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On Terraforming (Part One: An Introduction)

This will be the first in a series of posts on this topic, I’ll fully admit that I don’t have a plan but I have at least three more in mind, one on the legal aspects of the terraforming question, one on the ‘ethical’ aspects and one on the cultural (i.e. sci fi), I’m sure more will come in time.

If you hang around a space conference (or Elon Musk’s Twitter) long enough someone will bring up the idea of terraforming Mars. It is a mainstay of what Daniel Deudney has called ‘space expansionist’ thinking[1] (although as the O’Niell school[2] of space expansionists prefers orbital habitats they’re not so fussed about terraforming). This is logical, if you think colonizing Mars is an important, even necessary, part of the human future then making it a place humans can live is a reasonable extension of that view (whether terraforming is reasonable outside of that paradigm is a different matter…) and it its natural state Mars is about as far from being a place humans can live and it still seem viable for humans to actually go there (funnily enough Terraform Venus movement has nowhere near the same number of adherence). Therefore Mars needs to be made ‘habitable’ if future human inhabitants aren’t going to be stuck living underground or in domes. For the sake of simplicity but also because it is the primary focus of discussions I’m going to focus on the terraforming of Mars, although most of what I’m discussing applies to any notion of terraforming other planets too.

Four versions of mars increasingly terraformed o look Earth like

Source: CC BY-SA 3.0

I’m not going to focus too much on the ‘science’ of terraforming, for one thing I’m not qualified to discuss that, but also even as a scientific layperson its clear there are far too many unknowns to make a definitive judgement at this point, the process is theoretically possible and the key aspects I’m interested in are not overly dependent upon the science. Terraforming is an influential idea among the space community and is driving at least one of the ‘space billionaires’ long-term plans, as well as being an important element of many popular science fiction franchises (most recently The Expanse) so it is worth studying just to consider what it says about the ‘space community’s’ views on humanities relationship to ‘nature.’

That said, its probably worth spending a moment to discuss what terraforming is. First, PBS have produced a video that does a pretty good job of explaining it (see below) although I have some issues with the tone its presented, but I think that would make a good topic for another post, so I’ll save that for later.

Terraforming is a term that is used to refer to the process or processes of making a planet ‘earth like’ (terra is Latin for ‘earth’). While it has predominantly been a trope of science fiction works, there are also ‘scientific’ proposals for terraforming planets, especially Mars. Its important to note that there is no one ‘method’ but a combination of methods will be used over time. The goal can in essence, be described at warming the planet, making it warm enough that liquid water can exist on the surface. The composition of the Martian atmosphere will also need to change if humans are to live on the surface without protection (what is often called a ‘shirtsleeve environment.’) There are several methods proposed for doing this. One is to release greenhouse gases in the atmosphere as this will thicken it (Mars has an atmosphere less than 1% of Earths)[3], this will warm the planet as it is doing on Earth, as well as raise the atmospheric pressure closer to that which humans can live in. There have also been proposals to use nuclear weapons to speed up this warming process, I’ll come to the issues with that later. But Mars’ atmosphere is not only too thin, but it is 95% carbon dioxide (CO2), so we need to change its makeup as well. Some of this will happen ‘naturally’ as the planet warms, the water that currently exists as ice will melt, and evaporate adding water vapour to the atmosphere. But there probably isn’t enough water on Mars so proposal have included altering the orbits of comets and asteroids so that they impact Mars and release their gases (a lot of which will also be water held as ice). It is thought that a sizeable percentage of Earths water was acquired this way, so its not as ludicrous an idea as it might seem. Another idea is to release microorganisms such as algae (probably genetically engineered to survive on Mars) which will also convert carbon dioxide to oxygen as well as lay the foundation for the introduction of more complex plant and fungal life later down the road. All of these will take time, but that doesn’t mean that settlement has to wait until terraforming has been completed. That is of course assuming that terraforming is possible[4], which is a big assumption.

So, ignoring that and running with the assumption, why would anyone want to bother with such an effort? There are several ‘cases’ for terraforming Mars. And while there is an argument for terraforming a planet that centres on making it more habitable for indigenous life (i.e. ancient Mars life that has survived from a warmer, wetter period in Martian history)[5] the dominant arguments in favour of terraforming any world is to enable human habitation and colonization. Therefore, arguments for terraforming tend to parallel the arguments for ‘settling’ outer space. Most of these arguments centre on a need to make humanity (variously and usually vaguely defined[6]) ‘multiplanetary’ in order to ensure survival in the event of various catastrophes. There are secondary arguments about the need for expanded ‘living space’ and access to resource as well as the positive benefits that supposedly accrue from the challenge of taming a ‘frontier’. For terraforming specifically, one of these benefits is argued to be the lessons that can be learned and applied to geoengineering/climate mitigation for Earth (without any seeming regard to the disparate timescales involved). These arguments are worth examining in greater details. However, the next post in this series will focus on examining terraforming through the existing space law regime, essentially asking the question, is terraforming legal?


[1]See Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity (Oxford University Press 2020)

[2]Gerald K. O’Neill was a physicist and space advocate who developed ideas for orbital space habitats, it was his view that terraforming planets was a silly idea when you could construct an artificial world that’d be better suited to humans – his 1977 book The High Frontier: Human Colonies in Space (which thanks to the Space Studies Institute you can get for free on Kindle) has been quite influential in the ‘space expansionist’ camp perhaps most notably Jeff Bezos


[4]One of the issues that gets raised, including the video I’ve linked to is Mars’ lack of a magnetic field and while Mars not having a magnetic field is problematic for a number of reasons (solar radiation etc) my understanding is that the atmosphere being ‘blown away’ by the solar winds isn’t really one of them as it would be a slow process, and any society that is capable of terraforming Mars in the first place will be capable of replacing the atmosphere at a necessary rate – there are plenty of reasons terraforming Mars is not a great idea, as I will get to, but this isn’t really one of them

[5]This is one of the ‘benefits’ presented in Arthur C. Clarke’s The Sands of Mars one of the first sci fi novels to discuss terraforming, as the ‘native Martians’ are the survivors from the ancient warmer, wetter Mars and thus thrive due to the benevolence of the colonizers (this framing has, uh, problems… which I’ll get to later)

[6]Although often clearly synonymous with ‘Western’ or even just ‘American’


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