Oct 20 2017

Making Oxygen on Mars

Mars baseAt some point humans will travel to Mars. It seems inevitable, the only question being when that will happen. Optimists like Musk think it will happen before mid-century, but that may not be realistic. There are significant logistical hurdles without clear solutions.

Some argue, and I agree with this strategy, that we should focus first on a moon base. The moon is a lot closer, which solves many problems right there. But otherwise it would have many of the same challenges as Mars, and so if we develop a base on the moon we can use what we learn to be better able to tackle Mars. Further the moon can be a literal launching pad for Mars.

While Mars has some extra challenges, it may have some advantages as well over the moon. NASA experts have observed that Mars has just enough of an atmosphere to be a problem. It has 1% of the pressure of Earth, which means for astronauts it is functionally the same as a hard vacuum. You still need pressure suits, pressurized living spaces, and you need a supply of air to breath.

Further, it is not thick enough to help braking when landing on Mars, but it is thick enough to cause friction. You are better off having a thicker atmosphere you can use, or no atmosphere to get in the way. From NASA’s perspective, it is just a nuisance.

Although wispy, it is enough to cause dust storms, even planet-wide storms that last for weeks. This dust is more annoying to NASA than sand was to Anakin Skywalker:

“If you’ve seen pictures of Curiosity after driving, it’s just filthy,” Smith said. “The dust coats everything and it’s gritty; it gets into mechanical things that move, like gears.”

It is not strong enough, however, to blow people and equipment around as imagined in the book and movie, The Martian. That was one major scientific inaccuracy in an otherwise very diligently accurate book. The author acknowledged this and admitted it was a convenient plot device.

So the atmosphere of Mars seems to be a major negative, but can it be of any use to future Martian colonists? Perhaps – as a source of raw material

The Martian atmosphere is 95% carbon dioxide. Therefore there is a lot more CO2 in Mars’s atmosphere than Earth’s. Earth has 0.04% CO2. So even though the atmosphere is 100 times thicker, that is still only about 4% of the CO2 in the atmosphere on Mars.

If fact if we ever wanted to terraform Mars and give it a breathable atmosphere, we would have to get rid of all that extra CO2.

Well, it’s possible to kill two (or maybe even three) birds with one stone. A new study looks at the plausibility of using plasma to split CO2 into oxygen and carbon monoxide. Here is the highly technical summary:

Herein, it is argued that Mars has nearly ideal conditions for CO2 decomposition by non-equilibrium plasmas. It is shown that the pressure and temperature ranges in the $\sim 96 \% $ CO2 Martian atmosphere favour the vibrational excitation and subsequent up-pumping of the asymmetric stretching mode, which is believed to be a key factor for an efficient plasma dissociation, at the expense of the excitation of the other modes. Therefore, gas discharges operating at atmospheric pressure on Mars are extremely strong candidates to produce O2 efficiently from the locally available resources.

What all this means is that if we had an energy source on Mars we could use that to drive a process by which plasma is used to make oxygen and carbon monoxide from the CO2 in the atmosphere. The primary use of this process would be to make oxygen for colonists – oxygen that can be stored in tanks and used in space suits or habitats.

That could be a massive advantage to any missions to Mars, especially one that endeavors to establish a permanent colony on Mars. One of the biggest challenges to such a colony would be resources. A colony would need, at a minimum, energy, food, oxygen, and water. I could add shielding to the list, to protect against cosmic rays.

Energy can be made locally with solar panels. That is how our Mars rovers operate. However, solar panels are less productive on Mars because the sun is farther away. Also, the dust storms are a major problem for solar panels. Burning fossil fuel is not practical – that is just one more resource you will have to bring with you. Nuclear batteries are a great option, as long as they are handled safely.

I do wonder what power source a Mars colony would use. Probably solar panels and nuclear batteries, but I wonder if that will be enough. Perhaps they will use small self-contained nuclear reactors.

In any case, once they have an energy source, where will they get their food, water, and air. Research is underway to see how hospitable Martian soil is to agriculture. A self-sustaining colony will have to, at some point, grow their own food.

There is plenty of water on Mars, but that will have to be extracted. You can split water into oxygen and hydrogen, but that uses up your water.

Splitting CO2 to make Oxygen seems like a perfect solution. The raw material is readily available. It seems that extracting oxygen locally would be absolutely necessary to any self-sustaining colony.

If, in the far future, we want to terraform Mars this would also be a useful process. It will add a little O2 to the atmosphere (not nearly enough, but it’s a start) and can get the CO2 down to breathable levels.

The carbon monoxide can also be used as a raw material to make fuel, essentially serving as an energy storage medium.

This is one tiny step that may help our plans to visit and colonize Mars, but it is interesting to think about what the challenges are and what possible solutions may be.

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