Back to Failed Earth
A Short Lived Earth is a term used by terraformers. The term is not recognized by the scientific community. The term defines a terraformed planet or moon that has a limited lifetime. The planet itself might last longer, but at some point, it can no longer support life.
Maintenance Failure Edit
- Supply the atmosphere (in case of planets with low gravity)
- Protect the planet from impacts
- Adjust amount of greenhouse gasses
- Control natural toxins (from underground water, from volcanoes or geysers and not only)
- Control biodiversity and stop invasive species
- Interfere with local climate (divert rivers, connect remote seas, even create or destroy mountain ranges)
- Control human development
Maintenance will require money and money will be token from local economy. If at some point the economy collapses, it might no longer be cost effective to maintain a certain planet.
Human Intervention Edit
At some point, a terraformed planet can be deliberately destroyed. For example, in case of an Outer Planet, a terrorist group can use an atomic bomb to make a hole in the greenhouse layer, transforming it into a Snowball Earth.
Natural Countdown Edit
Without human intervention, every terraformed planet has its own lifetime. This is true also for Earth. At some point, when the Sun will expand, without anti-greenhouse gasses or cosmic mirrors, it will become a Fireball Earth.
Without maintenance, the lifetime of a planet is much smaller. Atmosphere Parameters is an article that has a few formulas that shows how stable is a specified gas in the atmosphere of a specified planet. It is clear that in some cases the atmospheres will not be stable. Even if gravity is strong enough, without protection from a magnetic field, the atmosphere will be slowly blown away. Maybe a terraformed Mars will last 100 thousands years, but a terraformed Moon will not make it to 10 thousands.
Ticking Bomb Edit
Main article: Ground Insulation.
There might be a scenario where there cannot be done much to stop a planet from doom. In a sci-fi novel, there was a terraformed moon, made by a mixture of rocks and ices. Engineers used the ices directly exposed to ground surface to create oceans and atmosphere. Then, where they thought there is a risk for heat to reach deeper ices, they covered the ground with a material that provided thermal insulation for a limited time. On a long timescale, deeper ices start to melt as they gradually receive heat from the surface. Water melts and gasses boil, up to a point where the gas erupts to the surface and the ground falls into the newly formed caverns.
Settlers know they have a limited time to stay on the planet (a few generations). The first generation is not interested. The second generation starts to do some minor work on insulating the underground frozen gasses. The third generation is confronting with greater problem, but still is not realizing that the end is coming. The 4th generation of settlers are seeing how ground caves in and the gasses are destroying their atmosphere. They go to large-scale measures to stop the destruction and save their world. Finally, the 5th generation of settlers realize there is no way, when the atmosphere becomes unbreathable. The 6th generation tries to re-terraform the moon into an Oceanic Planet, but the 7th generation of settlers give-up and most of them move to other moons.
If we look at our Solar System, we see Jupiter's moon Calisto is probably not differentiated (made of a mixture of rocks and ices that extend as far as the moon's core). If this is the case, then a terraformed Callisto might face a similar fate.
Another example of a short-lived terraformed planet is that of a planet with a highly elliptical orbit. At perihelion, the planet is so far from its parent star, that light is too dim for plants to survive. In this scenario, the planet is inhabitable for a while (let's say 150 years). Then, when plants can no longer survive, settlers will have to use artificial light to cultivate their crops. Greenhouse gasses might be enough to keep temperature at 15 C for a while (another 150 years). At some point, the planet will freeze. After a while, when the planet will come back closer to its sun, life will return, starting from the remaining settlements, but only for a limited amount of time. For more information, see Hyperbolic Planet.
It might be argued that any planet can be terraformed and that any maintenance required can be done in order to keep a planet habitable, but at some point the price might be too high and terraforming a new planet could be cheaper.