Lots of people, space agencies, writers, and filmmakers have a vision of space conquest. Usually the first colony is on Mars, then Galilean Moons and after that- planets outside the Solar System. In science fiction we often read about living on other planets, intergalactic unions, reaching FTL, terraforming etc. I wanted to take a little look on the matter of space colonization, its probability, possible locations, and impact it can have on humanity.
Reaching other planets or travelling in space in general, is not an easy thing. Enormous distances, lots of threats, lists go on and on, still growing. In the beginning of 2019, Voyager I, which is the most distant man-made object from Earth , was 145 AU from us. The closest star- Proxima Centauri is “only” 4 light years away and the closets galaxy- the Andromeda Galaxy- is 2.52 billion light years from Earth, where 1 light year is 6 trillion miles. Right now we are standing “on the shores of cosmic ocean” as said by Carl Sagan, but is it possible we will dive deep into it? And if so, what do we have to overcome, what technologies to develop and what kind of risks do we have to take to achieve it?
For the beginning, let’s think about possible destinations. It would be nice if the planet was located in the circumstellar habitable zone (CHZ), which means that there are physical and chemical conditions that are hospitable to life. The closest planet in CHZ and also the closets exoplanet is Proxima Centauri b, 4 light years from Earth, so it is a very logical and natural choice. And if we are talking about lately popular Kepler-176 system, there are 2,171 light years more.
If we know where do we want to go, then how do we want to do it? If we want to think about reaching Proxima Centauri b we should be able to travel with at least 20% of light velocity. Right now that kind of speed is only within reach of microprobes. Even if that changed, and we succeed in reaching that kind of velocity, hypothetical journey would take at least 20 years. For that much time astronauts will probably need an autonomic ecosystem inside space ship because it is not possible to take supplies for that long. Another solution is hibernation, both the medical and the one used by animals. Problem with the first one is, that there is no possible way of “waking” people from it. When it comes to the one animals use it is "… an adaptation to resource limitation." And “We don’t even know which gene expression is necessary to do it”, says Kelly Drew, a neuropharmacologist at the University of Alaska Fairbanks.
We should also think about landing on the planet with atmosphere without catastrophe and with keeping all necessary supplies, devices and tools. Another issue is being in contact with Earth. The further astronauts will be, the longer will take to collect the signal, so in case of any emergency, travellers will be all by themselves and people will know about success or failure of the mission long after it happens (when it comes to Proxima Centauri b, 4 years after it happens).
It is also important to mention issues involving possible influence on hypothetical travellers. Spending so much time in zero gravity and being able to normally function after that is probably impossible. Then there are lots of life and health threats in space, including cosmic radiation, possible collisions, and faltering contact with Earth. We should also think about who to send for the mission. If we choose a group of people in their twenties, by the end of the journey they will be in their forties. It seems logical to take a few experienced a little older astronauts and choose a few clever kids that will be raised in space and prepared for the mission, though that is extremely controversial. Is it moral to give those hypothetical young astronauts no choice, send them to be subject to all kind of influences of the travel, and can we deal with consequences on their psychic? One solution is creating an artificial gravity, that can be created, by making a whole system involving big, slowly rotating space vehicle, in which resultant force is similar to Earth’s gravity. There are a couple of researches about it, for example the one from 2014 held by Peter Norsk, M.D., Dr. med. in Johnson Space Centre. Next thing is impact on mental health. Spending twenty years in closed vehicle with a very small number of people and quite restricted routine, without possibility of taking a step back, rethinking career etc. cannot go without influence on psychic.
How to prepare to stay, create and live in a colony? One thing is to reach the target, staying is at least just as complicated. Before the journey we should send space probes, satellites, and rovers to explore the planet. According to NASA’s data, microprobes can travel with 20% of light velocity, so it will take at least 24 years before we get the data, though if we want space ships to travel with that velocity, we should be able to create way faster space probes. After that we will know what kind of danger to expect and what kind of conditions do we have to prepare for. Then we should actually think about using supplies available on the planet and take only those that cannot be created by travelers. Another important thing is purpose of the colony, tasks to do, and duration of the mission.
After the first successfully colonised planet there may come the time for another one. And maybe another, or even a couple more. In this kind of vision, at some point there may be a possibility of travelling between colonies, creating a system of laws about their relations, or the whole union. The vision of people living on a few planets, trading, living, probably fighting is both exciting and scary.
To conclude, space colonization is still far away, but I suppose one day we will at least try. There are lots of technology developments to make, satellites and probes to send, and problems to overcome. It is hard to say when and how exactly will it happen and what of mentioned problems are going to be the most significant. There is a tiny possibility of enormous breakthrough that will speed things up, though we should think about years of hard work not a sudden miracle. When time comes, we or our descendants will have to think about benefits, risks, costs, importance and impact of colonization.