Could we terraform Mars or Venus


Humanity continues to multiply unabashedly - in a few decades the world population will exceed the 10 billion mark. The earth will then hardly be able to feed everyone adequately. But maybe other celestial bodies can be made habitable ...?

Terraforming Venus
Terraforming Mars
Lunar colonies
Mass driver

Up until the 1950s, people were convinced that Venus was covered by great oceans, but that the view of it was blocked by thick cloud cover. And the canali on Mars gave rise to all kinds of speculations, since they could only have been created artificially by intelligent beings. Thoughts were not far off that one day one would travel to this planet and found colonies there. Yes, even when no suitable rocket was available to mankind, people believed that one day the moon would be colonized.

Today we have to look at such ideas somewhat disillusioned. With a temperature of around 470 ° C, the surface of Venus is much too hot for any form of life, Mars can only come up with an extremely thin atmosphere and our moon is completely "bare". The vacuum of space prevails on its surface. But not only the dream of conquering other worlds, but also the worrying increase in the world population (we have already exceeded the 7 billion!) Lead to considerations as to whether and how one can make other heavenly bodies habitable. The transformation of a dead, uninhabitable planet into a livable world is called Terraforming. NASA showed in 1997 that this topic is being seriously dealt with when it held its first terraforming conference with 100 scientific participants. Let's take a look at the possibilities:

Terraforming Venus

Venus, which is not wrongly referred to as our sister planet, is often considered for settlement due to its great resemblance to Earth. With a diameter of 12100 [km] it is almost as big and one would weigh just a little less on its surface than on earth. Another advantage is given by the relative proximity of Venus, which on the one hand facilitates communication and on the other hand also makes traveling there. Because every 584 days a start window opens to Venus, while to Mars this only happens every 780 days. Because the solar radiation there is almost twice as high as it is here, the energy supply with solar cells would be possible without any problems.

But Venus does not only offer us advantages. The first problem is the heat mentioned earlier. Almost 500 degrees in the equatorial area are absolutely hostile to life, as is the 90 [bar] of air pressure. The high temperature has set in because the dense atmosphere of Venus consists of 95% carbon dioxide, the greenhouse gas that is now also bothering us. In addition, there are clouds of sulfuric acid and sulfur dioxide, while oxygen and water are completely absent. Not to be forgotten is the long Venus day, which lasts 245 earth days. Even if the terraforming could succeed, one would have to deal with large temperature differences. Relatively constant conditions could only be established at the poles. So if you wanted to make this planet habitable, you would be faced with a daunting task!

The well-known American astronomer struck in 1961 Carl Sagan propose to inoculate the Venusian atmosphere with suitable algae. These could release oxygen from the carbon dioxide through photosynthesis. However, the great lack of water immediately nullifies such plans, the Venus atmosphere only has a share of 0.003%. Sulfuric acid, which destroys all organic matter, would also be the purest Algae killers. No, we would have to approach the problem differently.

Opposite is an artistic idea of ​​the terraforming of Venus. Geoffrey A. Landis, an American scientist and SF writer, had the idea that you could create colonies floating in the air. From an altitude of about 50 [km], the Venusian atmosphere only has a pressure of 1 bar and a temperature of 50 ° C, a few kilometers higher it even goes down to 0 ° C. Here one could deposit large bubbles filled with earthly breathable air that carry habitable stations. Helium and hydrogen, which are even more buoyant, could then be extracted from the atmosphere. If enough of these stations are installed, one could place huge screens in space in a further step, the only task of which would be to shield the sunlight. The material required for this - carbon - could be obtained directly from the atmosphere. In the form of nanotubes, very stable, yet ultra-light constructions could be realized. In this way, the temperature of Venus could be gradually lowered, until the carbon dioxide in the atmosphere as Dry ice freezes out and deposits on the surface. The sulfuric acid or sulfur dioxide would also be removed. The dry ice could then be brought to Mars, which could support the terraforming there.

However, this does not solve all problems! Although we have now theoretically cooled the atmosphere and the CO2 eliminated, but such a process will probably take centuries. Because the heated crust of Venus represents an enormous heat store that can only cool down over very long periods of time. What we can achieve by sealing off sunlight in terms of CO2 frozen out, which turns back to gaseous carbon dioxide when it sinks to the surface sublimate (sublimation is the direct transition from the gaseous to the solid aggregate state or vice versa) and rise again.
But let's assume that tolerable temperatures have now been reached and the greenhouse components have been removed. What is still missing is above all water! Comets could now be thrown out of their orbit and captured by Venus. However, these bodies are not available in unlimited quantities and they would also be much too small; too many would be needed. As an alternative, it was proposed to steer one of Saturn's moons, consisting mainly of ice, out of orbit and crash it onto Venus. Sufficient amounts of water could then be available.

With the express permission of © David A. Hardy

Finally, we still have to make sure that the planet gets a breathable atmosphere. By freezing out the carbon dioxide, Venus has become practically atmospheric. No not really. We removed carbon from the atmosphere for the construction of the sun shield, so sufficient amounts of oxygen were released. It is "only" to solve the problem of "blending" this oxygen with a good portion of nitrogen - otherwise smoking a cigarette could become a real adventure ...

Terraforming Mars

As we have seen, from today's perspective, the terraforming of Venus is an almost impracticable project that might take thousands of years to complete. What about the third planet next to Venus and Earth, which is still in the habitable zone, Mars?

If we wanted to walk around on Mars today, it would not be possible without a protective space suit. However, the prevailing conditions here are still to be regarded as paradisiacal if you compare them with the murderous conditions on the highly inhospitable Venus. The atmospheric pressure is not even 1% of the earth's value and the temperature at the poles can easily drop below -140 ° C in the Martian winter. The atmosphere, which consists mainly of carbon dioxide, then becomes even thinner because the gas now freezes out and precipitates as snow (Carbonated snow and the above Dry ice are both solid CO2). Although the temperature at the equator can rise to +15 ° C during the day, even up to 20 ° C, at night it can then drop to -70 ° C. To make a stay there a little more pleasant, we would first have to do the following:

  • The temperature must be increased by around 60 ° C
  • The mass of the atmosphere must be increased so that it meets human requirements
  • Liquid water must be available
  • The UV radiation of the sun as well as the cosmic radiation must be reduced
  • Oxygen and nitrogen must make the atmosphere breathable

Mars today

Mars after terraforming

These conditions must meet the needs of humans as well as those of plants and animals. Ultimately, it must also be possible to produce food there. In addition, a sufficient atmosphere also promotes mobility through aviation.

The initial spark of terraforming could be achieved through various techniques:

  • The simplest way would be to sprinkle the (snow-covered) poles with soot or other similar substances (Sagan, 1973). These would absorb light and heat from the sun, which would ultimately lead to the defrosting of the polar ice caps. A gentle increase in temperature would be sufficient here. CO2 and water vapor would thus enrich the atmosphere. Both, especially water vapor (four times more effective than CO2) are greenhouse gases that cause further warming.
  • There have also been plans to breed microbes with the darkest possible cell wall. These could possibly be a better substitute for the soot (consider the large areas that would have to be sprinkled with soot) if they could be made to multiply like crazy under the given conditions. But what should they feed on ???
  • One could also tap into heat from the sun. This could be technically realized by installing large mirrors in a stationary orbit (Zubrin, McKay, 1993). However, such mirrors would have to be truly gigantic, 125 [km] in diameter would be absolutely necessary. Although the construction could be carried out extremely easily due to the lack of gravity, it would require 200,000 tons of aluminum. Such a mirror could be stationed at a distance of 214,000 [km], which would then irradiate the South Pole with 27 terawatts. This would raise the temperature by about 5 [K], which should be enough to defrost the polar ice caps. However, this method would be a demanding, complex technical challenge. The aluminum required could be made available worldwide in just 5 days. A much lighter design with modern nano-carbon tubes is also conceivable. After about 100 years, a first atmosphere could have formed in this way, the CO2 now the greenhouse effect takes over the further warming.
  • Finally, the "hammer method" would lead to the goal of Mars warming much more quickly: Choose a suitable planetoid, change its orbit so that it hits Mars straight away. This not only releases the gases from the planetoid, but also melts the Martian rock and creates additional CO2 from the regolith of the Martian soil and thus increases the temperature very effectively. While you are so good at "asteroid cones", you could also throw a few comets afterwards, which then supplied Mars with water. This in turn could then release oxygen from the regolith along with the carbon dioxide. However, the way in which comets and asteroids are to be deflected from their orbits according to these ideas still needs to be carefully considered. After all, comets still have the advantage that they contain a lot of ammonia (NH3) can contain what the supply of necessary nitrogen could take care of. 40 comets of around 10 billion tons each should be enough ...

Unfortunately, we do not yet have the technical possibilities to transform Mars into a life-friendly planet. We can only take a few astronauts to the moon and give them a light vehicle in addition to a small capsule. A manned flight to Mars is far from in sight, and we certainly don't have any transport options for large payloads such as those we would need for terraforming. However, it should not be ruled out that the technical prerequisites for such ambitious projects will be developed in the future. After all, Mars lends itself to a possible settlement for other reasons: One could probably adapt to the earth's only 0.39 times the force of gravity, but the length of day and night would be completely normal, since a Martian day lasts 24.6 hours. However, the Martian year is more than twice as long, the planet receives only 43% of the sunlight as the earth. That would still be sufficient for the photosynthesis of the plants, but you have to be prepared for fairly cool temperatures even at the equator in winter.

Adjacent picture: Inspection of the progressing terraforming of Mars (artist's impression). What is almost unthinkable with Venus could work quite early on with Mars: The use of plants, initially only simple algae. After the polar ice caps have thawed, they could begin to produce biomass from the carbon dioxide through photosynthesis, releasing oxygen in the process. The polar caps are partly made of water ice, so after defrosting the atmosphere would also contain water vapor. The conditions for plant life could therefore be created relatively quickly, especially if the temperatures allow liquid water. To do this, however, the average temperature of Mars would have to be increased from the current -60 ° C to at least 0 ° C. Another problem could be the lack of nitrogen, which is also required by the plants. It may, however, be released from existing minerals. Another possibility would be the use of so-called cyanobacteria. For example, one knows one on earth with the unpronounceable name Chroococcidiopsisthat exists here under the most inhospitable conditions. It can be found in the driest and hottest deserts as well as in the most concentrated salt water or the coldest parts of Antarctica. With such a frugal creature one could begin to produce the first compost as a basis for the growth of plants. 500 years after terraforming began, the first, initially only shallow, waters could form. However, it is still completely unclear how much water Mars actually has. The fact that he once owned a lot of it shows us a variety of soil formations, such as dried up river beds. Much of its water supply, however, has certainly evaporated into space when the planet's magnetic field dried up and was no longer able to deflect the solar wind. The atmosphere disappeared and with it the water. With a little luck, there will still be sufficient frozen reserves in the lower layers of the soil, but it is doubtful whether the oceans can be filled with them.

With the express permission of © David A. Hardy

In order to create tolerable environmental conditions on Mars, there are still some problems to be resolved in the event of terraforming:

  • The magnetic field of Mars is only very weak, the constant stream of particles coming from the sun (Solar wind) is hardly distracted and can tear particles from the atmosphere unhindered.
  • Also due to its reduced gravity, it is questionable whether Mars can hold an atmosphere for a long time
  • If you were to create an earth-like atmosphere with an equilibrium temperature of 15 ° C, you would not enjoy it very much. Such an atmosphere is not a good heat store and Mars would therefore radiate more heat into space than it receives from the sun. The equilibrium temperature would soon drop to -55 ° C!
  • A tropopause would have to be created in the atmosphere in some way. Anyone who has ever traveled by plane will know that at a height of 10 [km], the tropopause, the temperature is below -50 ° C. That is the limit for water vapor, which freezes out up there and sinks back onto the planet. So our water cannot be lost to us. On Mars, however, the situation could be completely different.
  • Even if there is so much CO from the polar caps and the regolith2 can be released that a dense atmosphere is formed, this is initially completely toxic to humans. With certain algae, however, the photosynthetic decomposition of carbon dioxide could be initiated. But then you have to remove the organic waste, otherwise it would be oxidized again with the oxygen that has just been separated. For example, they would have to be sunk in great depths of the sea. In addition, the lower the CO2 the warming greenhouse gas also decreases - the temperatures would therefore drop again.
  • As already indicated, it is questionable whether Mars has enough material to initiate meaningful terraforming. Many billions of tons of gas just to create an atmosphere cannot be "carted" with future technologies.
  • Although the last Martian missions (Viking Lander, Mars Global Surveyor, Mars Express or Pathfinder etc.) have already imparted a lot of knowledge about the red planet, thorough research would be necessary before such a mammoth project as terraforming can begin. However, it is questionable and cannot be answered today when the first human will set foot on Mars.

There are certainly no concrete plans for the terraforming of Mars, it will only be a mind game for a long time. But because scientists are seriously dealing with it, this is a sign that we are not only dealing with fantasies. However, whether such projects can ever be implemented remains uncertain. Today, in any case, the technical possibilities for this are completely lacking, not to mention the financial outlay.

Lunar colonies

Yes, do we have to go that far to establish colonies on another celestial body? Why not on our moon right away? Indeed, that would have some advantages. The people there would have visual contact with the earth, at least on the front, and radio communication would also be possible without any problems. The relatively easy accessibility is also to be mentioned as extremely cheap, you would be "up" in just a few days. The inhospitable and completely hostile conditions on the moon, however, rule out the possibility that autarkic colonies could ever develop here, in which people spend their lives. Terraforming the moon is even more completely impossible. It is much too small, the gravity is simply too low to even begin to hold an atmosphere.

But what should move people to stay on the moon, at least temporarily? Some reasons speak for themselves:

  • The exploration of the moon that has already started (Apollo missions) could be continued and completed
  • The development of cheaper and better transport options, more powerful engines, etc. would be accelerated
  • Extremely large, manned or remote-controlled telescopes could be erected that would have a completely unobstructed view of space. Many such instruments could be linked into an array across the moon. It is not even imaginable in a dream what enormous possibilities this could open up for astronomy!
  • Finally, moon stations could serve as a stepping stone for interplanetary travel. Due to the low lunar escape speed and no obstructive atmosphere, take-offs from the moon would be much more fuel efficient than from Earth
  • After all, the regular operation of lunar stations could be described as a real step into space. Experience with real space travel would be gained.
Of course, stations on our satellite would also be burdened with many a problem. Everything you need to survive has to be transported there - even the air you breathe. Energy could be provided using solar cells, but that doesn't work during the long moonlit nights. Alternatively, solar power plants could be stationed at the poles, where some places are almost always illuminated. In addition, several such power plants in the network could permanently supply the stations with energy. In addition, extreme temperature fluctuations have to be overcome. And last but not least, it is questionable how long people can expose themselves to low gravity without becoming seriously ill. Last but not least, you have to protect yourself from the unhindered cosmic radiation. In contrast to the terraforming of Mars or even Venus, the first smaller stations on the moon would actually be technically feasible, but these should only be reserved for the satisfaction of scientific curiosity.

But how about a longer stay on the moon? There were already the most bizarre ideas for this. The well-known SF author Arthur C. Clarke suggested building inflatable stations that could be covered with moondust. Yes, until the first landings it was not certain whether the moon was not covered with a meter-thick layer of dust. So it is perhaps not surprising that people even thought of stations floating on the dust.

From today's perspective, however, it is essential that the people up there have to protect themselves from two dangers: Cosmic rays and micrometeorites. So it is conceivable to put stations together from empty fuel tanks, for example. The cosmic radiation could be shielded by artificial magnetic fields. Stations could also be relocated below the surface, but this would require heavy construction machinery that would also have to be suitable for use in a vacuum. Alternatively you could use something called Lava tubes use it to build stations in it. Such tubes have already been detected on the moon and they offer themselves as natural protective spaces. In any case, you will be forced to transport vast amounts of materials, which will ultimately be a question of enormous costs. Because the moon has no atmosphere, the braking effect is also missing here, as we have previously used in the earth's atmosphere for shuttle flights, for example. So you are forced to use precious fuel to brake. In the picture an artist's representation of how one can imagine a lunar station.

Courtesy of NASA, Pat Rawlings (SAIC)

Mass driver

Another idea of ​​what a future lunar base might look like. In addition to various interconnected living and working domes, we see a generously designed system for solar power generation and - a so-called Mass driver.

A mass driver is a device that could work great on the moon due to its lack of atmosphere. In principle, it's one Linear motoras he often does in industry or e.g. at Transrapid or used in electric toothbrushes. On the moon, this could be used as an electromagnetic catapult to cost-effectively launch payloads into orbit.
A mass driver consists of coils arranged in a row, which are surrounded on both sides by permanent magnets. The easiest way to imagine how it works is as if you had "unwound" the stator of a three-phase motor. During operation, the electromagnets are switched on one after the other, the "rotor", here e.g. a transport carriage, is moved forward by the moving field. The low gravity of the moon and the lack of braking effect of an atmosphere would favor such a transport option. Another advantage would be the low operating costs - the electricity required could be supplied by the solar cells. With a mass driver we could transport material and possibly also people from the surface of the moon to an orbit, where they would then be taken over by spacecraft parked there. That would save a lot of valuable fuel. Yes, it would even be conceivable to increase the acceleration so much that the lunar orbit is left, whereby e.g. a space glider could return to earth without its own drive.

With the express permission of © David A. Hardy

But mass drivers could not only be used for the aforementioned purpose. In this way, the transport of raw materials from the quarrying area to the processing site or passenger traffic over longer distances could also be implemented cost-effectively. A use in future, larger space vehicles is also conceivable, in order to bring payloads such as space probes onto their final flight path without using fuel. Mass drivers must be designed differently depending on their intended use. If passengers are to be transported with it, a length of e.g. 100 [km] or more is selected in order to achieve gentle acceleration without the burden of large g-forces to achieve. The acceleration path will initially run horizontally and then gradually increase at a certain angle. Possibly existing ground formations, hills or mountains can be used for this. If only material is transported, a great acceleration can be provided over a short distance.

A mass driver (on the left another presentation by NASA's Space Studies Institute (SSI)) can even be used as a weapon, namely in the form of a so-called railgun. Such weapons are being developed by the American military and have already been tested.
But we want to make transport to and from the moon as inexpensive as possible. For this purpose, we are constructing a (magnetizable) slide that, for example, is guided floating on magnetic fields as smoothly as the Transrapid. The payload, however designed, is located on the slide. When the maximum acceleration is reached, there are two possibilities: The payload is either released and flies towards its destination on its own, or the entire structure leaves the lunar surface as a unit. In the first case, the slide would be braked and could be used for further transports. Another variant would be that the payload is only given a certain initial speed and it then flies on with its own drive. The sled would ideally be an aluminum spool, which turned out to be the most suitable. Eddy currents flow in it, which interact with the generated electromagnetic field. Installed on the moon, there would be an additional advantage: Extremely powerful magnetic fields can be generated with superconducting coils. If you choose very cold environments, such as the Shackleton crater lying in the eternal darkness on the south pole of the moon, the energy required to operate these coils would be within manageable limits. However, the crater only has a diameter of 21 [km], but would at least be ideally suited for the installation of a telescope.


Mass drivers are real or realizable technical projects. On earth, its energy balance would be very bad, and due to gravity and the dense atmosphere, such a machine would not be profitable. On smaller celestial bodies such as the moon or possibly Mars, however, they could be used very effectively for future transports. Use is particularly useful on the moon (or even in free space) because no frictional heat can arise from the atmosphere. Very high speeds are supposed to be achieved, if the payload then left the catapult on earth, it would behave like a meteorite. She would be sure of great physical stress!

The above SSI has very successfully created and tested mass drivers in laboratory models (the first in 1976). You can even specify the dimensions of the devices installed on the moon:

machineaccelerationNecessary length around the
Leaving moon
Mass driver I33 g8905 [m]
Mass driver II500 g587 [m]
Mass driver III1800 g160 [m]

However, the accelerations given here would not be suitable for passengers; for passenger transport, mass drivers of a much longer design would have to be used.

Even if moon stations are still in the distant future and especially the use of mass drivers that still seem futuristic today, this would be technically feasible. Terraforming entire celestial bodies, on the other hand, would be an enormously complex task that humanity is far from capable of - if it is ever possible at all. We should keep in mind that humans are currently doing the terraforming on their own planets, and are doing so quite "successfully". In any case, the global, increasing global warming has slipped completely out of our hands until now ...

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