Human settlements nestled on other worlds. Planetary neighbors shaped in Earth’s image. It’s a thrilling concept that makes for unique environments – but is terraforming another world actually possible?
Not only is terraforming within human ability, it’s an avenue scientists have considered since the 1960s. But to actually do it requires massive technological, economic and ethical hurdles that – thankfully – no one in our generation will ever have to face.
Good News: It’s Possible
Bad News: You’re Doing It
If you’re reading this, you’re terraforming a planet. The energy your device consumes as you read, the car you drove to get where you are, and the air conditioning that cools you all release carbon dioxide into Earth’s atmosphere. The atmospheric change from all this carbon dioxide, and the solar heat it traps, melts polar ice and raises the sea level. That’s unintentional terraforming.
While we don’t usually think about it this way, terraforming would generally be much the same thing – manipulating a planet’s atmosphere to make it more hospitable for life. (Global climate change is, unfortunately, doing the opposite.) The difference between what we’re doing to Earth’s atmosphere now and what we may do to other planets in the future is that we’ll be manipulating them intentionally to create a desired result. Terraforming won’t be as simple as shipping water to Mars or pumping oxygen into Europa’s atmosphere, it’ll likely be a long-term chemical manipulation using elements already present on that world.
For example: in the 1960s Carl Sagan suggested that humans could begin terraforming Venus by seeding the atmosphere with genetically modified algae. The algae, he claimed, could convert carbon dioxide into organic compounds, removing enough carbon from the atmosphere to lessen the greenhouse effect and lower surface temperatures. Though later discoveries showed that this approach was impossible on Venus, it’s a good example of how planetary engineering theories often play out.
NASA considered terraforming important enough to conduct a study on it in 1976, and terraforming articles still appear in peer-reviewed science journals. In fact, one of the principal planetary scientists at NASA’s Ames Research Center – Dr. Christopher McKay – is one of the world’s foremost experts on terraforming.
So if we’re already studying it, what might terraforming look like?
Mars: A Terraforming Thought Experiment
There’s debate among terraforming theorists as to which planetary body would be the most conducive to alteration – some propose asteroids, while others look to Jupiter’s moon Europa that has liquid water – but most of the conversation settles around Mars.
Mars is the most Earth-like planet in our solar system, and scientists think that hundreds of millions of years ago it had a thicker atmosphere and water much like our own pale blue dot. The theory goes that because these elements are still present, future human settlers could use various shifts in climate to reverse-engineer Mars back to a habitable state.
A few years ago, National Geographic partnered with several terraforming experts – including representatives from NASA, CalTech, The University of Wisconsin and the Mars Society – to puzzle out what that might look like.
It might begin with several 18-month manned missions to Mars, with each expedition gradually adding habitation modules on the surface to create a functional base. A century later, workers at the base would start releasing carbon dioxide into the atmosphere, warming the planet to a suitable temperature.
The primary mechanism for this would be factories on the surface, which would manufacture chlorofluorocarbons derived from the air and soil. These would essentially be pollution plants meant to spray greenhouse gasses into the atmosphere and melt the polar ice caps, releasing the carbon dioxide trapped there. The added carbon dioxide would thicken the atmosphere, raise the atmospheric pressure, and warm the planet an average of 70 degrees Celsius, bringing it above freezing.
Two hundred years after the first manned mission arrived, rain would fall, and settlers – now dwelling in dome communities with their own sheltered gardens – would introduce microbes, algae and lichens. These simple organisms would break down the Martian rock into organic soil, further adding oxygen to the atmosphere.
Six hundred years after the first manned mission, settlers could introduce flowering plants and later – possibly as long as a thousand years – boreal forests such as redwoods. The ultimate aim would be to create enough vegetation to manufacture oxygen, but building up that concentration would take millennia. In the meantime, humans would wear oxygen masks as they walked outside – a detail that Destiny seems to retain.
Worldhouses: Life In the Bubble
You may have noticed that throughout the thought experiment above, humans weren’t living in the open air on Mars, but in habitation modules and “dome communities.” While these would be necessary for full-planet terraforming, another school of thought holds that rather than terraforming a whole planet, humanity should form colonies in closed ecological systems. Most likely these would look like enormous greenhouses or geodesic domes, with various climates inside.
There have been a few closed ecological systems built already, but none has achieved self-sufficiency. The most ambitious experiment was Biosphere 2, an odd project that replicated biomes including rainforest, mangrove wetlands, savannah, fog desert, agricultural systems, human quarters and even an 850 square meter ocean with coral reefs. The project, however, was a litany of hard lessons – population explosions from ants and vines, lower than expected oxygen production and even a schism within the human inhabitants. The experiment was such a disaster it inspired a Pauly Shore movie.
Biosphere 2’s failure notwithstanding, closed environments known as paraterraforming or worldhouses have a lot to recommend them. Because they’re smaller than full-planet conversions, the return on investment is more immediate, and artificially manipulating their environment will likely be easier. Their modular design means settlers can build outward from the initial habitation, and they allow colonization on small bodies like asteroids that can’t retain an atmosphere.
There are drawbacks too, of course. A worldhouse would need its own closed water system, continuous maintenance, and be more susceptible to catastrophic failure due to meteor strikes or warfare. But those issues aside, it’s likely any future space colonization will have these worldhouses as their hub.
The Economic Problem
Terraforming’s biggest hurdle is financial. An expert panel recently estimated that a manned Mars program would cost between $80 and $100 billion over twenty years, culminating in a single manned mission. While that’s not unfeasible (the F-35 fighter program alone may end up costing over a trillion dollars) it would only put one crew on Mars. The cost for building a long-term habitation would be much higher, not to mention the infrastructure necessary for terraforming. NASA estimates, for example, that each chlorofluorocarbon-producing factory in their scenario would have energy needs equal to a dedicated nuclear power plant, and those aren’t cheap to build on Earth – much less on Mars. While it’s true that there will be new industries and technologies by that time, we’re still talking about vast quantities of capital investment. Terraforming Mars would likely take an international effort, even a global one.
And that in itself runs into geopolitical issues. Since the days of Magellan, competition – not common interest – has spurred our need to explore. Our most productive period in manned space exploration was during the Cold War, when our main objective was to beat the Soviets. As tensions thawed and scientific inquiry became the focus, the U.S. public and politicians quickly lost interest in space travel. Terraforming planets will only happen after we’ve made a major shift in our politics – to conquer Mars, we will first have to conquer our own divisions.
Of course, we’re talking about great lengths of time here. Who knows what geopolitics and economics may look like a few centuries in the future? In three hundred years, capitalism may no longer be the world’s predominant economic system. The nations we know today may be as distant as Austro-Hungary or the Ottoman Empire are to us today. Technologies and industries we can only speculate about may unlock new avenues of capital and lower costs. We could be mining oxygen with microbes and have perfected the process for manufacturing concrete out of moon rock.
But even if we could terraform, there’s always the question of whether we should.
Terraforming opens up vast new ethical quandaries that we’ve never faced before – or have never faced on this scale. Is it ethical to terraform a planet with life on it? If we do terraform, should we try to accommodate or even aid existing life in its evolution? Are we, as proved by our custody of Earth, simply far too destructive to start changing climates another planet?
According to terraforming theorist Martyn J. Fogg, there are four major divisions in debates about the ethics of terraforming. Anthropocentrists think it’s not just humanity’s right, but its moral obligation to terraform other worlds, since it’s a continuation of life adapting to and changing its environment to survive. Zoocentrists worry that not only will terraforming harm native life, but that any animals humans export will suffer, or undergo unnatural evolution on other worlds. Preservationists believe that planets should be left alone as nature created them, without any interference by man. Ecocentrists strike a balance between these, saying that all life – even microbial life – has value, and that for terraforming to be ethical, it needs to preserve native life.
As in all debates, these aren’t rigid groups, but parts of a continuous spectrum. For example, Christopher McKay of NASA’s Ames Research Center considers alien biospheres to have value, and holds that they shouldn’t destroy them by terraforming. However, he also believes humanity could ethically terraform planets in a way that nurtures the life already there – both so we could observe and learn from new organisms, and so they could expand to create a planetary biosphere. “Mars is beautiful the way it is,” McKay said in a 2004 debate. “But I think it would be even better if we could restore the biosphere that it once had. So I vote for life.”
Anthropocentrists see this privileging of microbial life over human life is a threat to humanity’s survival. After all, we will eventually have to move off this planet or die when the sun explodes – if not from some earlier disaster – and in that circumstance it will be our evolutionary imperative, they claim, to displace less efficient forms of life.
This, at least judging from the trailers, seems to be Destiny‘s tack: that humanity and our allies should conquer the solar system and drive out any alien forms of life that reside there. The underlying message seems to be that it’s not only humanity’s goal to spread across the stars, it’s our destiny.
Terraforming Starts at Home
But of course, we’ll have to survive long enough to encounter these questions, and at this point that’s not a given. Our present terraforming challenge is how to balance the carbon ledger on our own world – indeed, it seems strange to talk about melting the polar ice on Mars centuries from now when we’re seeing historically-low levels of sea ice on our own planet, in our own time.
If we don’t tackle the accidental terraforming we’ve done on Earth, we may never plant a redwood on Mars. Even if the increasing climate extremes, famines and conflicts don’t wipe us out, their impact could make us less economically powerful and unable to sustain the technological establishment necessary to send expeditions to other planets. After all, it was going to be a stretch money-wise even for a future human species at full strength, never mind one weakened via environmental stresses. Unless we take our pedal off the floor before reaching the global tipping point, it’s possible we will have terraformed our own planet into a mass extinction.
At this point, just like in Destiny we may see our own collapse – and I doubt there will be a Traveler to save us.
Robert Rath is a freelance writer, novelist, and researcher based in Hong Kong. His articles have appeared in the Escapist and Slate. You can follow his exploits at RobWritesPulp.com or on Twitter at @RobWritesPulp.
Ethical Disclosure: The author has previously written for environmental groups including the Plasticity Forum and Mission Blue.