4 ms·

> atmosphere can be made from the rocks themselves. There is an effectively endless supply. Do Martian rocks have significant amounts of nitrogen?

adastra22 3y ago
Why would you need nitrogen in your atmosphere?
- just_boost_it 3y ago
  Presumably for whatever reason it worked well for us to develop as we did down here? Stops everything from exploding, dissolves all the other gases quite nicely? What other gas would you use?
  - adastra22 3y ago
    Nitrogen does absolutely nothing on Earth. It is inert.
    - just_boost_it 3y ago
      Like, without that inert gas there would have to be something else. Being in a pure oxygen environment for a prolonged period has health impacts to many animals including us. Anything even remotely flammable, like paper, wood, sugar, would burn uncontrollably with the slightest spark. If you didn't have nitrogen you would need another inert gas to make up 80% (or whatever) of the atmosphere you were going to make.
      - adastra22 3y ago
        For the most part, partial pressure is what matters, not absolute pressures. The only contribution inert nitrogen has to life is raising the boiling point of water. But on a frigid planet like Mars that’s not going to be an issue. Being in a pure oxygen environment does not have a long term impact on animals… if the pure O2 environment is 0.21 atm oxygen. There’s a long history of biological experimentation done by space agencies on this, and the Apollo missions operated on a 0.2 atm pressure for the duration of their missions. Apollo 1 famously had trouble not because it was pure O2, but because it was 1.2atm O2. There is no reason you need backfill inert gasses to have 1.0 atmospheres.
    - abdullahkhalids 3y ago
      The Nitrogen cycle [1] is a critical component of many ecological systems. Critical compounds in plants have nitrogen, and the nitrogen for these is absorbed from the soil, where it is fixed by bacteria. [1] https://en.wikipedia.org/wiki/Nitrogen_cycle https://en.wikipedia.org/wiki/Nitrogen_cycle
      - adastra22 3y ago
        The nitrogen cycle almost entirely involves fixed nitrogen, not inert N2. Nitrogen is fixed from the atmosphere slowly over time through lightning strikes and a very small number of nitrogen fixing bacteria that live symbiotically on the roots of very few plants. The vast majority of the biomass on earth, including about half of the fixed nitrogen in your body was synthesized industrially via the Haber-Bosch process over the last 100 years. Aside from those nitrogen fixing bacteria whose output we have already surpassed with industrial processes (artificial fertilizer), inert nitrogen plays no role in biological metabolism. It is not needed, at all. Mars colonists can import nitrogen, or mine fixed nitrogen from the few deposits that are known to exist. It doesn’t need a massive atmospheric reservoir.
- someplaceguy 3y ago
  A pure oxygen atmosphere would completely ignite itself in contact with a spark. So you need to have another gas to dilute the oxygen. Mars' (almost non-existant) atmosphere is mostly CO2, and you could use that, except that a CO2 level above 10% is lethal for humans and at 10%, it's still too oxygen rich. Nitrogen has the advantage that it's inert and non-lethal.
  - adastra22 3y ago
    There's no reason Mars' atmosphere needs to be a 1 atm pressure. For biological processes, it is partial pressure that matters, and nitrogen gas is inert. Mars' atmosphere could be 0.2 atm oxygen + trace gases and that would be perfectly acceptable for human beings. However people can wear breathing masks when outside of buildings. Plants cannot. Most terraforming proposals focus on supporting surface plant life, and plants thrive in high-CO2 environments. These proposals involve toxically high (for humans) level of CO2 in order to support lush plant life. Once the O2 and temp gets high enough, people can survive on the surface without space suits, so long as they carry a bottle of oxygen and a breathing mask. Longer-term, atmospheric pressure could be supplanted with a couple of Kuiper Belt objects consisting of frozen nitrogen and organics. Let it burn up in the thickening atmosphere and contribute to the developing pool of gases.
    - ben_w 3y ago
      Plants also need nitrogen. Even if you chose plants that can get it just from soil and not worry about any fixing from the air, you need to get a lot to Mars for a terraform.
      - adastra22 3y ago
        Not N2, no. There is not plant anywhere in the world that uses atmospheric N2. Plants used fixed nitrogen from the soil. In Martian greenhouses, that would be provided in the form of artificial fertilizer and/or organic waste.
        3y ago

adastra22 3y ago

Why would you need nitrogen in your atmosphere?

just_boost_it 3y ago
Presumably for whatever reason it worked well for us to develop as we did down here? Stops everything from exploding, dissolves all the other gases quite nicely? What other gas would you use?
- adastra22 3y ago
  Nitrogen does absolutely nothing on Earth. It is inert.
  - just_boost_it 3y ago
    Like, without that inert gas there would have to be something else. Being in a pure oxygen environment for a prolonged period has health impacts to many animals including us. Anything even remotely flammable, like paper, wood, sugar, would burn uncontrollably with the slightest spark. If you didn't have nitrogen you would need another inert gas to make up 80% (or whatever) of the atmosphere you were going to make.
    - adastra22 3y ago
      For the most part, partial pressure is what matters, not absolute pressures. The only contribution inert nitrogen has to life is raising the boiling point of water. But on a frigid planet like Mars that’s not going to be an issue. Being in a pure oxygen environment does not have a long term impact on animals… if the pure O2 environment is 0.21 atm oxygen. There’s a long history of biological experimentation done by space agencies on this, and the Apollo missions operated on a 0.2 atm pressure for the duration of their missions. Apollo 1 famously had trouble not because it was pure O2, but because it was 1.2atm O2. There is no reason you need backfill inert gasses to have 1.0 atmospheres.
  - abdullahkhalids 3y ago
    The Nitrogen cycle [1] is a critical component of many ecological systems. Critical compounds in plants have nitrogen, and the nitrogen for these is absorbed from the soil, where it is fixed by bacteria. [1] https://en.wikipedia.org/wiki/Nitrogen_cycle https://en.wikipedia.org/wiki/Nitrogen_cycle
    - adastra22 3y ago
      The nitrogen cycle almost entirely involves fixed nitrogen, not inert N2. Nitrogen is fixed from the atmosphere slowly over time through lightning strikes and a very small number of nitrogen fixing bacteria that live symbiotically on the roots of very few plants. The vast majority of the biomass on earth, including about half of the fixed nitrogen in your body was synthesized industrially via the Haber-Bosch process over the last 100 years. Aside from those nitrogen fixing bacteria whose output we have already surpassed with industrial processes (artificial fertilizer), inert nitrogen plays no role in biological metabolism. It is not needed, at all. Mars colonists can import nitrogen, or mine fixed nitrogen from the few deposits that are known to exist. It doesn’t need a massive atmospheric reservoir.
someplaceguy 3y ago
A pure oxygen atmosphere would completely ignite itself in contact with a spark. So you need to have another gas to dilute the oxygen. Mars' (almost non-existant) atmosphere is mostly CO2, and you could use that, except that a CO2 level above 10% is lethal for humans and at 10%, it's still too oxygen rich. Nitrogen has the advantage that it's inert and non-lethal.
- adastra22 3y ago
  There's no reason Mars' atmosphere needs to be a 1 atm pressure. For biological processes, it is partial pressure that matters, and nitrogen gas is inert. Mars' atmosphere could be 0.2 atm oxygen + trace gases and that would be perfectly acceptable for human beings. However people can wear breathing masks when outside of buildings. Plants cannot. Most terraforming proposals focus on supporting surface plant life, and plants thrive in high-CO2 environments. These proposals involve toxically high (for humans) level of CO2 in order to support lush plant life. Once the O2 and temp gets high enough, people can survive on the surface without space suits, so long as they carry a bottle of oxygen and a breathing mask. Longer-term, atmospheric pressure could be supplanted with a couple of Kuiper Belt objects consisting of frozen nitrogen and organics. Let it burn up in the thickening atmosphere and contribute to the developing pool of gases.
  - ben_w 3y ago
    Plants also need nitrogen. Even if you chose plants that can get it just from soil and not worry about any fixing from the air, you need to get a lot to Mars for a terraform.
    - adastra22 3y ago
      Not N2, no. There is not plant anywhere in the world that uses atmospheric N2. Plants used fixed nitrogen from the soil. In Martian greenhouses, that would be provided in the form of artificial fertilizer and/or organic waste.
      - 3y ago