Mars actually does have an atmosphere. It’s very very very very tenuous, but there’s something there (Think about it this way, the surface of the Earth has the pressure of ~101 kilopascals (that’s 101,000 pascals), whereas Mars has ~600 pascals. Big difference, but I would still call it an atmosphere. The planet is ¼ the size of Earth, but it should still have enough gravity to “hold on” to some of the heavier gases (carbon dioxide, methane, etc). If you’re talking about H, or He, then yeah, that might not be enough gravity to hold on it. But that goes the same for Earth. H and He are light in general.
Okay, so I’ve already answered the question way back about the ways which we can terraform Mars. Here’s the answer below, and this is the link to it:
Here’s the issue with terraforming Mars:
- Temperature: Martian nights average to approximately 186K (-87 ˚C), and an average Martian day is approximately 268K (-5˚C), both of which is below the freezing point of water, and thus all water on Mars exists in solid form. It would be difficult to find anything to drink—need energy to melt the ice. Also, there would be no lakes/rivers/oceans to drive the water cycle. No water for plants and animals. Worst of all, no coffee!!
- Atmosphere: Mars has a very tenuous atmosphere. It would be difficult to breathe because of the difference in pressure (again, we are used to approx. 1atm. Mars has about 6 x 10-3 atm). Also, it’s mainly composed of CO2, although too thin to provide a substantial greenhouse effect, it’s still at a high enough percentage for carbon dioxide poisoning for humans.
- Weather: Tidal heating can lead to a dynamic cycle of CO2 sublimation/condensation. This can lead to high wind speeds, which would not be good for structural engineering, or aerospace engineering. Also, prevalent dust storms can lead to issues with…dust getting everywhere…visibility…etc. Dust storms can also change the albedo, though that might not affect human habitability as it would have by directly affecting the surface inhabitants.
- Nitrogen: There’s missing nitrogen in the Martian atmosphere. The nitrogen gas is an important component of the Earth atmosphere. While this might not be a huge deal, the nitrogen cycle itself is crucial to Earth life forms. Plants and bacteria are in an extremely intimate relationship via nitrogen cycling (ammonia to nitrates back to ammonia, etc). This would make it difficult for plant life to exist on Mars. If there’s nitrogen fixing bacteria around, theoretically, it can recycle the nitrates that we *think* is locked up in Martian regolith, and provide nutrients to plant/animals. Nitrogen is a crucial element for life (DNA, protein, etc).
- Radiation: Because of its tenuous atmosphere, and negligible (or non-existent?) magnetic field, Mars does not have a steady protection from the Sun’s radiation. So the surface is constantly bombarded with UV, cosmic rays, crazy electromagnetic waves etc. Humans wouldn’t be able to withstand this high amount of a radiation—we don’t have the biological capacity to reverse such damage (some bacteria might).
- Geology: Mars has a super thick lithosphere, no tectonic plates, and has many inactive (big) volcanoes. This inactive geology would make habitability difficult because there would be no movements of plates, thus no water, thus no ocean (it’s too cold anyway), thus no water cycle. Also because it’s so small, Mars may have already lost most/all of its heat. Regardless of how much energy we can pump into the system to make it warm/habitable, it’s going to become a frozen world one day, completely unable to warm up enough using solely internal heat. But this would take a very very long time, so it might not be a huge issue with temporary terraformation.
Here is how to solve it:
- Temperature & Atmosphere: If we pump up the heat a *little* bit (no, actually, a lot—but a little bit on a thermodynamic scale), we might be able to unlock the subsurface water that is buried underneath Martian regolith as ice. Something like this can be solved by increasing the amount of greenhouse gas in the atmosphere, to drive up the effective temperature. Pumping CO2 would require possibly jump starting a volcano (how on Earth can that even be done??—not a pun). A more plausible idea is to build power plants all over the planet (as have suggested by Chris McKay from NASA). Or simply by seeding the planet with respiring life that uses inorganic molecules to utilize energy and produce CO2. Early microbial life forms do this (before the evolution of cyanobacteria/photosynthesis). Those microbes were methanogens, sulfur-loving, and can probably also metabolize nitrates.
- Weather: Dust storms can be mitigated by living in closed quarters.
- Radiation: The problem with UV radiation (and lack of magnetic field) can probably be solved by producing artificial magnetic field. This kind of engineering can only applied to small area, not globally. Again, it’s almost impossible to jump start the solid core again, therefore such an issue can only be tackled on a small scale.
- Geology: Mars would have a similar problem as Venus. While there might be enough water on the surface, there’s no convection in the mantle to drive tectonic plates. So while its geology might be change momentarily (lasting maybe about a billion years), it would be difficult to keep it stable as the planet loses more and more heat.
- Ethics!!: If there is no Martian life, yes, we should terraform it (although we could never be sure—ack, science!). If there is Martian life, we must do everything we can to preserve it—not necessarily protect it, but at the very least observe/study it without directly affecting it like we have done so for many other endangered species on Earth.
This is copied verbatim from one of my homeworks from my astronomy class last semester, The Science and Fiction of Planetary Systems
The actual problem with terrafoming Mars is MONEY. Who will pay for what, and which nation should get what piece of land— It’s all politics that I’m not willing to discuss.
But we will get there. I absolutely believe it. We will get there.