Chances are you’ve heard that word “terraforming” thrown around before, most likely in the context of some science fiction story or while drunk-scrolling through Wikipedia. However, in recent years, thanks to renewed interest in space exploration, this word is being used in an increasingly serious manner.
And rather than being talked about like a far-off prospect, the issue of terraforming other worlds is being addressed as a near-future possibility. Whether it’s Elon Musk claiming that humanity needs a “backup location” in order to survive, private ventures looking to send humans on a one-way mission to colonize the Red Planet, or space agencies discussing the prospect of long-term habitability on Mars or the Moon, terraforming is yet another science fiction concept that appears to be moving towards science fact.
But the question remains; what does terraforming entail? Where exactly could we go about doing it? And even if everything else were possible, does the technology to terraform an entire planet even exist? Answering any or all of these questions will become a central issue for the future of humanity. But as you’ll see as we dig into this topic further, not only is terraforming a concept that has been around for a while, but as it turns out, humanity already has quite a bit of experience in this area!
What is Terraforming?
At it’s most basic level, terraforming is the process whereby a hostile environment (i.e. a planet that is too cold, too hot, and/or has an unbreathable atmosphere) is altered in order to be suitable for human life. This could involve modifying the temperature, atmosphere, surface topography, ecology – or all of the above – in order to make a planet or moon more “Earth-like”.
The term was coined by Jack Williamson, an American science fiction writer, in story titled “Collision Orbit”, published in the 1942. But while this is the first known mention of the concept, there are examples of it appearing in fiction beforehand, including indirectly in the 1897 novel “War of the Worlds”.
But even though the concept has been around for quite some time, it is still an almost entirely hypothetical idea because it is plagued by a few fundamental problems. Case in point, all of the potential ideas for terraforming a rocky planet like Venus or Mars involve infrastructure that does not yet exist and would be incredibly expensive to create. There are also questions about the ethics of terraforming. Basically, some argue that altering other planets in order to make them more suitable to human needs endangers any lifeforms already living there. If in fact other planets have indigenous microbial (or more complex) life, then altering their ecology could impact or even wipe out these lifeforms. In short, future colonists and terrestrial engineers would effectively be committing genocide.
What We Could Benefit
When addressing the issue of terraforming, there is the inevitable question – “why should we?” Given the expenditure in resources, the time involved, and other challenges that naturally arise, what reasons are there to engage in terraforming?
Putting aside for the moment the prospect of some catastrophe like a nuclear holocaust, there is also the likelihood that life will become untenable on certain parts of our planet in the coming century. Carbon dioxide levels in the atmosphere have now surpassed 400 ppm, a level not seen since the Pliocene Era – when global temperatures and sea level were significantly higher. This trend is expected to continue for the rest of the century without serious counter-measures, and could result in an eight-degree increase in average global temperature.
If you haven’t already guessed, what I’m getting at is that humans have actually been altering climates at the planetary scale for quite some time now, we just didn’t fully realize what we were doing. And so we find ourselves in the situation where our own actions may make our own planet unlivable in a worryingly short amount of time. And while terraforming may allow us to create a second home to escape to on another planet, more importantly, it could also be a proving ground for the techniques and technologies we need to develop in order to make Earth more Earth-like again.
But even if we can all agree that terraforming is a worthwhile pursuit, the questions still remains… Where?
Making Mars Habitable
Within the Solar System, several possible locations exist that could be well-suited to terraforming. Consider the fact that besides Earth, Venus and Mars also lie within the Sun’s Habitable Zone (aka. “Goldilocks Zone”). However, owing to Venus’ runaway greenhouse effect, and Mars’ lack of a magnetosphere, their atmospheres are respectively too thick and hot, or too thin and cold, to sustain life as we know it. However, this could theoretically be altered through the right kind of ecological engineering.
Other potential sites in the Solar System include some of the moons that orbit the gas giants, several of which have an abundance of water ice which could make habitability especially easy. And there is even some research into whether our own moon could be terraformed, although what the moon may have going for it in proximity to us, it more than makes up for with the challenges it brings. What this all boils down to in the end, is that the primary contender for a first go at terraforming is, and really always has been, Mars.
There are several reasons for this, ranging from Mars’ proximity to Earth, its similarities to Earth in daily and seasonal cycles, and the fact that it once had an environment that was very similar to Earth’s. Lastly, of course, there is currently a lot of evidence that Mars may have additional sources of water beneath its surface.
Of course, that doesn’t mean that terraforming Mars would be easy. Mars would need to undergo vast transformations in order for human beings to live on its surface. The atmosphere would need to be thickened drastically, and its composition would need to be changed. Above all, Mars lacks a magnetosphere, which means that its surface receives significantly more radiation than we are used to here on Earth, and unfortunately leaves it vulnerable to atmosphere-stripping solar wind.
Luckily these problems aren’t insurmountable. There have been a range of different terraforming options proposed for mars which all could work including bombarding its poles with meteors to melt the ice caps, building orbital mirrors to reflect sunlight, building factories to release greenhouse gasses while manufacturing parts for a space colony, or even using bioengineered extremophile bacteria to convert the atmospheric composition into one we can breath. The essence of all of these approaches though is to thicken the atmosphere, thus initiating a greenhouse effect to warm the planet up, then refining the atmospheric composition once liquid water returns.
In short, there are plenty of options for terraforming Mars. And many of them, if not being readily available, are at least on the table. It is important to keep in mind though, that without some immense leap in these technologies, the process of terraforming any planet is something that will happen on the order of many decades if not centuries. So don't get your hopes up for winter holidays skiing the slopes of Olympus Mons anytime soon.
Beyond The Solar System
In addition to the Solar System, extra-solar planets (aka. exoplanets) are also potentially great sites for terraforming. Many of these planets we’ve discovered can be classified as “Earth-like” meaning that they are terrestrial planets that have atmospheres and, like Earth, occupy the region around a star where the average surface temperature allows for liquid water.
There are even star systems with multiple “Earth-like” planets occupying their habitable zones. Gliese 581 is a good example, a red dwarf star that is located 20.22 light years away from Earth in the Libra constellation. Here, three confirmed and two possible planets exist, several of which are believed to orbit within the star’s habitable zone.
In all cases, terraforming the atmospheres of these planets would most likely involve the same techniques we would use to terraform our own solar system. For those located on the outer edge of their habitable zones, terraforming could be accomplished by introducing greenhouse gases or covering the surface with low albedo (aka. light-absorbing) material to trigger global warming. On the other end, solar shades and carbon sequestering techniques could reduce temperatures to the point where the planet is considered hospitable.
Why do it at all?
So… after considering all of the places where humanity could, in theory, colonize and terraform, as well as the difficulties we might face in doing so, we are once again left with one important question. Why should we? Assuming that our very survival is not at stake, what possible incentives are there for humanity to become an interplanetary (or perhaps one day, interstellar) species?
Perhaps there is no good reason. Much like sending astronauts to the Moon, taking to the skies, or climbing the highest mountain on Earth, colonizing other planets may be nothing more than something we feel we need to do. We do it simply because we can! Such a reason has been good enough in the past, and it will likely be sufficient again in the not-too-distant future.