OT: Carbon Dioxide races -> known vs unknown -> terraforming mars -> is or is not

[General Woundwort]

Has anybody read the book Rare Earth? I think it bears directly on the discussion here re: the viability of non-oxygen based life-forms (and other conclusions even more depressing to avid sciffers).

[oleg]

Originally posted by dogscoff:
Sorry to double post, but I have a mostly on-topic question for my own sci-fi writing purposes, and this post has nothing to do with my Last.

I know Mars has a thin CO2 atmosphere. If we were to build a domed ecosystem on Mars, I imagine we could use photosynthesis or some chemical process to extract all the oxygen we needed from this CO2.

However, as has already been stated in this thread, our own atmosphere is mostly nitrogen, and that is also important to us. (Nitrates in the soil for plants etc)

Does anyone know if there is any useful amount of nitrogen present in the martian atmosphere, or is it all CO2? If there is none, would we be able to extract the required nitrogen from other nearby resources (rocks, asteroids etc)?

Finally, would an artificial atmosphere made up in this way (say ~75% nitrogen, ~15% oxygen, ~10% CO2) be viable for a human ecosystem, or would we need to import/ locally source all the other trace elements in our own atmosphere?

It is mostly CO2 with some water vapor. N2 is not important for us to breath, Appolo astronauts used pure oxygen. Proved to be very dangerous though - Appolo 1.

[Loser]

Originally posted by dogscoff:
I know Mars has a thin CO2 atmosphere. If we were to build a domed ecosystem on Mars, I imagine we could use photosynthesis or some chemical process to extract all the oxygen we needed from this CO2.

I'm not so sure there's quite that much. And the thinness of the atmosphere is going to slow down the conVersion.

Originally posted by dogscoff:
However, as has already been stated in this thread, our own atmosphere is mostly nitrogen, and that is also important to us. (Nitrates in the soil for plants etc)

Does anyone know if there is any useful amount of nitrogen present in the martian atmosphere, or is it all CO2? If there is none, would we be able to extract the required nitrogen from other nearby resources (rocks, asteroids etc)?

A good source for terraforming Mars is one particular sci-fi series: Red Mars, Green Mars, Blue Mars. I would recommend these, if you don't mind the excessive sex sci-fi authors feel they need to include to get their work of the juvi-fic rack.

Originally posted by dogscoff:
Finally, would an artificial atmosphere made up in this way (say ~75% nitrogen, ~15% oxygen, ~10% CO2) be viable for a human ecosystem, or would we need to import/ locally source all the other trace elements in our own atmosphere?

On Earth it's about 70% N2, 22%O2, 4% Argon, and the remaining 4% everything else (very small amount of CO2). But it's not the percentage of Oxygen that's important, it's the amount of O2 molecules per Liter of 'air'. So at lower pressures it's important to have a greater percentage of O2 and at higher pressures it's not only important to have a lower percentage of O2, but also to have less N2 or no N2. A high enough pressures N2 will act as an intoxicant, so an inert gas, such as He (elemental Helium), is used.

[DarkHorse]

Originally posted by General Woundwort:
Has anybody read the book Rare Earth? I think it bears directly on the discussion here re: the viability of non-oxygen based life-forms (and other conclusions even more depressing to avid sciffers).

This thread reminds me of a series I'm just about finished reading, concerning a large space based multi-species hospital called Sector General.

James White is the author; unfortunately many of them are out of print now, although there are two or three compendiums available that contain the earlier volumes, if anyone is interested.

[dogscoff]

It is mostly CO2 with some water vapor. N2 is not important for us to breath, Appolo astronauts used pure oxygen. Proved to be very dangerous though - Appolo 1.

Yeah, pure O2 would be a bad idea for several reasons. Nitrogen would be crucial if you planned to have any plant life (which you would need for food, oxygen, medication, fabrics and more) because it is required in the soil. I seem to remember from school something about a "nitrogen cycle", which involved nitrogen going from the air to the soil or something. I guess I ought to look it up.

I'm not so sure there's quite that much {Co2 on Mars}. And the thinness of the atmosphere is going to slow down the conVersion.

Well, I'm not talking about doming the entire planet, just a few limited domes. Also, the atmosphere doesn't have to be thin inside the dome- you can keep pumping CO2 in until you reach an Earth-like pressure, dump a load of plants and soil in there, then wait. Once the plants have done their job, you bottle the oxygen for use in inhabitted domes, lather, rinse and repeat.

A good source for terraforming Mars is one particular sci-fi series: Red Mars, Green Mars, Blue Mars.

Well, I've read "White Mars" by someone or other (it was terrible) and also an excellent book by Clarke about the possibilities for terraforming. Personally I think terraforming on Mars is a bad idea, unless you can do something to prevent the atmosphere being stripped away again by the solar winds. Mars is something of an obsession of mine.

On Earth it's about 70% N2, 22%O2, 4% Argon, and the remaining 4% everything else (very small amount of CO2). But it's not the percentage of Oxygen that's important, it's the amount of O2 molecules per Liter of 'air'. So at lower pressures it's important to have a greater percentage of O2 and at higher pressures it's not only important to have a lower percentage of O2, but also to have less N2 or no N2. A high enough pressures N2 will act as an intoxicant, so an inert gas, such as He (elemental Helium), is used.

Well for a permanent colony, I should think it would be important to have air pressure and content as close to Earth's as possible for morale and health reasons. However it seems as though O2 and N2 are the only important ones for humans, and CO2 will be required for any plant life. Maybe the pressure could be maintained at one earth atmosphere, with a mix of (say) 70% N2, ~26% O2, ~4% CO2. A balanced excess of CO2 could counter any ill-effects caused by the excess of oxygen. Maintaining that balance would be hard, what with all those life-forms on there respiring away, but there would be ways and means.

So my main question remains: Would nitrogen be available on Mars? If it's not iin the air, is it likely to be found in rocks, soil etc?

[geoschmo]

[quote]Originally posted by dogscoff:

So my main question remains: Would nitrogen be available on Mars? If it's not iin the air, is it likely to be found in rocks, soil etc?

Going strictly from my fractured memory, isn't Nitrogen supposed to be the second most abundant element in the universe after Hydrogen? I may be wrong about that, but if I am right then I think we ought to be able to find some significant quantaties in some form on Mars.

Geoschmo

EDIT: Nope, guess I was wrong. Looks like Nitrogen is fifth behind Hydrogen, Helium, Oxygen and Neon. Oh well. Guess I should look that stuff up before posting.

I did find an interesting and relevant link.
(click on the quote to go to the source)

Oddly enough, nitrogen is the limiting gas species for plant life on Mars. There is more than enough CO2 for photosynthesis, nearly enough oxygen for respiration and the atmospheric pressure is close to the lower limit. In fact in some regions, the atmospheric pressure reaches 9 or 10 millibars and some hardy terrestrial plants could be found to survive such conditions. However, there is too little N2 for nitrogen fixation for some plants by a factor of 5. Nitrogen must also be found in the soil for plants to thrive. Currently, the N2 levels in the Martian soil are unknown. If these are later found to be low, Robert Zubrin [Zubrin & Wagner, 1996] suggests we may be able to make fertilizer out of the atmosphere.

[ July 16, 2003, 16:41: Message edited by: geoschmo ]

[Suicide Junkie]

Maybe the pressure could be maintained at one earth atmosphere, with a mix of (say) 70% N2, ~26% O2, ~4% CO2.

That is dangerously close to a lethal atmosphere. Your colonists would suffer greatly, and casualties would be high.
Drop that CO2 concentration by at least an order or two of magnitude.