The big Martian problem is energy


Original author: Will Lockett. You ve heard of SpaceX s plans to send us to Mars and build a long-term base. Research of mankind in interplanetary space! Sounds fantastic, right? But there is one glaring problem with Mars that few people talk about. It is not toxic soil, not deadly radiation, not a thin atmosphere, weak gravity, or tiny amounts of water. Even if we solve these problems, Mars will not become our comfortable home. The big problem is energy.

It takes a lot of energy to sustain humanity, especially on an inhospitable planet like Mars. Compared to Earth, the Red Planet is cold, toxic and airless, which means that once we get there, we need a daunting amount of life support systems.

The base needs not only pressure, but constant balancing of carbon dioxide, oxygen and nitrogen levels, all while maintaining heat to keep out the cold outside.

For our pioneers to survive on Mars, food and water must be grown, distilled, and recycled. All this takes up quite a lot of energy. Not to mention how much coffee does it take to stay sane.

It is estimated that the Martian base will need about 90 kW per person, which means that a mission of 12 people will need 1080 kW. That s about the same power as the Bugatti Chiron at continuous full throttle. For comparison: the average American home consumes 1.4 kW, and this is the consumption of an always-on kettle. How to get such a huge amount of energy to Mars?

One option is the Sun. Solar panels are relatively inexpensive and easy to install and configure. Even I can take a simple solar panel circuit to charge my phone. You don t need to have a nuclear physicist degree to operate them safely. So why not build a massive solar cell farm on Mars?

mars1.png

Well, there are two reasons why this idea is bad. Mars is farther from the Sun and receives much less solar energy, that is, about 60% of that which reaches the Earth. I burn out easily in the Sun, so it sounds like music to my ears. Solar panels on Earth can produce 0.175 kW per square meter of battery, but on Mars they can only produce 0.105 kW / m. To power the base you will need 10,286 square meters, but this is provided that the panels are ideally lit all the time!

In fact, for half a day, one of the sides of the planet is not lit, so you need to multiply the area by 2, you get 20.571 square meters, which is 4.6 rugby fields. You need a huge battery with a capacity of at least 12,960 kWh to provide power at night.

If measured in current Tesla batteries, such a battery would weigh about 82 tons. For a team of 12 people, this is a huge burden to simply pick up and install, bearing in mind that this must be done quickly enough, otherwise our researchers will not have food, heat and oxygen.

But this figure also assumes a clear sky. Mars does not have a cloud cover like there is on Earth, but there are dust storms covering the entire planet that block the Sun for weeks or possibly months. When your life depends on solar energy, this is not good: because of these storms, the power will drop fatally. Plant growth will stop, that is, food will stop, oxygen machines will turn off, heat will go away, water processing will stop, even a coffee machine will stop working. Our solar base will die due to a big storm. So let s not rely on the sun.

mars2.pngModels of a view of the Martian sky during a dust storm in June 2018, Curiosity – NASA / CalTech.

What about renewable sources, wind or geothermal? The atmosphere of Mars is so thin that the strength of the wind is not suitable for us, but geothermal sources may work.

We have no direct evidence of the existence of thermal springs, except for occasional emissions of methane, but they can come from organisms like bacteria. Moreover, even if there are geothermal sources, they lie at a depth of kilometers. To get to such a source of energy would require a huge infrastructure, which is not on Mars.

Compared to Earth, Mars is geologically dead. There are no active volcanoes, faults or outbursts of magma on the planet, so the amount of energy from a single geothermal station is doubtful. It s possible that renewable energy won t be worth the monumental effort.

This means that no modern renewable energy sources will work on Mars. What about something more dangerous like nuclear power?

We would laugh if the fusion energy was already working on Earth. The flow of electricity could be used to split Martian water into oxygen and hydrogen, oxygenating the base and fueling the reactor. It s even sad that such a technological miracle does not exist.

We could use the same plutonium reactors that power the Opportunity rover (MMRTG), they are light, powerful and safe in design. They take the heat of radioactive decay and use thermoelectric generators to convert it into electricity, so there is no need for massive steam turbines that are used on Earth. But this will only give 0.124 kW for a 45 kilogram reactor. To power a base of 12 people, we would need 8709 of these reactors, which would weigh 391,905 kg!

mars3.pngOpportunity scheme

I don t know what you think about this, but to drag such a mass to Mars for only 12 people does not sound very practical.

Fortunately, NASA has developed a new reactor – the Kilopower system. This system uses uranium and Stirling engines to generate 10 kW of electricity for 15 years, and weighs only 1,500 kg! To provide power to the base and 12 people, we would need 108 such reactors, and it will weigh a total of 163 tons. This is a significant savings, but the weight is still great.

mars4.pngKilopower test prototype

The SpaceX spacecraft can deliver up to 150 tons to Mars. This means that multiple missiles could deliver the entire base, supplies, and the 108 Kilopower reactors needed to power the base. There is no need for solar energy – you just need a colossal rocket packed to the brim with a reactor and uranium. It seems safe … But the prospect here is short term.

Long-term Mars is a completely different story, these reactors will last 15 years, and our Martians need more. There is uranium ore on the surface of the Red Planet that our Martians could use. But there are two problems.

First, ore must be refined before being used as a fuel, which requires significant industrial effort and enormous amounts of energy. Even if you manage to reprocess nuclear fuel on Mars, we don t know how much there is. It is possible that large amounts of uranium decayed in natural reactors billions of years ago. In other words, it looks like the colony will always depend on nuclear fuel from Earth.

As the core depletes and power is lost, 108 reactors will need to replace uranium every 15 years. Each reactor needs 226 kg of uranium, that is, 24,400 kg, to load all the reactors with fuel. It is possible to do this with a single SpaceX interplanetary spacecraft, so refueling a 12-man base is quite feasible.

mars5.pngA fully operational base on Mars – SpaceX s vision

When we look at a large-scale Martian city rather than just a lone base, things get worse and Mars s dependence on Earth becomes apparent. Let s say in a Martian city with a population of 100,000 people, we can reduce consumption to 10 kW per person (an estimate). It will require 100,000 Kilopower reactors, requiring 22,600 tons of uranium every 15 years. This is a relatively small amount of uranium. A typical terrestrial nuclear power plant consumes 4.6 times more.

This sizable payload can fit into just over 150 ships at once, in a single run, 22 uranium-laden starships can be sent to Mars every 26 months when Mars is closest to Earth. It does not even take into account the containers that will be needed to safely store uranium, so even more missiles are needed. City electricity bills will be excruciatingly painful.

In reality, Elon Musk s dream of an independent Mars is a guarantee. If a colony relies on a constant flow of nuclear fuel from Earth, how can it become independent at all? It is unlikely that the Martians will be able to trade with the Earth, since there is not a single valuable resource on Mars that would not be abundant on Earth. In terms of energy, Mars seems to be forever linked to Earth.

To make matters worse, uranium reserves will run out. Even without taking into account the leakage of fuel to Mars, at our current consumption rates, we will exhaust fuel-quality uranium in a little more than 200 years: there are approximately 5.5 million metric tons of this substance left on Earth.

If by then Mars cannot switch to another source of energy, the colony will have to look for nuclear fuel elsewhere. It is difficult, even if possible. You can either process low-quality Martian uranium, or extract other radioactive elements from the asteroid belt. Both options will most likely not become practical for another 200 years, if practicality is possible here at all.

So what source of energy can we use? If the colony switches to solar energy and if there are not enough supplies of it, one large dust storm will kill all the people on the planet. Even with a very large solar farm and better batteries in mind, people would still live in fear of dust storms.

It may sound grim, but Mars is energetically dead. There is a chance that there is some kind of life on Mars, caught in a small amount of chemical and planetary thermal energy, but Earth in that sense is in a different league, which is why humanity can flourish here. If we are really going to occupy Mars, we need to adapt to a low energy environment. We can create airtight bases, even terraform the planet, but there is one thing we cannot change: Mars has less energy than Earth.

However, there is hope. We know that modern society is in dire need of energy, because of it we have turned into fat cats, but we do not want to live like this. Humanity is so successful because it can adapt to thrive; we can do the same on Mars.

While I have shown in this article that powering a Mars base or colony is difficult, I have also shown that it is not impossible to solve. We can do it. It will be difficult, but we humans are damn good at being difficult! So see you on Mars?

PS But what about the interplanetary Internet, and hence the energy for communication? Will we leave our Martian colony in an information vacuum? The eternal dependence of Mars on Earth also raises questions whether it is as eternal as the author of the article says about it. In general, there are many uncovered topics and unaccounted for factors, but we have something to talk about in the comments.

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