Terraforming of Mars
Terraforming of Mars
Science fiction writers began introducing a concept of changing a planet’s conditions in order to sustain human life or more generally suit a foreign planet to sustain conditions needed to support life for a specie. In H.G. Wells’ War of the Worlds (1898) when Earth is invaded by Martians, the Martians plant their vegetation in order to suit Earth’s conditions in their favor. In 1910 Octave Béliard writes a novel in which the Moon is given at atmosphere and vegetation acclimated in order to allow human colonization. Credit goes to Jack Williamson on coining and popularizing the term “terraform”. For practical purposes, terraforming would consist on modifying a planet’s temperature, atmosphere, climate and surface topography to Earth-like conditions.
In 1961 Carl Sagan proposed the terraforming of Venus by seeding algae on Venus to convert water, nitrogen and carbon dioxide into organic compounds. As CO2 is sequestered from the atmosphere, greenhouse effect would be reduced and so would temperature. Venus’ clouds have high concentrations of sulphuric acid. Supposing that algae could resist such conditions, Venus’ atmosphere is too thick. This high pressure would result in an atmosphere with nearly pure molecular oxygen and a surface covered in thick graphite. Carbon fixed in organic combustion would turn back to CO2 so the terraforming is unfeasible by this method. Two major changes are needed to terraform Venus. Most of it’s 9 megaPascals of CO2 need to be released somewhere else and reducing the 450 degrees celsius temperature. Modifying the atmosphere would likely help with the problem in temperature due to greenhouse effect.
The most popular option for terraforming is Mars. In Mars’ distant past it had a thicker atmosphere and lakes and streams of water. The main theory for the loss of Martian atmosphere is that due to a lack of a magnetosphere, solar wind gradually erodes the atmosphere. Some of the carbon is still present in a mineral form in carbonates. Here we face two main problems, we need to add up some atmosphere and heat it. Current atmospheric conditions are at 1 kPa. If Mars atmospheric pressure is raised above 19 kPa (Earth’s atmospheric pressure is 101 kPa).
The common solution hypothesized is to release the carbon dioxide trapped in the Martian surface to provide a better atmosphere and raise temperatures. The mechanism for the process has been a subject of debate. Not so long ago, Elon Musk proposed nuking Mars’ poles to liberate the ice and the carbon dioxide contained in it into the atmosphere. But recent scientific research says that is not enough to do the pressure job done because there is not CO2 retained in Mars that could do it. At present day conditions, Mars is too cold and it’s atmosphere to thin to support liquid water. It’s current pressure is less than 1% of Earth’s atmosphere pressure (it is 0.6%). Liquid water on the surface would either freeze or evaporate quickly. In order to thicken the atmosphere and warm up the planet (to a point where liquid water is stable on the surface) greenhouse gases need to be released. The likely to be present greenhouse gases on Mars are carbon dioxide (CO2) and water (H2O). Although there is a significant amount of water ice that could be transformed into water vapor, previous analyses show that water can’t provide significant warming by itself and temperatures wouldn’t allow enough water vapor to be present without first putting enough CO2 into the atmosphere. Other gases have been proposed for the task such as chlorofluorocarbons (CFCs) and other fluorine-based compounds, these gases would require large-scale manufacturing processes and are short-lived, so they are kind of unsuitable. The most accessible source for CO2 are the icecaps. It could be vaporized by spreading dust on it to absorb more solar radiation or by the use of explosives. However, this vaporization would only take the pressure to 1.2% of Earth’s. More sources are needed. A second source is CO2 attached to dust particles in the Martian soil which if heated, it could be released. The estimate, taking into account this other source, points to 4% of Earth’s. Another source would be carbon locked in mineral deposits, yielding less than 5% of the required pressure. Using these deposites would require extensive strip mining to a of depth around 92 meters. Carbon-bearing minerals buried deep in Mars’ crust may hold enough CO2 for the required pressure, but the extent of this other deposits is unknown, not evidenced by orbital data and would require a great deal of energy (with temperatures above 300 degrees celsius). The conclusion is that to deal with the task, we would need to take CO2 from somewhere else (I would suggest Venus).
Sources: https://phys.org/news/2018-07-mars-terraforming-present-day-technology.html https://en.wikipedia.org/wiki/Terraforming_in_popular_culture https://en.wikipedia.org/wiki/Terraforming https://en.wikipedia.org/wiki/Terraforming_of_Mars https://arstechnica.com/science/2018/07/sorry-elon-nuking-mars-icecaps-wont-geoengineer-it/