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The air on Earth is about 20% oxygen and about 78% nitrogen. Best case, there seems to be sufficient oxygen (in water) to support colonization in the polar ice caps. What about the other 4/5 of the atmosphere? Too much oxygen can be harmful. On Earth, we achieve balance by the ratio of oxygen to nitrogen.

According to NASA the Martian Atmosphere is 2.7% nitrogen (N2) and 0.13% oxygen (O2) is it reasonable to assume that we would be able to harvest sufficient nitrogen from the atmosphere or would it need to be imported, or obtained someplace else?

Note that nitrogen plays other important roles in the ecosystem and should be considered as well.

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    $\begingroup$ Given the small number of people likely to be going to live on Mars (100's or 1000's as opposed to billions living on Earth) the tiny amount in Mars' atmosphere - 2.7% of an atmosphere whose total surface pressure is less than 1% of Earth's - should still be enough for an indefinite time. $\endgroup$ – MercuryPlus Jun 20 '14 at 20:01
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    $\begingroup$ The partial pressure of oxygen should not be too high, but mixtures with more than 20 % oxygen are possible if the partial pressure of oxygen is not more than about 0.3 bar. $\endgroup$ – Uwe Oct 17 '17 at 10:10
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I think it's fairly safe to assume that Mars has plenty of nitrogen locked in its mineral deposits, since it's one of the most abundant elements of the Solar system and the planet formed out of the same protoplanetary disk as Earth has. Some nitrogen rich minerals are a safe bet, especially the ones of magmatic origins that might be easily accessible in top layers of the Martian soil in regions that were volcanically more active. Since we know of many such regions, this shouldn't be a problem. For example, silicate minerals are known to lock substantial amounts of environmental nitrogen when superheated (lava / magma), and chondrites can lock up to 27.96 % of nitrogen per weight (e.g. sinoite Si2N2O).

Such nitrogen rich mineral deposits could be used either directly as a fertilizer and let the plants and bacteria slowly enrich the atmosphere with it through their nitrogen cycle, or extract it chemically, with superheating, or other processes, possibly as a byproduct of extracting other sought after minerals and ores, perhaps titanium mineral osbornite (TiN) that consists of 22.63 % of nitrogen per weight.

So this extraction of nitrogen depends on how much of it you'd need. As an atmospheric gas, it's not really essential and could be substituted with other non-toxic inert gases (perhaps argon that's already roughly 2% of the Martian atmosphere?) to, e.g. increase the atmospheric pressure. Plants naturally don't take nitrogen from air (although we now have the technology to enable that for them), so it isn't essential for that, and the industry needs could be satisfied through already mentioned nitrogen gas byproduct of other processes, such as ore mining.

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Nitrogen is usually considered the key missing element to terraforming Mars. There might be some in existence somewhere, but yes, Mars would need a lot more nitrogen than it currently has in it's atmosphere. According to this article, it is very difficult to detect Nitrates via spectroscopy, and they typically would only exist at least 1 meter below the surface. Until we start digging on Mars, we won't know if it has enough nitrogen to be self-sufficient. But yes, Nitrogen will be the key to life as we know it on Mars, everything else life needs we know we can find there.

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    $\begingroup$ "Until we start digging on Mars": isn't there the Curiosity rover? It's not there for only taking pictures :p, isn't it? $\endgroup$ – user1397 Jan 16 '14 at 11:16
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    $\begingroup$ @Liviu Yup, MSL SAM is packed with mass spectrometer, gas chromatograph, and tunable laser spectrometer. It can detect nitrogen, and MSL just drilled a new hole in Mars yesterday. But it also took some pictures of it, and a new selfie two days before. So it's doing both :) $\endgroup$ – TildalWave May 1 '14 at 3:25
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For breathing, the cheapest and most plentiful source of N2 is going to be the martian atmosphere...as tenuous as it is, it is rather simple and low cost procedure to compress it, and the ratio of N2/O2 in the result will actually be HIGHER than our atmosphere on earth 20:1 as opposed to 3.7:1. In order to breath this, we would need some way of getting rid of the excess N2 actually, and the major gas CO2. This could be done with cyanobacteria, which loves both N2 and CO2. Terraforming would require release of N2 chemically from mineral sources, however. But for settlements this shouldn't be an issue.

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Actually oxygen-only atmosphere is not harmful if its pressure is equal to the partial pressure of oxygen on the Earth. Astronauts who travelled to the Moon had spent weeks in the oxygen-only atmosphere without any serious harm. At earth atmospherical pressure oxygen-only atmosphere is both harmful and flammable.

As to the need for nitrogen for long-term life function, it is another question.

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    $\begingroup$ Regardless of our nomenclature, which is due to the fact that the website is in English, there were quite specifically only astronauts that landed on and/or orbited the Moon. The point about the oxygen-only atmosphere not being harmful is also moot. First, pure oxygen atmosphere was abandoned and a switch to two-gas environment was made since Apollo 1 disaster. Second, Apollo astronauts didn't use open fire or use equipment that might spark. You would want that ability on Mars, and be safe on landing and occasional meteorids, otherwise there's no point in going there to burn in flames. $\endgroup$ – TildalWave Jan 17 '14 at 3:57
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    $\begingroup$ @Anixx Nitrogen would be needed for a long term colony, simply for nutrition. It makes up a significant part of protein. $\endgroup$ – Aron Jan 30 '15 at 6:59
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Actually, all things considered, Nitrogen doesn't have to be the primary gas, though for nitrogen-fixers, it's definitely important. If there were a cost efficient means of harvesting and transporting them to Mars, Helium or Neon would make very suitable replacements. For most organisms, molecular Nitrogen serves only as a filler: our bodies evolved to accept that 75%-80% of all of the gas around us and in us is, for physiological purpses, useless. Therefore, if Nitrogen were replaced with Helium or Neon, two inert gasses that have around the same density as air, the only difference would be a difference in how sound moves. We already use Helium in two gas breathing tanks, such as divers' tanks.

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  • $\begingroup$ 1. Isnt Helium the gas that gives ya a funny voice? if thats the case, future Martians may dont agree. $\endgroup$ – Jhollman Oct 16 '18 at 19:55
  • $\begingroup$ 2. Either choice give us back to the question of.. ¿Where the heck are we going to get all that [Place for Favorite Gas] to build the Martian Atmosphere? $\endgroup$ – Jhollman Oct 16 '18 at 19:57
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The Apollo 1 fire happened because they used an atmosphere without nitrogen or other essentially inert gas at sufficiently high percentage. Thus nitrogen is probably a good idea to have. Of course you now have concerns with the 'bends' during spacewalks, unless the suits maintain a similar pressure and gas mix. The pressure is the hard part, since it balloons the suits, and makes it hard to bend the joints, so they end up running lower pressure than the rest of the mission.

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It should be noted that the Apollo missions used a pure oxygen system throughout their service. However, after Apollo 1, the procedure on the launch pad changed, and the gas mix at launch as 40% oxygen, 60% nitrogen at 6 PSI. After launch, the command module's pure oxygen system kicked in, and the gas mix gradually changed to 100% oxygen as the mission progressed. The pure oxygen environment was only considered a danger on the launch pad.

Regarding the original question, given that Nitrogen is the fifth most common element in the universe, it is very likely that it is abundantly available on Mars, but we'll need more extensive mineral studies before we know for certain. The fact that we don't know this for certain shows that we've a lot to learn before we can establish a permanent presence on Mars.

I don't think this is the biggest problem Mars settlers will face. Protection from Radiation will be a more serious concern (probably solved by covering the base in a few metres of Mars soil). We also don't know how living in 1/3 Earth's gravity will affect us long term. Maybe it will turn out to be sufficient, but muscle and bone loss could be a very serious problem.

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First here is the big answer of what we have to start with on Mars. This is from the Atmosphere of Mars - Wikipedia

This pressure is well below the Armstrong limit for the unprotected human body. Mars 's atmospheric mass of 25 teratonnes compares to Earth's 5148 teratonnes ; Mars has a scale height of 11.1 kilometres (6.9 mi) [2] versus Earth's 8.5 kilometres (5.3 mi). [3] The Martian atmosphere consists of approximately 96% carbon dioxide , 1.9% argon , 1.9% nitrogen , and traces of free oxygen , carbon monoxide , water and methane , among other gases, [1] for a mean molar mass of 43.34 g/mol. [4] [5] There has been renewed interest in its composition since the detection of traces of methane in 2003 [6] [7] that may indicate life but may also be produced by a geochemical process, volcanic or hydrothermal activity .

en.wikipedia.org/wiki/Atmosphere_of_Mars

There are several ways that might work.

1 concentration on the atmosphere on Mars the 1.9 % oxygen and 1.9 % Argon components of a breathable atmosphere. 2 photosynthesis 3 using energy sources such as solar and geothermal to turn CO2 into O2 and CO this is and a serious amount of energy

Here is a NASA experiment in to doing just that

http://sciencenordic.com/scientists-are-trying-brew-oxygen-mars

How to brew oxygen on Mars There is practically no oxygen in Mars's atmosphere, but the MOXIE device will “brew” oxygen from carbon dioxide (CO2), which there is plenty of in the planet’s atmosphere.

The illustration shows the construction of the MOXIE instrument. If all goes according to the plan, MOXIE will be brewing oxygen on Mars six years from now. (Illustration: NASA) A carbon dioxide molecule consists of a carbon atom (C) and two oxygen atoms (O2), and it will be the job of the MOXIE apparatus to split the carbon dioxide molecules apart. The splitting process requires energy, but the end result will be oxygen molecules and a by-product in the form of carbon monoxide (CO). "MOXIE works like a sort of fuel cell in reverse. A fuel cell produces energy by melting together hydrogen and oxygen to produce water. Instead, we'll be using energy to remove an oxygen atom from CO2," says Madsen. He explains that MOXIE will get its energy from a Radio Thermal Generator (RTG) which generates electricity from heat developed in radioactive plutonium. Will provide oxygen people on Mars Around 96 per cent of the Martian atmosphere consists of carbon dioxide so there is plenty of raw material for oxygen production.

The MOXIE instrument will sit aboard the unmanned vehicle. Scientists from the University of Copenhagen are also involved in building one of the other instruments on board the vehicle, the so-called Mastcam-Z. (Illustration: NASA) NASA spokespersons have stated that MOXIE is only the beginning of oxygen production on Mars. "Having the ability to produce oxygen on the surface of Mars is a great step forward when it comes to mankind's future exploration of Mars," said Michael Meyer, a leading scientist at NASA's Mars Exploration Program, to Space.com. The plan is to build an entire oxygen factory on the red planet which will be about 100 times the size of the first MOXIE prototype which is to be launched from Earth with the Mars 2020 mission. The prototype oxygen factory will have to be ready when NASA sends the first humans to Mars at some time in the 2030s.

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  • $\begingroup$ Welcome to Space.SE. I am not sure this is an answer to the question. The first paragraph seems to focus on the atmosphere of mars, while the question assumes a sealed colony (but does not specifically say that), the rest of your answer focus on oxygen and the question is clearly about nitrogen. $\endgroup$ – James Jenkins Oct 17 '18 at 12:10

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