Beginner’s Guide to Terraforming Mars
Being a single planetary species increases our risk of extinction exponentially when compared to being a multiplanetary species. To ensure the survival of the human race, it is imperative that we travel to and colonise another planet. Right now, Mars is that destination. But once it’s been colonised, what will the next generations do?
What is terraforming?
Terraforming is the process of modifying a planet in the attempt to make it resemble Earth, so that it can harbour life. This may include changing the atmosphere, temperature, surface topography or ecology.
Initially when we go to Mars, obviously, it will not be terraformed. To begin with, at least until a substantial colony has been formed, we will likely either live in giant domes made of a certain polymer that can be produced using resources found on Mars, or we’ll live underground, perhaps in caves or in dormant lava vents. So, it is very possible to expand to and colonise other planets without terraforming them. In this way, terraforming is very much an end goal rather than a necessity for expanding the human race.
However, this in no way decreases the importance of terraforming. In fact, terraforming is perhaps the most significant part of the expansion process as it differentiates a dead planet from one where life can exist.
What kind of a life is it if you are literally surrounded by an entire unexplored planet 24/7, but have no choice but to be confined to a dome or cave. It sounds very much like some sci-fi prison analogy. So, there is no doubt that to colonise Mars, indirectly means to terraform it and thus to live on the red planet indirectly means creating a second Earth (which sounds far more enticing than the “dome life” mentioned above).
Is Mars our only choice?
Put simply: for our generation and likely the next, yes… Mars is our only choice. Currently we are limited to our ability to transport humans over long distances through space (sending cargo, or unmanned missions is a totally different situation and so is much easier). Therefore, we are undoubtedly confined to the solar system, and the closest parts of it at that. If we look at the planets, out of the 8, only Mercury, Venus, Earth and Mars are rocky (we obviously can’t colonise a gas planet). Out of Mercury, Venus and Mars, Mars is the only place we can go where there is any chance at all of being able to survive more than a few seconds without perishing due to the colossally hot temperatures. Despite its challenges, Mars is actually a reasonably desirable place to be (relative to other planets).
There is also the option of not picking a planet, but actually expanding to moons. The closest, and most well-known example is Saturn’s Titan. Although this moon seems to have some quite impressive potential, especially for terraforming, it is significantly further than Mars. Despite it being within our solar system, it is still over 1 billion miles away. For perspective, the Moon is about 250,000 miles away and it took Apollo 11 three days to get there, Mars is (at its closest) 30 million miles away and will take roughly 6 months to get there. And so, it is clear to see how this flight time eventually spirals out of control when looking at distances that range into the billions. Despite Titan being in our solar system, it is still a confident no for our generation (and most likely the next).
In fact, people are actually surprised when told that Mars colonisation is a goal for this generation. While terraforming may not be entirely for the current generation, initial living and building a colony most certainly is — likely beginning properly in the next decade.
What makes Mars suitable?
Mars is called Earth’s sister planet for many strong reasons. To start with, it has a 360-degree rotation time of 24 hours and 38 minutes, and sits on an offset axes. In this way, life will be relatively comparable to Earth when living on the red planet: days (known on Mars as “sols”) will feel practically the same in length, and we will experience multiple different seasons (due to the axes) — just like on Earth.
The average temperature is -60 degrees Celsius. Now although this value sounds daunting at first, there are a few points to make. As with the example of Mercury and Venus above, -60 degrees can be seen as quite reasonable — especially as it’s undeniably easier to warm up than it is to cool down. Not only that, but this value is an average in the broadest sense possible. In fact the temperature can (in the most desirable locations and times) consistently be around 20–25 degrees Celsius — a pleasant English summer’s day.
Furthermore, this temperature will only ever be an issue before terraforming. Part of the terraforming process will be to adjust the temperature to something more desirable across the entire planet. But the previous point remains: even before terraforming, Mars’ temperature shouldn’t be too much of an issue.
Mars used to be like Earth
Since Mars has ever been gazed upon, there has been substantial evidence that it used to be a very different place to the cold and dry desert it is today. The first piece of evidence came from the Dutch astronomer Christiaan Huygens who discovered the ice caps on Mars in 1672. This proved that water did exist on Mars, albeit in solid form. Other astronomers over the next century used telescopes to observe and discover that Mars is covered in what appears to be channels, valleys of basins, which can only have been formed from water erosion. Between then and the 1900s, there were no more major developments regarding evidence of water. The difference between then and now is that we have the capability to go there and take actual samples to test, rather than just gaze and guess from tens of millions of miles away.
We have sent multiple rovers to Mars including Spirit, Curiosity, Opportunity and soon to be Perseverance. These rovers have been able to use spectroscopic methods to analyse various rocks on Mars, and have discovered that many of these rocks contain up to 22% water by weight — further emphasising that water is not only present now, but was once very abundant.
Using a more modern understanding of how the planets in the solar system have evolved, we can see that it would make sense for Mars to at some point (and perhaps over the magnitude of billions of years) have been covered in oceans. The most prominent question from this is: “what happened to the water?”.
Well, our modern scientific understanding can explain this too:
Indeed, Mars and Earth are similar however, Mars has two main differing characteristics. 1. It is smaller, having roughly half the diameter. 2. It has no significant magnetic field. These two defining properties are what allowed Mars to deteriorate whilst Earth blossomed.
In order for water to remain on the surface of a planet, it needs to be warm enough, and clearly with Mars’ average temperature being -60 degrees Celsius, this heating requirement is not met. However, it once was. Like all planets (including Earth), when Mars was initially formed it was hot and volcanic, and naturally over time this heat dissipated (as it did with Earth). However, as Mars is small, it reached the point where the heat it naturally continued to generate (after the initial heat dissipated) was not enough. Furthermore, any heat it did generate in itself dissipated due to the planet’s lack of magnetic field.
A magnetic field has the ability to stop an atmosphere from escaping into space. Earth does have a strong magnetic field, and as Mars doesn’t, it can be explained why Mars has an atmosphere which is 1/100 the size of Earth’s despite only having half the diameter.
An atmosphere acts as a “blanket” to a planet, working as an insulator to keep in the heat that would otherwise be dissipated. So, it is clear to see that as a direct consequence of Mars having no significant magnetic field, it has no effective way to retain heat, thus explaining why overtime it cooled significantly more than Earth.
The lack of a Martian atmosphere’s effect on its water retention is twofold. As mentioned, it causes the planet to be cooler, thus causing liquid water to freeze. But secondly, no atmosphere means less protection from the sun. This therefore allowed much water to be evaporated from the surface, rise to the atmosphere, and then be lost to space… cooling it even further.
The point of this argument is to explain that unlike other planets, Mars has existed in a similar state to Earth in the past, thus suggesting that it can do so again in the future albeit with a small helping hand from us Humans.
How do we terraform Mars?
A potential burning question one might have is: if Mars was once like Earth but due to its properties it deteriorated, what is to stop that from happening again after we terraform it? Well… nothing.
In fact, it is almost a certainty that a human-terraformed Mars will deteriorate to the cold, dry desert again. However, one must bare in mind that this natural degeneration is not quick. It is a process that spans hundreds of millions of years (as can be seen by the “History of Water on Mars” diagram). Consequently, this is not a concern we need to have.
Thickening the atmosphere
The first step to terraforming Mars is to heat it up. This involves actually heating the planet, as well as ensuring that heat it generates is retained. To ensure this retention, we must rebuild its atmosphere. As mentioned, (but in a different context), the effect of rebuilding the atmosphere on heating is twofold:
- It will act as a “blanket” to keep in the heat, this is known as the greenhouse effect. It is where short wavelength radiation from the sun passes through the atmosphere, is absorbed and re-emitted by the ground as long wavelength radiation. This is absorbed by the atmosphere and re-emitted in all directions including back towards the ground, causing it to be trapped. Overtime the amount of trapped radiation builds, causing the planet to warm.
- As this heat retention warms the planet, more ice is melted and evaporated (converted to water vapour — an excellent greenhouse gas), building the atmosphere even more, allowing it to warm even further. This cycle is the exact problem we are concerned with on Earth… it’s called global warming. The difference is on Earth we don’t want it to occur, whereas on Mars we do.
So, an essential part of warming Mars is thickening its atmosphere. This process will allow the temperature to rise naturally. When done (if necessary), we can go on to use other processes with the sole purpose of heating the planet more. But how do we thicken the atmosphere?
Well as said above, we are doing it on Earth already without even wanting to. We can employ many tactics to global warm Mars. Luckily, many of these tactics serve two purposes. For example:
- We will need to generate energy somehow when living on Mars. If we use methods such as burning fossil fuels, this will not only supply us with the energy we want, but it will also emit carbon dioxide (a greenhouse gas), building the atmosphere. On a side note, Mars’ atmosphere is actually already 97% CO2 meaning it is compositionally very effective at trapping heat, however as explained earlier, the lack of magnetic field means the atmosphere has dissipated over time. So, it’s size is only 1/100 that of Earth’s, hence why we must rebuild it to make it more effective.
- Another example of a dual purposed tactic is livestock. Although we don’t necessarily need livestock for food (we can use other methods), it is certainly a good method: its presence releases methane (another good greenhouse gas).
- Just live itself being present on the red planet (be that humans, cattle, dogs, plants, termite, etc.) gives off CO2 as it generates energy in respiration.
- We can attempt to melt the polar ice caps, as well as any other ice caps found across the planet (for example at the top of Olympus Mons — an ancient Martian volcano that is 2.5 times the height of Mount Everest). In the case of the largest caps (being the poles), we can drop nuclear bombs onto them. Although this is a very crude and inelegant method, it certainly fulfils its purpose and melts the poles. And as for the other caps, we may be able to operate giant reflectors on satellites orbiting Mars. These should focus radiation from the sun directly onto a given spot (at a very high intensity), thus increasing its average temperature and in the case of ice caps: melting them. Both of these methods will 1. Melt ice, producing water, causing the volume of surface water to grow and 2. Evaporate much of this water, causing the amount of water vapour in the atmosphere to grow. Harnessing such dual purposed methods is the key to successfully getting to, living, colonising and terraforming Mars.
Making Mars wet
The key to a planet being able to support life is for it to be warm and wet. As shown above, we can warm it, but we still need to make it wet again. Fortunately, there is not much extra work we have to do after warming it. Thanks to our past experiments and gatherings, we already know that there is much water on Mars (especially beneath the surface). And so, heating the planet will not only melt the caps, creating huge spots of water, but will cause subsurface water to rise to the surface, forming huge lakes and oceans.
As a direct result of the planet being made warmer, water will continue to evaporate, forming clouds, resulting in rain (or even snow) on Mars. At this point, we have created a successful and effective Martian hydrological cycle.
Producing oxygen
Now the conditions are strong enough to harbour life, however the atmosphere is still almost entirely carbon dioxide… not very good if we are planning on breathing! At this point, Mars has actually been restored to its old self. As far as we know, Mars has never resembled Earth more than in this state.
Earth’s atmosphere was once very similar to this (mainly being CO2), and so it is important to draw comparisons between Mars and Earth, and hopefully use young Earth’s methods for forming oxygen.
Well, the opposite process to respiration is our key: photosynthesis. Earth’s atmosphere became oxygenated almost entirely due to the photosynthetic processes of tiny microorganisms known as cyanobacteria (or blue green algae). Putting this life on Mars and allowing it to “do its thing” is simple enough, but this will undoubtedly be that part of the terraforming process that takes the longest. It is almost impossible to say how long with our current understanding. However, our advantage (when compared to young Earth), is that we are here to encourage the growth and expansion of this life, and can place it on Mars ourselves, rather than having to wait for it to grow and expand naturally.
Furthermore, this is our best bet with our current understanding of science. It is important to remember that our understanding and knowledge is growing exponentially, and given that this is almost the final stage of terraforming (and to get to this stage may take over a hundred years, maybe even hundreds), by the time we reach this dilemma, it is likely we may have a totally different perspective, or solution which acts much faster.
This concept of growing knowledge and understanding also needs to be taken into consideration across all aspects of the terraforming process. All that I have explained is using what we currently know. I have no doubt that these ideas will change and improve with time. And that when this growth is taken into account, it is likely we will terraform Mars quicker than most estimates.
Creating a green Mars — conclusion
So now we have a warm, wet and oxygenated Mars… perfect for life. All we must do now is put some life on it! Plants and trees will be planted all across the planet. This may be manually planted on the ground or perhaps dropped as seeds in huge quantities from orbiting satellites, allowing rapid expansion. The excellent benefit of putting plants and trees on Mars is that they also photosynthesise just by living — so more CO2 will continue to be converted to oxygen.
At this point, humans should be able to lift off their helmets, exit the domes and take a deep breath of Martian air.
For the first time, we will be able to live a somewhat normal life on Mars…
Originally published at http://thephysicsfootprint.com on March 21, 2022.
