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One important step in the proposed terraforming Mars would be to give the planet a nitrogen atmosphere.

Now, most assume that nitrogen, (along with water and other luxuries of the sort) would have to be sourced from off-World via comets or asteroids, but as the curiosity shows us, there is in fact a large amount of nitrogen present in mars’s regolith, in the form of nitrates and other compounds. According to one source, processing an estimated 30 cubic kilometres of regolith could increase the partial pressure of the atmosphere to 0.3 bars; a level required for a nitrogen cycle, and which would provide 60% of the minimum pressure I believe would be needed for long-term Human presence.

What would be the most efficient and lowest-energy method of freeing nitrogen from large areas of martian regolith? My initial thought was nanotechnology, but I am open to other ideas.

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  • $\begingroup$ For information: 30 cubic kilometers of Martian regolith is about 45 billion tonnes of dirt, of which only a small fraction is nitrogen.Total amount of nitrogen in Earth's atmosphere is about 4,000,000 billion tonnes. To get an idea of the difficulty of processing 45 billion tonnes of stuff, any kind of stuff, the total amount of iron ore extracted in a year here on Earth, not on some farway frozen desert planet, is about 2.5 billion tonnes. Minus one for using the word nanotechnology as an answer to the question about how to do something. $\endgroup$
    – AlexP
    Apr 21, 2023 at 19:18

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There are three ways to look at this question:

1. Clarkean Magic

Nanotechnology is an example of Clarkean magic. It can do anything we want because we have no idea what limitations the technology may have when and if humanity ever gets around to inventing it to a degree that could conceivably solve this problem. Clarkean magic is a very common solution in Science Fiction projects because it's sometimes not worth the effort to try and figure out how it could be done. It's not cheap. It's not unrealistic. It's ambiguous because no author has the time to predict everything to science-grade detail. But! Let's assume you want a bit more than Clarkean magic.

2. Biology

This is how Mother Nature does it.

Nitrogen is released back to the atmosphere by bacteria[, which] get their energy by breaking down nitrate and nitrite into nitrogen gas (also called denitrification). (Source)

In this case, your ultimate goal is to get nitrogen into the atmosphere, but your immediate goal is to figure out how to get a thousand metric tons of bacteria scattered around the equator and not die, but actually proliferate. Per the quote, the bacteria that deals with this process is getting its energy through denitrification. So the big question is, what would keep such bacteria from happily digging into the martian soil?

Frankly, I don't know. Indeed, they may be happy to do so! NASA has a (remarkably) strict policy about letting terrestrial bacteria hitchhike on their probes and, today, there's a fair amount of resistance to doing anything that might change the nature of any celestial body we visit. Consequently, we might not actually know that the appropriate bacteria wouldn't be completely happy on Mars.

If that's the case, problem solved. Ship a couple of pounds of said bacteria to a lab facility on Mars and start breeding the snot out of them. (This assumes, of course, that there's sufficient Nitrogen in the Martian crust to pull this off. You're right that NASA has made some cool discoveries... so let's assume it's true to your needs.)

3. Chemistry

This will be the most intrusive of the solutions and the most intensive, but it also might be the most realistic compared to what will actually happen if we try to terraform Mars. We do this processing mine ore all the time. Shovel a load of dirt into the first vat of chemicals. Move from one vat to the next, removing undesirable byproducts, out the other end comes nitrogen... and something else.

That something else comes from two sources:

  • The shovel full of dirt you started with was more than just nitrogen. Those other chemicals in some form will come out the other end.

  • Aaaaaaand then there's the chemicals used to process the soil to release the nitrogen. I'll leave it up to the reader to Google that process and find things like this. The problem is that the chemicals used to free the nitrogen can have (and often do have) serious environmental consequences. Example: the cyanide and arsenic used to process gold and silver ore.

But that's part of what makes this solution more "realistic." It's lovely to think we'll have a utopian future. In reality, we'll have both good and bad, with a constant struggle to achieve more good than bad. Without the bad, a story feels unrealistic. But that may be just my opinion. Nevertheless, this would be a honking large factory/smelter setup with huge diggers moving gazillions of tons of soil to produce what would very likely be a contaminated soil and nitrogen.

Problem solved... kinda.

I'm rooting for the bacteria.

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