Throughout history, human curiosity has managed to propel our species from an insignificant band of apes to the dominant life form on this planet. It’s helped us split the atom, climb Mount Everest, build skyscrapers and most recently send people into space and to the moon. Exploration is in our DNA. Humans evolved in Africa two million years ago and slowly but surely spread across the planet by reaching into the wilderness that was beyond their horizons. Most of the greatest advances in our civilisation have come because we have explored. The next barrier for humanity seems to be Mars – a dream of creating the first permanent extra-terrestrial colony and terraforming it to create a second blue home. Pure curiosity may seem like the obvious reason for colonising Mars, however there are also other incentives. Humans could study Mars for scientific gain and Martian resources could have economic value. A colony on Mars would also serve as a foothold in our galaxy and help us expand further to other planets and systems. However, a more pessimistic outlook would say that colonising Mars would decrease the chances of our species’ extinction. Humanity is incredibly vulnerable to the whims of the galaxy, more so than most people realise. A single, deadly asteroid could take us out forever. So could a pandemic or a nuclear war. Colonising Mars would require three phases: sending unmanned missions to Mars to create an outpost; sending humans to create a semi-permanent colony and finally upgrading that to a self-sustaining home. Doing so would arguably require overcoming the greatest barrier ever faced by humanity.

Earth, Mars comparison

Mars is the obvious next step in our galaxy: it bears similarities to earth with a similar day, polar ice caps and liquid water hidden underground. It’s not exactly Earth-like, but it’s by far the most liveable other place in our solar system. The picture represents the true size of Mars compared to Earth. Mars is far less than half the size of the Earth, however the land surface area of Mars is equivalent to the surface area that of the Earth because the Earth is mostly covered by water. Despite the initial glamour that comes with the idea of colonising Mars, the planet is in reality a barren rock without an atmosphere. It has an inhospitable, radioactive surface where breathing is impossible, huge storms regularly ravage the planet and the ground is toxic. Creating life support systems for humans to survive is incredibly challenging. However, as the saying goes, “anything is possible” and humanity has the resources along with the ideas to colonise Mars. In this essay, I’ll assume that there have been prior unmanned missions to Mars which have found suitable places to live and have delivered the necessary equipment. I’ll also assume we have sufficiently advanced rocket technology to bring over humans and resources. Instead, this essay will explore the challenges that the first colonists will face and how they’ll try to overcome them on the surface of Mars.

The first major challenge for an outpost on Mars will be the question of energy, needed to power life support and everything else that’ll keep humans alive there, since it turns out that Mars is very energy poor. Mars is 49 million miles further away from the Sun than our planet, which means light has to travel 52.6% further to reach it. Since Mars is about 52% farther from the Sun, the solar constant (amount of solar energy reaching the upper atmosphere per unit area) is around 43.3% of what reaches the Earth’s upper atmosphere. This isn’t the whole story though: Mars has a significantly thinner atmosphere which results in a higher percentage of solar energy reaching the surface. Thus, optimal solar power on Mars is about 59% of that on earth: 590 W/m2 on Mars compared to 1000 W/m2 at the Earth’s surface. The weather on Mars is difficult though. There is no rain and clouds barely cover the sky, so it is constantly sunny and solar panels can operate at maximum efficiency under normal weather conditions. However, this isn’t the whole story: dust storms on Mars pose a challenge to the effectiveness of solar energy. They are common throughout the year and can cover the entire planet surface for weeks, blocking sunlight from reaching the surface. These dust storms have a huge impact on the Martian climate and can drop the planet’s average temperature by up to 4 °C for several months after the storm, significantly worse than the eruption on earth of Krakatoa that covered the sky with ash in 1883, dropping the global temperature by 1°C. Subsequently, these storms affect electricity production from solar panels for long periods of time and this means that if people on Mars were to rely on solar, they would require massive energy storage units which would have to be brought over from earth. Solar power alone would probably not be enough. When looking at alternatives, forms of energy such as tidal, wind and geothermal that are common on Earth are unfeasible on Mars. Initially, the only other form of energy that people on Mars could access with today’s technology would be nuclear power. Mars doesn’t have easily accessible radioactive elements and people wouldn’t be able to build a reactor on Mars, so everything needed for a nuclear power plant would have to come from Earth. A combination of nuclear power and solar energy would be able to power an initial colony on Mars.

The next challenge we’ll face is trying to breathe on Mars. The atmosphere of Mars is about 100 times thinner than Earth’s and extremely toxic: composed of 95% carbon dioxide, 2.7% nitrogen, 1.6% argon and 0.13% oxygen along with traces of other gases. Originally, colonists would live in pressurised habitats filled with an atmosphere of nitrogen and oxygen until we terraformed the planet. Oxygen becomes toxic to humans at high levels, so the atmosphere would need another inert gas to fill it and using nitrogen would be a good idea. There is lots of nitrogen locked up in Mars’ mineral deposits and certain nitrogen rich minerals can be found in the top layers of Martian soil in volcanically active areas. NASA’s Curiosity Rover detected nitrogen on Mars in the form of nitric oxide which could be extracted by living organisms. Nitrates contain nitrogen in a form that can be used by living organisms to form the building blocks of larger molecules like DNA and RNA which encode the genome for life. They can also be used for proteins, which organisms use to grow and repair themselves, as well as to catalyse or regulate chemical reactions. Such nitrogen rich mineral deposits could be used either directly as a fertilizer, letting the plants and bacteria slowly enrich the atmosphere with it through their nitrogen cycle or could be extracted chemically with superheating. Either way, extracting enough nitrogen would either be time or energy intensive. Making oxygen would be similarly energy and time intensive but is now technologically feasible. MOXIE (Mars OXygen In situ resource utilization Experiment) is a NASA funded venture. It’ll suck in the Martian atmosphere, compress it and use the collected CO2, electrochemically splitting the CO2 molecules into O2 and CO via a process called solid oxide electrolysis. If successful, such a process could be used at a larger scale to produce breathable oxygen for humans as well as liquid oxygen for rocket engines to make the return trip to Earth.  The process would need to be done at an industrial scale for this to be feasible.  Solid oxide electrolyser cells need to operate at high temperatures for electrolysis to occur – somewhere in excess of 600 °C. The process is efficient but still requires a high amount of energy.

Breathing on Mars

All of this oxygen would be useless if there were no habitats for astronauts to live in. First, habitats would need to be pressurized and filled with the artificial atmosphere created with the processes mentioned previously. This would come with more problems. Corners and flat walls are weak points, so the habitats will have rounded and smooth shapes to handle the stress of great pressure differences between the interior and exterior. This pressure has been estimated at over 2,000 pounds per square foot for a pressurized habitat on the surface of Mars. A closer comparison can be made to crewed high-altitude aircraft, which must withstand forces of 1,100 to 1,400 pounds per square foot when at altitude. The airlocks would also need to be very airtight and work perfectly every time. Not just to maintain pressure in the habitat, but because of Mars dust. Mars dust is finer than dust found on Earth. This means that it can find its way into machines and make them break down. It’s also toxic and thus could pose a serious health risk to humans. Mars dust is so dangerous because not only is it really fine but also electro-statically charged and so it sticks to everything. It would be practically impossible to avoid contaminating the habitats with Mars dust with current technology. There have been several Mars base projects on earth, aiming to figure out what infrastructure works best. The image on the left shows ‘Mars Base 1’-a facility located in the Gobi Desert in China. The project aims to create excitement about the idea of colonising Mars and shows China’s growing interest in space.

water recycling plan on the ISS
Mars Base-1

Humans will require water and nutrition on Mars. A settlement positioned near the Martian poles with their subsurface ice would be able to access water. If that wasn’t sufficient, water could be brought over from earth or even extracted from the humid Martian atmosphere. Nevertheless, water processing systems would need to be extremely efficient. Astronauts on the ISS have shown it is possible to recycle 90% of what is used. Similar systems would be needed on Mars, but would need to be even more efficient, since regular robotic deliveries of water to Mars would not be realistic. However, all things said, having enough water on Mars wouldn’t be too difficult. On the other hand, making food is a completely different kind of problem. Initially, food could be transported from earth. That said, eventually food would need to be grown on a sufficient scale to make the colony relatively self-sustaining. Mars’ soil is soaked with toxic perchlorate chemicals across the entire planet. The soil also lacks vital nitrogen compounds that plants require to grow. This soil would need to be decontaminated before plants could be grown: this would not only be time-consuming but energy intensive. Then, the soil could perhaps be fertilized using recycled human waste or with fertilizers brought over from earth. This soil would then be grown inside to prevent harmful radiation leaking in. An idea to make growing food more efficient would be to use aquaponics. This would be effective and would help the astronauts have a more varied diet.  Aquaponics is the term for combining aquaculture or raising fish with hydroponics or growing plants without soil. Fish would live at the bottom of a tank with plants at the top. Plants would absorb nutrients from water as well as filtering it. Since the whole system would need to be inside, LEDs powered by nuclear energy or solar power could provide the light necessary for the aquaponics system. Plants could also be grown in soil in an isolated system with relative ease. Another way of creating food on Mars that would perhaps be easier and less resource-intensive would be cultivating cyanobacteria. Cyanobacteria have unique abilities that could make them very useful for humans on Mars. They have a huge range of practical applications. They could feed other more advanced organisms; support plant growth; produce oxygen and produce biofuels. Plants are significantly more demanding and require stricter environmental conditions to grow properly and so cyanobacteria could be a very good solution to a difficult problem. However, this technology is still unproven and would need to be tested before it could be implemented in the future.

Managing water usage

Without an extensive magnetosphere, or a dense atmosphere, half of all radiation coming from space reaches the ground. A person on the surface would be subjected to 50 times the radiation that they would be on Earth. Three years on the surface of Mars exceeds the radiation dose limits imposed on NASA astronauts for their entire career. This increases cancer risks significantly, as a large amount of ionizing radiation reaches the planet surface. Radiation levels in orbit above Mars are 2.5 times higher than at the ISS. Occasional solar proton events produce much higher doses, as observed in September 2017, when NASA reported radiation levels on the surface of Mars were temporarily doubled due to a massive and unexpected, solar storm. Much remains to be learned about space radiation however. There is some evidence that low level, chronic radiation is not quite as dangerous as once thought; and that radiation hormesis occurs. Radiation hormesis is the idea that low doses of ionizing radiation are beneficial, stimulating the activation of repair mechanisms, similar to the effect of vaccination, however this is merely a hypothesis. On the other hand, recent studies point to the fact that cosmic radiation may cause twice as much serious damage to DNA as previously estimated. Existing technology would likely not be sufficient to protect astronauts sufficiently to guarantee their health if they stayed on Mars for a period of over five years. Most likely, astronauts would need to stay inside the majority of the time to be safe and robots would do any routine surface work. Living quarters could be possibly built underground in Martian lava tubes. Another idea would be to shield habitats with a thick layer of frozen CO2, which could be harvested directly from the atmosphere which it consists 95% of. This could be covered with another layer of Martian dirt on top to further increase the level of protection. These measures would probably make radiation levels survivable for long periods of time.

Radiation doses

Colonists on Mars would be subjected to zero gravity for the duration of their 6-month trip to Mars. Once on Mars, surface gravity would be only 38% of that on Earth. There are two stages to this particular problem. After being in zero gravity for six months, adjusting to Martian gravity will be difficult. While rotating living spaces could slow down the effects of living in zero gravity in the future, with current technology crews would have to live in low gravity. Upon return to Earth, recovery from bone loss and atrophy is a long process and the effects of microgravity may never fully reverse, and would cause muscle-wasting, bone loss, and cardiovascular problems. While this might be solved in the future by setting up rotating living spaces, for now, the crew would have to live with low gravity and exercise a lot to slow the degradation down. Mars is a really tough place and more likely than not, crews would need to rotate. Current rotations on the ISS put astronauts in zero gravity for six months, a comparable length of time to a one-way trip to Mars. This gives researchers the ability to better understand the physical state that astronauts going to Mars would arrive in. While astronauts could permanently stay on Mars in the future if a permanent colony existed, in the first phase of colonisation, crews would need to regularly rotate.

Crews wouldn’t just need to rotate due to high radiation levels posing a significant health risk. Imagine being stuck indoors in a narrow, confined place with no windows, performing the same routine tasks every single day with little variation, with the same people, worrying about dying in space with limited communication to Earth and to your loved ones. Colonists going off to Mars would need to undergo intense psychological screening in order to make sure that they’d be able to get through such a taxing lifestyle. They’d need to be more resilient than submarine staff or Antarctic scientists. Special protocols would need to be created to monitor crew members’ psychological health. Colonists on the way to or on Mars would need help and assistance to stay mentally healthy. Computer programs are being developed to assist crews with personal and interpersonal issues in absence of direct communication with professionals on earth. This is in case any problems were to arise to do with communications – the main reason would be global dust storms. Mars and Earth are separated by tens of millions of kilometres and due to their orbital periods, travel between Mars and Earth is prohibited to a narrow travel window every two years. If a problem were to arise, Earth couldn’t help until the next travel window opens, at which point it could be too late. Mars-500 was a psychological experiment conducted between 2007 and 2011, designed to measure the effects on people of going and returning from Mars. A crew of people underwent 520 days of isolation. There weren’t any conflicts between the crew members and the experiment proceeded successfully. The crew worked to overcome difficulties and employed friendly and constructive communication with each other. However, various psychological problems were encountered: overall activity levels plummeted in the crew for the first three months and continued to gradually fall as time went by. Four of the crew members suffered from psychological issues and sleep problems. One crew member suffered chronic sleep deprivation, and could not successfully complete computer tests used to measure concentration and alertness levels.


Settling Mars will be the toughest challenge we have ever faced and establishing the first permanent outpost on Mars will be humanity’s greatest achievement. The dream of making life multi-planetary would be accomplished. Once we overcome the initial barrier of establishing a permanent colony, anything is possible. Imagine cities illuminating the dark Martian night; the human species journeying beyond Mars to the rest of our galaxy; entire industries emerging in space, creating a real multi-planetary future. In the past, the birth of the first child was a sign of the seed of a colony irreversibly taking root. The first extra-terrestrial child will be the sign that humans have colonised Mars and aren’t leaving. Going to Mars will be tough, but worth it.

“You want to wake up in the morning and think the future is going to be great-and that’s what being a spacefaring civilisation is all about. It’s about believing in the future and thinking that the future will be better than the past. And I can’t think of anything more exciting than going out there and being among the stars.” Elon Musk, 2017

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