“The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars”
Chances are, Earth isn’t going to be the sole home of humanity forever. Overpopulation, irradiation or sheer bull-headed curiousity may one day send us far from our spawning ground. If our species does end up gallivanting off into the final frontier, we’re going to need some help settling into our new planetary homes…
Terraforming is the process of artificially converting dead rocks into worlds suitable for human habitation by giving them a climate matching Earth’s. It has long been a favourite of science-fiction writers as an explanation of how so many worlds in their canon are habitable by humans, in stark contrast with our hostile planetary surroundings in this universe.
At present we are so far from properly safeguarding even our own planet that ideas about colonising other planets hover in the realm between science and sci-fi. Still, if Star Trek foresaw the mobile phone and the iPad, perhaps it could be right about this too… right? How might we go about achieving this?
Hot and lively – all about the atmosphere
Just like parties (so I’m told), planets need a decent atmosphere if they’re going to get lively. Earth’s atmosphere protects us from the brunt of the sun’s radiation, and acts like a blanket keeping the surface at a constant temperature. The heatwaves and blizzards we still get on Earth are nothing compared to what the bare rocks of the solar system face. Mercury may be over twice as close to the Sun as us, but every night the temperature on this naked rock drops to around -170oC. It’s cold in space without a blankie.
If humans are going to go anywhere beyond the Moon, Mars will be our next stop. It may be cold and forbidding now, but it has actually got a lot of promise for supporting life. It may even have resembled Earth at one point in its history, and it has water and oxygen locked away in the rocks, ice-caps and underground. But before we can get really comfy there, some massive changes must be made. Mars does have an atmosphere, but it’s more of a thin moth-eaten sheet than a cosy blanket. It can actually get up to a pleasant 20oC on the Martian equator in summer, but that heat dissipates into space so quickly after nightfall that the temperature quickly plummets to around minus 100oC. A crucial part of terraforming is atmospheric control, and for Mars that requires kickstarting the greenhouse effect.
Climate scientists are pretty concerned about the greenhouse effect here on Earth. Human activity like deforestation and burning of fossil fuels is releasing huge amounts of carbon dioxide, methane and other greenhouse gasses into the atmosphere. Together these are thickening our blanket and raising the average temperature.
Given that the Martian atmosphere is actually 95% carbon dioxide, but Earth is struggling slightly with just 0.04%, it might be surprising that we’re the ones with the global warming issue! But the problem isn’t just the percentage, it’s the overall amount. Mars’s atmosphere is 100 times thinner than Earth’s, and it needs to be denser to stabilise the temperature as well as warm it up. Palaeontologists suspect that the planet has huge reserves of carbon dioxide beneath the surface which would be released into the atmosphere if the global temperature was raised even a little. This sets up a nice positive feedback loop where more CO2 means more heat retention means more CO2 etc… so give it a couple of hundred years and we could have a nice warm planet!
Assuming we decide to go ahead, how might we jump-start this process? Technological ideas have been suggested such as spraying super-greenhouse gasses called PFCs, giant mirrors reflecting more sunlight onto Mars’ surface or even diverting asteroids so they crash into the planet, releasing gas and dust into the atmosphere. The trouble with most of these ideas is that they all seem unfeasibly expensive to design, build, transport and maintain until they have fulfilled their purpose. What’s really needed is something more sustainable and self-running.
But we don’t necessarily have to start with the temperature. With biotechnology at a very exciting time of discovery and invention, the best way to terraform Mars may be to let bacteria do the dirty work, just like they did in the early Earth. Once life is seeded, it tends to help itself. Life begets life.
Terraforming – Just Add Life??
Humans are pretty squishy and fussy about where we can live, but other lifeforms are crazy tenacious. Deinococcus radiodurans is a bacterium that copes so admirably with freezing, irradiation, dehydration and vacuum conditions that it holds the known record for extreme survival. It’s been suggested that we could use the endurance skills of these organisms, genetically engineer them to perform chemical processes in the place of expensive and inefficient robots, and send them to Mars in order to do some of the terraforming for us.
Earth would have been a nasty place to live billions of years ago, to put it mildly! Yet life arose and thrived nevertheless. Once photosynthesis evolved in organisms like cyanobacteria to make use of the sun’s light energy, carbon dioxide was taken away to build into biomass and oxygen was released as a waste product. It may soon be possible to engineer organisms that can photosynthesize even so far from the Sun as Mars is. This would be really exciting because it would start to bring the carbon-dioxide/oxygen balance to something approaching Earth’s.
Of course, there are ethical caveats. It would be devastating if we popped our bugs onto Mars only to find they’d killed off a completely alien species before we had the chance to study and learn from it. There is currently no direct or indirect evidence for life existing on Mars, although that’s not to say it’s not there. I think it’s very important to wait until we’re confident beyond reasonable doubt that there’s nothing living on Mars already (something else Star Trek covers!). Once we’re sure, seeding life on Mars and letting it bide its time for a few decades while we develop knowledge and technology might help us greatly in the future, if we ever need to get off this planet fast.
Should we do it?
These steps are only the very start of making Mars suitable for human habitation, and there are so many aspects I haven’t even touched upon here. Decisions of who might get to live there and why are not ones that will have to be made for a long time, perhaps a couple of hundred years after we start terraforming. There is another important issue. Should we be spreading ourselves around the solar system when we can’t solve problems well enough to make even one peaceful planet? Even if we could afford it economically AND we overcome the technical problems, will having two or three homeworlds make anything better? I would argue “perhaps not any time soon”, but somehow I don’t think that’s going to stop people trying. Earth has cradled us nicely thus far, but keeping our pale blue dot as the sole refuge for life as we know it seems like a pretty big gamble to me.
“I don’t think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet. But I’m an optimist. We will reach out to the stars.” Stephen Hawking
Thanks to Martyn Fogg and Joseph Grace for reading through this post. Joseph’s video about terraforming and how the way could be paved by modified extremophiles greatly informed and inspired this article. Martyn Fogg is an internationally recognised authority on terraforming and has written numerous scientific papers on the subject. I am very grateful for their feedback.