no feasible methods for interstellar travel do  exist. Besides the lack of means for interstellar space travel, our Solar System contains huge quantities of natural resources, which can be used by humanity.

Because there is no technology available for achieving fast interstellar space travel, proponents of interstellar space colonization have proposed several alternatives. The three most important ones are: generation ships, sleeper ships and embryo space colonization. In this post we will discuss the latter option.

The rationale behind embryo space colonization is simple: interstellar travel takes much more time than the average life span of a human being, but (human) embryos can be stored frozen for an infinite amount of time. This concept faces several technical difficulties, but we want to limit ourselves here to the sense of embryo space colonization.

An ESC program  would be an expensive enterprise, and especially if tax money is involved, such a project is in need of a good justification. What are possible arguments in favour of Embryo Space Colonization?

Arguments for the colonization of our own Solar System include, among others: the mining and exporting of extraterrestrial resources for terrestrial consumption, to create enough room for a growing world population, or the establishment of better societies for political dissatisfied terrestrials. None of these arguments applies to embryo space colonization.

Provided that an ESC mission can be completed successfully, the export of resources to Earth is almost out of question, for the same reasons that have led to the very idea of ESC: long travel times. (Paul Krugman has written an essay in defense of extraterrestrial trade, however we are still sceptical about it.) And how embryo space colonization can solve overpopulation on Earth, is everyone’s guess.

As far as we can see, the primary, if not only, reason for ESC is to ensure the continued existence of the human species. However, as we have argued in an earlier post the fact that at some point in the (distant) future our species might become extinct, is not something we should worry about. In contrast, we should care about the well-being of the currently existing population, which includes the possible evacuation of humans to space colonies in case of a global catastrophe.

However, the supporters of Scott Adams’s theory that the continued existence of the human species is required for the reconstruction of God, could argue in favour of embryo space colonization. In this view there’s reason for the survival of our species, which is independent of our particular interests. Though we might wonder whether we have any duty to help with the reconstruction of God.

Another argument which could be raised by proponents of embryo space colonization, is that this project would stimulate scientific research in several fields. The subsequent spin-offs could be used for the benefit of the current population. Well, the second part of this reasoning, is on itself enough justification of investing in scientific research, even without the prospect of embryo space colonization.