Choosing Colony Planets

An alien civilization with a philosophy of life requiring it to spread and disperse life throughout the galaxy, as far as it can, would need to be very circumspect about where to send a seedship. This adventure would require a great amount of effort from the civilization, and perhaps a good fraction of the resources available to it. On Earth, we have not even begun to figure out how this might be done, but we can assure ourselves this is not going to be easy for any civilization. As little would be left to chance as possible.

If we ask ourselves about the possibility of our civilization encountering another one, knowing where they would likely be is a critical question. They start on their origin planet, but then where do they go? We have learned over the last decade or two that there are huge numbers of exo-planets in the galaxy, but of these, which ones might be even initial candidates for an alien civilization's colonies? What are the characteristics of a possible colony planet? If we know that, then we can concentrate our search for alien life, or rather alien civilization, on that class of planet, and spend less on others.

What we cannot assume is that they will only go to other planets which have already originated life. If their philosophy and reason for continuing their existence is to spread life throughout the galaxy, an origin planet would be low on their list – it already has life and there is no need to go there and seed it. That would be superfluous. Instead, they would want to go where there is no life and is not likely to be if the planet is left to itself. Not just any planet would do. There are certainly some detailed criteria for a reasonably nearby planet, within a hundred or two light years, to even be considered as a possibility.

Many planets might only support the alien civilization itself, and not some ecology of plants, animals, microbes or whatever on it.  Their mandate is to spread life, but if the only way that can be done is to establish a colony, then that is the solution to the lack of planets which might be harbors for primitive life.  The alien civilization can set up colonies in many places, but needs to discriminate as to what distinguishes one possibility from another, as far as spreading life goes.  

One dominant aspect of the choice is sustainability. Sustainability means, for some particular alien species or collection of them, the ability to live for a very long period, measured in lifetimes, on the resources and energy located near and accessible to them. It includes the idea that the population should be able to grow up to some minimum value and still live there for that long period. It is about resources existing on the planet, near the surface, but also about being able to extract enough materials to make an energy source that produces much more energy than all the energy needed to collect and process the materials used in the energy generation and distribution process. There must be enough surplus energy for the other half of the problem, providing all the components, such as habitat and food, needed to sustain the new alien population.

The colony starts out with only the equipment that can be carried on the seedship. The development of the colony would consist of several preliminary stages before the uniform growth stage expands the colony up to the desired population. The first stage involves the landing of whatever is necessary to initiate power production with a minimally sized power reactor, create a habitat, and locate and start to mine and process all necessary mineral deposits. A central manufacturing complex would need to be created that can produce, from the ores found, all the specialized items needed for all the operations of the civilization.

Control of this process is not so critical. Can this be done in an automated fashion, or is it necessary to spend time in orbit, gestating the first generation of aliens, before sending them down with the initial lander? Whether the seeding operation is under AI control or under alien control, much the same steps have to be done. The principal difference is that habitats need to be made for the alien landing party, or some additional manufacturing facilities need to be made to enable expansion of the AI capability.

The question of sustainability is not easy to calculate in advance. Yet this is what an alien civilization must do before attempting to spread its population to a new planet or satellite in a distant solar system. They must make an estimate of whether or not a colony could survive on an exoplanet before taking the extreme expense of sending a seedship there The question is not just can the colony survive for a while, but survive and build a large civilization on the planet. The ultimate question involves the possibility that an alien colony, on a colony planet, could create a civilization large enough to send out its own seedship. If the colony planet was a dead-end, without enough resources for the civilization to grow large enough for the project of going out yet further to another colony planet, it should not be chosen.

The calculation depends on what goes along with the seedship. How much energy does it carry to support the transition from nothingness on the planet to a viable colony? Before this is used up, a seedship must arrange for native energy sources on the planet. This might seem to mean a uranium mine, but the uranium metal is actually a small part of what is needed to build an energy-producing fission reactor. Some parts for the first reactor might come from the ship, and this means that sustainability in energy is going to be developed in stages. The energy from the first reactor would need to be deployed toward a variety of tasks.

Total sustainability means that all mandatory mineral resources are present in the planet's crust, easily accessible, and with not too large a cost in transporting them from their mining site to the central location where the colony's initial population will be centered. For an alien civilization attempting to create a very credible and accurate estimate of this, which they would need before a launch, they would have to first collect all possible information about the planet and the solar system it is located in. The only way to do this from their planet is to build huge telescopes, and it also means asymptotic technology as far as planet formation goes, i.e. having geology completely understood, from the time of the gas cloud through all the changes that go on with the crust of the planet. They would need to be able to tell from the spectrum of the star what the gas cloud that created it contained, as for different elements and the relative concentrations of each.

At this point in Earth science, we have not attempted to make any such calculations, and so we don't really know if it is possible, or how accurate it might be. The accuracy is likely a function of the age of the star, as mixing will take place over its history, and the origination elements will also be burned up as they go deeper into the star's core. Light comes from the star's corona, where elements will linger the longest and where transmutation would be slowest.

Data is also available from the spectrum of the planet itself, where it is simply the reflected spectrum of the parent star. This might tell what was in the atmosphere, and what the large areas of the surface have, to a degree. Reflection spectroscopy is necessarily more difficult that emission spectroscopy, but if the telescope is large enough to portray the planet across many pixels, then some information might be gained from each one. Planets rotate, but that should not interfere with the data collection, once the images start coming in. A telescope of large size, perhaps ten kilometers or more in aperature, would be needed.

Information about the nature of the gas cloud that formed the target exo-planet might be gained also by looking at the other planets of the solar system containing it. A gas cloud which undergoes the great transformation from a rotating self-gravitating glob of dust and gas into a proto-star and spinning disk would also have undergone much diffusion, and this implies that at the radius where the target exo-planet condenses there would be some distribution of elements, but at the radii where other planets condense, there would be a different one, and knowing each of them helps the alien scientists to determine the larger picture of the composition and evolution of the cloud.

One kink in this process is that planets don't necessarily stay at the radius where they condense. The effect of the largest planet or the largest few planets might, in some instances, drive a smaller planet to a different orbital radius. The largest planets might also mutually share angular momentum, and drift to different radii as well. Can this be determined from telescopic observations so that the data from all of the planets can be put to use? A good question, and one we on Earth have not begun to fathom.

None of the scientific steps needed seem to be impossible, even from the viewpoint we have now, with our very limited science. An alien civilization a few hundred years further in science than ours should be able to accomplish them, as far as it is possible. Once this mass of data has been collected, perhaps over a century of observation, the estimation of which visible planet would be best to seed can be done.

Population Reduction in Alien Civilizations

After an alien civilization gets to the point of asymptotic technology, that is, science is over and done with, they have a number of choices to make. One of them is how much population they wish to maintain. The choice is directly related to how long their resources will last, as for a given level of recycling, twice as many aliens use twice as much resources per time period. 

One aspect of this question relates to the process for reducing population. The direct and immediate solution is to simply gestate fewer aliens and allow the population to shrink at whatever level they could choose. It could be as drastic as going from a billion to a million over a few centuries or generations of alien life. The choice of what target to use is related to their view of themselves and their role in the universe. Is it to simply go extinct, or do they plan to go to some other solar system, in one of the many ways possible? If they choose to travel, there is a minimum population necessary to build the ship or ships. If they just are content to go extinct, an unlikely alternative, they could do it quickly with lots of aliens, or slowly, with only a few. Neither is very pleasant, as resource shortages do not make for high living standards.

This question is interesting, but also interesting is the process for getting the population down. There is one question that stands out: what about all the infrastructure? They don't need all the infrastructure that a larger population needs, and they probably don't want to spend the additional energy and resources to maintain it if it is only there for a ghost population.

Consider first fungible architecture. By this time, resource pressure, or at least the knowledge that it will be happening in the future, has mandated that the aliens will live in large arcologies, where recycling is pretty much total. One arcology might be almost identical with another, so there is no reason to keep the second one going if the first one can handle the population post reduction. In an advanced alien civilization, recycling will be part of everyone's life, and everything will be recyclable, even the entire arcology. So over a period of time, the second arcology might be taken apart, and fed into the recycling system of the first one, supposing they are not too far apart so transportation costs are not a significant factor. This adds to the longevity of the resource base.

In order to make an arcology recyclable, it would have to be divisable into parts, so there would not need to be any crowding of a double population into an arcology. Time for this could be stretched out, as by this time the civilization will have figured out it might have a million years on their home planet, so there is no rush to do anything in a short time. If gestation cycles are a hundred years or so, spending a few of them combining arcologies will not affect much over the long term. Aliens in the superfluous arcology could be given the choice of moving to the remaining one, or staying in the part of it which was not yet taken down. By this time, the arcologies would be self sufficient, with their own power plants, industrial sources of nutrition, air filtration, internal transportation, and everything else necessary to have a comfortable life for the alien population. There could well be some residual agriculture, for specialty products or for the amusement of aliens who wanted to be involved with farming for a period of time, and these would simply be reduced according to the population level drop.

What about the non-fungible parts of the infrastructure? Would there be any monuments, historic places, unique but antique buildings? There might have been, but the lifetime of any of these might only be a few thousand years at the highest, and after that, deterioration unless it was periodically rebuilt. Suppose they had preserved something from their earliest eras, before technology was greatly developed, and this was a part of their culture and something they used to maintain their heritage. With a drastic population reduction, as in the example above of a billion to a million, or something proportionate to this, a few heritage sites might be maintained, but not a large number.

It might not be appreciated that heritage could be a very important part of the alien civilization. Heritage is the reason they decide, over and over again in each generation, that they think their civilization is worth preserving and should not be allowed to become extinct. Each generation would have the possibility to reverse the decisions of previous generations, and, for example, stop work on a starship and instead use the capital to change their activities, to, perhaps, have more jet aircraft and spend much more time flying over the landscape and visiting unique sites on their planet, in person. Without heritage sites, the pressure to keep on track with previous generations might grow less, and reach a tipping point.

So, perhaps there is another factor which comes into play when an alien civilization is thinking about its target population for the long, long term. Having sufficient population to build starships may be one, but another might be having enough to maintain a critical number of very important heritage sites.

Almost everything else would have been conquered by technology. There might not need to be a minimum number to maintain the automated operations which provide energy and the standard of living to the population. This particular factor is not clear, but it could very well be that star travel and heritage sites are the only things which feature in the choice of population numbers.

What this means to us is that if these two problems of minimum population result in numbers fairly small, there might only be one arcology on an alien planet. When we have our huge telescopes, able to focus in on planets in different solar systems, looking for one with a thousand dots of light, probably infrared only, this may not be the signature of an alien civilization that we can find. There might be one dot of light, where they all live, and the rest of the planet has been returned to nature. This would be the situation for almost all of the million years of existence of the alien civilization, whereas the huge populations might be only a thousand or less, meaning a tenth of a percent chance of seeing them during this phase. This is one more signature of an alien civilization that needs to be carefully thought through.

Imagining the Goals of an Alien Civilization

It is much easier to imagine some aspects of alien society, such as their energy sources, than other aspects, such as their goals, because we have on Earth made some progress in understanding the possible sources of energy and can make some good guesses as to what might exist in a more advanced society. But with respect to social goals, our technology is very primitive. We hardly understand anything about societies and their goals; even the basis for this technology or scientific knowledge is vague and undeveloped. We have some observations, but nothing equivalent of Newton's law has been figured out yet. Just to appreciate the difficulty involved, think of asking someone in Columbus' time about energy, after explaining the concept to him. He might answer there was wind power, and that's about all. A person who had some education involving ancient Greek science and who had heard of Hero of Alexandria's aeolipile might add steam power, which comes from fire. There would be no way that such a person could estimate what energy usage would look like five hundred years later, or a thousand.

On the other hand, we have some confidence now in understanding electromagnetic energy, kinetic energy, chemical energy, equation of state energy such as compression, and nuclear energy, along with the many ways they exist in nature and how they can be harnessed and converted. A person on Earth today might be able to do a good job in describing the use of energy, and might even be able to imagine how energy might be used in the far future. And if we subscribe to the concept of societal convergence, meaning technology drives society and since technology is the same no matter what planet you live on, all sufficiently advanced societies will have similar features, and therefore what this person imagines for Earth five hunderd years from now would be quite insightful as to what a similarly advanced alien civilization might be doing.

We are in the Columbus era stage of understanding neurology, politics, governance, societal arrangements and whatever else relate to the goals of an alien civilization. We would make grave mis-assumptions to try and use what we think are the goals of Earth's various societies, current and historical, as possible goals of an alien civilization.

Some goals that might pop up from the study of Earth societies' history include empire expansion, maintenance of the existing power structure and factionalization, development of profitable trade connections and routes, collection of items of universal value such as gold, the pursuit of scientific progress and technology, revenge or hatred directed toward some group, usage of a particular economic system, the spread of medical technology to various factions, and so on. These are goals which are appropriate, if at all, for a single planet. Ones which relate to multiple planets might be the expansion of life to dead planets, resettling on other planets as an insurance policy against catastrophes or other events which eliminate life on the home world, and a few others.

Our knowledge of energy and astronomy enable us to realize that some of the one-world goals are ineffectual for a multi-solar system civilization. Each planet of the civilization is almost totally isolated with respect to transportation and communication, not absolutely, but almost totally, by the distances between different solar systems and the huge amounts of energy needed to move anything from one civilization to another. Some minimal communication might be attempted between two solar systems which are not too far from one another, but little can be done with simple information transfer with no transport to implement any agreements, requests, or orders from one planet to another.

An alien civilization which is somehow frozen in its level of technology at something like what Earth has now might also have its goals be chosen from the ones listed above, but technology does not plateau easily. It proceeds forward to the asymptotic conclusion or the society degenerates. So at the very least, we can say that multi-planet civilizations do not have empire-building as their goal, nor the development of trade routes, collection of items to be brought from one solar system to another, and perhaps more.

After an alien civilization moves through its technological development of electronics, robotics, and artificial intelligence, the next area it encounters is genetics. The genetic revolution will overwhelm the electronics revolution, and the concept of factionalization, based on legacy concepts of genetics, local origins, language preferences and so on, will drift away as good genes are made available to all members of future generations beyond some point in time. Technology has shown cost reductions in the electronics phase of development, and when this wave passes genetics, there will be little reason to suspect that good genes would not be universally available.

The same wave of technology would also pass through the quasi-sciences of politics and economics, transforming them into fact-based sciences and enabling an alien society to have wise political structures and economic arrangements. The idea of an alien society having a goal of enforcing some legacy economic system on its members seems a little ridiculous; the optimal system would be known and used everywhere. Why would any region or goup want to use antiquated systems when better ones were instantly available?

For one-planet goals, the one which passes through the filter of advanced society might be the preservation of the civilization via wise use of resources, and the expansion of it to other appropriate planets. The other one is the preservation of life in general on the planet, but more importantly of spreading it to other planets. These are quite dissimilar goals in their effect on the civilization, even though they both originate from the abstraction of the goals of life across all species. There is no reason that both of them could not be accepted and acted upon by any particular alien civilization, except for the cost in resources they both have. If it is true that civilization can establish itself on a much different class of planets that life can evolve upon, it is fair to say that they operate almost independently.

It does not seem possible to extrapolate from goals of Earth societies, current and recent, to goals of a civilization with more advanced technology, by a few centuries of progress. The only way forward is to look for the simplest possible ones, those which derive from the nature of life. Perhaps some others can be found with a different approach, and that is certainly an interesting avenue to follow.