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| Image: ESA/DLR/FU Berlin/J. Cowart, CC BY-SA 3.0 IGO |
Mars is, as far as we have been able to tell so far, a lifeless world. It might not have always been so. For millions of years the planet had a denser atmosphere and likely running water. It's uncertain that was long enough with the right conditions for life to evolve, and for at least 3.8 billion years Mars has been frozen, with an increasingly drier and thinner atmosphere. When a massive meteor strike ended the Cretaceous period the impact was so great that some of the debris escaped Earth's gravity and was strewn through the solar system. A great deal of it found its way to the surface of Mars, but that was roughly 66 million years ago, when the planet had already been cold and dry for billions of years. While mathematical models have indicated that at least some of this debris carried viable microbes, only the hardiest of extremophiles could still be active there.
If a magnetic field were created at a point between the Sun and Mars where their gravities cancel out, that could theoretically encircle Mars and provide the needed protection. The magnetic field would need to be between 10,000 to 20,000 Gauss to sufficiently shield Mars against the solar wind. With our current available means we could only put a field of about 2,000 Gauss where it would need to be.
To me, it seems only a matter of time before scientists and engineers are able to create the magnetic field needed. Whether decades or centuries, so long as civilization isn't disrupted we should eventually have the proper technology. At that point we would have a number of different warming methods to pursue, restoring as much as a seventh of the liquid water that Mars once had. If comets could be directed towards the planet they could provide additional water, though it's uncertain how much. In any case, it would take hundreds of years to reach a point of basic habitability, but with less than 40% of Earth's gravity the atmosphere would perhaps be maintainable at only 0.38 bar. For comparison, on Earth the air pressure at sea level is 1.01325 bar, and at the top of Mount Everest it's 0.337306 bar. In case that mistakenly sounds reasonable to you, here's a video showing how difficult it is to sustain life at high altitude.
That isn't to say that it's entirely impossible. If our species reaches the point of being able to generate a magnetic field and rehabilitate the atmosphere of Mars to this degree, surely genetic engineering will also have developed to the point of enabling some forms of life to make it there. Tibetans already have a gene that they inherited from the Denisovans, a species that went extinct about 40,000 years ago, that enables them to breathe easily at much higher altitudes than the rest of humankind. Tibetans actually have less hemoglobin in their blood than other humans, which is believed to help avoid clots and strokes when the blood thickens with red blood cells. In fact, they have several genes that enable them to use less oxygen. In the future, human DNA could be engineers to make life more doable on the surface of Mars. Additional breathing equipment and pressurized habitats would make it possible to maintain a population on Mars. Just recently (April 2021) the Perseverance rover succeeded in converting carbon dioxide from Mars' atmosphere into oxygen. The atmosphere there is 96% carbon dioxide, providing a steady source for conversion to oxygen.
Much of science requires work that goes well beyond the lifetime of any single person. There are breakthroughs and discoveries, to be sure, but then decades of work to test them and explore their implications and applications. No one alive nor anyone for generations will breathe on Mars without protective gear. The research we do now is for the benefit of all our kind for many generations to come. This is us at our finest, when we take consideration for others we'll never know and can hardly imagine.
