Can We Colonise Mars?
It has been pitched as everything from humanity’s ‘backup’ planet to Elon Musk’s future retirement home.
For decades, the concept of humans living on Mars has been a topic of interest whether it's between space scientists, sustainability experts or even science-fiction writers. SpaceX openly talks about building a city with over a million inhabitants by the end of the century while NASA has longer-term plans and is not so ambitious as it aims to send astronauts to Mars by the late 2030s. But is this reality something we can bring to life, and if so, is it really worth doing? The question remains full of ambiguity; while it is possible to set up a small colony on mars, research and evidence has shown the negatives to far outweigh the positives.
Why Mars?
Among all planets in the Milky Way, Mars is unique in so far as it contains all the raw materials that a civilisation needs to flourish, as well as temperatures closest to those of the Earth. It possesses water - mainly in ice and permafrost - and has enough that ancient rivers, lake beds, and minerals like ferrihydrite (which only form in cool wet conditions) to give evidence for the idea that Mars was once much warmer and wetter than it is now. NASA highlights the scientific benefit of exploring a world which once had liquid water, and potentially even life. Geothermal heat back then may have allowed liquid water to exist beneath the ice sheets and subsurface environments on Mars may have offered shelter from the ultraviolet and cosmic radiation that Mars fails to provide protection from due to it lacking a global magnetosphere (protection from charged particles). However today Mars’ atmosphere is very thin, primarily composed of carbon dioxide, which provides little to no protection from cosmic and solar radiation. Mars still remains a hot target for colonisation due to 5 main reasons that Orwig put forward, stating that Mars' colonisation is a necessity, rather than an option:
- Survival of humans as a species
- Exploring the potential of life on Mars to sustain humans
- Using space technology to positively contribute to our quality of life (e.g. health)
- Developing as a species
- Gaining political and economic leadership
The Journey
The colossal distance between Earth and Mars already provides significant challenges in regard to communication and logistics. Resupply missions would be quite rare, taking several months to arrive, which demands careful planning along with vast resources and funds. Communication would also face a noticeable delay, especially for the initial settlers, signals would take between 4 and 24 minutes to travel, significantly affecting contact and coordination in regards to mission control. This means that future Mars settlers would need to operate with a high level of independence, adding to the difficulty and danger of the expedition. Dayna Ise, the director of the Mars Campaign Office within NASA, pointed out a more important flaw; solar conjunctions happen every 26 months when the Sun is between Earth and Mars. In the event of a Mars landing, this would create a 2 week communications black out due to radio signals not being able to pass through the Sun or close to it. If emergency issues were to arise then the crew or small number of inhabitants would be completely on their own. As well as this an astronaut on a mission to Mars could receive radiation doses up to 700 times higher than on our planet, increasing risk of mutations and therefore cancer dramatically.
'One day in space is equivalent to the radiation received on Earth for a whole year' explains physicist Marco Durante, who studies cosmic radiation on Earth. Marco points out that most of the changes in the astronauts’ genes are thought to be due to radiation exposure, according to the recent NASA’s Twins study. This research showed DNA damages in astronaut Scott Kelly compared to his identical twin and fellow astronaut Mark Kelly, who both remained on Earth. However there is still a lot of uncertainty surrounding the risks with radiation as further long-lasting effects are unknown, and NASA are currently exploring this issue.
Another difficulty would be the cost. NASA's estimate of the first human mission to Mars suggests it could cost half a trillion dollars; assuming a typical crew size of 6 astronauts, that is around 83 billion per astronaut. To give some perspective, NASA’s Artemis missions cost around 4 billion to launch, and those were without humans.
The Landing
Landing on Mars is extremely difficult owing to its very thin atmosphere (around 1% as dense as Earth’s). This creates two issues simultaneously; it is too thin for parachutes to slow down a spacecraft effectively, yet thick enough to cause dangerous amounts of heating and turbulence upon entry. Spacecrafts would arrive at speeds of around 20,000km/h and must decelerate to a safe landing in a matter of minutes without the help of people on Earth due to the communication delay being between 4 and 24 minutes long. Commonly occurring dust storms further add risks; historically, nearly half of all missions to Mars have failed, most of which failed during landing attempts. It gets even worse when you consider the weight of a spacecraft in a human mission to Mars. The Perseverance rover - currently the largest rover ever sent to Mars, has a mass of 1 metric ton; a human mission will likely require a vehicle weighing in between 50-100 metric tons. These vehicles will be too heavy to be slowed significantly by aerodynamic drag of Mars’ atmosphere, which means previous technologies of parachutes, airbags, or sky cranes have likely reached their limits, forcing physicists and engineers to come up with an entirely new solution.
Surviving on the Surface
As discussed earlier the thin atmosphere of Mars provides minimal protection from harmful cosmic and solar radiation whose full effects are unknown. Mars also has an lacks a global magnetosphere, unlike Earth, which leads to further exposure to radiation. Risks we know of so far include an increased risk of cancer, radiation sickness, and genetic damage. To solve this a huge amount of research and development will need to be put into shielding for habitants living the surface as well as for people travelling in the spacecraft.
With regards to the oxygen problem, NASA’s MOXIE experiment, costing $42.8 million, successfully produced 122 grams of oxygen on Mars — enough for a small dog to breathe for about 10 hours — demonstrating the technology’s feasibility for larger scale oxygen production and therefore supporting life on Mars. Despite this small success, its tiny scale highlights the technological challenges and high costs of scaling up oxygen production to a point where it can support human missions.
Temperatures can swing dramatically, from daytime highs of around 20°C near the equator to lows of −73°C with the average surface temperature sitting at roughly −63°C. The atmosphere not only creates trouble when landing but also for human survival. The martian atmosphere is composed of around 95% carbon dioxide and is 99% thinner than that of Earth’s. This makes it impossible for humans to survive without pressurised habitats and protective spacesuits. These conditions require reliable life support systems that humans can depend on at all times. These systems need to supply breathable oxygen and regulate internal temperatures; if one of these systems were to fail for even five minutes it could lead to the end of a human life. This means that a Mars landing depends almost entirely on the development of new technologies that can actually sustain life on Mars, meaning that until the technology is finalised, all hopes of colonising Mars are essentially put on standby.
Mars also has a gravitational force of about 38% of Earth’s. This may have long-term effects on human health such as; muscle atrophy, bone density loss and changes to several other bodily systems.
Terraforming
Musk’s idea to ‘nuke the poles’ on Mars has become quite popular recently. This idea would involve detonating special nuclear devices over the poles and would, in theory, generate large amounts of heat, therefore vaporising and releasing the carbon dioxide contained in Mars’ polar ice caps. This would instantly thicken the atmosphere on Mars; a thicker Martian atmosphere could trap heat from the Sun better, solving the temperature problem. This would also have a knock-on greenhouse effect by continuing to heat up Mars until the surface pressure is enough for liquid water to exist. Not only is this essential for human life but it could also be very useful for oxygen-producing plants. On the contrary there are clearly significant ethical, legal and environmental arguments to argue against this suggestion.
Timelines and Prospects
Mars colonisation is a vast project, and timescales are far longer than many people appreciate — centuries, not decades. SpaceX will look to send its first crew within the next decade through multiple missions with its Starship while NASA's path through Artemis is much slower and reliant on hefty government subsidies. However, crew landing is quite distinct from maintaining a sustainable colony: long-term survival requires habitats, life support, farms, and power systems, all of which significantly increase cost, complexity and risk. Planetary protection is also a principal challenge as going to Mars could harm Earth’s environment by increasing rocket emissions that worsen climate change and ozone depletion while also draining natural resources through the intensive mining, energy use and material extraction needed for space travel.
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