Colonising Mars
What is mankind’s plan B for when poor old Earth has ceased to be. Gone to meet its maker, rung down the curtain and joined the choir invisible? What happens when Earth is an ex-planet. Well, then it’s time to hop over the fence and set up camp in our neighbour’s garden, even if it’s a red and desolate wasteland. Just over 78 million kilometres away on average, Mars isn’t quite our closest neighbour, that’s normally Venus, depending on its position in its orbit. But Mars is definitely the best candidate to sustain life. And we’re not talking about just going and living in a caravan full of baked beans and oxygen, we’re talking about a full civilisation, out walking on the surface of the red planet. So is this really possible? Could we actually make Mars into a place where humanity could survive? Could we breathe? Could we grow food? Are there any good bars? Today we look at the steps we would need to take to become the Martians of the future. Now getting to Mars is something of a challenge and it could take anywhere between 150 to 300 days, depending on space traffic. But this timeframe is perfectly manageable, although a bit boring. The real issue is getting the huge volume of stuff we’d need to colonise from the surface of Earth out into space and then over to Mars. Right now, it costs around $25,000 to get just 1 kilogramme into orbit around earth. And although the money is obviously an issue, think of all the resources, time and dedication it takes to launch just one rocket into space, never mind a continuous fleet of spaceships travelling to Mars with supplies. Think how much effort it was to build the International Space Station, and that’s only 400 tonnes – that would barely carry the toothpaste and peanut butter needed by the Mars colonists. One proposed idea is to build a space elevator. It’s a surprisingly simple concept; you just need a cable attached to the Earth that extends out beyond the distance of a geo-synchronous orbit. By that I mean the orbital distance where a satellite rotates at the same speed as the Earth, so it stays in exactly the same position out in space as the start of the elevator, back on Earth. The cable would have a counterweight at the end. The counterweight would swing around, like a tetherball, and the centrifugal force would be enough to counteract Earth’s gravity, which would mainly be acting on the lower end of the cable, having much less influence on the further away parts and the counterweight itself. This would keep the cable taught and now you could run an elevator up and down it, using much less propulsion than you’d need for a rocket. Some estimates say that it would bring the cost of putting 1kg of supplies into orbit down from $25,000 to under $250. The obvious technical difficulty is building a cable that would need to be around 100,000 km long. But with the development of materials such as carbon nanotubes, it’s beginning to look more possible. The cable cars, called climbers, would probably use rollers to pull themselves up using friction but there’s a limit to how fast they could go up the cable, partly because of the strength of the material but also because as you get higher, you are picking up a huge horizontal speed, caused by the rotation of the earth. This is called the Coriolis force. You’d also need to power the climber. The journey would probably take 5 days, so you’d either need a powerful nuclear reactor or, the most likely solution, you could beam the energy up to the climber using a laser – meaning less weight being carried on the vehicle itself, and more room for snacks. So if the elevator works, and all we need to do to get material into space is listen to a few days of awful elevator music, the next step is sending everything over to Mars. This is where the moon could come in very useful. The moon would never be able to have an atmosphere, so it’s hopeless as a colonisation prospect, but its lack of atmosphere is actually a huge advantage because it means there is no friction. The great science fiction writer Arthur C Clarke discusses this in his non-fiction collection Voices From The Sky. It’s worth pointing out that he also popularised the idea of the Space Elevator in his 1979 novel The Fountains of Paradise. One idea that Clarke put forward is that you could build a giant space gun that would fire spacecraft down a track on the moon’s surface, and fling them out into space. The craft would only need small propulsion rockets to make adjustments for its entry into Mars. This space gun wouldn’t be possible on Earth because the friction of the atmosphere would create too much heat, and you’d probably kill about a million pigeons every journey, as well as everyone on board. But on the moon, with a track just 30km long, you could get the acceleration you need and remain under the 10G that astronauts currently experience when they leave earth. If you weren’t sending people, you could use a much shorter track. The technology that we currently use for maglev trains would work extremely well for this, using a magnetic field to both float the vehicle above the track, and to pull it forward. This is why Elon Musk and others are looking into creating vacuum train tunnels for terrestrial transport; no air means no friction. Speaking of Elon Musk, the amazing achievements of Space X and the privatisation of space travel is probably what will make this whole colonisation project a reality. We’re still going to need rockets, at the very least to build and maintain space stations. But when Falcon 9 landed on an automated drone ship this April, after sending supplies on to the ISS, it showed that we can finally start reusing rockets, potentially turning a $60 million trip, into just $600,000 for fuel and maintenance. To get started on Mars, we’d need some pre-made living spaces. They’d probably initially be something like those put forward by the Mars One project – a small series of contained compartments, which you could link up. Therefore, it would be easy to just shut one part off when you have a problem. And when it comes to keeping the astronauts alive, well Mars has some very important features. Thanks to the work of our first Martian, the hard working Curiosity rover, we now know that there are all of the basic elements we need in the ground and the atmosphere, so we can create breathable air from what is already there. There is ice in the soil that could be used both as drinking water and to produce oxygen. There’s nitrogen in the atmosphere so we could make our favourite cocktail of earth-style air, more or less. So that’s water and air covered, but what about food? Future colonisation attempts on Mars, such as Mars One, plan to send a boatload, well a spaceship load, full of fresh food to the planet in advance so it will be waiting for the colonists when the arrive. But when that food runs out… well lets just say things get pretty grim. The Martians will live mostly on a diet of algae and insects. Food will be produced hydroponically using artificial lighting. Martian soil will be used to grow plants and carbon dioxide will be provided from the Martian atmosphere. The nutrients for the plants will come from recycling human waste. Lovely. And if we move beyond just the basics of keeping people alive, what about things like communication? Even though you moved millions of miles away, your grandma is still going to expect a call at Christmas to explain why you aren’t married yet and why didn’t you get a real job rather than all this fancy space nonsense. Depending on the relative positions of Earth and Mars, a message travelling at the speed of light can take between 3 and 22 minutes to go from one planet to the other. That means phone calls are out but texting and internet messaging would be fine, so one day the solar system will be cluttered with a constant stream of emojis. So, how’s Mars? Desert icon, skull and crossbones, sad face. One other idea that Arthur C Clarke put forward in Voices From The Sky is that you could use lasers to beam much higher volumes of data across space, if you make use of the moon once again. Lasers would be distorted by Earth’s atmosphere but you could use the moon as a relay station, so messages could be sent that short distance to the Moon by radio waves and then converted to the more powerful laser form, and vice versa. This means large data dumps of technical information would be much easier and you wouldn’t need to limit the coloniser’s communications. So the Martian folks would be able to send all the selfies they want from Mars back to Earth; Yeah we get it, you guys are holding a Mars bar on Mars, very funny. But now we come to the really important question; can we make the whole planet liveable? Humans are actually pretty limited in terms of the environment we can survive in. It’s not just the chemistry of the air but also the temperature and the pressure that are important. Of course we could spend all our time in spacesuits but it wouldn’t really be a normal life and it would make Martian Next Top Model a whole lot more repetitive. Besides, no one wants to spend all day in a suit. The atmosphere on Mars is mainly carbon dioxide and it’s at a far lower pressure than we have on Earth. At our sea level, the pressure is about 100 kilopascals. To make life easier, we normally refer to this as one atmosphere (101325 Pa). The lowest pressure us puny humans can breathe in, unaided, is about 0.4 atmospheres. Anything under 0.2 would require us to wear a suit. Mars is all the way down at 0.01 atmospheres. You really don’t want to be out in that. In 1966, a technician was testing a spacesuit in a vacuum chamber. The suit failed and there was a rapid loss of pressure. The man quickly fell unconscious but he recalls that the last sensation he had, before he passed out, was feeling the saliva boiling off his tongue; so without a spacesuit on Mars you would rapidly boil alive before exploding dramatically. To increase the pressure of the atmosphere, we would face some major issues, one of the biggest being that Mars lacks Earth’s powerful magnetic field, called the magnetosphere. The Sun creates a solar wind; a stream of matter, such as protons, electrons and alpha particles, that are sent out in all directions. The part of the Earth facing the Sun, the day side, is shielded from this particle breeze by the magnetosphere and deflects much of it away, keeping us safe. Some does enter through the poles and this is how you get the Aurora, otherwise known as the Northern or Southern Lights. We believe Earth has this magnetic field because of its liquid outer core. The moving molten metal deep inside the Earth acts like a dynamo, just like how the spinning metal of a bicycle wheel can create an electric field and power a light bulb. Mars once had this too eventually the planet’s core cooled down and now its core is totally solid, so its magnetic field was lost. Without the protection of a magnetosphere, the solar wind blows away much more of the atmosphere, thinning it out. We have not yet come up with a good solution to this problem. What we do have are a variety of ways that we could at least create the atmosphere once again and raise the temperature of the planet’s surface. The south pole of Mars holds a lot of frozen carbon dioxide. If we could heat the surface a few degrees, the CO2 would be released into the atmosphere and would then act a greenhouse gas, like it does in a problematic way here on Earth. This would then warm the planet and you could use simple life forms, like Phytoplankton, to convert some of that carbon dioxide into oxygen. You could then slowly introduce more complicated organisms and carefully build the eco system. As our knowledge of genetic engineering grows, we will probably be able to alter the organisms to work better in each stage of the changing environment. We’ll also be able to make 6 armed monkeys, orange dolphins and dangerously fat mice, just because we can and it’s funny. So how would we give the planet that initial kick of energy to release all the CO2 and create the desired greenhouse effect? One idea put forward is to just bounce more sunlight up to the pole with a series of giant mirrors. We could use a substance called PET (polyethylene terephthalate) as you can stretch it very thin while maintaining a reflective surface. It would be pretty slow though and I’m not sure Mars would want to be staring at its awful red face in the mirror every day. A quicker method, although much more difficult, would be to go asteroid hunting. If we could find a few massive asteroids, rich in ammonia since this is also an excellent greenhouse gas, and smack them into Mars, then it would really speed up the whole process. But it would be a bit more complicated than just sticking some cheese on a big stick and hoping the asteroids are lured across the solar system. We’d need to play a gigantic game of pool, bouncing smaller asteroids into bigger ones to put them on the path we want. But all of these challenges are just going to make us push all that bit harder to find a solution. And every year, new technologies are emerging and new ideas and approaches come from across the globe. Of course, we still haven’t thought about the question of Martian society. Who knows what new religions and cults will spring up on the red planet. And will it be a separate nation and have a whole new set of laws of its own? Will they have a Pappa Johns, we’re all dying to know, but we’ll just have to wait and see what the next few decades bring.