4 ms·

That seems like an extremely pedantic complaint. Sure, the breathing gas for a crewed mission or habitat would need to include an inert gas as well as oxygen.

That seems like an extremely pedantic complaint. Sure, the breathing gas for a crewed mission or habitat would need to include an inert gas as well as oxygen. But oxygen is consumed during respiration and the inert gas isn't, so oxygen will be needed in much larger quantities, so in-situ production is a much more pressing problem.

PaulHoule 4y ago
You are probably recycling the CO2 from the astronauts breath which is easier than cracking it from the air. Also many practical breathing systems (especially for spacesuits) leak some of the inert gas for cooling and other purposes. The real thing you’ll need O2 for is an oxidizer for fuel but of course you need to make fuel too. If you are interested in making anything interesting such as large plastic sails or small biospheres nitrogen is the big missing piece of the puzzle right now in the moon, mars and asteroids.
- ben_w 4y ago
  > recycling the CO2 from the astronauts breath It’s literally exactly as difficult as cracking out from the air, because breath is in fact made from air.
  - sigstoat 4y ago
    being extremely generous, and assuming he meant "martian atmosphere" when he said "air", it _might_ be a bit more challenging (depending on your process and what you've got available) to convert the CO2 at 0.095 PSI into O2, than it would be to pull the CO2 out of ~14.7 PSI human exhalations and convert it to O2. seems like the kind of thing where there is a bunch of engineering that could be productively done.
- MichaelCollins 4y ago
  CO2 needs to be scrubbed/vented out of the breathable atmosphere. Even if there is abundant of oxygen anyway, too much CO2 will make people feel dizzy and confused, cause splitting headaches, increased heart rated, reduced senses, and eventually death. CO2 can't take the place of inert nitrogen in a breathable atmosphere, that much CO2 in the air just isn't compatible with human life.

PaulHoule 4y ago

You are probably recycling the CO2 from the astronauts breath which is easier than cracking it from the air. Also many practical breathing systems (especially for spacesuits) leak some of the inert gas for cooling and other purposes. The real thing you’ll need O2 for is an oxidizer for fuel but of course you need to make fuel too. If you are interested in making anything interesting such as large plastic sails or small biospheres nitrogen is the big missing piece of the puzzle right now in the moon, mars and asteroids.

ben_w 4y ago
> recycling the CO2 from the astronauts breath It’s literally exactly as difficult as cracking out from the air, because breath is in fact made from air.
- sigstoat 4y ago
  being extremely generous, and assuming he meant "martian atmosphere" when he said "air", it _might_ be a bit more challenging (depending on your process and what you've got available) to convert the CO2 at 0.095 PSI into O2, than it would be to pull the CO2 out of ~14.7 PSI human exhalations and convert it to O2. seems like the kind of thing where there is a bunch of engineering that could be productively done.
MichaelCollins 4y ago
CO2 needs to be scrubbed/vented out of the breathable atmosphere. Even if there is abundant of oxygen anyway, too much CO2 will make people feel dizzy and confused, cause splitting headaches, increased heart rated, reduced senses, and eventually death. CO2 can't take the place of inert nitrogen in a breathable atmosphere, that much CO2 in the air just isn't compatible with human life.