Terraforming Mars – Part 2
In the first article in this series, I looked at some of the reasons for terraforming Mars, as well as some of the obstacles facing us that make Mars uninhabitable for humans in it’s current form. Scientists have noticed similarities between Mars and Earth that suggest Mars once was capable of supporting life, and once had liquid water flowing on the surface. Currently, however, Mars is cold and -as far as we know- lifeless. Provided we don’t find any alien life on Mars in the form of fossils or microbes living under the surface, there are a few options to look at for changing the Martian climate to better suit humans.
When Earth first formed, it’s atmosphere was composed almost totally of carbon dioxide and nitrogen. It was life that formed in the oceans that started transforming the atmosphere into the form we have today. The early Earth atmosphere resembles the current Martian atmosphere, so ideas for terraforming Mars are based on emulating the conditions that transformed Earth. The first issue is the atmospheric composition of Mars:
- 95.3 percent carbon dioxide
- 2.7 percent nitrogen
- 1.6 percent argon
- 0.2 percent oxygen
This is significantly different than the Earth’s atmosphere, which contains:
- 78.1 percent nitrogen
- 20.9% oxygen
- 0.9% argon
- 0.1% carbon dioxide and other gases
In order to make the Martian atmosphere breathable and habitable by humans, the composition needs to be changed to more closely emulate that of Earth. The Martian atmospheric density must also be increased, as the surface pressure averages only 0.7-0.9 kPa compared to Earth’s 101.3 kPa.
This thin atmosphere is unable to hold heat resulting in an average surface temperature of -62.77° Celsius, although parts of the planet can reach an average high temperature of +23.88° Celsius. In comparison, Earth’s average surface temperature is approximately 14.4° Celsius. If the Martian atmosphere were thicker, it would be capable of capturing more heat, and would be able to retain it as well.
The Martian polar caps contain large amounts of carbon dioxide in the form of dry ice. During the winter months, Mars gets so cold that up to 25% of the atmosphere freezes and forms huge slabs of dry ice at the poles. When the planet warms up again, this ice sublimates and creates intense storms of carbon dioxide that sweep around the planet, stirring up dust and creating the reddish atmospheric tint that is visible from the surface. There is more carbon dioxide frozen in the permafrost, although Mars doesn’t get warm enough for it to be released. Several ideas have been proposed to release this trapped carbon dioxide, which would thicken the atmosphere and warm it as well due to the well-known Greenhouse Effect.
NASA has proposed building massive mylar mirrors 250 kilometers in diameter, to reflect sunlight to Mars to heat the surface. The space mirrors would be placed approximately 200,000 kilometers from Mars, to be able to reflect sunlight during the coldest parts of the Martian year. This would theoretically have the effect of raising the temperature enough to keep more of the carbon dioxide in gaseous form, and over time release more carbon dioxide from the permafrost. Another application of this concept would use ground based mirrors and/or solar collectors to heat the ground. This is discussed in more detail below. Even with a significant amount of carbon dioxide released into the atmosphere, the Martian atmosphere would still be thin and lacking in some elements. To remedy this issue, more materials would need to be added.
In order to thicken the Martian atmosphere and add required elements, additional material would need to be added. We can’t just bottle up oxygen and nitrogen from Earth and ship it to Mars, so it needs to come from somewhere else. Large amounts of water ice is required, as well as nitrogen gas. An ideal source for both of these are comets, which contain water ice and frozen ammonia. Catching a comet would be a difficult task, but recent space missions to land a probe on a comet have proven that it can be done. What we need to do is land a probe on a comet that has a powerful propulsion system, capable of altering the comet’s trajectory. Over a period of years or decades, several comets would be steered towards Mars, and sent into the Martian atmosphere. The impact would serve to increase the temperature, and as the comet sublimated during it’s journey through the atmosphere it would release water and ammonia vapour, adding to the atmosohere. Many comets would be required, over a period of several decades.
‘GREENHOUSE GAS FACTORIES’
Another option is the construction of factories on the surface, designed to produce carbon dioxide and other greenhouse gases from the rocks. Carbonaecous rocks are formed when water interacts with carbon dioxide in the atmosphere, which is how rocks such as limestone were created. Such types of rocks are abundant on Earth, but so far large quantities of them haven’t been found on Mars. The erosion patterns and other evidence on Mars however, suggests that there once was large quantities of liquid water. This means that there may be big deposits of carbonate rock located under the dusty surface, waiting to be discovered. Carbonate rocks can hold a lot of gas, in fact just 2% of a planet’s crust as carbonate rock such as limestone, can hold several times the volume of our atmosphere. If large deposits of carbonaceous rock can be found on Mars, then significant quantities of carbon dioxide and other gases could be released from it.
In order to release the gas from carbonate rocks, intense heat is required. The generation of this heat requires a heat source, and options for this include nuclear reactors or solar furnaces. Since nuclear reactors are heavy and rather dangerous once operating, they aren’t an ideal solution. Solar furnaces on the other hand, are simple to build, lightweight, and safe to transport. Solar furnaces consist of mirrors or lenses to concentrate solar energy onto a single point, for the purpose of melting or burning material, or for boiling a liquid to create steam for power generation. In our application, it would be used to heat carbonate rocks to release gas. An automated system could be set up to collect carbonate rocks and feed them into the focal point in a steady process.
A combination of these processes should result in a thickened atmosphere over the course of several decades, and the planet would warm at the same time; from the increased solar radiation, from the comet impacts, and from the increased capture of solar radiation due to the greenhouse effect resulting from the larger volumes of carbon dioxide. The issue remains however, that the atmosphere still has little to no oxygen.
The transformation of the Martian atmosphere will be discussed in Part 3.