There is only one planet in the entire Universe that can warm up complex, intelligent life, and that is Earth. Although distant worlds near other stars may, in principle, be similar to Earth and even inhabited, we do not yet know for sure. And until now, we have not found anything close to our home planet. But what if we look for it in our own solar system? The most likely candidate is, of course, Mars. In the past, scientists believe, the Red Planet had many "earthly" qualities. Can I get them back? Can Mars become habitable again one day? This question will be answered by Ethan Siegel of Medium.com.
So far, people are trying to master Mars. It is difficult enough - the soil is toxic, the atmosphere is absent, bacteria do not survive. But if the planet is terraformed … Then the biggest problem will remain the lack of a magnetic field on Mars that holds the atmosphere on our home planet. We have the right to be as pessimistic as we like when looking at our modern technologies, but the transformation of Mars into an inhabited world may be quite possible. Once.
If you want to make the planet habitable without an airtight environment, you need to add a dense atmosphere
Of course, the soil of Mars itself can be toxic, but there is a lot of toxic soil on Earth too. There are several criteria that determine the hospitality of the environment: soil acidity, moisture content and the ability to retain the elements, molecules and nutrients that are needed, while not poisoning everything. Soil can be cultivated or restored with simple chemical manipulations on Earth, and there is no reason to doubt that we could do something similar on Mars. This is probably the easiest part. As soon as we have microorganisms, even a small part of those that we have on Earth, that can develop in Martian soil, we will go on the path of creating a suitable habitat.
A tinted view from the inside of Newton crater, in which they found the very streams of liquid water that turned our understanding of Mars
Mars also has a deeper problem: it is dry. Not that it doesn't have water vapor or ice on it, it definitely does. The problem is how to transfer a large amount of water to a liquid phase, gradually. Although there are streams of liquid and salt water on Mars at certain times of the day, the vast majority of the time they are either frozen or vaporized into a gaseous state. Liquid water, as far as we know, is essential for life on Earth, and Mars does not.
Seasonal frozen lakes appear all over Mars, showing water (not liquid) on the surface
The physical reason is simple: Mars' atmosphere is too thin to support liquid water on the surface. Liquid water requires a certain atmospheric pressure: about 1% of what we have on Earth, at least. Mars has only 0.7% of Earth's atmospheric pressure, so a liquid phase is, for the most part, impossible. This is partly due to the salinity of the surface and partly because the craters go deep down, much lower than the atmosphere and pressure allow liquid water to exist. In fact, if humans were defenseless on the surface of Mars, the liquid in their bodies would boil as conditions on Mars are below Armstrong's limit.
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Armstrong limit - it is the altitude above sea level where the pressure drops to such an extent that the blood in the human body boils. It is 19,200 meters above sea level
If you wanted to restore soil, create stable microscopic life, habitable biosphere, oceans and other forms of surface water, you would need to add more atmosphere. To get an atmosphere comparable to that of Earth, you would need to add about 140 times more atmosphere than is present on Mars today: about 3,500 teratons, or 3.5 x 1018 kg. It is roughly the mass of asteroid Astrea 5 or Uranus' inner large satellite, Pak, and represents about 70% of the earth's atmosphere. You would have to transport a lot of atmosphere - mostly nitrogen and oxygen - to get there.
Mars, which is roughly the size of Ganymede, Jupiter's largest moon, would require additional atmospheric mass, comparable to Uranus's moon Pak.
But there is one problem, even if you add the atmosphere: Mars does not have a magnetic field to protect it from the solar wind. Mars still loses its atmosphere to this day, thanks to charged particles colliding with the atmosphere and knocking out various molecules. The atmosphere of Mars today is mostly carbon dioxide, which is heavier than nitrogen and oxygen. If we wanted to terraform Mars, we would not only have to add more atmosphere, water and chemically treat the surface, but also protect this additional atmosphere.
Mars does not have a magnetic field that will protect the planet from the solar wind, which means it will lose its atmosphere, but the Earth will not
Maybe it's not that bad. You see, when it comes to physics problems, it is very important to calculate everything: ask not only what will happen, but also at what speed. The solar wind, no doubt, blows the atmosphere of Mars away, but when asked how quickly the planet's atmosphere is depleting, the MAVEN mission answered: at about 150 grams per second. Of course, during solar storms, the speed increases tenfold. But if you take and calculate how long it will take to blow off the atmosphere created by terraforming, the answer is: hundreds of millions of years, and that's at least. Instead of creating an ultra-strong magnetic field, one could simply add particles to the atmosphere to compensate for the losses.
Earth's atmosphere from the height of the International Space Station. Perhaps someday Mars will be like this
Of course, by no means should we consider abandoning Earth in favor of Mars; any terraforming that will happen to Mars will in one way or another be more intense than our attempts to save the Earth. No matter how badly we pollute our home planet, it still remains the most populated world in the solar system.
Mars and its subtle atmosphere, photographed by Viking in the 1970s. With all the damage the Earth has suffered from human activities, it's hard to imagine that healing the Earth will be more difficult than terraforming an entire desert planet.
If you think you should consider Mars as the place we will go to when we make the Earth inhospitable, then this is wrong. Earth is planet number one, and you need to solve problems with it first. Mars may become our home in the distant future, but we must not forget about the alma mater either.
Ilya Khel