After a planet or moon is terraformed, colonization starts. Planetary Colonization At Apogee is a period of time when population does not change significantly over time, population age structure is stable and the economy is well developed. Usually, the number of inhabitants is close to Population Limit. This period can last from years to millennia, sometimes altering with recessions and second growths. However, like history tells us, at some point, the history of a planet or moon can enter a terminal decline. In tine, states, empires and cities have passed through this phase and will pass.
Beginning of the end Edit
Sometimes, violent incidents (like a war, solar flares, impact with an asteroid or a deadly disease) can destroy a whole planet beyond recovery very fast. In other cases, processes leading to the fall of a planet or moon can be not so violent and can take a long time. Maintaining a terrafomed world is expensive. If maintenance work (replenishing the atmosphere, avoiding collisions, control of ice caps) is not done, slowly the planet can become uninhabitable. Some planets and moons can be made habitable for a limited period of time (for example if we are using Ground Insulation, in case of a Hyperbolic Planet passing through a solar system or if a star will go supernova). And also there are cases when concurrency from a better planet can attract people (in case of corruption, high taxes or a planet that is not so habitable).
Violent incidents Edit
A violent incident happens fast and affects the planet beyond recovering. Sometimes, the risks can be seen, but either local government keeps the truth hidden or residents on the planet don't think this is going to happen. There could be, however, situations when the state takes actions trying to avoid the danger or order massive evacuation. In some scenarios, people will not have time to relocate.
Future wars will use weapons that are far more powerful then what we know today. Also, terraformed planets are more sensible then Earth is. An Outer Planet can be easily sent to an ice age if you detonate a few atomic bombs on the surface. They will make holes in the layer of greenhouse gasses. Temperature might fall to -70 C, freezing all land for decades. An Inner Planet can also be rendered uninhabitable in the same way. If you affect the protective layers like Anti Greenhouse Gasses or Micro Helium Balloons, more heat will reach the planet that will enter a runaway greenhouse effect.
Future wars might not use only explosives or diverted asteroids. The use of biological weapons is also possible. A deadly virus or a wide-spread toxin can kill most of the population. If biological weapons are used, the planet will be placed under quarantine and a strict embargo. This will affect the economy.
Violent incidents like the ones listed above will destroy the biosphere. A significant part of the population will die during the event, others will runaway. Some people will survive. The economy will collapse. It is possible that, if the ecological equilibrium is not completely destroyed, nature will recover, but it will never be like it were. Many species will be lost and climate patterns will never be the same.
Just like in Pompeii or Herculaneum, survivals that returned there, were unable to rebuild the cities. The destruction was too much. Instead of cities, they had small villages. Majority of them just moved to other places. The same will happen during a violent incident. There will still be a few inhabitants on those planets, but they will be unable to rebuild their cities, even with all financial support from other planets.
Concurrency and economic failure Edit
Let's look at this scenario: Ganymede became habitable and experienced an economic and demographic boom. But, at a certain point, Titan is also terraformed. Both moons become independent states. On Ganymede, taxes increase, while on Titan, taxes remain low, people are given economic freedom and settlers receive land for free. As this happens, many settlers from Ganymede will relocate to Titan.
What will happen in this situation? The first to move will be teens, young adults and adolescents. they will go to work on Titan or to start a new, free life. On Ganymede, this will not be visible as a significant population decline, but the economy will sense it. Those who will go are those who work better. Those who remain are those who don't produce much or are paid by the state: elders, children, people with diseases or state employees.
The economy of Ganymede will be affected, but not on a short timescale. State budget will be on debt, so it will increase taxes. As this happens, companies will start to relocate to Titan and more people will go with them. The state will borrow money and that will only worsen things in the future.
As children grow, they move out, alone or after their parents. And as this happens, the economy contracts and depopulation is visible to all. Following this trend, Ganymede becomes depopulated, with a fallen economy and with high debts. It will be impossible to recover from this for many years.
Here is another scenario: Mars is terraformed and colonized. But, at some point, power goes to a party that starts to ruin the economy. As jobs are lost, poverty is everywhere and hyperinflation occurs, people try to survive. The economy is affected and might not be able to completely recover. What is expected, with so many terraformed worlds around, is that people, especially teens, will relocate to places where they can live better.
A third scenario is the following one: On a planet, a virus is released. This virus destroy only genital cells, so that people cannot have children. There are no other health effects. For a while, there will not be serious problems for the economy. We can expect a small economical growth, since there will be less costs with school. However, as time will pass, there will be no new generation to start working. People will get old. And at some point, the economy will collapse.
All these scenarios end with a planet that is habitable, but with a very low population density and with a fallen economy. A new series of settlers can boost the economy again. However, if the planet or moon requires maintenance, during a long crisis, there will not be enough money for this. The planet can slowly become uninhabitable.
Terraformed for limited time Edit
There are celestial bodies that can be terraformed only for a limited time. For example, a hyperbolic planet. These planets are not bound to a star. In fact, they might just pass through a solar system and for a limited time be heated enough to be terraformed. Another example I an icy planet that has been terraformed with ground insulation. Ground insulation covers the icy crust and allows us to build oceans and land above. However, after some time, heat will pass through the insulation and will make the ice melt. There is not much we can do about this. A third example is of a planet orbiting a star that will go supernova.
Why would one terraform a planet that is doomed? It is just like with miner towns built around coal deposits. The mines will last only until the coal is exhausted. Thermal plants will also last only until there is no coal to feed them. But until that day, people come and work there. Recent history has shown that when coal mines close, villages and towns around them are seriously affected, they are depopulated but not completely abandoned. So, we can expect that people will move to a planet that will not be habitable for long. They will move there, but when the planet is no longer habitable, most of residents will relocate to other places. Still, there is a chance the planet will not be completely abandoned.
In the end, there are 3 scenarios for a planet that enters planetary colonization decline:
- Recover and start a second life.
- Remain with fewer population and smaller economy.
- Complete abandonment.