Future Tense

The Problem With Terraforming Mars

What do we lose if we make the Red Planet hospitable to humans?

A rocky hill on the surface of Mars.
A view from the mast camera on NASA’s Curiosity Mars rover shows a sloping hillside within the Murray Buttes region on lower Mount Sharp.

Mars has loomed large throughout human history, our imaginations filling its red vistas with fantastic detail long before our space missions returned even rudimentary photos. Back when our best observations of the Red Planet showed only a rusty disc mottled with fuzzy dark patches, people debated whether those marks were natural features, or perhaps the engineering projects of technologically advanced Martians, or maybe something wilder: In 1912, the Salt Lake Tribune ran a headline that read “Mars Peopled by One Vast Thinking Vegetable!,” accompanied by an illustration of a mossy-looking Mars, with one enormous eyeball on a stalk protruding out into deep space.

Because we have imagined Mars so long, it’s easy to forget that Mars’ history is its own. Written into the desert are bygone epochs of the Red Planet, hidden beneath plains peppered with cantankerous-looking boulders, their expanse interrupted by shining, silken dunes and towering volcanoes. Modern Mars research tells us this landscape once boasted vast stretches of water, a warmer climate, and thicker atmosphere, but all have since been lost, leaving the cold, dry surface we see today. In some places, tire tracks mark the record of human exploration—at least by our robotic avatars, the Mars rovers. While Mars is a “dead” planet in the sense of having no notable geologic activity and no known forms of life today, it still has weather (including the massive global dust storm now enfolding NASA’s long-lived Mars Opportunity rover). Unlike the moon, where the entire record of humanity’s off-Earth adventures lays written and unperturbed in the lunar dust, Mars’ winds will eventually wipe these rover tracks away.

For would-be explorers of Mars, these barren plains are a tempting destination—but why anyone wants to go to Mars depends on whom you ask. Some look at the pristine landscapes and imagine that they may answer some of our most pressing questions about the origins and evolution of life in the universe: Has life ever existed on another world? Might it still exist under the Martian surface today? If Mars has ever had life, how different (or not) is it from the life we find on Earth? And if life never got started there (or started, but failed to flourish)—why? Mars’ proximity, and the (relative) ease of translating terrestrial exploration tools to its rocky surface, makes it one of the prime places to both ask and answer these questions.

However, others see these Martian vistas as a blank slate, a drawing board upon which to write a new history for both Mars and humanity. Terraforming, or the idea of radically transforming another world’s environment to be more hospitable to life, has been around for a long time in both science fiction and the scientific literature. One of the most influential books about terraforming straddled the line between fiction and fact: Scientist James Lovelock and writer Michael Allaby’s 1984 novel The Greening of Mars used science fiction to lay out possible means of transforming the Red Planet into literal pastures. While ideas for terraforming methods vary wildly, the basic reasoning is that putting greenhouse gases (usually more carbon dioxide) into the planet’s atmosphere might create enough warming and atmospheric pressure for liquid water to exist on the Martian surface again—a toe hold in the uphill climb toward a once-more habitable Mars. Today, visions of a terraformed Mars come from SpaceX’s promo videos: an animated Mars spins into the future, its surface becoming green, clouds wafting in its thickened atmosphere. Presumably, the water, oxygen, and carbon dioxide implied by these images have been “liberated” by the inescapable enfant terrible of technology, Elon Musk, whose terraforming proposal consists of dropping thermonuclear weapons over the polar ice caps.

Despite terraforming’s hold on the popular imagination, it remains solidly in the realm of fiction. For one thing, Mars seems to lack the necessary reserves of carbon dioxide to pump up its atmosphere and warm it in the first place. Just recently, researchers examined all the inventories of carbon dioxide known from the past several decades of Mars research—concluding that even if one could somehow put it all, from every source, into the atmosphere, it would achieve only minuscule changes in the atmosphere’s pressure and warmth. What’s more, raising the temperature and pressure of the atmosphere only means that any available water won’t boil off immediately, but it would still evaporate, and fast, disappearing into the (still) thin air. Because the Martian atmosphere is incredibly dry, that water would never rain out and return to the ground, as our water does on Earth, and would instead remain sequestered in the (still) dry air. While the authors admit that one could always appeal to possibly hidden deposits of carbonate that haven’t been found yet, making any carbon dioxide available from those deposits would require a planetary-scale strip mining operation to harvest and process it out of the rocks.

In short, a planetary environment is not an empty swimming pool that can simply be refilled with a garden hose and brought back to its previous function. That fact should come as no surprise to anyone paying attention to climate change, a global disaster composed of both inexorable alterations to the habitability of Earth and the ongoing failure of both governments and industry to act with sufficient urgency to preserve it. While we might debate the possibility of transforming the habitability of Mars, we only have a demonstrated track record of unintentionally changing a planet to be less hospitable to humanity and no practicable idea of how to do the reverse.

In many ways, questions of whether we could technically terraform Mars are beside the point—it’s the way we ask them that reveals so much about how we imagine ourselves in relationship to land and environment, especially those here on Earth. After all, one needn’t go to Mars to find a pristine frontier, or at least the idea of one—the concept of wild, untouched land is a deeply embedded part of the American mythos. Wild landscapes were memorialized by the rapturous paintings and prose of naturalists like Thomas Cole and John Muir, and when national parks were first created in the 19th century, they were (and still are) seen as safeguarding something truly unique, precious, and yes, American, for generations to come. In 2017, when the Trump administration announced its intention to shrink the Grand Staircase-Escalante and Bear Ears national monuments, there was widespread public outcry. Around the same time, Utah Rep. Jason Chaffetz, a Republican, introduced a bill into the House that would allow for the sell-off of public lands in Utah. He was forced to withdraw the bill after immediate, broad-based opposition.

But pure wilderness, much like the invocation that humanity’s destiny is to leave the Earth, is an invention—and a relatively recent creation, at that. Though national parks are now beloved treasures, their preservation as untouched wilderness came as a surprise to the many indigenous nations who were actively living on those lands at the time. Because the settlers’ idea of nature was of a place in which humans did not live, the preservation of these lands fundamentally meant the removal of the people who did live there—and because those settlers could not fathom the humanity of native peoples, the separation of people from their homelands drew the blueprints for forcible relocation and assimilation, as well as the reservation system that persists today.

Advocates of humans living on Mars argue that no such ethical quandary exists for Mars: No life seems to live there, and if it does, it is likely mere microbes. After all, we kill microbes all the time here on Earth—in fact, we kill those microbes that might otherwise hitch a ride on our spacecraft and contaminate the environment of Mars. What’s a few more? Even those who are compelled by studying Mars’ own history sometimes argue that the transformation of the Martian environment is a foregone conclusion, so we may as well get it over with. Within this camp, there are researchers who eschew the word terraforming in favor of ecosynthesis, a term borrowed from restoration ecology here on Earth, meaning an intervention to restore a previous disrupted environment. Where “terraforming” implies that the planet will become more like our Earth (terra), ecosynthesis implies that restoring Mars’ previously thick atmosphere, even if unbreathable by humans, is a moral imperative that humanity bears to any Martian life that might survive today. One wonders whether these would-be saviors of Mars would argue for a return to Earth’s early atmosphere, before cyanobacteria provided the oxygen humanity breathes.

Does an environment’s worth exist only in relationship to humankind, or more broadly, in relationship to life? If so, whose life? Must an environment have a purpose to be worthy of existence? If so, whose purpose? In Harper’s this month, Mort Rosenblum and Samuel James’ depiction of copper mining in the Southwestern United States argues that we behave as though the merit of land is only in its use. James’ photographs show a vast, terraced network of pit mines ripped into the ruddy desert, yawning like the mouth of hell. The open pits drool turquoise rivulets of toxic waste into some of the most stunning spaces on the continent—is this environmental devastation the Silver Bell Mine of Arizona, or a future terraforming operation on Mars?

Terraforming might seem like just a particularly difficult engineering challenge, but in reality, it is an escape hatch from the far more difficult task of confronting our past, present, and future here on Earth. When we invoke worlds like Mars as our new frontier, we are erasing the complex history of what frontiers have meant here on Earth, as well as the legacy of inequity that continues on today. We must recognize that the radical transformation of land—whether on this planet or beyond—is also the erasure of history, and in that erasure we may be giving up something profound on Mars, just as we do here on Earth.