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A Fireball Earth is a term used by terraformers to described a planet that has undergone a runaway greenhouse effect. The term is not accepted by the scientific community and is often used by people using Universal Sandbox.
A fireball Earth can be caused by a series of factors, like excess greenhouse gasses, changes in orbit, changes in parent star's behavior or human activity. In some cases, maintenance is required before terraforming to ensure the planet does not become a fireball or a Snowball Earth.
Large-scale natural disasters Edit
The collision with a large asteroid, with a dwarf planet, the gravitational influence of a planet (that can dramatically change orbit) or a change in parent star's behavior might be enough to change the natural equilibrium of a planet. However, since terraforming requires many years and huge investment, probably nobody will try to terraform a planet that is in risk of impact or that has an unstable orbit.
Of particular interest are planets that orbit M - type stars, since many of those stars are flare stars. A flare star can dramatically increase its luminosity and heat even up to 100 times in less then a minute during a flare, then it can cool down very fast. M - type stars are the most common stellar population in the Universe and they host many potentially habitable planets. Before terraforming, we must make sure that a flare will not be strong enough to send our planet on a runaway greenhouse effect. Since flares don't last too long, it shouldn't be the case. Still, in case of Proxima Centauri, there have been reported flares to occur at every two hours. Over time, flares will erode the atmosphere.
During terraforming processes Edit
What can send a planet on a runaway greenhouse effect ever before it is terraformed? Many things. For example, a planet might have in its ices huge amounts of carbon dioxide, methane and other natural greenhouse gasses.
In some scenarios, it might be recommended that the planet is first heated and then cooled. This might be the case if it contains some toxic molecules that can be destroyed more easily by heat then by cold. Other planets might contain high amounts of methane, that can be burned with the oxygen created by genetically modified plants. The best way to do this is directly in the atmosphere, when lightning occurs (or by creating artificial lightning). It is better to burn methane and other combustible gasses in a controlled way, during terraforming process, then when the planet is already colonized. Still, the process has some risks, including that of a runaway greenhouse effect.
During terraforming process, if too many greenhouse gasses are released, the planet can become a fireball Earth. It might be required in the first part to use a higher amount of greenhouse gasses, to speed-up the heating process.
After terraforming Edit
A terraformed planet has some great risks:
- - Atomic Carbon. Probably the best way to get rid of carbon dioxide is to use genetically modified plants (or other technology) that will split this gas into oxygen and atomic carbon. Carbon, in its natural state, when the atoms are not connected one to each other or to any other atom, has the form of a black powder. It can easily be blown away by the wind and it can ignite. On Earth, carbon is stored underground as fossil fuel or is linked with calcium in various rocks. However, the short time of a terraforming process will not be enough to block all carbon underground. If the process was done by algae, most of the carbon should be stocked on ocean floor or on the floor of various lakes. If the process was done by machines, the fastest way to get rid of excess carbon is by storing it on the ocean floor (where it will naturally sink). Still, there are many ways all this carbon can get out (for example water currents, or the draining of a large lake).
- - Natural Greenhouse Gasses. What if a planet has intense volcanism? It is known that volcanoes bring to the surface gasses (like carbon dioxide and sulfuric oxide). It is thought that Venus was more habitable until a massive volcanic eruption made it today a fireball. The process might not happen during a single eruption, but in hundreds of years, during multiple eruptions.
- - Anti - Greenhouse Failure. An Inner Planet is exposed to excess of radiation from its parent star. During terraforming process, it was required the use of anti-greenhouse gasses or space mirrors. If somehow these methods fail to protect the planet, it will enter a runaway greenhouse effect.
- - Greenhouse Gasses. If added in excess, they can have a deadly effect.
- - Human Activities. If we look at Earth, we see the that the planet is heating. It is possible that an uncontrolled level of pollution can lead to a runaway greenhouse effect.
There is a particular type of fireball Earth, where humans deliberately destroy a planet, as the only way to re-terraform it. For example, if a planet is contemned with a deadly virus, it might be better to heat it until all life is extinct, then to cool it down and terraform it again.
On a Fireball Earth Edit
If temperature increases too much, the planet enters a runaway cycle. After a certain limit, water evaporates and increases atmospheric pressure, creating more greenhouse effect. As temperature rises further, many compounds that are inert at room temperature, become caustic. The planet becomes a new Venus. However, if we talk about a small planet or a planet that lacks a magnetic field, over a long time period it will lose its water and part of its gasses.
If we want to save a fireball Earth, it is very difficult, but not impossible. The first step should be to decrease somehow temperature. It is, however, better to try to avoid sending a planet on a runaway greenhouse effect.