Washington, DC, May 9, 2017 --  

Plans to build Martian colonies are long on fantasy and short on purpose.

With both SpaceX and the United Arab Emirates planning to build a human colony on Mars¹, there is one nagging, obvious question: Why?

When Spain sent colonists across the ocean to the New World, it was filled with advanced civilizations, exotic crops, precious metals and vast fertile lands. Mars, by contrast has none of these things save minerals, and their value is nothing compared to the huge costs of shipping them home.

The absence of any practical value to a Martian colony has caused advocates to resort to the life boat theory. We need a Martian colony as a hedge against disasters that would make earth uninhabitable. Such a need is so dire, according to Physicist Stephen Hawking, that humanity must establish a colony in the next 100 years or go extinct.²

This is a fantastic claim. And it's fantastically wrong. Whatever the risks of disaster on earth, it's hard to imagine any of them making our planet anywhere close to as uninhabitable as Mars already is. Consider various global disaster scenarios:

A nuclear holocaust would immediately destroy the world's major cities, destroy the world economy and cause a nuclear winter that would last for many years and destroy the world's agricultural systems. Radiation from fallout would linger for many decades.

Yet Mars already has no agriculture, no cities, and radiation on the surface of Mars is already a lot worse than it would be on earth in this scenario.

Consider the case of Pripyat, the evacuated city near the site of the Chernobyl reactor, which released more radiation in its disaster than the atomic bombings of Hiroshima and Nagasaki. Two decades on, the typical radiation levels in the ghost town are at around 1 micro sievert per hour.³ This is about four times the background radiation on earth.

The normal radiation on Mars, however, is much, much higher than even near Chernobyl, owing to the planet's non-existent magnetic field and thin atmosphere. Measurements from the Curiosity rover showed average radiation levels of 28 micro sieverts per hour.⁴ This is 28 times the radiation you'd get by living near Chernobyl. Bottom line: Normal radiation on Mars is far worse than the aftermath of a nuclear holocaust.

Then there's global warming. In the worst-case scenario where carbon dioxide emissions continue to increase for decades, the World Resources Institute predicts that average global temperatures will jump nearly 5 degree centigrade, leading to widespread extinctions and declines in agricultural productivity.⁵

Yet such an earth would be a much, much better place than Mars. Unlike Mars, crops would continue to grow in vast areas of the world, many species of animals would continue to live, and liquid water would still be present in huge quantities. None of these things are true for the surface of Mars. No matter how bad global warming gets, earth will still be paradise compared to neighboring planets.

How about an asteroid collision? If an asteroid were to hit earth similar to the one that killed off the dinosaurs 66 million years ago, three quarters of species would once again go extinct⁶, largely due to all the debris kicked up into the atmosphere that caused something akin to a more extreme nuclear winter. But even after the last major impact, conditions were good enough to allow a large percentage of species to survive -- something impossible on Mars even under the best conditions because it has no breathable air and no liquid water.

Proponents of a Martian colony have plenty of solutions to these problems. Colonists can build homes underground to protect against radiation. They can build greenhouses to grow crops. They can get water by mining the ice caps or chemically combining hydrogen brought from earth with oxygen extracted from Mars' carbon atmosphere. Similarly, chemical processes could be used to create breathable oxygen from Martian air.

While these solutions may work, they are far, far harder than simply living with the conditions caused by some earthly disaster. Why not just build homes underground as a hedge against a nuclear holocaust? Why not just build greenhouses in Antarctica in the event of worst-case global warming? At least on earth you won't have to bother making your own oxygen and water.

When it comes to Martian colony enthusiasts, such simply logic will always fall on deaf ears, because the Martian dream isn't about anything practical. It's about living out a fantasy. That may be fine if you have billions of dollars lying around -- like SpaceX's Elon Musk, or the government of the United Arab Emirates.

But for the rest of us who must live within our means, and care about real-world things like financial responsibility or cost-benefit analyses, the idea of a Martian colony is a starry-eyed dream that has no practical purpose.

Notes:

1. Christian Science Monitor, UAE Wants to Build Chicago-Sized City on Mars by Next Century, February 16, 2017

2. Popular Science, Stephen Hawking Says We Have 100 Years to Colonize a New Planet—or Die. Could We Do It? May 4, 2017

3. The Chernobyl Gallery, Radiation Levels, As posted May 9, 2017

4. Science News, Mars: First Radiation Measurements from Planet's Surface, December 19, 2013

5. World Resources Institute, Infographic: Choose Your Future: 4 Possible Emissions Pathways, August 2014

6. Live Science, Dino-Killing Asteroid Impact Triggered Lethal Algal Bloom, December 13, 2015