Terraforming is hard. Could evolution help?
Humans have it pretty cushy here on Earth. By the time our existence came about, our planet had undergone millions of years’ worth of transformations, revamping itself from a lava-oozing hellhole to the seemingly tailor-made paradise we live in today. Paradise, in this case, is a relative term; our planet can pelt us with deadly weather, shake us up with earthquakes, and bombard us with volcanoes, but these nuisances are nothing compared to what we’d experience elsewhere in the cosmos.
Depending on your choice of planet (or moon), you might experience severe illness from cosmic radiation, asphyxiation due to a deadly atmosphere (or lack of one), or a decidedly miserable death by means of being either sizzled or frozen – among many other possibilities. Earth, meanwhile, has an atmosphere that keeps this radiation out and allows us to breathe, orbits at a ‘Goldilocks’ distance from the sun – not too hot and not too cold – and has the gravity we are accustomed to. Easy living.
Colonization of space, therefore, seems like an unnecessary and rather unpleasant escapade. But what if there was a way to mold these hostile planets to look more like Earth? Turns out, there is (at least in theory); known as terraforming, it involves using a combination of technology, chemistry, and even biology to renovate a fixer-upper of a planet and make it the perfect new home for humanity. Still, such a planetary makeover won’t come easy; several problems must be considered and solved before we send in the spaceships.
Problem One: Magnetic Field
A planet or moon’s magnetic field, also called a magnetosphere, is crucial to the habitability of a world. As explained here, it works like a bicycle’s dynamo in reverse. On a bike, the pedaling causes a magnet to rotate, and the resulting magnetic field creates an electric current that powers the light. Earth’s innards of molten metal do this backwards; the process is even known as a geodynamo. It is driven by so-called convection currents, which happen when the blistering core heats up the surrounding metal; while colder and denser materials stick to the core, hot and buoyant materials rise to the surface. These then cool and sink again. As this cycle continues, an electric current is created, which in turn generates a magnetic field. The Coriolis effect (an inertial force which determines the motions of objects not connected to the ground but still within a rotating system, like weather patterns on Earth) causes these convection currents to line up with the Earth’s axis as the planet spins.
Our magnetosphere is our planetary shield, protecting us from almost anything space throws at us. This can include solar wind, consisting of charged particles – mostly electrons and protons – escaping the sun’s gravity and hurtling through space at supersonic speeds (solar wind’s scary bigger brother, coronal mass ejections, cause much more of these particles to be emitted). The particles can also originate from outside our solar system, in which case they are known as cosmic rays.
Earth’s magnetic field deflects these particles, often temporarily redirecting them to the poles, where they collide with atmospheric elements such as oxygen and nitrogen, heating them up and causing them to glow in green or pink hues: the Northern (or Southern) Lights. But if it weren’t for our shield, the particles could strip away our atmosphere, diminishing atmospheric pressure and leaving us vulnerable to ultraviolet radiation emitted by the sun, which would, among other things, vaporize our water and render our planet an arid wasteland. At least, that’s what happened to Mars (it lost its magnetosphere billions of years ago as its dynamo shut down).
So, a significant point of order in terms of Martian colonization – Elon Musk and SpaceX’s holy grail – would involve fitting our rust-colored planetary neighbor with a magnetosphere of some sort. Easier said than done, but NASA has already spitballed an idea; it involves a magnetic dipole – which would create such a shield – being suspended at a stable gravitational point in space near Mars, known as the L1 Lagrange point. Here, the artificial magnetosphere would be permanently placed between the sun and Mars, deflecting the dangerous particles. Its magnetotail – the side of the magnetosphere pointing away from the sun – would eventually envelop the planet, protecting it from radiation.
As explained here, Mars’s atmosphere is about 1% as dense as Earth’s, and despite the constant battering of particles, it is maintained by gases regularly escaping from the planet’s interior. With magnetic protection, this atmosphere will build up and the planet will warm; at a temperature of about 4 degrees Celsius, frozen CO2 in the Martian ice caps will melt, contributing to the greenhouse effect we know from Earth and further heating the planet. Previously frozen water could refill Mars’s forgotten oceans and the red planet would become blue. But while a magnetosphere allows for the existence of an atmosphere, what that consists of is another concern, leading us to…
Problem Two: Atmosphere
In the long term, it’d be nice if humans could breathe on their planetary colonies, not to mention keeping the protection against energetic radiation that our own atmosphere does so well. Other planets aren’t quite as friendly; take Venus, a hellscape of a planet whose atmospheric pressure is 90 times as high as Earth’s, or Mars, with its thin yet toxic wisp of an atmosphere. Neither scenario is appealing, but according to NASA, both planets technically orbit within the habitable zone of our solar system. While current research focuses more on Mars, how would one transform the atmosphere of Venus (or a distant exoplanet with a similar situation)?
Venus, in case you missed it, is hot; very hot. But it wasn’t always like that. As explained here, 4.5 billion years ago, the Venusian landscape looked a lot like Earth’s, with liquid water flowing over its surface. The sun was younger and dimmer then, and as it grew in brightness, it caused Venus’s oceans to evaporate and hang out in the atmosphere as a gas. The vapor trapped incoming infrared radiation, or heat, and the planet started to warm; this then caused even more water to evaporate, and so on, creating what is known as a runaway greenhouse effect. As water acts as a kind of lubricant for plate tectonics, the lack of it caused massive outbursts of carbon trapped in the ground. Eventually, sunlight broke down the water vapor and caused it to dissipate into space, and Venus became the toxic 475-degrees-Celsius furnace we know it as today.
To transform Venus’s mostly CO2-based atmosphere and its extreme pressure, several methods have been suggested. One process proposed by British scientist Paul Birch involves cooling the planet down by means of a sunshade suspended in – once again – the L1 point between Venus and the sun. This would cause the CO2 to rain back down to the surface. Subsequently, the temperature would be decreased further to -56.5 degrees Celsius, at which point the CO2 would freeze into dry ice. This could be buried or shipped to another planet, and the planet warmed again to meet human standards. Birch then suggests crashing an ice-moon into Venus to reintroduce water., and photosynthesizing organisms such as algae would be used to convert leftover CO2 and CO (carbon monoxide) into oxygen. Birch proposes a ‘thermally insulating cover’ to keep the atmosphere in since Venus is also lacking in the magnetosphere department, but a similar method to that proposed for Mars could be used here.
Speaking of Mars: as the sun grows more energetic, it will fry Venus and then Earth, making Mars an ideal place to set up camp. A multitude of proposals to craft Mars an atmosphere exist; one by a certain Mars-hungry billionaire involves nuking the planet to release the CO2 from its ice caps to cause a greenhouse effect, warming the planet (though a paper on this concept showed that there may not be enough CO2 readily available for this to work). Another method suggests using giant orbital mirrors to reflect sunlight to release the CO2, but this faces the same problem. Sending microbes ahead to prepare the planet for us is another possibility; our planet’s very own oxygen was converted from CO2 and pumped out by primordial cyanobacteria, and several proposals (partially even sponsored by NASA and DARPA) suggest letting similar organisms work their magic on our neighbor, too.
Still, as noted here, Mars would ultimately only be able to sustain an atmospheric pressure of about 0.38 bar, compared to Earth’s roughly 1 bar; this is due to Mars having only 38% of Earth’s gravity. Though not detrimental, it would mean that Martian air would, at its thickest, be akin to that of the Himalayas. It simply cannot hold on to more. But what about messing with gravity itself?
Problem Three: Gravity
Regrettably, no fancy machine exists to change an object’s gravity. The only way to do so is to change its mass; technically, you can bombard a planet or moon with asteroids, but this would take an exorbitant amount of energy to have even a negligible effect. Zero gravity during spaceflight – and by extension the weak gravity on certain bodies such as the moon – has been shown to have implications for the human body, making this a significant concern. But while gravity itself is set in stone, you can trick yourself into feeling it.
Made famous by the blockbusters of science fiction, using a centrifuge – a rotating machine, often depicted as a ring – can bring about the effects of gravity, too. As the machine rotates at certain speeds, objects within the ring are thrown to its edges. This is known as the centrifugal force (though it is technically an effect rather than a force), and it is defined by the revolutions per minute of the centrifuge. This pseudo-force is expressed in terms of g, relative to the Earth’s gravitational pull of 1g (as explained by the theory of relativity, acceleration and gravity can feel the same if you don’t know any better; this is why Earth’s gravity, in this light, can be said to have an ‘acceleration’ of 9.2m/s2). Therefore, it is theoretically possible to use a centrifuge with a relative centrifugal force of 1g to recreate Earth’s gravity in space.
In terms of planets and moons, plans laid out by researchers from Kyoto University and Japanese construction company Kajima Corp. propose huge vase-like centrifuges on the surfaces on the moon and Mars that spin parallel to the body’s surface to create artificial gravity. Inside them, colonists would be able to walk around as if they were on Earth – albeit sideways relative to someone standing outside – and only leave for expeditions. While not ideal, this may be the only way to maintain a presence in space without compromising colonists’ health. The company states that it may take around 100 years for the project to become fully operational; depending on how things go, colonization might be well on its way by then, bringing new problems with it…
Problem Four: Geo(astro?)politics
We know how hostile space is. Granted, research concerning issues such as, for example, just how much CO2 is on Mars and how to operate a centrifuge is still ongoing, but it’s clear that those challenges exist. What is less clear is how we will deal with them, especially given mankind’s long history of colonial warfare. Space law is already painfully underdeveloped (read my summary here), its cracks already showing in matters of space debris, mining, and satellites; while the UN’s Outer Space Treaty essentially defines space as a global commons – free to use for anyone, no sovereignty allowed – countries are already testing these limits by making their own laws. As it stands now, people can barely manage to get off Earth, let alone establish a colony beyond it. But when the time comes and valuable resources such as the moon’s Helium-3 or Mars’s water are within reach, terraforming technology and who owns it may determine who will ultimately be in charge.
Another consideration is that instead of fueling the fire of off-world colonization, political and economic constraints may ultimately be what stop terraforming from happening – at least by governments. Though the US and China, among others, harbor lunar and Martian ambitions, it is companies such as SpaceX who are known for their ambition to colonize – and terraform – our cosmic neighbors. At least in the US, private companies are already far ahead in the space race while governmental programs lag behind. One day, the transformations of our cosmos may end up not in the hands of governments, but those of corporations, whose goals and methods to go about them could be much more volatile.
While the science described above can be rationalized, human behavior cannot. The clashing of geopolitics and space is truly unbroken ground; it is possible to roughly estimate how technologically hard or even impossible colonization is, but this is one thing that – especially given the state of space law and its lack of reinforcement – we cannot account for.
With all this talk of terraforming and the headaches that come with it, there is one common denominator: us. While talking about adapting entire planets to fit our very specific needs, a logical yet harrowing conclusion is that one day, it may become easier to not terraform entire planets but… astroform ourselves instead.
Genetic editing methods such as CRISPR are already old news, though their ethics are still a topic of debate. Still, as Stephen Hawking notes in his book Brief Answers to the Big Questions, it may just be a matter of time before someone enhances themselves genetically, however illegal it may be. Depending on how important space colonization is believed to be in the future, it is not impossible for countries or companies to create an enhanced set of humans custom-made for space travel.
Research is well underway. It is already known that tardigrade, microscopic creatures sometimes referred to as water bears, are all but indestructible, surviving in the vacuum of space and shrugging off mind-boggling amounts of radiation. As explained here, geneticist Chris Mason of Weil Cornell combines human cells with a certain gene found in the hardy little critters that minimizes DNA damage from radiation. Other proposed methods include editing human genetics in order for us to be able to survive off of sugar water alone (making deep space missions easier); George Church, a Harvard geneticist and leading synthetic biologist, has identified about 40 genes pertaining to anything from bone density to oxygen requirements that could come in handy for astronauts.
And that’s not even all; in addition to genetics, cybernetic enhancements may have a part to play as well. The idea isn't new, either; the word cyborg was actually coined in a paper defining the concept as an ‘enhanced human being specifically doctored to survive in extraterrestrial environments. Without a space suit’. The authors’ ideas, while outdated, describe implants controlling blood pressure to work on a hostile planet (among other ideas). Though this is perhaps a little exaggerated, concepts such as China’s proposed exoskeleton for astronauts and the US Defense Advanced Research Projects Agency’s (DARPA) similar designs to aid diagnostics and enhance stamina show that it isn’t so far-fetched after all. And simple technological enhancements such as smartwatches measuring your heart rate and phones yelling at you when your music is too loud are already commonplace.
Only time will tell how all of this will play out. Technologically, overcoming certain barriers of planet-wide transformation is clearly possible; we are already (inadvertently or not) transforming our planet by means of climate change. But throughout Earth’s history, it has always been life that adapted to its surroundings, not the other way around. Thus, humans – and our fellow inhabitants – have evolved to be at home in the harshest conditions our planet can create. Evolution – or rather a rapid, artificial version of it – could once again prevail with space colonization. Will the new horizons change us before we can change them?