Minimal Martian Terraformed Atmospheres

JoshNH4H · 2008-03-06 08:22:20

I am considering this atmosphere: 225 mb O2, 100 mb N2, 50 mb CO2, 1 (?) mb CF4, 1 (?) mb N2O. I use CF4 instead of SF6 because it's less likely to just sink to ground level and be useless. (GWP: 6500, atmos. life: 50,000 y)

RickSmith · 2008-03-06 15:23:37

Hi Jumpboy11j, everyone.
I did the calculations in this post here...

Filling Hellas Basin up with Greenhouse Gases.

and it should not be a concern. The other gases buoy up the SF6 and in any case even if it was by itself it would have a scale height of several km.

Warm regards, Rick.

nickname · 2008-03-06 17:24:48

Just thinking about the waste products from converting water into 02 and hydrogen, and C02 into 02 and Carbon.

CH4 (methane)and 3 Carbon for soil building.

If we do discover that we need to separate water and separate C02 we can use up all the waste products as more greenhouse gas and soil amendments.

SpaceNut · 2008-03-08 22:23:14

Plants cannot survive in a partial pressure CO2 level greater than 0.2 kPa. But will tolerate much lower partial pressure O2 levels than humans.

Plants grown at pressures as low as 14 kPa have only slightly lower germination percentages and stem lengths. Plants grown at 33 kPa do not show any significant changes in germination percentages and stem lengths as those grown at 101 kPa.

Tests in the vacuum test chamber at Kennedy Space Center indicate that plants tolerate pressures down to 0.2 atmosphere or about 20 kPa without problem, but begin to wilt below this value. In other tests at KSC, plants survived below 10 kPa.

Midoshi · 2008-03-09 01:41:23

Plants cannot survive in a partial pressure CO2 level greater than 0.2 kPa.

That's a lot lower than the sources I've seen:

(Chagvardieff et al. 1997) grew wheat, tomatoes, potatoes, and peas at 0.37 kPa (3.7 mbar) CO2 from seedlings to harvest. They did find that wheat suffered at these levels, but response was extremely variable between species: one variety suffered a 50% reduction in edible mass while another suffered only a 9% drop. The main thrust of the paper, however, was the tremendous benefits for all the other vegetation grown: tomatoes increased edible output by 46-59%, potatoes a modest 6-16%, and peas an incredible 245%. A further experiment raising potatoes in 2 kPa (20 mbar) CO2 found the only effect to be that the tubers grew much faster.

(Tikhomirov et al. 2007) grew radishes, beets, carrots, and cabbage at 0.7-0.9 kPa (7-9 mbar) CO2 and found significant enhancement in edible biomass (~20%) over the previously assumed optimal range of 0.15-0.3 kPa (1.5-3 mbar) CO2.

(Wheeler et al. 1994) found that while 1 kPa (10 mbar) CO2 was not optimal for the growth of soybeans and potatoes, neither was it injurious: the plants were in all respects either comparable to or far more productive than those grown under normal CO2 levels.

(Wheeler et al. 1997) successfully grew tomatoes at 1 kPa (10 mbar) CO2 and found that there was no significant effect on mineral and nutritional composition of the fruit.

(Grotenhuis et al. 1997) studied wheat and (Bugbee et al. 1994) studied wheat and rice at up to 1 kPa (10 mbar) CO2. Like many other studies, they both found that while not optimal, such CO2 levels were not lethal or even seriously detrimental to the plants. It should be noted that a drop in seed productivity associated with CO2 interference with ethylene was observed. This is one of the major problems with high CO2 among plants. CO2 stimulates ethylene production at a few kPa, but then begins inhibiting it above ~5 kPa (50 mbar). While plants can still survive above these levels, ethylene is an important plant hormone, and modification of reproductivity begins to be experienced.

I would also like to reference the series of papers by Kidd in the first half of the 20th century. He remarks upon many studies that found pea growth to be stimulated by a few percent CO2, and then inhibited by higher levels. The level at which growth was constrained below normal levels was consistently 7% CO2 (7 kPa, 70 mbar). Kidd himself also did extensive research into the effects of very high CO2 on germination and respiration in a wide variety of plants. He found that sensitivity in germination varied significantly between species, with white mustard being totally intolerable of >18% CO2, while peas were still capable of germinating at 100% CO2, albeit at greatly reduced rates.

But what takes the cake in my experience is the study of (Pfanz et al. 2007) on timothy grass around mofettes, i.e. natural CO2 springs. The researchers found plants growing with air in the soil being 26% CO2; that's 26 kPa or 260 mbar. Described in the paper as living "a life on the verge of death", these plants experienced CO2 levels 800 times normal as well as permanent hypoxia and even transient anoxia in the soil. Understandably, this grass was extremely stunted in height and had nitrogen, phosphorous, zinc, and sulfur nutrition absorption deficiencies. But they were alive, reproducing, and persisting in a natural microecosystem. In a similar study with reeds, Pfanz et al. found that photosynthetic inhibition occured at 20-98% CO2 (20-98 kPa, 200-980 mbar) in both mofette and control plants, but that the mofette acclimated plants were far more robust. They were even able to maintain 20% normal photosynthetic electron flow for several hours at 98% CO2; by comparison the control plants were totally shut-down.

References:

Effects of Modified Atmosphere on Crop Productivity and Mineral Content (Chagvardieff et al. 1997)
Effect of Increased CO2 Concentrations on Gas Exchange and Productivity of Cultivated Vegetables Contributing to the Phototrophic Component of Biological Regeneration Life-Support Systems (Tikhomirov et al. 2007)
Growth of Soybean and Potato at High CO2 Partial Pressures (Wheeler et al. 1994)
Effect of Elevated Carbon Dioxide on Nutritional Quality of Tomato (Wheeler et al. 1997)
The Controlling Influence of Carbon Dioxide in the Maturation, Dormancy, and Germination of Seeds.--Part I (Kidd 1914)
The Controlling Influence of Carbon Dioxide in the Maturation, Dormancy and Germination of Seeds.--Part II. (Kidd 1914)
The Controlling Influence of Carbon Dioxide. Part III.--The Retarding Effect of Carbon Dioxide on Respiration (Kidd 1916)
Photosynthetic performance of timothy grass is affected by elevated CO2 in post-volcanic mofette areas (Pfanz et al. 2007)
Physiological Reactions Of Reed Growing Under Co2 Extremes Within a Co2 Emitting Mofette Field (Pfanz et al.)

Midoshi · 2008-04-26 12:27:31

As an addendum to my previous post, I've found a body of research on trees in the area surrounding Mammoth Mountain, a dormant volcano in California. Some CO2 vents here have become especially active in the past few decades, producing soil concentrations high enough to kill swaths of forest in some locations. These tree-kill zones were found to occur when soil air was above 30% CO2 (300 mbar), though many trees began exhibiting problems above 20% CO2 (200mbar). At these levels death was determined to be due to CO2 "overdose", not lack of O2. The trees were primarily pines and firs, which is especially relevant for early Mars terraformation because of their tolerance of cold and aridity. It is thought that the trees might have been able to handle even higher CO2 soil levels if their exposure had been more gradual.

Reference:
Forest-killing diffuse CO2 emission at Mammoth Mountain as a sign of magmatic unrest
Farrar et al., Nature, Vol. 376, No. 6542. (Aug 1995), pp. 675-678.

JoshNH4H · 2008-04-26 20:39:43

this has immedite practical applications. THis means that greenhouses on mars, if the outside pressure is 10 mb, the farm, at equal pressures, could have an atmosphere of 5 mb CO2, 5 mb O2. conversely, you could just heat the surface to 10 C.

Midoshi · 2008-04-26 23:00:19

I just had a brainstorm. My apologies if anyone has already had this idea.

It started when I was trying to come up with a fast and easy way of producing an atmosphere with sufficient pressure for surface activity without a pressure suit. Yes, yes, I know we're talking about transforming an entire world, but we're also an impatient species with a short attention span in geologic terms.

I began by being depressed over the estimate of (Zent et al. 1995) that in all likelyhood only 30-40 mbar CO2 could be outgassed by warming the Martian regolith. I know they put a tantalizing 190 mbar upper limit on things, but they in no way seriously believe that this is realistic. And even if there is that much, warming things to high enough temperatures and deeply enough to get most of the gas out requires a serious amount of time and engineering, no matter what warming process you use (mirrors, supergreenhouse gases, albedo darkening, etc.).

This reminded me of the discovery in recent years that there is actually very little CO2 ice at the Martian poles. This puts a huge hole in the archetypical "give it a nudge and let the atmosphere run away into a thick, stable state" that so often gets people hooked on the idea of terraformation. Easily released forms of CO2 are apparently drying up as we learn more about the Red Planet.

So my next line of thought was the route of thermal carbonate decomposition. But again, in realistically looking at the amount of mining required, not to mention building furnaces (be they solar, geothermal, nuclear, etc.) or bombs to liberate the CO2, it is a truly phenomenal task taking either millenia or efforts orders of magnitude above current terrestrial mining endeavors. There just aren't any shortcuts around the amount of material that needs to be physically handled.

Then I got to thinking about where the carbonate is on Mars. The 2-5 wt% we see mixed into the surface dust probably formed via CO2 and water vapor after the carbonate destroying acidic oceans had receded. This represents a CO2 reservoir at least 2-4 times as large as the estimate for adsorbed gas. Any subterranean deposits are almost certainly in hydrothermal veins, like the estimated 2.5 mbar locked up in Iceland on Earth (and that's only been from the past 16 million years). Based on extrapolations from Iceland and Martian meteorites, there could be several bar of CO2 locked up as carbonates in areas of Mars with evidence of volcanism.

Suddenly I realized that the reason any of these deposits formed at all was because they never had contact with the acidic oceans, either because they formed afterward or formed underground in alkaline conditions. But the thing is, all the sulfuric acid is still on the Martian surface in the SO3 anhydrous form. Just add water to the regolith, and...

BAM! As the water allows aqueous reactions to occur for the first time in billions of years the carbonates will be stripped of their metals by sulfuric acid and booted out of the regolith as CO2. An added benefit is that the acidity of the regolith is reduced as the sulfuric acid is neutralized to salts, allowing a better medium for plants to grow in.

If you want to accelerate things with a little engineering, you could tap hydrothermal carbonate veins and pump your acidic solution in and back out. Sulphates are more soluble than carbonates, so the solution would eat its way along the veins as it converted them, resulting in a reduced need for traditional mining through the surrounding rock.

I really like this tactic for two reasons: first, it could be started simply by getting Mars to the point where it can rain (maybe increase pressure a few mbar and get things consistently a bit above 0°C in the tropics?), and second it kills two birds with one stone by deacidifying the regolith.

Comments, constructive criticism?

noosfractal · 2008-04-26 23:41:49

This analysis ...

http://chapters.marssociety.org/winnipeg/soil.html

... seems to suggest that adding water to Martian regolith will get you a base, not an acid.

As a related aside, you might want to put this idea in the back of your mind ...

http://www.newmars.com/forums/viewtopic … 450#100127

Midoshi · 2008-04-27 05:57:47

This analysis ...
http://chapters.marssociety.org/winnipeg/soil.html
... seems to suggest that adding water to Martian regolith will get you a base, not an acid.
As a related aside, you might want to put this idea in the back of your mind ...
http://www.newmars.com/forums/viewtopic … 450#100127

Ah yes, I've seen that analysis. I did similar calculations on the new MERs data and got similar results, which really puzzled me because the "official" conclusions were going on about how acid it was...

...then I realized you have to take solubilities into account. While Na2O and K2O (which exist in lesser quantities than SO3 for most of the surface), are reasonably soluble, the bulk of the bases are CaO and MgO, which are slightly soluble and insoluble respectively. On the other hand, SO3 is "miscible" in water when it becomes the acid H2SO4, i.e. it's "completely soluble" and will probably be the first thing to go into solution.

Redoing the calculations you get a very acid solution for small amounts of water which becomes neutral and then basic as you add enough water for all the bases to completely dissolve. At that point you need 68 cm^3 of water for every 1 cm^3 of soil, which is a lot of liquid. Given a regolith depth of 100m you'd need 6.8 km of water globally to get all the base to dissolve...I don't think Mars ever had that much water on the surface by any estimates (that's significantly deeper than Earth's oceans).

As for your second link, I apologize, but I'm not sure I get the connection...?

louis · 2008-04-27 08:07:05

Hi - I've got a question which I hope you more scientifically literate types can answer.

Can a laser beam deflect gas molecules?

If so, would it be possible to secure atmospheric retention in a crater on Mars by creating a network of laser beams overhead - reflecting backwards and forwards and at the crater rim?

JoshNH4H · 2008-04-27 08:14:39

yes, I would say so (i'm no scientist), but it would take MW's of energy per square metre or more, and you have to remember that the lasers would go places.

noosfractal · 2008-04-27 11:53:56

Redoing the calculations you get a very acid solution for small amounts of water

Well, that's really exciting then. So warming to the point of allowing liquid water for any significant period should set off a nice positive feedback that liberates, say, at least 200 mbar of CO2? And this mechanism (liberation from carbonate by acid waters) hasn't been taken into account by previous terraforming estimates, so its a big bonus.

As for your second link, I apologize, but I'm not sure I get the connection...?

Oh, I just wanted to make sure you'd seen the idea of using the carbon of Phobos to make ice deposit impactors. I hadn't seen it before, and I think it might be a way of getting things going relatively inexpensively.

Midoshi · 2008-04-27 17:02:19

So warming to the point of allowing liquid water for any significant period should set off a nice positive feedback that liberates, say, at least 200 mbar of CO2?

Zent et al. used a ~100m regolith depth for their adsorption estimate to get 30-40mbar, and adding in the effect for 2-5 wt% carbonates gives you an additional 50-160mbar. So once things thaw to a depth of 100 m, yes, 200mbar is not impossible through natural feedback consequences. It's on the upper end of the the plausible range. Some synergetic solution mining of hydrothermal veins could improve things of course.

Ironically, we seem to have already demonstrated this simple carbonate release process on Mars! During the infamous Viking Labeled Release Experiment when water was added to the soil sample an initial acidity of around 4 or 5 pH was recorded. However, it then dropped asymptotically to between 6 and 7 pH (i.e. it was partially neutralized by something basic in the soil that dissolved slowly). The fact that CO2 was indeed released from the experiment and that the amount was consistent with the decomposition of a few weight percent of carbonate is very exciting. Similar results have been found for soil from the driest parts of the Atacama desert, one of the best terrestrial Martian analogs.

Oh, I just wanted to make sure you'd seen the idea of using the carbon of Phobos to make ice deposit impactors. I hadn't seen it before, and I think it might be a way of getting things going relatively inexpensively.

Ah, okay. Yes, it does look like a good idea. A similar but somewhat reversed proposal I've heard is to clear or compress the existing Martian dust to improve the surface's thermal properties and make temperatures more stable. This is probably more relevant for the local level, but moving dirt is a nice low tech process. (:

The great thing about CO2 feedback is that most of work boils down to getting it to rain at Mars' equator (that being the easiest location to initiate liquid precipitation). Once carbonates begin decomposing there, things spread to higher latitudes naturally. So even "local" warming tactics could help kick off a global transformation if judiciously applied to the right areas.

References:

Spectroscopic Identification of Carbonate Minerals in the Martian Dust
Bandfield et al., Science 22 August 2003: V 301, N 5636, pp. 1084 - 1087

Dry Acid Deposition and Accumulation on the Surface of Mars and in the Atacama Desert, Chile
Quinn et al., Lunar and Planetary Science XXXVI, 2005

nickname · 2008-04-28 19:05:35

Hi Midoshi,

Interesting idea about acid mining for C02 on Mars.

One big trouble with having it just warm enough to rain on the equator means it will be snowing almost everywhere else.

The reflective properties of the snow will quickly cool Mars below the heating induced to make it rain at the equator.

I think to get past that problem we need to make the heating of Mars similar to what we have on earth, 70% of Mars will need to stay snow free to maintain whatever heating we do.

Whatever we do i think it needs to be quick before Mars self cools as a natural process.

Any partial warming of Mars could actually make it a much cooler place than before you started.
I think we need an all out attack plan of many methods all at once to keep Mars out of the snowball state.

JoshNH4H · 2008-04-29 14:25:17

so biological and industrial greenhouse outgassing, this strategy, carbon from phobos and deimos on the ice caps etc?

nickname · 2008-04-29 16:44:56

jumpboy11j,

All of the above all at once
Then maybe a healthy dose of super greenhouse gas to keep it that way, or warm it even more, or at least keep the snow away long enough for us to finish the process.

We might get only a 1 to 2 year window before it stars to snow in quantity, so that is all the time we would have at the triple point of water and the formation of clouds.
With so much fine dust in the Martian atmosphere it will snow as soon as the clouds can form.
Even very local conditions early on in a terraform above 0c with an atmosphere thick enough that can form clouds will cause snow.

I have a feeling no matter what we do it will snow first on all areas and most of Mars as we warm the planet enough to have clouds, we will have to be quick at that point before we loose the gains we have made.

I also see a second problem later on for Mars terraformers, after the initial rains on Mars clear most of the fine dust particles it will be difficult for Mars to rain.
No good natural mechanism exists to return fine particles back to the clouds on a warmer wetter Mars for rain to form once the fine dust is gone.
As a wet planet most of Mars would be wet or covered in water, so natural fine dust will not return in quantity to the cloud level as it does now on the freeze dried Mars.

We will really need to pick up the man made pollution levels on Mars to have rain.
Or figure a way to induce a few volcanos on mars.
Or Mars might be a very cloudy place with little rain, cloudy enough to impact surface temperatures.

JoshNH4H · 2008-04-30 13:57:50

surely, after all of this, it won't be too much to throw some dust back into the air. I think there could be biological 'dust grabbers' if needed, algae/protist that makes some sort of solid waste, and releases it in the atmosphere.

nickname · 2008-04-30 16:29:22

jumpboy11j,

Good idea to use biology to form particles for rain.
Maybe something like mushrooms or fungus that produce huge quantities of windblown spores might do the trick.

I was thinking just how big a project it would be to have to pollute Mars atmosphere with fine particles of the man made sort just for rain.

JoshNH4H · 2008-04-30 19:11:16

You think of a climate problem, Then there is always some arcane biological solution.

But the spores would have to be small, right?

Midoshi · 2008-05-01 09:00:52

On Earth dimethyl sulfide (DMS) is released by bacteria breaking down dead algae in the oceans. The molecule is released into the atmosphere where it is oxidized and forms very good cloud nuclei. Since every single terraformation plan out there includes algae and bacteria, I suspect that what works for Earth will work for Mars. It may even be more effective, considering that there is way more sulfur on the Red Planet.

JoshNH4H · 2008-05-01 14:36:13

this sounds like a good idea. BTW, is it a greenhouse gas? What is it oxidised to?

Midoshi · 2008-05-01 17:44:18

is it a greenhouse gas? What is it oxidised to?

While it is a pretty good absorber of IR, the DMS molecule is highly reactive. On Earth it has a typical lifetime of just over a day. This means it doesn't have time to build up in the atmosphere and become an effective greenhouse gas. Major oxidation products are SO2, SO4²⁻, dimethylesulfoxide, and methanesulfonate.

Now, if you could "trick" bacteria into making hexafluorodimethyl sulfide (C2F6S), you'd have a molecule that's both potent and long lived. One might be able to do it by inserting the gene that produces the rare fluorinase enzyme found in the bacteria Streptomyces cattleya. This exact transgenetic insertion has been already done with a chlorine transferase, and there is research going on with the intent of having bacteria generate complex fluorinated compounds for pharmaceuticals. It would be comparatively easy to make fluorinated supergreenhouse gases by the same technique. No such designer molecule synthesis has been done yet, but bacteria have been engineered that can manipulate halide ions in solution.

Mars_B4_Moon · 2023-10-01 05:25:37

maybe worth bumping

Terraforming the Planet would be perhaps too difficult but in certain regions

Somewhat warm in the Biosphere but it might be cool like the Antarctic or the Tundra, the air might even be primitive like ancient Earth maybe a dome where the pressure of oxygen can sustain some kind of life for an extended time you might aim in the region of 10,000 ft - 20,000 ft where atmosphere is greater than 380 millibars, some radiation shielding. Mankind without technology or specialized food or clothing or heating can not survive in places like Alaska or Nepal or Tasmania or Norway or the French Kerguelen Islands also known as the Desolation Island, the colony on Mars will be far more difficult but just needs to support something maybe not 'people' it does not have to be fit for humans just fit for some kind of eco-system once an ecosystem is created chemicals and biofuels can be taken to support the man on Mars. You might have a mix of some type of grass or hardy bush plants, you should build something below the traditional Mountain Cold tree line on Earth, an edge of a habitat at which trees are capable of growing. You could have a type of system like the New Zealand Subantarctic Islands and the Australian Macquarie Island, Magellanic subpolar forests of South Chile and South Argentina, Nothofagus antarctica. There is alpine climate, and the habitat can be described as the alpine zone often found high elevations and high latitudes, above this Tree-line, trees cannot tolerate low temperatures, extreme snowpack, or associated lack of available moisture, the northern tree line on Planet Earth occurs at low elevations.

Nothofagus antarctica in Washington Park

PDF
https://web.archive.org/web/20061007235 … Report.pdf

I would think growing any kind of primitive system ,any types of moss or trees or Prehistoric Air would be a benefit, set up artificial ponds then you have Stromatolite types the photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, Stramatolites change the air, Biodiesel is takne from farmed plants, trees or compost or from algae. An industry which dumps large levels of Nitrogen trifluoride, Sulfur hexafluoride, Hexafluoroethane would change the Climate of Mars, Hexafluoroethane is a risky gas, it gathers in low-lying areas and it can cause asphyxiation but industry might Terraform Mars.

The Quest to Colonize Mars Is Uncovering New Mysteries About Human Psychology
https://www.inverse.com/health/quest-co … psychology

Inside the small world of simulating other worlds
https://www.popsci.com/science/small-worlds/
A niche research community plays out what existence might be like on, or en route to, another planet.

Last edited by Mars_B4_Moon (2023-10-01 05:49:51)

Calliban · 2024-01-08 04:51:07

Keeping Mars warm with super greenhouse gases.
https://www.pnas.org/doi/10.1073/pnas.051511598

Interesting. I havn't reviewed the paper in any detail yet. But the mass of the required gases is sufficiently low that a Martian industry could eventually export surplus gases to Ganymede and Callisto. On Ganymede, a thin 10mbar pure O2 atmosphere would shield out Jupiter radiation. It would also allow breathing on the surface using a suit fitted with a compressor. There is probably enough radiogenic oxygen in surface ices of these worlds for a 10mbar atmosphere.

For Mars, the authors suggest that it should be possible for a gas combination to heat the surface to an average of 280K. On Ganymede and Callisto, we might set a minimum temperature requirement for habitability at -50°C. This is the approximate lowest temperature that humans can work outside with very warm clothing.

Getting back to Mars: The authors suggest a colume density of 5E22/m2 would be needed to maintain a 70K warming on Mars. For the whole planet, that equates to about 1 billion tonnes of gas, taking flouromethane (MM = 0.088kg/mol) as a baseline. If an atmospheric lifetime of 100 years is assumed, future Martians would need to be making about 10 million tonnes of these gases per year. This is about 4 times as much flourocarbons as humanity is making on Earth at present. So this wouod be a significant mining and industrial programme. But it should be achievable when the population of Mars rises into the tens of millions.

Making more of the gas an shipping it to the Jovian system is a trickier proposition. But we should be able to build some large interplanetary ships by the 22nd century. Once the body in question has a thin atmosphere, aerobraking can be used to slow incoming projectiles. This avoids the need to precisely match orbits with Ganymede or Callisto. So we would pack the gases into basalt lined plastic bottles and just let them explode in the atmosphere after they have slowed down enough to avoid dissociating the gases.

Last edited by Calliban (2024-01-08 06:27:50)

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