Focus on terraforming planets (Mars, Venus …)
On August 15, 2019, Elon Musk tweeted a strange idea : atomize the planet Mars, not as an act of war but as an attempt at terraforming. According to the SpaceX leader, exploding nuclear bombs above the Martian polar ice caps would release large amounts of carbon dioxide and water vapor into the atmosphere, two greenhouse gases. The planet Mars would heat up then and would become more hospitable for potential Martian settlers. Such a statement may surprise, worry or make people laugh.
Terraforming is a recurring theme in scientific studies and science fiction
Although so far no project of this type has been studied seriously, terraforming certain bodies of the solar system has already been the subject of numerous studies. It is also one of the favorite subjects of science fiction. Is it possible to generate oceans on Venus ? Or to breathe air outside on the planet Mars or on the Moon ? We are unfortunately experiencing it on Earth, the human species is quite capable of modifying the climate of a planet. So far, this phenomenon is not controlled and does not benefit at all to the occupants of the Earth.
Because we are not able to contain our production of greenhouse gases, some people hope to be able to set up artificial countermeasures such as ocean fertilization and massive forest plantations to capture CO2 or the installation of gigantic space umbrellas. This discipline is called geoengineering. As absurd as it may seem, it is more or less terraforming the Earth.
By using terraforming, humanity hopes to master parameters that it does not even control on Earth
Humans and most of the species found on our planet can only survive under very specific conditions. Temperatures, pressures, atmospheric composition or even symbiosis between different species constitute a fragile equilibrium. The slightest change of a few percent in any of these parameters can lead to mass extinctions.
The bet of the terraforming is that the human species can manage to control these parameters and to bring them in an acceptable range on other planets. Of course, this is a completely illusory prospect today. We are still unable to understand the precise functioning of the Earth, so we are not ready to control it. However, we can imagine how certain processes could help a civilization that would really like to tackle this task on the planet Mars for example.
How to terraform the planet Mars
When we talk about terraforming, it is actually a whole range of results that can be envisaged with more or less important means to put in place. If for example we wanted to make the planet Mars a perfect twin of the Earth, the task would be daunting.
The planet Mars is about ten times less massive than the Earth, so we would have to bring back the equivalent of several small planets, organize collisions and wait a few million years for it to cool down. We would then have reached the first stage of terraforming. At such a level of engineering and such energy expenditure, even interstellar travel seems to be a more credible alternative to finding a second home.
To reach a more acceptable solution, we can start by making concessions. Let’s suppose that the planet Mars retains its current mass. The planet Mars has a surface gravity of a little more than a third of gravity on Earth. This assumes a time of adaptation but is probably not a fundamental obstacle to life on the planet Mars. We could imagine that a successful terraforming of the planet Mars would consist in making it a planet where it is possible to breathe in the open air. Again, the challenge seems huge. There are three major projects to implement : increase the atmospheric pressure, change its composition to make it breathable, and bring temperatures into an acceptable range.
Even if it was successful, it would be as difficult to maintain these conditions over time. Indeed, the planet Mars has difficulty retaining its atmospheric layers in the face of solar winds, mainly because of its low gravity and lack of magnetic fields. To make it a sustainable project, we should also find a way to counter solar winds. If we try to envisage a Martian terraforming, it is perhaps by this that we have to begin.
To protect the planet Mars from solar winds thanks to a gigantic magnet in space
In 2017, Jim Green, the director of NASA’s Planetary Science Division, made a proposal. By placing a very powerful electromagnet at the L1 Lagrange point of the Sun-Mars system, it should be possible to encompass the entire Mars planet in its magnetosphere.
This would act as a kind of shield against the solar winds. To achieve this result, it would be necessary to set up a very powerful magnetic field. So we are still clearly on the side of science fiction, but this human modification could allow the planet Mars to develop a slightly thicker atmosphere. Surface temperatures would increase by a few degrees, which is already a small victory.
To breathe in the open, to create a cycle of water… Is it possible on the planet Mars ?
However, we must go much further to achieve our goal of breathable air. We can try to continue to increase the atmospheric pressure and the temperatures by several processes like the melting of the polar caps using orbital mirrors or nuclear bombs, the importation of greenhouse gases by millions of tons or by reducing artificially the albedo of the planet Mars. There are a lot of ideas but they all require means far beyond human capabilities and the results are very hypothetical.
Even if we could melt all the polar caps of the planet Mars and release all the CO2 they contain, the atmospheric pressure would only rise to 7% of the atmospheric pressure on Earth. The remaining 93% would have to be imported, which is an absolutely Herculean task. Here again, the alternative of interstellar travel is rather attractive.
Introduce extremophile living creatures to create oxygen
Achieving acceptable atmospheric pressure and acceptable temperatures does not solve the problem of oxygen either. On a small scale, NASA has worked on this issue. Since 2014, the American space agency has been developing a small experiment that could one day equip a Martian rover. In the presence of light and in contact with the soil of the planet Mars, some cyanobacteria and extremophilic algae could possibly produce oxygen. NASA is developing this concept in the hope of being able to easily create oxygen for a possible Martian base. It would obviously require a gigantic scaling to supply in this way the entire atmosphere of the planet Mars.
Now let’s imagine that all these problems are solved. After insurmountable efforts, humanity has thickened the atmosphere of the planet Mars and supplied it with oxygen. This atmosphere is further protected by a magnetic shield. It is now possible to land on the planet Mars, take off your helmet and breathe fresh air. Thanks to this thick atmosphere, liquid water has returned. Some rivers and seas crisscross the planet Mars, enough to organize some nautical races. However, terraforming is far from being achieved.
Martian settler, do not remove your helmet too fast…
Martian soil is still infertile. Worse, it is toxic. There are large amounts of perchlorate, a carcinogenic compound that permeates the soil and dissolves in water. Now, powerful winds agitate the atmosphere, with large quantities of dust. The great breath of fresh Martian air is likely to make you spit out your lungs. If there was liquid water, it is not sure that it is in sufficient quantity to set up a real water cycle. The rains are probably very scattered and regional. Except for some extremophilic species, the planet Mars remains not hospitable.
It is now necessary to fertilize the soil and introduce little by little some species that can form ecosystems. Of course, we hope that once this stage is achieved, humanity will have a better understanding of how ecosystems function. We have not yet listed all the species that live on Earth and we still do not fully understand the synergies that unite them. In other words, the road is long.
Even with gigantic means, the terraforming of a planet seems to be insurmountable
Terraforming the planet Mars means to take back the 3 billion years of work that have enabled the Earth to become what it is today. Things are not much better if we look at Venus. Venus has the advantage of offering a surface gravity almost similar to the gravity of the Earth. The other tasks look even harder than on the planet Mars. We have to succeed in dividing the atmospheric mass of the planet Venus by 90, reintroduce water and agree to live equivalent days to 216 Earth days.
Like the planet Mars, terraforming Venus requires extraordinary resources, much greater than what humanity has been able to exploit since its origins, for a very uncertain result. We may envisage more realistically a very partial terraforming which would not have the objective of transforming the planet Mars or Venus into a new Eden, but of making them destinations a little less hostile. A few millipascals and a few more degrees are still valuable if the energy cost is relatively contained.
The protection of the Earth and even interstellar travel seem preferable to terraforming
If humanity had a huge amount of money to spend, it could also choose to live in a controlled environment, be it tunnels and domes on the planet Mars, or even space stations built from asteroids. At a similar level of spending, interstellar travel aboard multigenerational spaceships is a viable alternative for a day to offer humanity several homes.
But if two planets are better than one, it’s good to remember that a planet is better than zero. The Moon and Martian bases may become a reality in a near future, but life will never be so enjoyable as on Earth. Our role is to take care of it so that we never have to wonder how to terraform it.
Images by Daein Ballard [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)] / U.S. Environmental Protection Agency [Public domain] / D Mitriy [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)] / NASA/Green / NASA/Techshot Inc.
