Life on Mars: how recent discoveries bring us closer to moving to the Red Planet and how long it will take.
On August 16, 2019, eccentric billionaire and inventor Elon Musk tweeted Nuke Mars! ("Let's hit Mars with nuclear bombs!"). Mars - and what a person can do with it - worries humanity at least since Ray Bradbury's The Martian Chronicles. But there is a huge difference between the fantasies of half a century ago and our days: the latest scientific discoveries have transferred conversations about life on Mars from fantasy circles to the offices of researchers and even businessmen.
The fourth planet of the solar system is half the size of the Earth in radius, but it is equal in area to all the earth's continents combined (fortunately, there are no oceans there), plus in 2008 the NASA research probe found water there (in the form of ice). It is not surprising that there is a temptation to populate the planet, and literally in July 2019, rocket engines for a flight there for the first time were able to lift into the air Starhopper, a prototype that in a few years will turn into Starship - a rocket and spacecraft created specifically for flights to Mars. Thanks to the full reusability of Starship (more than a hundred uses), the cost of flights to Mars should plummet.
At the same time, the average annual temperature on Mars is -63 degrees Celsius, approximately the same as at the Vostok Antarctic station. It's so cold there because its atmosphere is 150 times thinner than Earth's. With such a thin gas shell, the greenhouse effect is very weak, which is why it is cold. The problem can be solved by bringing the climatic conditions on Mars closer to the Earth's climate - this process is called terraforming. In the case of Mars, for this it is necessary to somehow sharply heat the surface of the planet, which even in the best years is 56 million kilometers away.
Scientists are fighting this problem quite hard, and recently, in the summer of 2019, an unusual way was presented to make the Red Planet habitable - for a start, at least partially. It turned out that a transparent dome made of an exotic gel material only a couple of centimeters thick warms the terrestrial imitation of Martian soil so much in poor local lighting that it is able to support plant life without additional heating. And this is a real sensation. We tell you what can be done in general so that after a certain number of years people walk through the Martian fields and admire two moons at once.
Airgel domes: level 80 greenhouses discovered by scientists a month ago
Let's go straight to the most recent discovery. In July 2019, a team of scientists conducted simple laboratory experiments in which they placed an analogue of Martian soil in a chamber with a rarefied atmosphere and Martian temperature. Then they shone on the domes with lamps, giving 150 watts of energy per square meter - exactly as much as the sun gives on average to the surface of Mars.
It turned out surprising: without the slightest external heating, the surface of the Martian soil, covered from above with a gel dome, warmed up just above zero degrees. The dome, only two centimeters thick, transmits visible light well, heating the soil, but very poorly transmits ultraviolet, infrared radiation and heat. There are more than enough raw materials for its production (ordinary sand) on Mars, as well as on Earth.
Heating the soil by 65 degrees with a simple transparent dome looks like a miracle, because below the soil there is no special thermal insulation and some of the heat still goes to the sides. That is, it's like covering the frozen ground with a cleverly arranged oilcloth - and then everything happens by itself. But there is no particular miracle here. Aerogels were discovered in 1931, and, in fact, it is a regular alcohol gel, from which all alcohol is evaporated by heating, leaving a network of air-filled channels. Its thermal insulation properties with the same thickness are up to 7.5 times higher than that of foam or mineral wool, while it is practically transparent. A conventional dwelling made from it and on Earth, being completely transparent, would not require heating, except during the long polar night.
Interestingly, in fact, this material has already been tested on Mars: American rovers use airgel so that their internal instruments do not get overcooled during the Martian night, when the temperature can drop to -90 degrees.
Researchers who have proposed such domes as a way to one day move to Mars note that airgel domes are easy to transport over long distances. Moreover, experiments in terrestrial laboratories have already shown that even tomatoes grow completely on an analogue of the Martian soil, if the temperature would be normal. There is no need to spend much water for them either: it has nowhere to evaporate from under the dome, that is, even a small amount of it will be constantly consumed by plants "in a circle". By the way, in order to confirm these proposals, the authors plan to transfer the experiments to Antarctica - the dry valleys of McMurdo, in terms of climate and waterlessness, extremely close to Mars.
Musk is right: Mars can indeed be bombed - and possibly usefully (but not fact)
The most radical way to solve the problem, as is often the case, was proposed by Elon Musk: to bomb the poles of Mars with thermonuclear bombs. The explosions should vaporize carbon dioxide, which makes up most of the ice in this planet's polar caps. CO2 will create a greenhouse effect, that is, from nuclear bombings on the fourth planet it will warm up seriously and for a long time.
True, in 2018 a study sponsored by NASA put forward a completely different point of view: it is useless to bomb the poles. And in general, all of Mars' carbon dioxide is not enough to create an atmosphere dense enough for serious warming. According to the calculations of the "nasov" scientific group, having melted the polar caps of carbon dioxide, the pressure there can be raised only 2.5 times. It will get warmer, but it's still Antarctic temperatures - and the atmosphere is 60 times thinner than ours. The authors of the work directly mentioned the person whose point of view they criticize: Elon Musk. But this, it seems, did not bother him in the least.
Even on Mars, you can find a canyon thousands of kilometers long - and settle in it.
Mars has very unusual relief features that are not found on Earth. One of these is the 4,000-kilometer long Mariner Valley canyon system, the longest known in the solar system. Its width is up to 200 kilometers, and its depth is up to 7 kilometers. This means that at the bottom of the canyons, atmospheric pressure is one and a half times higher and there is noticeably warmer and more humid than on the rest of the planet. It is over part of the Mariner Valleys that spacecraft photograph real fogs from water vapor (pictured below), and on the slopes of other areas - dark traces of streams in the sand, and these streams are suspiciously similar to water.
The Mariner valleys are not wide everywhere - in some places their width is only a few kilometers. It has long been proposed to cover such places with a glass dome, believing that this will be enough to retain heat and form a local high temperature. An airgel dome over such an area with water can lead to the formation of a local relatively warm climate with its own precipitation and water. Such places can be built up gradually, and the larger the area covered with abutting domes, the higher the average temperature will be (less heat loss through the walls). So, in fact, such a gradual, "creeping" terraforming can take up a very large area of the planet.
What's wrong with NASA's calculations and why are dissenting scientists already hired at SpaceX?
There is an easier way to global warming of Mars to Earth's temperatures. As noted by another group of scientists, we have already tried this method on Earth, without wanting to - emitting 37 billion tons of carbon dioxide into its atmosphere and gradually increasing the temperature on the planet. This path is greenhouse gases.
Of course, there is no coal on Mars that can create a greenhouse effect if burned. And CO2 is not the most efficient greenhouse gas. There are much better candidates, of which the most promising is SF6. Its molecule consists of one sulfur atom, around which six fluorine atoms stick out. Due to its "bulkiness", the molecule perfectly intercepts both ultraviolet and infrared radiation, while transmitting visible light well. In terms of the strength of the greenhouse effect it causes, it is 34,900 times greater than carbon dioxide. That is, just a million tons of this substance would give the same greenhouse effect as the tens of billions of tons of CO2 emitted by mankind today.
In addition, SF6 gas is very tenacious - its life time in the atmosphere is from 800 to 3200 years, depending on external conditions. This means that you do not need to worry about its decay in the Martian atmosphere: once produced, it will remain there for a very long time. In addition, the gas is harmless to humans and all living organisms. In fact, on Mars, it is rather useful, because it intercepts UV rays no worse than ozone, which is not there yet.
According to calculations, in about 100 years, the injection of super-greenhouse gases of this type can raise temperatures on the planet by tens of degrees.
Interestingly, a little earlier, with the support of NASA, another scientific work was carried out that described just such a scenario - terraforming Mars due to man-made greenhouse gases of increased efficiency. One of the authors of this work was Marina Marinova, who worked for NASA for a long time, and today she got a job at SpaceX. Moreover, Elon Musk himself referred to it as a co-author, criticizing the work that speaks of the lack of CO2 on Mars, allegedly preventing it from turning into a planet with temperatures close to Earth.
An important feature of such a super-powerful greenhouse effect: after warming up the Martian soil, the CO2 bound in it should be released into the atmosphere, further increasing the heating of the planet.
When will Mars actually look like Earth?
While SF6 can indeed transform the entire planet, it must be clearly understood that this will not happen tomorrow. According to calculations, for this you need to spend billions of kilowatt-hours a year - and spend them on Mars, making the same SF6 gas from a soil rich in fluorine and gray soil. That is, those wishing to terraform will have to build an entire 500 megawatt nuclear power plant on the planet, automated production facilities that constantly release SF6 gas into the atmosphere. This process will give tangible results after a hundred years of work. Well, or a little faster with very large investments in the creation of factories.
All this time, people who provide their activities and study Mars will have to live somewhere. It is obvious that the best solution for the local transformation of the planet in the places of their settlement will be airgel domes. That is, if necessary, terraforming will proceed in two ways at once: local - for the current colonists with the help of domes - and global - for the planet as a whole.
Who can already live on Mars - and why it matters
Apple trees on the Red Planet won't bloom in the near future, but outdoor vegetation may actually come there sooner than we think.
Back in 2012, the German Aerospace Agency conducted an experiment with the arctic lichen Xanthoria elegans. He was kept at a pressure 150 times lower than that of the Earth - without oxygen, at Martian temperatures. Despite the alienation of the environment, the lichen not only survived, but also did not lose the ability to successfully photosynthesize (during periods that mimic daylight hours).
This means that in a number of regions of Mars - the same Valleys of the Mariners - such organisms in the equatorial zone can already live today. And after the start of the production of SF6 gas on Mars, the territory suitable for them will begin to expand rapidly. Like other lichens, the elegant Xanthoria produces oxygen during photosynthesis. Actually, it was the release of lichens on the earth's land about 1.2 billion years ago (0.7 billion years before higher plants) that allowed the earth's atmosphere to sharply raise the oxygen content to the level of today's terrestrial highlands. Most likely, lichens on Mars will have the same function - to prepare the atmosphere so that it would be easier for more complex creatures to live in it.