Ask Ethan: Isn't it silly to dream of terraforming Mars?

Mars and Earth on a scale - it is clear how much larger and more friendly our planet is to life than our red neighbor

In the entire known universe, there is only one planet capable of supporting a complex intelligent life: the Earth. And although the distant worlds, moving around other stars, may have a potential similar to that on earth, and they may even be inhabited, we still have to learn how to travel so far. And what if you look at another world in our solar system? The most likely candidate is Mars, which, apparently, in the past had many properties comparable to those of the earth. It is possible that with a little help, he can again become so. A question on this topic is asked by our reader:

I read different materials on this topic, and most of them describe how you can live on Mars at the moment, which looks like a rather complicated enterprise. And now we also learned that the local soil is toxic and quickly kills bacteria. But the real terraforming of Mars? It seems to me that the greatest problem will be the absence of a magnetic field, which is why any atmosphere you create will simply fly away from there. Why don't we terraform the Earth - it will be much easier!

There are good reasons for being pessimistic about what we can do with our current technologies, but it turns out that, in principle, we can turn Mars into an inhabited world.


Possible way to transform Mars into a more Earth-like view. Bringing the world to an inhabited species without the need to erect structures within which air pressure is maintained, always begins with the construction of the atmosphere

Of course, the soil of Mars may be toxic, but there are toxic soils on Earth. The parameters that determine the possibility of living in specific conditions are few in number: these are pH, moisture content and the ability to retain elements / molecules / nutrients, and not to be poisoned by everything else that is present there. The soil of the Earth can be processed and made habitable by conventional chemical processes, and there is no reason not to do something similar on Mars. This is most likely the easiest. Having received microorganisms that can multiply on Mars, even if there are not so many of them as on Earth, we will already take a big step in building habitable environments.


Newton's crater in the corrected colors. Visible leaks, the strongest evidence of the presence of flowing water on the surface of Mars

Mars has a worse problem: it's dry. Not that there was no water vapor or ice; they are there. The problem is to take somewhere a large amount of water, its steady flow in the liquid phase. And although there is saline liquid water on Mars at a certain time of the day - we can see this by the increasing flows [linea] on the slopes of the Martian landscape - most of the time, the water is either frozen or evaporates. Liquid water, as far as we know, is extremely necessary for life processes on Earth, and it is not on Mars.


Seasonal frozen lakes appear on the entire surface of Mars, which indicates the presence of water on the surface (not liquid)

The physical reason is simple: the atmosphere of Mars is too thin to keep the water in a liquid state on the surface. Liquid water requires a certain atmospheric pressure - at least 1% of the earth's. On Mars, it is only 0.7% of the Earth, because of which the liquid phase can hardly exist. Some kind of liquid exists only due to the salinity of the surface and the length of deep craters, at the bottom of which there can be more atmosphere and more pressure. If people are left unprotected on the surface of Mars, the liquid in their bodies will boil, since the conditions on Mars do not reach Armstrong's limit


Armstrong's limit is the altitude (on Earth), where the atmospheric pressure is so low that the liquid boils at normal human body temperature - about 18-19 km. If in a jet plane at a height higher than this one, the pressure disappears, the pilot will lose consciousness even if there is an oxygen mask.

If it is necessary to make the soil again habitable, to create a macroscopic life capable of supporting itself, the habitable biosphere, oceans and other types of stable water on the surface, you need to add an atmosphere. To obtain an atmosphere similar to Earth, it is necessary to increase the amount of the atmosphere on Mars 140 times: it will be about 3500 teratons, 3.5 × 10 ¹⁸ kg. This is comparable to the mass of the asteroid 5 Astrea , or Pak, the internal satellite of Uranus, and accounts for approximately 70% of the earth's atmosphere. To do this, you have to deliver a lot of material there - preferably nitrogen and oxygen.


Mars, in mass and size comparable to Ganymede, the largest moon of Jupiter, will need to increase the atmosphere by a mass comparable to the mass of the moon of Uranus, Pak

But even if you add so much atmosphere, the problem remains: Mars does not have a magnetic field that can protect it from the solar wind. As NASA’s MAVEN mission confirmed, Mars is still losing the remnants of its atmosphere due to collisions of charged particles with it, with the result that many molecules fly into space. The atmosphere of Mars today is almost entirely composed of carbon dioxide, since this molecule is heavier than the other components of the atmosphere, nitrogen and oxygen. If we wanted to terraform Mars, we would have to not only add atmosphere, water and chemically transform the surface to make it habitable, but also protect the added atmosphere — wouldn’t it?


Mars does not have a magnetic field that would protect its atmosphere from the solar wind, so it loses it, unlike Earth. But you need to calculate the time scale at which this loss occurs.

It is possible that this is not required! You see, in physical puzzles a quantitative approach is needed: to understand not only what is happening, but also about what speed. The solar wind, of course, carries off the atmosphere of Mars, but only the MAVEN mission answered about the speed of its disappearance: about 110 grams per second. During solar storms, this speed can grow tenfold, and this seems to be quite fast. But if you count how long it will take to remove the terraformed atmosphere, you get a very large number: hundreds of millions of years. Instead of creating an extremely strong magnetic field, you can simply schedule a constant influx of molecules into the atmosphere to compensate for the loss.


The Earth's atmosphere, the view from the ISS at sunset, May 2010. Perhaps, after terraforming, the atmosphere of Mars can look about the same

Of course, we should under no circumstances consider the option of leaving the Earth for the sake of Mars: any terraformation of the red planet will be more costly than efforts to preserve our Earth. No matter how much we make or damage it, it will still be the most habitable world of the solar system.


Mars and its subtle atmosphere, photo from the Viking satellite in the 1970s. Even after all the damage caused by the people of Earth, it is difficult to imagine how the repair of the Earth can be more difficult than the terraforming of an entire desert planet

Get rid of the illusions of all those who believe that we can move to Mars after we make the Earth uninhabitable. Earth is the first planet, and we have to figure out how to solve our earthly problems in order to set up humanity for long-term success. Mars may be part of this long-term plan, but the most difficult part of its transformation will be the creation of a much more massive atmosphere. But if you deal with it, then oceans, rain, fertile soil, and a thriving ecosystem will follow!

Ethan Siegel - astrophysicist, popularizer of science, blog Starts With A Bang! He wrote the books Beyond The Galaxy , and Treknologiya: Star Trek Science [ Treknology ].

FAQ: if the universe is expanding, why aren't we expanding ; why the age of the universe does not coincide with the radius of the observed part of it .