PART SEVEN
(The next 100–200 years)
WHAT CAN WE MAKE OF MARS?
Given that Mars isn’t what we might want it to be, the question – unspoken, but present from the very first word – is what do we do with all this? Do we treat our exploration of Mars as an academic exercise, a worthwhile but ultimately esoteric study of a neighbouring planet that has both marked differences from and odd similarities to our own? Is it something we need to do in order to know our home better? Are we intending to use Mars as a first step, a proving ground, on our way to moving our nascent spacefaring civilisation out of the fragile basket that currently holds all our eggs? Or is it simply a place to exploit – a land-grab for pristine real estate, a new frontier that represents riches for a few or, less likely, for the many?
What we know of Mars has changed and is changing. The more robotic probes we send to trundle over the cracked lava flows and dusty sediments, the more detailed and accurate a picture we see: the only thing that’s guaranteed is that there’ll be more surprises along the way. But we already know enough to have a serious discussion about what Mars represents, as a laboratory for our research, a destination for our scientists and a place for us to colonise.
Our robotic ambassadors are still few and far between. Overall, two out of three Mars missions have failed – getting out of Earth orbit was particularly difficult early on – but we’ve been getting better. And while it’s significantly easier to put a satellite into orbit around Mars than it is to put a lander on its surface, there have been some interesting mistakes there, too. For example, 1999’s Mars Climate Orbiter was brought down when its thrusters were calibrated in imperial units but the on-board computer expected metric values.
Barring those missteps, getting to Mars orbit is simply a question of celestial mechanics and having enough propellant. Certainly, designing a mission, deciding what scientific instruments to put on it and how it can relay its information back to receiving stations on Earth are all difficult, technical problems: every kilogram of useful payload represents 100 kilograms of fuel required to get it to its destination. And while there are ways of helping ourselves to free energy – by waiting for preferential alignments between the planets and using gravity to slingshot our spaceship into position – it still comes down to how much grunt a launch system can provide.
We can put increasingly sophisticated sensors into orbit – including, but not limited to, cameras that use visible and infrared light, radar, lasers, spectrometers and magnetometers – and we can send probes down to the surface. These are sophisticated laboratories in their own right, whether they’re static or on wheels, and in concert with their motherships, they represent the very pinnacle of our scientific and engineering capabilities. These landers have to survive the ferocity of launch, the months of space travel, the moment of separation from their carrier and the descent to the Martian surface – a descent with the entirely unironic name of ‘seven minutes of terror’.
During this time, any and all difference between orbital height and speed and achieving a stationary landing on the surface needs to be accounted for, and there are no margins for error. One single slip will result in losing the ship, together with all the time and money spent on making it and getting it there and there’s nothing anyone can do about it. Mars, at this point, is light-minutes away; any instruction we might send from Mission Control – to change an angle or the duration of a rocket burn, or even to abort the landing – will arrive long after the commitment to action has been made. The on-board computer can only do so much. Everything either happens close enough to the plan or we make a new crater on the surface.
A lander in low-Mars orbit is moving at between 3 and 4 kilometres per second. We need to slow it down in order to land, and we do that by throwing the lander at an angle at Mars. As it barrels at supersonic speeds through the upper reaches of the Martian atmosphere, it strikes the gas that makes up the atmosphere, transferring the energy of its motion to the atmosphere itself. Each individual impact with a gas molecule creates heat, and there are plenty of those, even in Mars’s thin atmosphere. This means lots of heat – more than enough to destroy the lander – so there needs to be a heat shield between the working parts of the lander and the onrushing air.
But while there’s enough atmosphere to cause us problems, there’s not enough to help us. As soon as the lander is moving slowly enough that it’s no longer at risk of burning up, we can deploy our parachutes and discard the heat shield. If the atmosphere were thick enough, we could float down to the ground from there. It’s not. Even if we use huge parachutes, specially designed to work at very high speeds, then we still can’t brake sufficiently hard not to plough into Mars.
To overcome this, we need to either absorb the inevitable impact or use another method to slow our descent to practically nothing. Most successfully, retro-rockets are used, either on the lander itself or as part of a sky-crane mechanism, where a framework hovers on spears of flame above the ground as it slowly winches the lander to the surface.
Each stage is fraught with danger. If one thing goes wrong, it all goes wrong. There can be no human intervention. Mars is a graveyard of our hopes and ambitions. Of the twelve landers to have made it as far as Mars orbit, fully half of them failed to get to the surface in good-enough working order, either burning up in flight or crashing into the ground – most recently in 2016, when a joint European and Russian lander called Schiaparelli misread an input and jettisoned its parachutes early. It was still 4 kilometres above the ground. The retro-rockets became very confused and the half-tonne lander made a new crater on the Meridiani Planum.
Of course, no one plans to fail: every lander sent so far has gone with the very best technology available at the time, but there are inevitably compromises that have to be made simply to get the spaceship there. It would be far safer for a descending craft to cut its orbital speed outside the atmosphere and coast to the ground in a controlled, powered descent, but the weight cost would be prohibitive, and it may be beyond our capability to deliver that much payload even into Earth orbit, let alone further away. We can argue that having a highly trained crew – a pilot, an engineer – on board any human mission to Mars will improve the odds of a successful landing significantly, but that’s far from guaranteed.
This means that some of the people we send will die before they even take a step on Mars. It’s inevitable, and we need to think about that. And the risks don’t end with a successful landing. Mars is almost unconscionably far away – at best, 56 million kilometres or 3 light-minutes; at most, the other side of the Sun, 400 million kilometres. Messages – if they could be sent at all – would take more than 22 minutes to travel one way. Once on Mars, the crew would be on their own, with only the equipment and resources they brought with them or could scavenge from the environment.
They would have landed in an incredibly hostile environment. The atmosphere is both too thin and the wrong mixture of gases, rendering it unbreathable at any pressure. The soil is toxic, contaminated with chlorine-rich compounds called perchlorates at a level that is lethal to humans. With no Martian magnetic field to deflect, nor enough atmosphere to absorb, high-energy particles from the Sun, Mars is sleeted with radiation even on a normal day. If there’s a solar flare, the radiation increases two hundredfold. Not everyone who goes to Mars and stays there will get cancer, but everyone who goes to Mars will run a much higher risk of getting cancer than they otherwise would.
The more insidious problem is that of the dust. We know that people who work in environments where they’re exposed to ultrafine rock particles are going to breathe them in unless great care is taken and protective masks are worn. Silicosis is a grave threat to a person’s health. More so are the associated cancers that go with certain types of rock dust. While outside, in a spacesuit, using tanked air, the dust would be safely away from an explorer’s lungs. But if they brought it inside with them, the always-circulating air of the habitat would ensure it never settled and it would have to be deliberately removed – but these are the very smallest particles, so the filters would have to be the finest available.
The first humans on Mars would always be one step from disaster. A vital spare part, a chemical, a drug – all would be at the far end of the longest supply chain in history. That’s the hard truth. But there’s a very great deal we can do to make those risks as small as we can.
Firstly, we shouldn’t go until we are ready. We already know that any Mars mission would need to get our explorers there, give them enough time on the surface to do useful science and then get them back again. We wouldn’t be abandoning them there: we’re not monsters. We’d plan everything carefully. We could pre-seed the landing site with everything the team would need, making sure it was all there before we committed to sending a crew. We could even land a return ship first, that would synthesise its own fuel from the Martian air – by splitting the carbon dioxide in the atmosphere into carbon monoxide and oxygen, or by adding hydrogen from Martian ice to create methane. And of course, the oxygen we farmed from the atmosphere or the ice for fuel could also be used to provide a breathable atmosphere, either of pure oxygen or buffered with nitrogen that we’d bring along to simulate Earth-normal conditions. As for water, it’s too heavy to take with us, but we know we could just take a shovel to the ground, pressurise it and heat it to get all the water we would need.
The soil might be toxic, but we should be able to clean out the perchlorate, rendering it useful as a plant growth medium. The Sun would provide the bulk of our energy, although the sunlight is weaker on Mars than on Earth, and during dust storms that would reduce to almost nothing. A reliable backup would be needed: currently the only sources of that are highly radioactive and very heavy thermoelectric generators, but we do have them.
The radiation is dangerous for certain, but by burying our habitats under a thick layer of bulldozed soil, or by constructing them inside the entrance to a lava tube on the side of one of Mars’s volcanoes, we could protect ourselves for the majority of the sol. For outside work, the astronauts would wear dosimeters to measure their exposure. Any Martian weather forecast would include a radiation rating, and there would be days when everyone would have to stay inside, no matter what.
Electric-powered rovers, assembled by the astronauts on the surface, would be simple enough to send ahead of time, as would the self-build habitats that the crew would create from kits. A successful Mars mission would see experiments in botany, geology and meteorology, as well as in the practicalities of growing food, harvesting water and air and surviving the harsh surface conditions. The architecture of any habitation would have to cope with wildly fluctuating temperatures between the very cold nights and the still-cold days, without leaking precious air. All these are engineering problems and not impossible to surmount.
To combat the dust, we’d have to think about washing spacesuits, vacuuming them off or trying to remove the dust using a static charge. Whichever solutions we chose, they’d need to be carried out regularly and rigorously to minimise the potentially fatal consequences of dust inhalation.
Beyond that? One of our chief concerns ought to be how to avoid contaminating Mars with our own bacteria. All landers – and all orbiting probes, but especially landers – are constructed in a surgically clean environment and undergo several rounds of decontamination, and even then the idea is only to minimise, not to completely eliminate, any microbial passengers. We could transport our terrestrial organisms to Mars and not realise it, but once we send a crewed mission, that scenario is inevitable. We cannot decontaminate a human being without killing them. We live in symbiosis with our bacterial load – without a panoply of flora both inside and out, we get very sick indeed. The consequence of contaminating Mars is that we could miss the signals of indigenous Martian life by masking it – or worse, exterminating it – with an invasive species from Earth. That would be a shame, since finding life is one of our principal reasons for going to Mars in the first place.
All of this is the context for scientific exploration. But what if we wanted to go and live there?
WE ARE THE MARTIANS
We realise that sending robotic probes and crews of scientists to Mars is both a worthy endeavour and a high-risk strategy. We can learn an enormous amount about another planet, and our own, by studying Mars in detail, even while we acknowledge that this will come at a cost: in terms of money, time, human life and the potential of ruining the environment we want to study.
Colonisation is a different matter. Permanent settlements on Mars would transpose our current economic model onto a new world, with all the exploitation of unrenewable resources and alteration of the landscape that this entails. We’d create buildings out of Mars material. We’d use Mars’s atmosphere and water to make them habitable. We’d mine metals and engage in complex chemistry to form the hydrocarbons that are the rootstock of our plastics industry. We would, inevitably, produce waste that was seething with bacterial life.
Even if we started out with good intentions not to change Mars, we’d do it anyway. Humans are successful not because we fit in with our environment, but because we alter it to suit us. The high-stress situation we’d find ourselves in on Mars – no breathable air, no edible food, no sheltering structures, no potable water, no temperate climate – would require a technological, resource-heavy intervention.
The beautiful white pearl of the Korolev crater. Metal ores present in hydrothermal veins throughout Tharsis, Elysium and the highland volcanic provinces. Gold deposits in sedimentary sands on riverbeds and in ancient lakes. Once we arrived on Mars, the pressure to use them – even just a fraction of them – would be overwhelming. The cost of shipping everything we’d need from Earth would be huge, and we must never underestimate the satisfaction and the drive to gather resources from around us. The colonists will want to do this, not just to become less reliant on the old world, but actively to show their independence from it.
For the new Martians, being able to fix a broken valve, repair a split module or put a new wheel on a rover would all be matters of survival, not just contrariness. Even if there were a moratorium on strip-mining the water out of Korolev, if the choice was between dying and taking a pickaxe to the ice, the pickaxe would win. It’s our nature.
This isn’t to say that this scenario is intrinsically bad, but it’s a debate that we have to have at the beginning of the process, not after it’s under way. How do we want to treat Mars? Do we want to have a completely hands-off approach, which will preclude any of us ever planting a single ridged boot in the ochre dust of the Vastitas Borealis? Do we want to designate it as a planet purely for science? We have a model for that in our own Antarctic, where no country and no company can claim property or mineral rights on the entire continent, and where an international treaty oversees any conflicts that might arise. Or do we want to open Mars up to colonisation and exploitation, allow ownership on it and let those with the wherewithal to get there crown themselves kings?
There’s a step beyond even colonisation that wouldn’t just alter the planet, but change it utterly. The idea of terraforming Mars – making it more Earth-like – is a well-worn science-fiction trope, and as preposterous as it might at first seem, we have to have regard for the fact that we’ve been able to change the climate on our own planet in as little as two centuries by increasing the carbon dioxide content of the atmosphere. We already know that the Martian climate can be shifted using just one factor, the atmospheric pressure, and we can speculate on how we might boost that.
Most obviously, given our knowledge of how high-obliquity Mars sheds its ice caps, could we do something like that? Turning Mars would be beyond us, but deliberately heating the polar regions might not be. We could put large, thin, silvered mirrors in orbit and reflect sunlight downwards. If we melted the polar ice, we’d immediately double the current air pressure, but that would still put it at barely 1 per cent of the pressure at Earth’s sea level. We’d need more gas from somewhere.
Dark objects absorb more heat than light ones. We could destroy Phobos and Deimos, both almost black, and scatter them across the water-rich northern plains to encourage them to defrost. Then there’s comets, those leftovers from the solar system’s formation, which regularly swing past the inner planets. If we could redirect them to strike Mars, then we’d inject fresh volatiles directly into the Martian atmospheric budget. We could head out to the tenuous trans-Neptunian storehouse of icy bodies and mine them, sending streams of precisely directed ice pellets inwards.
Perhaps you’re now thinking, if we had the power and the technology to do all that, then we wouldn’t need to live on Mars after all. We could use our expertise to build entirely artificial orbital habitats, or hollow out asteroids and pressurise them, rather than attempt to fundamentally transform Mars into something it could never really be: a home. There’s a whole raft of difficult ethical questions to ask ourselves here, and the answers aren’t obvious.
Mars has always been with us, that red point in the sky with a name in every language, freighted with meaning and endowed with supernatural powers. Mars is still there in our imaginations, even though our understanding of it has grown and grown, beyond the baleful influences of war gods, beyond the place from which three-legged death machines are launched across space in a green glow. It’s become a solid reality that’s no less wonderful and terrifying than those visions of our ancestors.
We cannot stand aside from the conversation to come – and it will come soon – as to what we do with Mars.
ACKNOWLEDGEMENTS
When I was first approached with this project, I distinctly remember telling my agent ‘I will pay them to let me do this.’ It didn’t come to that, and in retrospect, asking a science fiction author who has a background in planetary geophysics to write a book on Mars wasn’t such a random call after all – just one I never expected.
But my over-enthusiasm for highly detailed, specific, technical explanations had to be reined in somehow – and the four people who made this book even marginally readable need to be lauded for their patience, encouragement and clarity of thought and purpose. So, please – Antony Harwood, Simon Spanton, Pippa Crane, Clare Diston – take a bow.