There are many things essential for human life to thrive that must be present on Mars to make it like home for colonists. First, you have to have breathable air with enough pressure to maintain the human body’s physical integrity. The average human can hold his breath for only three minutes. Second, you need water that is clean and free of dangerous bacteria. The average human can live for three days without water. Third, you need shelter. Depending upon environmental conditions, the average human can go for hours to a lifetime without shelter. But we must assume the conditions on Mars will require shelter at the short end of that spectrum. Fourth, you need food. The average human can go for six to ten days without food before suffering harm to internal organs. Fifth, you need company. The average human suffers severe psychological distress after only twenty-four hours of isolation from other humans.
We can assume any colony mission will bring with it as much of each of these needs as can fit in the spaceship. What can’t be brought is an atmosphere that will support human life without carrying supplemental oxygen and wearing a pressure suit. But an atmosphere can be generated on Mars to support a human colony. We only need to overcome the conditions that have stripped Mars of its atmosphere in the first place.
If enough air was released on Mars to give it and atmosphere of 50% of the Earth’s at sea level, it would be blasted away in the Solar wind. The reason Earth doesn’t suffer this fate even though it is so much closer to the sun and the Solar wind is so much stronger here than on Mars, is that Earth has a strong magnetic field protecting it from the charged particles blowing out of the sun at a high force. The Van Allen radiation belts are made up of these particles caught in the Earth’s magnetic field. The aurora, both borealis and austrialis, are the particles leaking into the atmosphere at the magnetic poles.
Why doesn’t Mars have a magnetic field like the Earth? There is evidence in Martian rocks that a magnetic field once existed on Mars. But looking at the planet, anyone can see that one hemisphere of crust was blasted off and the core leaked onto the opposite surface at Olympus Mons. Scientists speculate that a comet struck Mars in the prehistoric past, and did the damage. When the object passed through the core of Mars, the molten core was solidified, and the magnetic generator shut down.
So in order to keep any atmosphere we generate on Mars, we need to establish a magnetic field around the planet strong enough to protect the nascent atmosphere from the Solar wind. We could build a superconducting coil about the equator of the planet, generating a magnetic field by brute force. This method would be prohibitively expensive in both construction and operational costs. Or we could melt the Marsian core to allow a natural magnetic generator to be reestablished.
The easiest way to do that is to set a number of piles of fissile materials around the planet and let them melt their way into the core. In the power generating industry that is called China Syndrome. We could “kill two birds with the same stone” by using terrestrial nuclear wastes from our own power plants. That way the waste is not polluting Earth and is will be shielded from irradiating the Marsian surface by the bulk of the planet.
I have not calculated the amount of heat necessary to melt enough Marsian core to generate a field strong enough to protect the atmosphere. I don’t have the math. But there are enough planetologists around that can do that job. I’m just throwing out ideas anyway. What do you think?
I think you need to read a novel or see the movie called "The Martian" by Andy Weir. The book and movie both are fairly recent like in the last two years. It addresses a lot of what you are discussing, and as well, solutions are only limited by imagination. It is a futuristic novel, and easy read. Very informative.
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