One of the rationales suggested for going to Mars is that given all the vagaries of the universe, human culture would have a better chance of surviving far into the future if humans settled on two (or more) planets. In the abstract, this statement seems axiomatic.
Before accepting this proposal, however, it might be worthwhile to ask where else we might use resources devoted to establishing a permanent human colony on Mars. First, let's examine the logic behind the "two planets" idea.
The logic is simple. If humans have established cultures on two planets, the separation between the planets will generally keep a major catastrophe including an extinction event on Earth—say, a highly lethal pandemic or the eruption of several supervolcanoes—from affecting the other planet. In the case of Mars the separation at its closest is about 34 million miles. At its farthest, the separation is 250 million miles. It is this isolation which offers protection.
So, the question arises then whether something approximating this isolation might be achieved right here on Earth. The answer is that it has already been tried, and it works. The isolation of peoples across the globe was a longstanding fact in prehistory and even in historical times until relatively recently.
The inhabitants of the Americas were spared the ravages of the Black Plague in Europe—half of Europe's population perished—because at that time the Americas were unknown to Europeans. Asia was not spared and is believed to have been the origin of the disease. The vast distances between Europe and Mongolia (where the plague is presumed to have begun) did not offer protection for one simple reason: Europeans and Asians were connected by trade routes. The Silk Road had been operating for centuries by the time of the Black Plague outbreak in Europe.
No such connections had yet been established with what later became known as the New World. When the Europeans arrived there, they brought with them a plague far worse than the Black Death. It was smallpox. The native population had no immunity and in a few short decades, the disease dramatically reduced native populations across the Americas by an estimated 90 percent.
Now, let me offer the following thought experiment. (I'm not actually proposing to implement this.) Let's assume that our sole purpose is to ensure the continuation of human culture far into the future. If that's so, one of the most effective strategies would be to create isolated autonomous regions right here on Earth and insist that these regions sever all ties with one another. If the regions were large enough and with enough diversity of resources to supply the needs of those living within each region, then their isolation could be maintained. There would be plenty of internal trade WITHIN a region, but no external trade with other regions (probably on pain of death).
There you have it. With maybe 20 to 25 autonomous and isolated regions, humans in many regions might live relatively comfortable lives, develop distinct cultures and live far into the future even if some other regions experienced devastating catastrophes and even extinction events. In fact, by establishing just one such isolated region, we would largely achieve what Mars enthusiasts are proposing in their two-planets proposal, but at far less cost and risk. (Please keep in mind that this is strictly a thought experiment, and I am therefore not trying to work out all the details of such a scheme here.) If many regions were established, some might pursue unsustainable practices that lead to depopulation. But others might pursue sustainable strategies and survive and thrive in the long run.
But what about the supervolcanoes I've already mentioned and what about a wandering asteroid smashing into the Earth of the kind that is supposed to have killed the dinosaurs 65 million years ago?
Regarding super volcanoes, the last one was more than 26,000 years ago and it did not lead to human extinction. Whether future ones alone or in concert with others might cause a worldwide catastrophe is unknown. But it seems unlikely in any time period that matters to humans. It's hard to plan for millions of years into the future.
The same applies to extinction-capable asteroids. But there is an added wrinkled since asteroids would also threaten any human populations on Mars, especially if these asteroids come in the numbers predicted by the so-called Nemesis theory. This theory posits that a "dark" dwarf star is perturbing the orbits of objects in the Oort Cloud sending them hurtling toward the inner solar system every 26 to 30 million years.
There are certain advantages to the solution proposed in my thought experiment over a Mars colony. First, the Earth provides copious and readily available access to water, air and soil and a livable climate (though that appears to be imperiled). No special gear is required by humans to wander about the surface of the Earth.
Mars lacks air and complex soils made fertile by organic matter though it does appear to have some water—just not in the vast quantities available on Earth. The temperature is generally quite chilly, on average minus 80 degree F (minus 60 degrees C). In summer near the equator, daytime temperatures can approach 70 degrees F (20 degrees C) only to plummet to minus 100 degrees F (minus 73 degrees C) overnight. Mars' whisper-thin atmosphere cannot retain much of the daytime heat, most of which escapes into space.
Of course, one cannot run around in just street clothes on Mars, even in summer during daytime at the equator. This is because Mars' atmosphere—what little there is of it—is 95 percent carbon dioxide.
And then there are the galactic cosmic rays, very high-energy particles moving near the speed of light. We Earthlings are largely protected from them because of the Earth's magnetic field which deflects them. But Mars has long since ceased to have a magnetic field and so anyone on the surface would be bombarded constantly by cosmic radiation. Those outside the Earth's protective magnetic shield on a mission to Mars could receive up to 700 times the cosmic radiation compared to we who are earthbound.
Let's read NASA's take on cosmic radiation (referred to as space radiation here):
Space radiation can lead to other effects. Radiation can alter the cardiovascular system, damaging the heart, harden and narrow arteries, and/or eliminate some of the cells in linings of the blood vessels, leading to cardiovascular disease. Radiation exposure can hinder neurogenesis, the process of generating new cells in the brain. If neurons or supporting cells are damaged or killed, there is less potential for the development of new cells, especially at the rate a person would need to minimize or eliminate the damage. In the central nervous system, this could lead to cognitive impairment and memory deficits.
In other words, any space colonist to Mars could quickly become an Alzheimer's patient with cardiovascular problems unless living behind dense lead shielding on the way to Mars and also while residing there. Plants, too, are not liable to thrive even in greenhouses due to radiation exposure. Unlike humans who could conceivably cower under lead shields all day, plants actually need sunlight. And, with that sunlight comes destructive cosmic radiation.
All of this is to show that talk about achieving a two-planet solution for the continuity and survival of the human race is only a huge piece of misdirection. The solutions to our continuity and survival on Earth are here on Earth. We humans are uniquely adapted to the thin layer we call the biosphere. For that reason the biosphere is likely to be the only place we call home for the duration of the existence of the human species.
Those whose financial and political interests run contrary to earthly solutions want to direct your eyes to the heavens. That's so you won't notice how much peril these same people are subjecting the whole human race to with a continued focus on wealth accumulation, perpetual growth and externalizing the costs of toxic pollution, climate-changing emissions and resource depletion.
Kurt Cobb is a freelance writer and communications consultant who writes frequently about energy and environment. His work has appeared in The Christian Science Monitor, Resilience, Common Dreams, Naked Capitalism, Le Monde Diplomatique, Oilprice.com, OilVoice, TalkMarkets, Investing.com, Business Insider and many other places. He is the author of an oil-themed novel entitled Prelude and has a widely followed blog called Resource Insights. He can be contacted at firstname.lastname@example.org.