It is no secret that Mars is currently a hauntingly-beautiful, deadly wasteland. Characterised by its deep scar from an ancient collision of large proportions, Mars' Valles Marineris trench shows the raw and unforgiving land. However, it also presents an opportunity buried just beneath the surface. In this article, I'll cover the key threats that face the crew, and how they will meet them.
At 4000 km long, and up to 8 km deep, this series of trenches could easily accommodate the equivalent land mass of some countries on Earth. Indeed they could be fertile ground for investigating the geology and ancient past of Mars, how minerals and water moved around the planet. Although the chief concerns of Martian colonists will be initial safety and establishing equipment and material for longer-term survival, so too they will immerse themselves in science and discovery about our celestial neighbour.
Elon Musk, during interviews about SpaceX and his quest for a Martian city, has made no effort to hide the fact that an expedition there is a deadly endeavour, akin to Shackleton's ill-fated journey to Antarctica.
This is the chief challenge to those who assert that a Martian city would be the preserve of the super-elite and those with mega-wealth. Right now, there is not a scrap of any ready-to-use resource on Mars, let alone any facilities or anything that could enable such folly. This means that any facilities brought with the Martian Crew would be spartan at best, and due to lengthy delay between supply runs, and a lag time to start manufacturing on-planet, it is likely to be that way for some time.
Musk, in all candidness, advised that to sign up to the first and early missions to Mars would come with a similar recruitment to that of the Shackleton endeavour ( see below). The ad that preceded the Antarctic journey advised applicants of bleak prospects, listing explicit greater-than-even odds of no safe return. The same spirit and acceptance of the high risk should be acknowledged by the Mars crew. I think it is quite apt that there are parallels being laid down between classical exploration and space exploration.
The team must accept and manage the risk, preparing heavily to get as many threats under some degree of control with some reasonable countermeasures. This is how veteran test pilot and astronaut Chris Hadfield describes necessary preparation for missions, in space and life. His visible reassuredness is owed to preparedness and is visible stillness of self.
I would propose that all the hazards that our crew can encounter on Mars (and indeed on the journey there and back) are related to the fragile nature of the human body.
After establishing this as the baseline, I feel we could categorise the hazards thereafter into two main categories - human-need related, and environmental hazards.
Human Need related
Most of these needs will - in the short term - be met through Earth-supplied materials. Perhaps the most tricky of these to achieve will be the appropriate mental health support for the crew.
Water
Food
Exercise - mental and physical
It is covered well elsewhere how astronauts exercise in space, and there are some concrete plans for how space-farers can maintain relatively strong, healthy bodies while undertaking inter-planetary transits. Even on Mars, there is some material starting to grow around planned exercise routines for Martians.
However, what isn't covered so much, yet there is some significant experimental data gathered already on long-term isolation such as what will be seen on Mars. This topic of maintaining mental health while undertaking arguably one of mankind's most hazardous adventures will be critical.
Consider that extended suboptimal crew performance owing to poor mental health will put in jeopardy not only their day-to-day welfare, but will also add risk of not ever returning home. Missing day to day maintenance tasks could quite quickly cause critical systems to break down. And what the martians have, they have. There is no back-up back-up coming in the mail next week. As each package of material takes approximately 6 months, and can only be attempted once every 2 years, they are on their own with what they have at the outset.
This is immense pressure. Linking back to the earlier part of this article - it will not only take good mental health cultivation, but also a baseline of strong, resilient mental performance. Astronauts already undertake batteries of health tests, including psychometric and mental health evaluation as part of their work. This will be an on-going evaluation during the Martian crewed mission.
Environmental hazards
Radiation
Reading across resources online, there is agreement that people in developed nations typically receive the equivalent of 0.62 rads / year dose of cosmic radiation. This is the equivalent dose of just going about your business in daily life. For context in space exploration, the astronauts on the ISS receive 12 rads / year.
On Mars, we must consider that - because of an ancient celestial collision, and the fact that Mars is about half (~53 %) as massive as Earth, the outer core of Mars is not liquid metal flowing around a solid metal inner core.
Because of this, Mars cannot leverage the dynamo effect which is in play on earth. The dynamo effect is a geophysical model of a self-sustaining dynamo - whereby moving liquid metal around another solid metal core causes magnetic excitation.
Writ large, say up to a planetary scale, this effect provides enough magnetic field to engulf a planet. On Earth, we enjoy this passive effect as the magnetic field deflects a good proportion of the harmful radiation reaching us, in the manner of a science fiction shield defending from phasers, lasers and other fictional space weapons. However on Mars, because this effect is not in play, the harsh radiation penetrates the Martian atmosphere, both irradiating the soil and scrubbing the atmosphere away. As a result, the martian atmosphere - has to do all the work in shielding the ground from these rays.
Mars has an atmospheric pressure of approx. 1% of that of Earth's, and is almost completely comprised of CO2 (~95%), with the rest Nitrogen, Hydrogen and Argon. With such low concentration of molecules between the surface of Mars and space, light from the sun has very little mass to intercept it, on its way to the terra. As a result, our Martians have to contend with levels of irradiation over twice that of the crew of the ISS.
Temperature Imbalance
Being 1.5 AU away from the sun, Mars has ~40% less radiation reaching the surface. Couple that with the lack of a high heat capacity atmosphere (like Earth), and no liquid water oceans (or other material) and you have no way to effectively move heat around the planet. On Earth, these effects are called the Jet stream and the Major Ocean Currents respectively.
As a result, the thermal energy reaching the red planet tends to stay where it is during the day, and almost immediately disappear overnight. This results in lower temperature equilibration across the day and across the surface of the planet. This means that at the equator, where the crew can sustain with 20 degC temperatures in summer, this temperature can plummet overnight to (-)73 degC. Worse still, the poles can see (-)60 degC during the day, and (-) 124 degC at night in Winter. Given that carbon dioxide itself freezes from a gas state and directly deposits as a solid at - 74 degC, it makes sense that we see images of frozen CO2 lakes on Mars.
This hazard is constant and requires that the crew think carefully about home construction and moving around the planet. Getting stuck outside or even in a vehicle immobilised in a dust drift while investigating the polar lakes could easily spell curtains and the end of those explorers.
Contamination/ Toxicity Exposure
- Perchlorate dust
Perchlorate is a fancy term for chlorine with four oxygen atoms which carries a negative charge. Because ions don't hang around on their own - it means these perchlorates are compounded with another positively charged ion. Given that Mars carries a lot of rusty red dust on its surface, it could be a fair assumption that the perchlorate salts on Mars are actually Iron (iii) perchlorate.
However, this is wrong - these Martian salts use the minerals we have on Earth - Calcium, sodium and magnesium. These components make up from 0.5 to 1% of the mass of martian soils across the surface. This concentration of perchlorate is easily about humans' toxicity threshold and accordingly must be processed before the soil can be used for growing food.
To achieve this, the crew can leverage the ionic nature of this salt and simply wash the soils with water. The water will have strong affinity for these ions and retain them. Setting up a soil washing machine/ perchlorate extraction and leaching system is essential - both to achieve and to achieve with good energy and water efficiency. The impact of inefficient use of solvents in industry was targeted at Tesla's Battery Day 2020, considering there the impact on Battery cathode construction.
- Fineness of Martian Dust
Not only is the perchlorate dust toxic, the soil itself is very very fine and carrying an electrostatic charge. As a result, in the same way that a feather is attracted to a plastic ruler which was rubbed to gather a charge, so too the dust will instantly stick to moving machines and crew members as they reach the planet.
This means that every exposed surface will attract and retain dust, and simply dusting off mechanically will not remove all the dust. There is some discussion around even the shape of the dust particles and their impact of shape on ill-health.
This raises a real risk of the crew themselves contaminating their living quarters and exposing themselves to long term health hazards associated with inhaling fine dusts.
- Carbon Monoxide exposure / water contaminant exposure
All the air the Martians will breathe, and all the water they will drink will come as the result of processed air and water. This is the case after the initial self-supplied food and drink have run out. These systems are not perfect, and while great effort will be made during design and manufacturing, and on Mars in maintenance, there could there could be some chance of contamination.
Carbon monoxide - While it is true that humans do not produce carbon monoxide as a respiration by-product, there is some produced both by the MOXIE units. As written in an earlier Building-out Mars article, the MOXIE electrolyte stack aims to convert compressed carbon dioxide to oxygen and CO2 byproduct. This process comes with some small component of Carbon Monoxide. If this remaining trace isn't scrubbed, a persistent low-level of contamination could come from processing and reprocessing external air.
CO is quite toxic because it binds irreversibly with the active oxygen-bearing molecules in red blood cells. This means that once it is breathed in, CO puts some proportion of oxygen transport out of commission permanently - requiring replacement blood cells to be produced - which can take on the order of days.
Contrast this with the quality of air and water we breathe as humans around the world and even here the data is strikingly different depending on where you are.
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