Terra-forming Mars

This is a personal pet peeve of mine that I'm asked about quite often by my friends and family: So when are we going to build cities on Mars?

It. Will. Never. Work.

Not in the way that people would imagine it to work. For those of you who don't know, terra-forming is the process of making another planet or moon Earth-like. It's something that you see in science fiction quite prominently, and it is often applied to Mars.

Not to go into it too deeply, Mars would seem to be a good candidate for terra-forming because all that is needed is for it to warm up and to increase the atmospheric pressure. Currently the atmosphere on Mars is very thin, and so the air pressure is very low.

If you've ever looked at the instructions on a cake mix or other recipes, you may have noticed separate directions for high altitude areas. This is because the atmosphere is thinner the higher up you go, and so the air pressure is lower. Liquids both expand and boil much faster when there is less pressure.

Your body is 70% water. Think about that for a minute.

So increasing air pressure is a must. It is also so cold on Mars that carbon dioxide can freeze, which forms most of the Martian polar caps. That is too cold for any human habitation, so the planet needs to warm up as well. I've just given an obvious answer to both problems though.

There is a large amount of carbon dioxide locked into the polar caps and in the soil of Mars. Carbon dioxide is a very good greenhouse gas, as you've probably heard from the debate on global warming on Earth. That is what we need to do on Mars - global warming. Increasing the amount of carbon dioxide in the air would increase the atmospheric pressure, and the greenhouse effect would warm up Mars.

If there is one thing humanity knows how to do, it is put carbon dioxide into the atmosphere. So what is the problem?

Mars can't hold onto an atmosphere. It used to have a thick atmosphere, and the conditions were right for water to flow on the surface. We can tell because of various clays we observe in the Martian soil which require there to be water for a substantial period to form. However, these regions are billions of years old.

Mars is much smaller than Earth. It's interior cooled much more rapidly. Think of a chicken nugget. After a short time, a chicken nugget will cool off from being cooked. A chicken breast though, after the same amount of time the center will still be warm. The same is true of planets. It is more complicated than that, but the premise is the same.

The cooling interior means that there is no molten core, like on Earth. We currently believe that the Earth's molten core, or rather the rotation of hot metals in the core are the source of the planet's magnetic field. When Mars cooled, this motion stopped and its magnetic field went away.

Without that magnetic field to deflect high energy particles, the atmosphere of Mars was blasted by the solar wind. This slowly stripped the atmosphere of Mars, and Mars doesn't have enough gravity to hold onto an atmosphere anyway. So the Martian atmosphere disappeared.

If we put a new atmosphere on Mars, the same things will happen again. And Mars will end up exactly like it is now.

So, at least in my opinion and with my understanding of science, any settlements on Mars would have to be enclosed in some way. Avoid the losing battle of trying to stick an atmosphere on Mars.