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#76 2008-03-01 13:50:49

Midoshi
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From: Colorado
Registered: 2007-07-14
Posts: 157

Re: Minimal Martian Terraformed Atmospheres

Going just on memory here because i can't find the original posts.
I believe 70mb of C02 just warms Mars enough to keep Mars at 0c or just at melt point as an average temperature.

The only way 70 mbar of CO2 could get the average Mars temperature into the 0°C range is if you have ~1/2 bar of other gases (like N2 and O2) to broaden CO2's spectral lines through pressure. That's even including the greenhouse forcing due to more water vapor being in the warmer air. I'm sure you'd be the first to admit that amount of gas is unrealistic, nickname.

By way of comparison, the 100 mbar CO2/160 mbar O2 atmosphere I suggested before would just get you an average of -11°C at Mars' equator. Since Mars' orbit is fairly elliptic you'd get seasons even at the equator, and the climate would be wind up being comparable to the Canadian or Siberian tundra.

Just to be thorough, I want to mention that the existance of ozone would boost temperatures a bit. So would the low levels of methane, nitrous oxide, and ammonia produced by organisms introduced to Mars.

I know it's been linked to before on these forums, but I thought I'd remind people that a nice tool for such calculations is the Terraforming Calculator by Martyn Fogg.


"Everything should be made as simple as possible, but no simpler." - Albert Einstein

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#77 2008-03-01 15:00:52

noosfractal
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Re: Minimal Martian Terraformed Atmospheres

thx noosfractal that's real interesting.

Thanks to Midoshi!  I'm sure he's already trying to convince a bunch of people to live in a high CO2 environment in order to get better data  smile

Perhaps a insignificant question but Mars today has a 95%CO2 3%N2 atmosphere, Venus has a 96.5%CO2 and 3.5%N2 atmosphere.
With the exception of density they're pretty much the same. Is there some little rule in this or just coincidence?

A very good question actually.  Current speculation is that the atmospheres of Venus, Earth and Mars started similarly (they were born from the same primordial gas cloud, after all), but that Earth's is so different after these billions of years because of Earth's magnetic field (Venus and Mars both lack a significant magnetic field).


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#78 2008-03-01 15:42:58

Terraformer
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Re: Minimal Martian Terraformed Atmospheres

Then how does Venus mange to maintain its atmosphere with 2x the sunlight and no magnetic field????


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#79 2008-03-01 17:12:46

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Re: Minimal Martian Terraformed Atmospheres

Hi Midoshi,

Thanks for the details about C02 needs for Mars.
Not sure what i was remembering, maybe minimum C02 totals with super greenhouse gas totals included.
Never pays to use your memory only. LOL

So an absolute minimum C02 pressure we need on Mars to keep the chill off might be 200mb of just C02.?
With that maybe 1mb of super greenhouse gas and we get close to or just above 0c at the equator as an average most of the time.?

If 200mb of C02 is needed for warmth and it can only be 10%- 15% of the total atmosphere, i think a minimal terra form atmosphere is impossible on Mars.
We would need 600mb N2 import and 1+bar 02 import for that atmosphere. (ouch)

Unless someone can come up with a super greenhouse gas formula Vs C02 for Mars i think the idea is dead in the water.

I think we have 3 options.
1. Engineer organisms that can live with mostly C02 for Mars.
2. Just warm Mars and give up the idea of an earthlike place with land life, concentrate on Water life.
3. Don't do anything other than create domed structures.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#80 2008-03-02 06:37:55

dunwich
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Re: Minimal Martian Terraformed Atmospheres

some anaerobic organismes produce methane. Could a genetic manipulated bacterie be created that generates large amounds of potent greenhouse gases?


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#81 2008-03-02 09:52:01

JoshNH4H
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Re: Minimal Martian Terraformed Atmospheres

Well, midoshi's figures say that 10 kPa of CO2 (100 mb, trying to standardize) are the max livable.  So that will be the CO2 content of 'my' atmosphere.
:?: Question: What do current figures say that the total amount of CO2 that will be released from the poles/clathrates etc.? :?:

Now this is not the 200 mb of CO2 needed to keep mars warm.  Firstly, I would like to point out that most, or at least a lot, of the warming on earth, comes from water in the atmosphere.  because we're going for lower pressure, I give water 1 kPa of pressure. (Correct me if I'm wrong on anything)

Next, we need a super greenhouse gas, still.  I suggest Ammonia.  It should have a decently long atmospheric life, and can be produed by bacteria.   I give it 200 Pa (2 mb) of pressure.  This is made by the haber process, the hydrogen gotten from electrolysis.  If 200 Pa is too much, tell me.
:!: :!: The ammonia may help to counter CO2 blood acidosis :!: :!: (http://en.wikipedia.org/wiki/Ammonia#Natural_occurrence)

Oxygen, of course, is vital to terraforming.  Midoshi says the lowest is 16 kPa, but I would like to be a little more conventional on this one, and give it a full 20 kPa.  I'm assuming that it is 'fixed' from the CO2.

Finally we need nitrogen gas and a filler gas.  To get the final pressure to an even 40 kPa, I would suggest 8.8 kPa of nitrogen.
  :?: Does mars have this much nitrogen?  :?: [/url]

Final Atmosphere:
20 kPa (200 mb) O2
10 kPa (100 mb) CO2
8.8 kPa (88 mb)  N2
1 kPa  (10 mb)    H2O
0.2 kPa (2 mb)    NH3

Total: 40 kPa (400 mb)


-Josh

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#82 2008-03-02 10:44:00

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Re: Minimal Martian Terraformed Atmospheres

dunwich,

Great idea with anaerobic bacteria.

Mars right now at some depths and locations should be warm and wet enough to seed bacteria like that.

We could engineer all sorts of custom bacteria to produce all sorts of super greenhouse gasses on Mars in those areas that have liquid water beneath the surface.

All we would need is a drilling machine and a packet of those custom bacteria, place them into the bacteria friendly locations.
The drilling machines could be mobile so they can seed all of Mars underground water resources.

Time scales might be a problem to show any buildup of gasses in Mars atmosphere, but they will accumulate over time.

We can engineer custom bacteria to make copious amounts of the gas or gasses we choose.
We are sure to have all sorts of chemicals mixed in that ground water, so sky is the limit for gasses we can have bacteria create.

Might be a great way to get Mars warm enough so all the frozen C02 starts to release from the frozen layers.

Interesting thought and efficient possible way to warm mars with little input from us.
Wonder how much Methane, PFC's, etc we would need and the time scale for bacteria to create that?

A snippet from an article on Super greenhouse warming of Mars.
........

The researchers say that adding approximately 300 parts per million of the gas mixture in the current Martian atmosphere, which is the equivalent of nearly two parts per million in an Earth-like atmosphere, would spark a runaway greenhouse effect, creating an instability in the polar ice sheets that would slowly evaporate the frozen carbon dioxide on the planet's surface.

http://www.scienceagogo.com/news/200501 … _sys.shtml
..................................

A snippet from an article about Mars liquid water.
...
Liquid water apparently carved Mars's large channels, its smaller valleys, and its young gullies. In addition, there are vast quantities of ice within about 3 feet (1 meter) of the surface near the south pole and perhaps near the north pole. Thus, water apparently has existed near the surface over much of the planet's history. And water is probably present beneath the surface today, kept liquid by Mars's internal heat

http://www.nasa.gov/worldbook/mars_worldbook.html
.............................................


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#83 2008-03-02 10:57:38

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Re: Minimal Martian Terraformed Atmospheres

jumpboy11j,

"The ammonia may help to counter CO2 blood acidosis"

Interesting idea to allow us higher C02 levels.
Would the same thing work on plants?


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Knowledge is only as good as the facts.
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#84 2008-03-02 13:11:56

JoshNH4H
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Re: Minimal Martian Terraformed Atmospheres

I don't know, but I read on that wikipedia page that

The kidneys secrete NH3 to neutralize excess acid

, so it should be okay to have even more CO2 if we add ammonia, but I have no idea for plants.  I would think that they would merely grow more quickly, right?


-Josh

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#85 2008-03-03 00:23:41

Midoshi
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From: Colorado
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Re: Minimal Martian Terraformed Atmospheres

Final Atmosphere:
20 kPa (200 mb) O2
10 kPa (100 mb) CO2
8.8 kPa (88 mb)  N2
1 kPa  (10 mb)    H2O
0.2 kPa (2 mb)    NH3

Total: 40 kPa (400 mb)

Oh my goodness, at 2 mbar of NH3 our eyes and lungs would immediately begin corroding upon contact with such an atmosphere. That won't do at all.

While a tolerance for acute exposure to 100 microbar NH3 levels may be developed in humans, true chronic acclimation in animals does not seem to be possible at +10 microbars. One might be able to get away with 1 microbar of NH3, but even that is really pushing it. Levels in the 0.1 microbar range are much more realistic if you want to avoid chronic respiratory problems. And while it might slightly accelerate adaption of first generation animals to acidosis, atmospheric NH3 would do nothing to prevent CO2 neural interference, which is the real limiting factor with CO2 breathing levels.

Unfortunately, even in the 0.1 microbar NH3 range many plants will die due to nitrogen overdosing. Above just 0.01 microbars NH3 most lichens, mosses and confiers (all key plants in early terraformation due to their climatic hardiness) will kick the bucket. This is because these plants are used to harsh climates with low nutrient input; the ammonia goes straight into their leaves and overwhelms them. There are a few lichen and moss species that have evolved to tolerate higher nitrogen inputs, but the limits of this are not well defined. A critical load of 0.1 microbars is a generous upper estimate.

However, there is a more serious problem: it is very difficult to get anywhere near this amount of ammonia into the air completely naturally. This is due to the fact that ammonia is so water soluble and such an easy nitrogen source to assimilate that after emission (from, say, bacteria) it gets reabsorbed into the biosphere almost immediately. Perhaps the only way to do it would be to have micro-ecosystems like the "lagoons" that farmers use to get bacteria to digest manure and dead plant matter into methane, ammonia, nitrous oxide, and many other gases, as well as to produce clean fertilizer (actually the farmers don't want the ammonia to volatilize because it removes nitrogen from the resulting fertilizer, but we would want it to leave for greenhouse effect purposes).

I've done some calculations on the plausability of the lagoon idea in the past, but I don't recall them at the moment. I'll elaborate on it in another post soon.


References

Ammonia Regulations and Advisories
http://www.atsdr.cdc.gov/toxprofiles/tp126-c8.pdf

Chronic Toxicity Summary: Ammonia
http://www.oehha.ca.gov/air/chronic_rel … 664417.pdf


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#86 2008-03-03 06:12:44

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Re: Minimal Martian Terraformed Atmospheres

Final Atmosphere:
20 kPa (200 mb) O2
10 kPa (100 mb) CO2
8.8 kPa (88 mb) N2
1 kPa (10 mb) H2O
0.2 kPa (2 mb) NH3

Total: 40 kPa (400 mb)
...............................

At 100 mb of C02 in this 400mb atmosphere we have a total of 25% C02.
In a 400mb atmosphere, i think around 5% would be the maximum amount of C02 we could expect life to endure at 400mb.

100mb of C02 will require an atmosphere of around 1.5- 2 bars total to be at 5% C02.
1 bar of atmosphere on earth and 2% C02 is pushing the limits for life.
So a 1.5 -2 bar atmosphere on Mars would require C02 levels to be maybe 1.75% or less of the total atmosphere.
We might get away with 5% C02 since 02 levels would be much higher, so a 2 bar atmosphere would be a minimum for 100mb of C02.

No math works for 100mb C02 as the primary warming gas on Mars if we also expect it to be a terra formed place for life.

It's not realistic to think of a 2 bar Martian atmosphere, so we need something other than C02 as the main warming gas, or at minimum we need much less C02 reliance on warming allowing us to have C02 in realistic totals for life.
Or we need to alter life for Mars.

Just my opinion on the C02 math problem for Mars.


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Knowledge is only as good as the facts.
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#87 2008-03-03 11:26:34

dunwich
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Re: Minimal Martian Terraformed Atmospheres

a short article of genetics who try to modify CO2 breathing bacteria to produce octanes perhaps similar techniques could be used to  make bacteria produce more methane or other stronger greenhouse gases

http://news.yahoo.com/s/afp/20080228/ts … nYcJcPLBIF


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#88 2008-03-03 13:51:26

Midoshi
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From: Colorado
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Re: Minimal Martian Terraformed Atmospheres

At 100 mb of C02 in this 400mb atmosphere we have a total of 25% C02.
In a 400mb atmosphere, i think around 5% would be the maximum amount of C02 we could expect life to endure at 400mb.

That seems awfully low to me. Many plants do take some sort of productivity/germination rate hit at >50 mbar CO2 (i.e. >5% CO2 on Earth) due to interference with the plant hormone ethylene, but that doesn't mean they can't survive at those levels. For example, (Ostaplyuk et al. 1974) found that wheat germinates totally normally at 20% CO2 on Earth; that's 200 mbar CO2, well over the 100 mbar that's being suggested.

Reference:
Germination of winter wheat seeds depending on oxygen and carbon dioxide concentrations
ED Ostaplyuke, OF Cherkauskii, and LL kurochkina, Fiziol. Biokhim. Kul'turnykh Rastenii 6:401-405, 1974


"Everything should be made as simple as possible, but no simpler." - Albert Einstein

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#89 2008-03-03 15:26:02

JoshNH4H
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Re: Minimal Martian Terraformed Atmospheres

but what level of CO2 is the most for biosphere survival?

SF6 as a super greenhouse gas for any other necessary warming?  As mars has an Iron-sulfur core, the sulfur should be present, but what about fluorine deposits to make enough?  But .1 microbars should do. (GWP- 23,000, atmospheric lifetime: 3200 years.


-Josh

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#90 2008-03-03 16:47:15

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Re: Minimal Martian Terraformed Atmospheres

Midoshi,

Ok lets say 10% C02 as a maximum for argument sake.
We are still stuck with a 1 bar atmosphere for Mars.
And that probably won't be a real warm Mars.


Just one of many papers on elevated C02 levels and unexpected plant problems.
Was a short one so thought it would make for interesting reading.
............

Doubling the concentration of atmospheric CO2 often inhibits plant respiration, but the mechanistic basis of this effect is unknown. We investigated the direct effects of increasing the concentration of CO2 by 360 [mu]L L-1 above ambient on O2 uptake in isolated mitochondria from soybean (Glycine max L. cv Ransom) cotyledons. Increasing the CO2 concentration inhibited the oxidation of succinate, external NADH, and succinate and external NADH combined. The inhibition was greater when mitochondria were preincubated for 10 min in the presence of the elevated CO2 concentration prior to the measurement of O2 uptake. Elevated CO2 concentration inhibited the salicylhydroxamic acid-resistant cytochrome pathway, but had no direct effect on the cyanide-resistant alternative pathway. We also investigated the direct effects of elevated CO2 concentration on the activities of cytochrome c oxidase and succinate dehydrogenase (SDH) and found that the activity of both enzymes was inhibited. The kinetics of inhibition of cytochrome c oxidase were time-dependent. The level of SDH inhibition depended on the concentration of succinate in the reaction mixture. Direct inhibition of respiration by elevated CO2 in plants and intact tissues may be due at least in part to the inhibition of cytochrome c oxidase and SDH.
................................


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#91 2008-03-03 16:55:22

Midoshi
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From: Colorado
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Re: Minimal Martian Terraformed Atmospheres

Ok, here's that promised post about lagoons.

High volatile flux anaerobic lagoons emit 10 tons/hectare/year NH3 and 20 tons/hectare/year CH4, give or take a factor of 2. In order to sustain 0.1 microbar NH3 on Mars you'd need to cover at least 4% of the surface with lagoons in order to counterbalance the absorption by plants (assuming they cover the rest of the surface). This neglects NH3 destruction by UV and atmospheric hydroxyl radicals, which are comparatively unimportant. At this lagoon coverage you would also get at least 30 microbar CH4, and perhaps 10 times that if the hydroxyl concentration on Mars was low compared to Earth.

Now there are a lot of holes in this calculation, some lethal. I don't know what the ammonia deposition rate over desert is (probably lower than over vegetation), so that could lower the required lagoon surface coverage. On the other hand, this model just takes into account "dry deposition" (when NH3 molecules directly deposit on surfaces), assuming it dominates over "wet deposition" (when ammonia dissolves into water vapor and is then deposited by rain). On Earth the deposit rates of the two processes are roughly the same magnitude. However, with the extremely high concentrations we're talking about, far more NH3 will dissolve into rain and be removed from the atmosphere. We're talking deposition rates 100-1000 times higher than on Earth, assuming similar rainfall on Mars. This means that 0.1 microbars is unreasonably large: you'd need the Martian surface to be one giant, smelly lagoon. This conclusion is reinforced by NH3 measurements on the order of 0.1 microbars in the atmospheres over lagoons (Goorahoo 2005).

With jumpboy11j I was hoping that NH3 might be a good greenhouse gas for Mars. Unfortunately, it appears to be far too reactive/soluble a species to be gaseous in the amounts required for more than a degree or so of warming. ):


References:

Measurement and estimation of ammonia emissions from lagoon–atmosphere interface using a coupled mass transfer and chemical reactions model, and an equilibrium model
KS Bajwa, VP Aneja, S Pal Arya, Atmospheric Environment 40 (2006)

Ammonia Emissions from Swine Waste Lagoons in the Utah Great Basin
LA Harper, KH Weaver, and RA Dotson, J Environ Qual 35:224-230 (2006)

Reduction of Ammonia Emissions from Swine Lagoons Using Alternative Wastewater Treatment Technologies
A Szogi & M Vanotti, Proceedings of the Workshop on Agricultural Air Quality: State of the Science, June 5-8, 2006, Washington, DC. p. 1155-1160
http://genes.pp.ksu.edu/research/public … 115=192837

Use of Laser Technology to Monitor Ammonia Emissions from Dairy Lagoons
D Goorahoo, C Krauter, B Goodrich and M Beene,  14th International Emission Inventory Conference, Las Vegas, Nevada, April 11 - 14, 2005
http://www.epa.gov/ttn/chief/conference … o_pres.pdf


"Everything should be made as simple as possible, but no simpler." - Albert Einstein

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#92 2008-03-03 17:44:25

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Re: Minimal Martian Terraformed Atmospheres

jumpboy11j,

Underground water deposits should have florine mixed in the water already.
Some water won't have any flourine but some will and the bacteria we design would be very efficient at using it all up.
We should get all sorts of goodies from the ground water for bacteria to grow gas for us, iron, sulphur, flourine, hydrogen, carbon, oxygen etc.
With just that mix of elements we have lots of gas options.

It's really quite a small quantity of super greenhouse gas we need on Mars to get the C02 liberated.


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Knowledge is only as good as the facts.
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#93 2008-03-03 20:17:28

Midoshi
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From: Colorado
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Re: Minimal Martian Terraformed Atmospheres

It was mentioned earlier in the thread that subsurface hydrothermal carbonate deposits are postulated to exist on Mars. I just wanted to note that the terrestrial analogs of such deposits typically contain significant amounts of fluorite (CaF2, calcium fluoride). Concentrated sulfur rich minerals are also common in these deposits on Earth, and would probably be even more so on Mars.


"Everything should be made as simple as possible, but no simpler." - Albert Einstein

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#94 2008-03-04 15:38:38

JoshNH4H
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Re: Minimal Martian Terraformed Atmospheres

so that seems to leave 2 questions:

How much CO2 is the maximum?
How much SF6 is needed to make up for the lost wwarming of not enough CO2?  I personally think that there will be enough S and F to make enough SF6.


-Josh

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#95 2008-03-04 17:02:16

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Re: Minimal Martian Terraformed Atmospheres

jumpboy11j,

I personally see about 50mb of C02 as the max for Mars.
At 50mb of C02 even with C02 in 10% concentrations we end up with a 500 mb atmosphere.

Moving 150 mb of filler gas and finding 300mb of 02 i think will be about a maximum we could expect of any terra form plan.
Even doing that is quite the long term project.
Many thousands of years or much longer.

At 50mb of C02 and .1 micro bars SF6  i think we fall well short of anything near the melt point of h20.
We would need a host of different super greenhouse gasses in every spectrum to have any hope of 0c average Mars and the input from water vapor.

After the initial C02 releases and the contributed warmth from super greenhouse gas SF6 and others.
Mars might be semi warm with perhaps 150mb of C02, maybe somewhere around 0c with enough greenhouse gasses and water vapor in the atmosphere.

It would be a toxic place for life on land but probably not toxic for some life in ponds.

Maybe that should be our only goal is to make Mars warm and not worry about how much C02 we end up with.
Making Mars life friendly on the surface seems impossible or at minimum so long term for the import penalties as to be impossible.

For me i see a minimal Mars atmosphere as whatever C02, O2 and N2 is liberated when a healthy dose of super greenhouse gas is mixed in to liberate them.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#96 2008-03-04 21:26:13

SpaceNut
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Re: Minimal Martian Terraformed Atmospheres

The new atmospheric pressure and make up seems right as far as for man or animal to learn to breath after a period of time but for plant life it would seem that nitrogen is critical for it to grow correctly in a high CO2 concentration.

Located this web site earlier in the day
http://www.greenhouse.crc.org.au/research/b.cfm

Where the work was done in response to Global warming and climate change as a result of human-induced increases in greenhouse gases.

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#97 2008-03-05 06:34:22

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Re: Minimal Martian Terraformed Atmospheres

I think this might be a better way to approach the problem.

1. How much super greenhouse gas do we need to liberate frozen C02.?
2. How much C02 do we liberate.?
3. How much more Super greenhouse gasses do we need beyond that before we begin to liberate H20 vapor at a rate higher than it re freezes.?

Some educated guesses here will give us a final C02 Total for Mars.
We are probably stuck with that quantity of C02 less the percent we can use up when we replace C02 with water vapor warming.

I think if we can't get a formula to keep C02 in the 50mb range or less and keep Mars warm enough to melt H20 we have little hope of making Mars a life friendly atmosphere.

We can't grow anything without liquid water and to get liquid water to form i think Mars will not be a life friendly atmosphere.

We always have the option of altering life to suit Mars.
Just create life that is suited to Mars and not a Mars that is suited to our life.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#98 2008-03-05 07:09:11

JoshNH4H
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Re: Minimal Martian Terraformed Atmospheres

I think you're getting something wrong:  It's partial pressure that matters, not percent.  For example, say the max is 50 mb.  with a 5 bar atmos., that's 1%.  But that will have the same effect as 50 mb in a 500 mb atmosphere (10%)

As another Idea, could N2O also be made by bacteria?  Would it be a drain on valuable nitrogen.  The biggest problem is that SF6 is so heavy that it tends to sink. to ground level.


-Josh

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#99 2008-03-05 12:35:05

Midoshi
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From: Colorado
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Re: Minimal Martian Terraformed Atmospheres

As another Idea, could N2O also be made by bacteria?  Would it be a drain on valuable nitrogen.

NO and N2O are produced in tiny amounts as side-effects of both nitrification (NH4+ -> NO3) and denitrification (NO3 -> N2). I understand that they are produced more often when more O2 is available to the bacteria. However, witness that NO and N2O are just trace gases in our atmosphere (<1ppm); they are unimportant as a biological sink of nitrogen.

For everyone's edification, here's an inventory of nitrogen on Earth:

Earth
Atmosphere........3.87e18 kg
Sediment............1.00e18 kg
Ocean.................2.00e16 kg
Soil.....................9.50e13 kg
Biomass..............4.00e12 kg  (the vast majority is on land)

Let's say as an extreme case we terraform Mars into having 1/3 of its surface covered by ocean. We're left with a land area 65% that of Earth. Now, if we scale the soil and biomass from Earth:

Mars
Soil.....................6.20e13 kg
Biomass..............2.60e12 kg

This mass of nitrogen, 6.46e13 kg, amounts to just 0.016 mbars on Mars. The red planet currently has over 10 times this amount in it's atmosphere alone, and there is probably of order 1e17 kg fixed nitrogen in sediment and soil on Mars (several tens of mbar).

One could also scale Earth's ocean nitrogen content to a (extreme case) 3km Martian ocean covering 1/3 the surface to obtain an estimate of 2e15 kg, which is well within Mars putative inventory. On the other hand, you get into trouble when you scale for sediment, getting 3e17 kg. In fact, neither of these values are realistic for Mars because the amount of nitrogen deposited in the ocean and as sediment will depend on many factors (including biological) and are not directly scalable from Earth.


References:

Where is the nitrogen on Mars? (Mancinelli et al.  2003)
Isotopic Composition of Nitrogen: Implications for the Past History of Mars' Atmosphere (McElroy et al. 1976)


"Everything should be made as simple as possible, but no simpler." - Albert Einstein

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#100 2008-03-05 15:15:18

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Re: Minimal Martian Terraformed Atmospheres

jumpboy11j,

Partial pressure does come into play with quantity of C02.
The C02 rules change with pressure.

At 125mb total atmosphere we might get away with 20% C02 content.
At 250mb maybe 15%.
At 500mb maybe 10%

The trouble with those partial pressures and percent of C02 is probably none of them have a hope of keeping Mars warm and keeping plant life happy without lots of help.

The obvious solution is just to keep adding bar pressure until C02 levels are both safe and keep Mars warm.
But we must keep in mind to keep things happy for life, for each 100mb we increase the pressure we need around 30mb of N2 and 60mb of oxygen of the total 100mb we increase pressure.

At 1 bar we will probably be in the 1% to 5 % C02 allowable content anyway, so going much beyond 500mb seems like a lot of effort for little gain.

The ideal solution might be a Mars with a total pressure of 150mb.

30mb C02.. about 19% (in life levels maybe)

70mb 02 ...about 49% (all from converted C02 and free 02 released, water separation when needed)

45mb N2 ..about  29% (5mb from Mars gas release, 20 mb bacteria released, 20 mb import)
We have a bit of leeway on 02 % levels so import of N2 might not be needed.

5 mb other gasses including super greenhouse gasses.. about 3% (nearly all made with bacteria on Mars, some trace gasses released at melt)

I think that is the most efficient plan that requires little to no import of any gasses.

We might get away with a 200mb Mars atmosphere with no imports.
Beyond 200mb i think we are stuck with lots of imports.

Now how the heck can we get a melted h20 Mars with just 30mb- 40mb of C02 with whatever content of super greenhouse gasses we choose. ?
We can have C02 content much higher for a time, but the final Mars will need to be no higher than about 40mb C02 of 200mb total.


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Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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