How many people are needed for a space colony?

Shifting Reality is set in a space station orbiting Epsilon Eridani b. The planet, which my characters call Sarasvati, is a gas giant which I have given rings, and the station’s main industry is the harvest of ice from these rings for the production of water, oxygen and fuel. The station is one of four human settlements in the solar system, three of them mining stations. These four settlements survive as independent communities, if not entirely from each other, then certainly from Earth, 10.5 lightyears away.

All of which raises the question: just how big does a community need to be to be truly independent, while maintaining the standard of living we’re accustomed to?

Let us take a few steps back and ask a question that will probably sound stupid, and variations of which make up many jokes: how many people does it take to change a lighbulb.

Duh, I hear you say. Changing a lightbulb is so easy, that’s why the jokes exist. I totally just googled “lightbulb jokes” and there is an entire site devoted to them, from which this beauty: How many porn actresses does it take to change a light bulb? A: Well, it looks like 2 of them are really doing it, but the real answer is actually none. They’re just faking it. Mwahahaha!

Anyway, the point is, changing a lightbulb is an extremely easy task.

Or is it?

Think of all the assumptions underlying the word lightbulb: that we know what it is, what it does and how it works. That there is a reliable supply of electricity. That there is a company that makes ladders. That we have a house that has a ceiling for a lightbulb to hang on.

So, how many people does it really take to change a lightbulb? How many people does it take to make sure that lightbulbs can exist and work so that the Irishmen, or Canadians, or porn actresses, can change them?

There’s the manufacturing: the glass, the metal, the factory that puts it together and puts it in a box. There is the mining. There is the power stations and the industry associated with making them work (coal mining, hydro-power and dams, wind farms, whatever). None of those industries will work without buildings or other places to house them. People make these buildings. Those places need to be cleaned and maintained and you need people to do this. None of those companies can survive for very long without an influx of new workers, so there are places for the new generation to be trained. Looking further into the future, each of those companies needs to make provisions to allow their workers to look after the very young. None of any of these people do well without food, so there are the people who cook, and they, or course will need something to cook, so you need agriculture, after all those people have used transport to get to their work, and would like to flush the toilet after they’re done, and would also very much like to buy all the items they need in a shop. And doing all of this naked could get rather embarrassing, not to mention cold. I have not yet mentioned the internet, or medical care.

By the time the insignificant light bulb is screwed into its insignificant fitting, many people have made contributions to it. Yes, many of those contributions are exceeding fleeting, but in terms of our question–how many people would a truly independent human colony need–by no means insignificant. All those things need to work and need to be in place before someone can climb up the ladder and change that lightbulb.

Medieval humans spent a hideous amount of time simply surviving: chopping the wood, hunting the game, toiling in the fields. They might have been smart, but only the very rich ones had the time to do something with it, by buying labour to do their domestic work. When technology lifted, the growing of food was one of the first things to be large-scale outsourced to other parts of the population. Ditto with the building of houses, the very basic level of health care, the making of clothes, the raising of farm stock. Then: transport. Many people who first bought cars still did a lot of their maintenance themselves. The cars, of course, were manufactured, but these days very few people maintain their own cars. Your car might even need a computer technician. The making of clothes has gone the same way. Of course none of us, barring people in remote areas, ever produced our own electricity or looked after our own water and sewerage.

Each time living standards jump, we add an extra level of service, with associated necessary people to maintain it. If you are astonished by how many people’s efforts have touched the humble light bulb, you will be blown away by the number of people who have breathed over the space program.

I wanted to know what the web says about minimum population requirements, and if you google “how many people are needed for a space colony” the number that’s most quoted is ten thousand. I haven’t discovered the source of this number. Will quote it here when I find it.

Ten thousand is a large-ish village. My husband’s family lives in a town roughly that size. It’s very agricultural, so food isn’t a problem. There is a council that maintains roads and sewerage. But no one makes washing machines. And if someone is sick, you have to go to the hospital in the city. There is also no high school, and I’m not even speaking about a university.

Picturing that village with the people in it, it is my guess that if the rest of the world disappeared, they’d survive fine, but it would be accompanied by a very sharp drop in living standards.

Yeah, yeah, I can hear the protests. You train the people. And they multi-skill. Yep. Sure. And the people starting the colony could decide to only include smart people, and not take loafers, and expect everyone to put in their very best effort. But you know what? That will only work for so long. Loafers, disagreers and political stirrers are born. We’re in space 10 lightyears from Earth. What are you going to do? Execute them? And the last time a society as a whole tried to give everyone jobs and be hyper efficient, we called it communism. Ain’t gonna work.

What is more, society needs a fairly large proportion of people who are happy to just consume stuff. A lot of the above services will only work well at large scale. Ten thousand might be a nice number for a seeder population or might be a genetically justified number (it gets quoted in this respect), but it’s not a long-term viable population.

Approaching the problem from the other side, and forgive the macabre-ness of the following: if a quarter of the world population disappeared overnight, would our standard of living drop?

Yeah, yeah, I hear you, it depends on which ones. You could argue bluntly that the world could well do without the poorest people, but don’t go telling me that the rest of the people could just go on living as before. For one, who made that shirt you’re wearing?

A quarter isn’t that much, so what about if half the world population vanished, and let’s be fair and distribute the vanishing evenly over the entire population. Three and a half billion people, and you’d miss half the people who normally share your table at dinner. Don’t tell me worldwide standard of living wouldn’t be affected.

OK, still, it’s a matter of choosing the right people, and training. But, in order to have the same standard of living, those supposed ten thousand colonists will need the same access to extremely specialist medical care that we have. We have this care because people are allowed to specialise–because they outsource everything else. Forcing fewer people to do the same work means unspecialising them. A jack-of-all-trades will not do the same job as a specialist. End of story.

But, you can automate tasks.

Yes, and each level of technology you jump will require more dedicated specialists to maintain it. Dog, meet tail.

You need more than ten thousand. Substantially more. You need something the size of a decent city, just to maintain our current western standard of living.

Oh, I forgot, we expect these folk to maintain an interstellar space service as well…


Communication in space

Electromagnetic waves, whether gamma ray, microwave, radio or visible light frequencies, travel through vacuum at the speed of—well, uhm—light.

When on Earth, this means communication is pretty much instant. If the distance travelled in one second by a photon, a light particle, were a string, it would wrap around the Earth almost five times.

You will notice that if your call goes via satellite, there is a small time lag. This is because your voice has to travel all the way up to the satellite in Earth orbit, and back down again. Communication satellites generally reside in geostationary orbit, at 35,000km above the Earth** so there is still a small, but noticeable time lag.

This time lag becomes larger the further you go.

If you were to call someone on the Moon, at 380,000km from Earth, your voice would take a bit over a second to get there.

Travelling time for a signal from Earth to the planets, travelling outwards:
Mars 19 minutes
Jupiter, 47 minutes
Saturn 74 minutes
Uranus 174 minutes
Neptune 258 minutes
Pluto 271 minutes

We say that Mars is 19 light minutes from Earth. Note that a light minute, like a light year, is a unit of distance, not time. A light minute is sixty seconds times 300,000 kilometres, which is the distance traveled by light in one second.

That’s right. If you were on the outer edge of the solar system, a radio signal would take at least four hours to get back to Earth, and another four hours to get a reply, presuming the receiving party doesn’t have to think about the response for too long. At this point in time, barring magic and wormholes, this is the fastest possible travel between these points. Immediate communication by radio between Earth and even Mars is physically impossible. This is an important point to consider if you write space-based Science Fiction

Think of the consequences:

You’d have to think very carefully about what you say. Your questions would have to be very detailed, efficient and concise. No chit-chat.

If there was an emergency, you’d have to figure things out by yourself.

If you were facing a hostile alien army, you would not have the time to ask a base on Earth if it was OK to attack, because by the time you got a reply, you might have been shot to bits.

On top of this, the strength of a radio signal is directly related to the square of the distance from the signal. Double the distance between transmitter and receiver, and the signal is reduced to a quarter of the strength. This would severely limit your options to communicate if you were talking to someone in the outer reaches of the solar system.

There might well be political consequences for your made-up solar system-wide human empire. They would suffer a lack of communication reminiscent of that which existed in the early days of European colonisation. They had no radio and letters took months to get to their destination. Lack of efficient communication may well have contributed to the fact that those new colonies went their own way within a generation, even if they were nominally still within the formal colonial structure. Eventually, wordwide communication problems were solved by radio and the telephone.

That won’t happen so easily to distances from here to the outer planets. Unless we find faster-than-light communication, which physics tells us is impossible, even the solar system will probably be too big for a connected human empire. For coherence of a human society, communication is essential.

**Geostationary orbit is the altitude at which an object orbiting the equator of a planet or moon travels at the same speed as the rotating body. In this way, the orbiting object is always in the same position over the surface of the planet or moon.

Why should we colonise space?

A post based on my recent reading of some of these books.

That is, of course, a very good question. It seems that at the moment no one has a satisfactory answer. Space travel is expensive, it’s risky, only few people appear to benefit directly, for a questionable gain, and there are more ‘worthy’ causes to spend our money, so why indeed should we go?

In looking at this question, let’s take a step back.

In an earlier post, I outlined that my field of studies is ecology and population dynamics.

In a population of organisms, migration happens when there is population pressure in a species’ current range. The greater the pressure, the stronger the urge a small percentage of individuals feels to leave.

In a purely ecological sense, any species that doesn’t take advantage of opportunities for colonisation is one that may be threatened with extinction. It implies that this species has never built up enough internal population pressure to desire to find greener pastures. A species of plant or animal that only lives in a small area is called vulnerable or endangered. Maybe it hasn’t adapted. Maybe its gene pool is too shallow to allow it to adapt. Maybe it lacks the drive to try new situations. In any case, the species is conservative and not very adventurous.

Humans are not like that. Humans evolved in Africa and spread throughout the world. Humans then evolved different cultures, and some of those cultures developed the ability to re-establish contact with other subcultures. First, humans colonised the world in a biological sense, and then we did it again in a cultural sense. There was great excitement and controversy attached to the great sea voyages of the explorers who put previously unknown continents on the map. Now, with the internet and instant communication, we’ve seen it all; there is no more new frontier.

Or is there?

Well, there’s this lump of rock that orbits us, and there’s this other lump of rock a bit further away from the sun, which we suspect may once have been lush and green. We’ve even discovered ice there. And some of us are starting to smell a new frontier.

On certain levels, the comparison with the ‘discovery’ of and subsequent colonisation of places like America and Australia is strong. Of course we won’t find Martians in the same way as there were native peoples of those continents, and I in no way wish to negate the negative effects on those people, but it’s beside the current point. The expansion/settlement/consolidation cycle into space would look somewhat like this:

1. Exploration
This is the stage we’re at now, where we send unmanned probes and short manned missions. The only place we’ve sent missions, of course, is the Moon, and that was done for political rather than exploration issues.

2. Temporary missions
These would involve semi-permanent habitats with temporary crew, mostly for the benefit of science and exploration. One could argue that the ISS is such a mission. Being in Low Earth Orbit, however, it is really the least far we could go.

3. Permanent habitation
Eventually, we would send people to live and work in these places. They would be leaving just as the colonists of old left England for America or Australia, to set up a new life and not come back. The new colonies would have to be self-sufficient in the basic sense of the word.

4. Autonomy
Just like the new world countries, the newly settled bodies (artificial or natural) would become independent. This requires, more than anything, a self-sufficient habitat, and most likely a degree of income-generating export. Mining of rare elements (for sale to Earth-based businesses), helium (for energy) or water (for space travellers or for terraforming) is often mentioned. All of these cane be made economically sound

But the question remains: why should we go?

As insurance policy in case something happens to Earth?
That’s a really stupid reason. We should look after Earth first, but there is no reason that doing this should preclude us from going to space at the same time. In fact, going to space may relieve some of the population pressure on Earth. Going to space may also help us look after Earth better, through the development of new technology that is cleaner and more efficient (just remember that rocket fuel, essentially is nothing more than liquid hydrogen and liquid oxygen: water – no burning of fossil fuels involved).

For research?
Maybe, yet research leaves a lot of people (especially bean counters) cold. Research is one of those airy-fairy things that’s considered property of the community at large, so by its very design doesn’t generate an income. Research can and will certainly play a role in the early stages of colonisation, but it should be a means to an end, not the end in itself.

For profit?
Well, that can be done, but it requires independent, probably autonomous settlements and we’re not that far ahead by a long shot. For the time being, it will require heavy investment by those willing to stick out their necks. But those people exist.

Just because it there?
After all, what other common reason motivated the Spaniards, the English, the Portuguese and the Dutch travel the globe? Because it was there. Because we might find something that’s useful. And that is what a successful species does: it colonises. There is no intrinsic ‘why’.

Let me reverse the question:
If space colonisation can be done with private funding at no cost to the public and the environment, all of which is possible, why should we not do it?