New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: As a reader of NewMars forum, we have opportunities for you to assist with technical discussions in several initiatives underway. NewMars needs volunteers with appropriate education, skills, talent, motivation and generosity of spirit as a highly valued member. Write to newmarsmember * gmail.com to tell us about your ability's to help contribute to NewMars and become a registered member.

#26 2007-07-18 06:33:18

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Building soil

Thanks Midoshi, nice analysis.

I guess there will be a layer of cold for a very long time, but eventually (after 1000s of years?) you'll have to fill down to the bedrock.  Do you think that's true?

The whole transition time after the poles start melting is interesting to think about.


Fan of Red Oasis

Offline

#27 2007-07-18 12:08:52

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

Re: Building soil

It'll definitely take a good long time for Mars' crust to completely thaw out. It's hard to estimate that sort of thing since we don't know how deep the bedrock is for much of Mars or how the regolith parameters change, but based on extrapolation of that formula in my last post and what we know of how Earth responds to global climate change, it will probably at least a millenia before the soil +100 meters deep begins to thaw.

I do think that terraformers will ultimately have to fill down to bedrock for the areas that are above the groundwater freezing point on average and thus unable to support permafrost. I also think that's a water sink that many people don't consider. People talk about the caps "creating an ocean X meters deep" when evenly spread out across the surface, but that water would slip into the parched, porous regolith pretty fast!


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

Offline

#28 2007-07-18 18:54:44

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

It'll definitely take a good long time for Mars' crust to completely thaw out. It's hard to estimate that sort of thing since we don't know how deep the bedrock is for much of Mars or how the regolith parameters change, but based on extrapolation of that formula in my last post and what we know of how Earth responds to global climate change, it will probably at least a millenia before the soil +100 meters deep begins to thaw.

Tundra plants and desert plants only grow roots a few centimetres beneath the soil. Even wheat normally grows 0.7 to 1.0 metre root depth, although it can grow as deep as 2.8 metres if soil nutrients near the surface are scarce. Water avilablility is the most dramatic, plants will quickly grow roots down to where the water is. If permafrost keeps liquid water near the surface, there won't be a need to grow roots deep. There certainly isn't a need to grow 100+ metres deep.
References:
http://www.cropscience.org.au/icsc2004/ … altaja.htm
http://www.grdc.com.au/director/events/ … geNumber=3

The goal is to grow oxygen generating plants on the surface, and to grow crops for settlers. Does permafrost deep beneath the soil matter?

Offline

#29 2007-07-18 19:41:15

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

Re: Building soil

Tundra plants and desert plants only grow roots a few centimetres beneath the soil. Even wheat normally grows 0.7 to 1.0 metre root depth, although it can grow as deep as 2.8 metres if soil nutrients near the surface are scarce. Water avilablility is the most dramatic, plants will quickly grow roots down to where the water is. If permafrost keeps liquid water near the surface, there won't be a need to grow roots deep. There certainly isn't a need to grow 100+ metres deep.
References:
http://www.cropscience.org.au/icsc2004/ … altaja.htm
http://www.grdc.com.au/director/events/ … geNumber=3

The goal is to grow oxygen generating plants on the surface, and to grow crops for settlers. Does permafrost deep beneath the soil matter?

I completely agree and understand that you don't need a very deep active layer to get vegetation to grow on the surface. The only reason I mentioned thaw time for deep soil was to answer noosfractal's question about how long it could take for the permafrost to thaw down to the bedrock.

I do think that permafrost deep beneath the soil matters because it can determine how much water you will 'loose' into the ground before you create a water table high enough for plants roots to reach. At first things will be nice beause the premafrost will be shallow and you needn't have much water, but later as the permafrost becomes very deep you will need lots more water to create a root-reachable watertable. By the time things thaw to the point where that becomes an issue Mars may very well have been warmed enough that there is plenty of liquid water to fill in the ground with. I just think it's something to keep in mind.


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

Offline

#30 2007-07-19 06:17:39

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Building soil

There certainly isn't a need to grow 100+ metres deep.

Not to grow roots, but there is a bit more going on there.  Say you need just the first meter for growing wheat.  I'm guessing that the temperature of that first meter needs to be ... what ... 15 C?  Certainly it can't be just above zero.  And I can't imagine that you can have ice right beneath that first meter - there is going to be a temperature gradient. 

Maybe you can have ice at the 10 meter level, or say the 15 meter level for this example to give a gradient of 1 C per meter.  But is that gradient right?  It depends on the soil, I know, but if the gradient is closer to 0.1 C per meter, then you do need 100 meters or 150 meters between the ice and the bottom of your roots.


Fan of Red Oasis

Offline

#31 2007-07-19 12:26:17

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

Re: Building soil

Maybe you can have ice at the 10 meter level, or say the 15 meter level for this example to give a gradient of 1 C per meter.  But is that gradient right?  It depends on the soil, I know, but if the gradient is closer to 0.1 C per meter, then you do need 100 meters or 150 meters between the ice and the bottom of your roots.

That's a good point noosfractal.

The subsurface temperature gradient in a locality is dependant not only on the soil's thermodynamic properties, but on the past history of that area's surface temperature. I talked about the soil before, but you've made me realize that the past history is more complex and important than I initially thought.

As I said in my analysis above, I was taking 0C to be the average annual temperature. Implicit in this is the assumption that seasonal temperature variations dominate the determination of a locality's surface temperature. However, this is not always the case.

I mentioned before that there are three time regimes that come to play in determining surface temperature: diurnal, seasonal, and geological. Which of these influences dominates depends on the situation. On Mercury, which has very little atmosphere and tilt, there are huge diurnal fluctuaions, ranging from 90 K to 700 K, and virtually no seasonal changes. On Earth the diurnal and seasonal effects are roughly equivalent at the equator, while at the poles seasonal fluctuations dominate. A similar situation would be found on Mars, except that in the midst of terraformation there would be a very pronounced 'geological' effect of global warming (much more so than on Earth).

The upshot of all this is that you will have very different subsurface temperature gradients on Mars-in-progress depending on what latitude you are at, how stable your diurnal fluctuations are (i.e. how thick your atmosphere is), and how quickly you are warming the planet. That all sounds complicated, but a first-order approximation for the subsurface gradient is actually not hard to derive given a function that describes the surface temperature history of a given area. I should probably try slapping a parametric general equation together...


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

Offline

#32 2007-07-22 22:07:27

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

I found a couple interesting papers. The following talks about acid produced by sphagnum in a peat bog.
http://courses.mbl.edu/SES/data/project … xander.pdf
It says:

Because of unique cation exchange properties generated by Spahgnum plants, they have been studied as important sources of acidity in Sphagnum-dominated bogs. Sphagnum growth results in the continuous formation of cation exchange sites at the plant apex (Clymo, 1967). Most (if not all) uronic acids at these sites are manufactured in a free acid form: -COOH. When precipitation or groundwater flows over the plants, the hydrogens (H+) on the carboxyl groups are then exchanged for cations in the water. This displaces the H+ into solution, lowering the pH of surrounding waters (Gorham and Cragg, 1960). Clymo found that growth rates of Sphagnum are adequate to maintain a typical bog at pH 4, entirely by ion exchange mechanisms (Clymo, 1964).

Ion exchange by Sphagnum is just one of the various factors that may control bog acidity. Other studies have attributed possible sources of acidity to CO2 build-up, oxidation of reduced N and S, assimilatory cation uptake, production of organic acids during decomposition, and acid deposition (Urban, 1987). Potential sinks include decompositional release of cations, alkalinity inputs, assimilatory anion uptake, dissimilitory anion reduction, and weathering reactions (Urban, 1987). The contribution to total bog acidity by each of these mechanisms varies among specific environments, and the relative importance of each has been argued over past decades.

In a salty environment, hydrogen ions of acid will work with chlorine ions of salt to effectively form hydrochloric acid. Although carbonic acid dissolves feldspar, hydrochloric acid works much faster. Dissolved CO2 atmosphere in the bog will create carbonic acid, reduceing pH (increasing strength of acid) and releasing more H+ ions. That will combine with chlorine from salt making more hydrochloric acid. Strong acid means fast hydration of minerals and leaching nutrients.

I also found a paper that talks about effects of UV-B on sphagnum.
http://www.ingentaconnect.com/content/b … 2/art00009
The abstract says:

Plots receiving either near-ambient or reduced UV-B radiation were established using different louvered plastic film filters over Sphagnum bog and Carex fen ecosystems in October 1996. In the Sphagnum bog system, growth measurements during the late spring and summer showed no significant differences in the moss Sphagnum magellanicum, or the vascular plants (Empetrum rubrum, Nothofagus antarctica, and Tetroncium magellanicum) between near-ambient and attenuated UV-B radiation treatments.

This implies sphagnum is not sensative to UV-B. Since UV-C doesn't reach the surface of Earth (stopped by the ozone layer), experiments are more difficult. UV resistance is good for Mars.

Offline

#33 2007-07-23 00:13:28

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

Re: Building soil

This implies sphagnum is not sensative to UV-B. Since UV-C doesn't reach the surface of Earth (stopped by the ozone layer), experiments are more difficult. UV resistance is good for Mars.

Pretty interesting. And it turns out we don't need to worry about the whole UV-C spectrum either:

CO2 absorption is significant at wavelengths < 204 nm and effectively provides a shield below ~190 nm [on the current Martian surface]. Above 204 nm, the CO2 extinction cross-section is equivalent to the Rayleigh scattering cross-section, i.e., there is negligible CO2 absorption...On present day Mars, the total integrated UV flux over 200-400 nm, is comparable to the Earth’s. However, on Mars the shorter wavelengths contribute a much greater proportion of this UV flux. These wavelength ranges, such as UVC (200-280 nm) and UVB (280-315nm) are particularly biologically damaging.

http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6128.pdf


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

Offline

#34 2007-07-23 13:23:42

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

Very interesting. Thank you. That relieves one worry: X-rays. The next band in the electromagnetic spectrum with higher frequency (shorter wavelength) than UV-C is X-rays. In tern X-rays are subdivided, low frequency (long wavelength) are soft X-rays, then medium, then hard. Above hard X-rays are Gamma rays. I had worried about soft X-rays because Mars has very little nitrogen; nitrogen absorbs X-rays, particularly medium X-rays. This says CO2 blocks X-rays. Great! One less radiation to worry about.

CO2 absorption is significant at wavelengths < 204 nm and effectively provides a shield below ~190 nm
...
These wavelength ranges, such as UVC (200-280 nm) and UVB (280-315nm) are particularly biologically damaging.

Notice CO2 will not block wavelengths longer than 204nm, so the band 204-280nm will get through. That's UV-C, so it is a concern. The spectrally selective coating on a spacesuit helmet visor or spacecraft windows will block UV, but this thread is about terraforming.

Offline

#35 2007-07-23 17:54:46

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

Re: Building soil

We need to be careful which sphagnum moss is used. I found a very interesting and somewhat sobering paper on one kind of sphagnum moss's reaction to UV-B.

"Effects of enhanced UV-B radiation on production related properties of a Sphagnum fuscum dominated subarctic bog"
1. The aim of the study was to investigate effects of enhanced UV-B radiation on the balance between biomass production and decay in an ombrotrophic bog which is dominated by one species of Sphagnum (S. fuscum). This paper concerns production.

2. Enhanced UV-B radiation (simulating 15% ozone depletion under clear sky conditions) was applied by means of fluorescent tubes during two growing seasons.

3. In S. filscilm, shoot density, mass relations and length increment over time were measured and productivity was estimated. Pigment concentration, rates of dark respiration and maximum net photosynthesis were recorded.

4. Sphagnum filscum productivity was not changed by enhanced UV-B radiation while properties determining production were highly influenced although in opposite directions.

5. Height increment was decreased by 20% in the first growing season and by 31% in the second growing season under enhanced UV-B radiation. After two growing seasons spatial shoot density was decreased by 8% by enhanced UV-B radiation. The shoots became stunted as capitulum dry mass and stem dry mass per unit length were increased by 21 and 17%, respectively, under enhanced UV-B radiation.

6. Dark respiration was significantly decreased by 31% after growth under enhanced UV-B radiation.

7. The UV-B induced change in shoot biometry together with the reduced spatial shoot density involve potential long-term effects on peat structure with possible feedback on productivity, decomposition and the strength of the system as a carbon sink.

...From this study it cannot be proposed that productivity and thus carbon capture from the atmosphere do change directly owing to enhanced UV-B radiation. Variables determining productivity in S. fuscum were affected by enhanced UV-B radiation in opposite directions and may have compensated each other. However, the studied system is dominated by the hummock forming species S.fuscum while bogs often contain a mixture of Sphagnum species forming a mosaic of hummocks and hollows. Responses to UVB radiation can highly differ in both magnitude and direction between species as shown for vascular plants (Caldwell et al. 1995). Thus extrapolations to more complex peatlands should be made with care.

Note that the paper can be taken both ways: it found that increased UV-B didn't really hurt the species of moss studied, but it also cautions that other mosses often react differently and extrapolation must be done carefully. Biodiversity is good, so we'd need to round up as many of the UV-B tolerant sphangum species as possible.

I still think that sphagnum bogs are a critical step in the terraformation of Mars. It's not widely known, but Mars DOES have a permanant ozone layer. It is formed by the breakdown of CO2 by high frequency UV. It is currently not enough to produce significant protection, but if the CO2 atmosphere were thickened and some preliminary microbial mats began pumping out a small amount of oxygen maybe it could begin to become substantial?


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

Offline

#36 2007-07-23 18:56:28

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

Don't want to wreck this thread but ......
Has anyone checked to see if sphagnum will even grow in a mostly C02 atmosphere?

I don't think any plant can tolerate high atmospheric levels of C02.
I seem to remember reading a bio paper limiting plant life to around 12% C02.

Seems to me on Mars before the introduction of plants we will be well beyond the 12% c02 content?


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.

Offline

#37 2007-07-24 11:52:01

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

Re: Building soil

Don't want to wreck this thread but ......
Has anyone checked to see if sphagnum will even grow in a mostly C02 atmosphere?

I don't think any plant can tolerate high atmospheric levels of C02.
I seem to remember reading a bio paper limiting plant life to around 12% C02.

Seems to me on Mars before the introduction of plants we will be well beyond the 12% c02 content?

Granted, moss are not as hearty as bacteria, algae, fungi, or lichen. However, they are sturdy organisms:

Bryophytes (mosses) are small photosynthetic organisms, with quite simple physiological requirements. They can grow and photosynthesize at low temperatures. They tolerate a high CO2 level. It was found that, in moss colonies, CO2 partial pressure is around 3,6 mbar, compared to the 0,36 mbar in the terrestrial atmosphere (Tarnawski et al., 1992). Some experiments shown that bryophytes can resist to CO2 partial pressures as high as 20 mbar (Tarnawski et al., 1992). The oxygen quantity needed is also small: below 30 mbar...(Aro et al., 1984). They can resist for years to severe dryness and, when humidity increases, they can restart their photosynthetic activity.

Now, that "below 30 mbar" of oxygen needs some explaning. While it's only 14% the partial pressure of oxygen we have on Earth, it still seems a rather high value for a terraformed-Mars-in-progress, where the current oxygen pressure is currently something like 0.01 mbar. The truth is that 30 mbar O2 just happens to be the lowest that Aro et al. examined; in fact, with 30 mbar O2 and (Earth) normal CO2 levels, the moss was 40-45% more productive in net photosynthesis than under normal Earth conditions! This improvement was also true for higher CO2 levels at 30 mbar O2, though with less drastic enhancement. The highest Aro et al. took it was 1 mbar CO2, but even at this concentration the effects of positive photosynthetic effects had not fully saturated (i.e. raising the CO2 level further would have given more benefits). As you can see from the other references, deleterious effects of high CO2 concentrations do not become serious until 20 mbar, or about 3 times the pressure of the current Martian atmosphere.

The real question is "How low can the O2 go?" The current 0.01 mbar is undeniably low. Some (not all) bacteria and algae don't mind 0% O2, while yeasts need at least 0.1 mbar. Lichen are a symbiosis of algae and fungi, so their minimum requirement would be similar to that of yeasts. I can't find any studies about the minimum O2 requirements of moss (in fact, the lack of data is bemoaned in many terraforming papers!), but it's certainly at least 0.1 mbar. It is also possible that the O2 requirement of moss could be satisfied by oxygen dissolved in the bog water, which could be locally provided by bacteria and algae, so that significant global preliminary alteration of the atmosphere would not be necessary.

At any rate, you can't wreck the thread just by proving moss can't live on Mars without higher O2 levels. Remember, the original point was just to produce good soil, not terraform Mars solely by moss.


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

Offline

#38 2007-07-24 16:42:25

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

Midoshi,

Difficult to find facts is an understatement. smile

We almost need a study on probable conditions and what will grow under those conditions on Mars.
Then we could have a decent plan on the best way to alter things in an ordered pattern best suited to what we plan.

Although it's possible to grow sphagnum on a slightly thicker atmosphere on Mars beyond 30mb we don't get free water at those bar pressures and little UV protection under 100mb.

Minimum pressures that produce enough heat insulation , UV protection and free melt water are around 100mb of almost all c02.
A catch 22 here for sure if our intentions are plants on Mars at reasonable time frames.

I think you are correct in selecting the other organisms to start getting things rolling.
Those tougher more primitive organisms should do much better in a higher c02 atmosphere, the water ones even better than the land ones.
If we are very high in c02 I'm not sure any of the even very primitive ones will endure it either, the water will also have a pretty high c02 content on a world with an atmosphere made up of it.
We might have very few selections of any life that are capable of the initial conditions.
No oxygen will exist in the water for a long period of time even with cynobacteria growing happily, due to so much free iron in the water.

Earth atmosphere at worst was maybe 25% c02 at its most primitive times.

Going from Frozen desert Mars to Earth like wet Mars looks pretty simple until we start dealing with the details and set of rules Mars will impose on us.
I have a feeling we are going to have to follow the same sort of path nature took on earth to get to the final goals on Mars.

If we do end up with a Mars around 300mb of mainly c02 it will take a very long time to make it safe for plants on land.
Almost as long again or longer before its safe for animal life as 1% c02 is unsafe for most animals.
Rain patterns on a less energized world and 1/3 G may also play a significant role in what happens and what can live on Mars.

Interesting to think about how difficult Mars will really be to teraform though smile
You are probably right that most plant forms need a minimum oxygen content, yet another problem that needs looking into.
The dark cycle of plants uses quite a bit, we can guess from Earths content when plants first appeared on land as to what that is.

Lots of options for greenhouse pet bogs early on, so we need not try to teraform the entire planet, maybe just small bits at a time.
0xygen content control not to difficult in a greenhouse either. smile


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.

Offline

#39 2007-07-26 00:22:13

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

Re: Building soil

Bacteria, algae, fungus, and lichen are crucial in kickstarting terraformation, and their contribution cannot be understated. They are the most readily suited organisms to the current (or an only slightly changed) Martian environment, and will be key in colonizing the initially rather nasty conditions with briny water and a thin, oxygen deprived atmosphere. However, we want to make the transition to more advanced lifeforms as quickly as possible. Moss and other bryophytes are the natural (in every sense of the word) second step. Once the Martian environment has been altered just enough to allow their growth outside greenhouses, they should be spread as quickly as possible to accelerate the terraformation process beyond what is possible with the "first step" lifeforms.

Although stream environments present a number of challenges for bryophyte reproduction and survival, some bryophytes have characteristics that allow them to persist in a wide variety of stream types (e.g., adaptations to low light and temperature, rapid nutrient uptake, resistance to scouring and spates). Primary production by aquatic bryophytes can equal or exceed that by epilithic and periphytic algae, which have been much more widely studied.

Mosses...are the most productive autotrophic component in the [Moisie River] watershed (3.9 x 10^10 g/yr); by comparison, periphyton [algae and cynobacteria] produce only 2.1 x 10^10 g/yr.

Absence of some groups of invertebrates, which are widely distributed in tundra (earthworms, Tipulids, Oribatid mites, beetles) was recorded. Population density of invertebrates in moss-lichen communities was relatively high and their biomass averaged 6-8 g m-2 and in some plots up to 20 g m-2. Invertebrates hardly occurred in the bare ground, where lichens and algae only were found. The biomass in such habitats reached over 1 g m-2.

Even artificially iron nutrient enhanced algal blooms are incapable of approaching the sphagnum peat bog's ability to sequester carbon (and thus produce humus and an oxygen rich atmosphere). At 2 grams/m^2/yr for the algae (Buesseler & Boyd 2003) versus 14-72 grams/m^2/yr for the sphagnum (Belyea & Malmer 2004), the bog is about an order of magnitude or more efficient. Note that both these studies took place at extreme latitudes on Earth, and so are not bad analogies for Mars in some ways.

By the way, iron radicals grabbing all the oxygen will not be the limiting factor for O2 concentrations in Martian bog water. Iron depends quadratically on OH- concentraions to oxidize with dissolved O2. This means that in a typical pH 4 bog Fe+2 will oxidize to Fe+3 at a rate 1,000,000 times slower than in neutral water. In fact, ~pH 4 is considered something of a transition point at which there is so much unreacting iron and dissolved oxygen sitting around that it becomes energetically favorable as a metabolic pathway. The bacteria Thiobacillus ferrooxidans is famous for exploiting this. Another factor reducing oxygen solubility is salinity, but even in solutions 2 times as salty as Earth's ocean the O2 saturation point is reduced by less than half its pure water value. Unfortunately, it turns out that the most serious limiting factor to O2 solubility in water is the partial pressure of oxygen in the atmosphere, which means we still have to substantially raise O2 levels. It will require at least 2 mbar O2 and probably more like 10 mbar to raise solubility to the point that water at 10°C can accept the dissolved oxygen values typically found in peat bog water (Rigg et al. 1927). Colder water would require slightly less pressure and warmer water would require slightly more. Note these minimum O2 values are consistent with the >0.1 mbar lower limit that the fungus analogy provides and the "below 30 mbar" upper limit from the study that I mentioned in my last post.

A final note on protection from UV and elevated CO2. Many mosses, including some Sphagnum species, are quite capable of thriving completely submerged, provided there is sufficient dissolved CO2 (not a problem on Mars) and O2 (which must first be raised by algae or some other organism). Since a fairly thin layer of water can very effectively block the most damaging UV rays on Mars, many mosses (and other aquatic bryophytes like some hornworts and liverworts) can be protected from radiation early on when the atmosphere might not otherwise be thick enough to satisfactorily block radiation. This technique has been discussed several times before in these forums for other organisms. Another benefit of being underwater is that it limits the amount of CO2 that will reach the moss from the atmosphere. Bogs are often naturally supersaturated with CO2 formed by biological processes, and have been found at up to 6.5 mM (Nilsson & Bohlin 1993). This suggests that a submerged sphagnum bog in 10°C water could easily take a 130mbar CO2 partial pressure atmosphere, and probably much more before the moss became uncomfortable. This is remarkable considering that the experiments I mentioned in my last post determined a maximum 20 mbar CO2 partial pressure for unsubmerged moss. As with O2, an increase in temperature will lower solubility in water (here increasing the maximum CO2 pressure that a submerged bog cold take), while decreasing the temperature will raise the solubility (requiring a lower atmospheric CO2 pressure to avoid damaging the moss).

I also happen to think that mossy bogs are prettier than puddles of algae. smile


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

Offline

#40 2007-07-26 01:11:53

RickSmith
Banned
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: Building soil

Hi Midoshi,
  Wow, what a great post.  I always enjoy reading your stuff.

  You were talking about the UV protection of water but there is likely to be a thin layer of ice on things much of the time in the early days of terraforming.  Some times the electromagnetic radiation transmission thru a crystal is much different from that thru the same substance as a liquid.

  I was wondering if water ice gives more or less protection to UV and water?  Does anyone know?

  Warm regards,  Rick.

Offline

#41 2007-07-26 01:26:30

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Building soil

Just awesome data Midoshi.  I can't believe how quickly we'll be able to start establishing these bogs.  Even 2 mbar O2 won't be instantaneous though.  I looked at how much energy it would take by electrolysis: 32 terrawatts for 100 years (yikes!  current energy usage on Earth in all forms - coal, oil, nuclear, etc - is ~14 terrawatts).  Any idea how long it will take algae to get us 2 mbar?


Fan of Red Oasis

Offline

#42 2007-07-26 06:16:32

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

Midoshi,

Nice info about the ability of moss to adapt to Martian conditions.
Moss in water is very adaptable and tough as i expected.
Wish more people would inject realistic details like that, instead of trying to hop to conclusions about plant life or any life on Mars.

Nice to see that the iron quantity in the water won't be as big a problem as i expected, iron could have been a long time killer, a degradation of the water and made our life selection small indeed.

Maybe we are looking at the problem from the wrong perspective.
We should probably look at what bar pressure, atmospheric contents, temperature, background radiations and UV quantities we will have on a mars with surface water/rain.
Then decide what is best suited to those conditions, we are probably going to have to do that anyway.
Mars will settle into a balance somewhere, our job will be to select things that work in and around that balance.

Sure we will have a brief period that atmospheric conditions won't be as high as they will be after the regolith fully joins the party.
If that partial pressure period is only a few decades is it worth being in the plans for plant life or any life?

I have to agree that pond scum VS Pete bog is no contest in prettiness factor smile
Although pond scum is pretty sexy under a microscope smile


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.

Offline

#43 2007-07-26 06:38:22

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

noosfractal,

Lets not forget that we need a minimum 100mb co2 atmosphere for liquid water on Mars to seed algae.

Ice algae is possible, but we would still need snow or rain for that to form at the minimum bar pressure we get either.

Ice algae is very slow growing and i think we would want to avoid adding much ice/snow to a world we are trying to warm.


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.

Offline

#44 2007-07-26 16:59:28

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

I looked at the next step of using a peat bog: draining the bog and neutralizing acid to prepare soil for crops.

I calculated time based on a fixed pH of 3.5 and temperature of +25°C. Using weather statistics for Bissett Manitoba, within the Boreal Shield ecozone in Manitoba, the mean daily temperature is between 11°C and 19°C for May through September. Using the average +15°C and extrapolating from the anorthite dissolution table, we get -12.68 as a logarithm in mol/cm2/sec. That will take 749.5 days. There are 153 days in those months, so it will take 4.8987 years; round it off to 5 years. It may take one year for sphagnum moss to grow to cover the area and produce strong acid, and a summer season before that to clear-cut the land and grind bedrock into rock flour, so 7 years from setting foot on the land to completion. Assume something similar on Mars: 7 Earth years to complete conversion of rock into soil, with clay deep soil and peaty top soil.

Once complete, acidity within the soil will have to be neutralized. The Boreal Forest Research Centre lists wood ash as an effective means to neutralize acidic soil. Soil pH lower than 5.1 is considered very acidic and infertile. The 3.0-3.5 pH of a peat bog is well below that. Fine textured Black soil, organic, and peaty soils require 3-4 tonnes/acre wood ash to raise pH by one point. To raise soil from 3.5 to 5.5 is two whole pH points. The way pH works, it takes 10 times as much ash to raise 2 points as it does one. That means 30 to 40 tonnes per acre, assuming soil is pH 3.5 after draining. Moderately acidic soil is pH 5.5 to 5.6, so this treatment is minimum. Growing trees in the bog will be a necessity on Mars, just so they can be burned for wood ash. Once burned and mixed with top soil, it will still be moderately to strongly acid soil.

Moderately acid soil: pH 5.5 to 5.6
Direct effects on crops
Improved survival and growth of rhizobium bacteria, which fix nitrogen in association with alfalfa and sweet clover. Yields of alfalfa and sweet clover increase. Small increases in yield of barley occur in the first two or three years following lime applications with larger increases (25-30%) occurring in subsequent years. Yields of wheat and canola will be increased less than barley.
Indirect effects on crops
Liming may improve physical properties of some medium and fine textured soils as indicated above. Plant availability of phosphorous fertilizer is improved. Increased microbial activity and release of plant nutrients. Yields of more acid tolerant crops may be increased as a result of indirect effects of lime as outlined above.

Strongly acid soil: pH 5.1 to 5.5
Direct effects on crops
Increased nitrogen fixation and yield of legumes. Soluble aluminium and manganese are reduced to non-toxic levels.
Indirect effects on crops
Indirect effects as outlined above for moderately acid soils. Yields of most crops are increased as a result of improved availability of phosphorus and other nutrients.

Offline

#45 2007-07-26 21:25:11

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

RobertDyck,

1/2 the light on Mars =1/3 the growth rate.

Average temperature on Mars might be 5c so we can also multiply times 3.

Additional UV and radiation on mars = 25% or more decreased growth rate.

7 years X 3 years X 3 years by 3/4

100 years or so on Mars to do what happens on Earth in 7.
This is very rough, probably the real Mars would impose many more restrictions.

How do we burn anything on Mars with almost no oxygen in a c02 environment trees wont grow in?
The typical answer of the moss will convert the c02 wont work either since converting even 50 mb will take longer than mankind has been mankind.
Best guess is we will need to convert about 100mb of c02, mars should do the rest for us.

I'm just touching on the main problems everyone has with converting Earth to Mars results without the Mars math included.

I see so much of the Earth related results, like adding just a small bar percentage to mars then growing moss, but forgetting that moss needs water that can only be achieved with a higher bar pressure than the goal bar pressure to begin with.
Cant have plants without water and cant have water without insulation.

I think planting anything on Mars will be a challenge.
Mars has many distinct challenges for all life.

1.UV and other radiation doses maybe big enough to change genetics faster than species can keep up with causing sterility in just a few generations.
Water species might be the exception.

2. 1/3 G, many many problems here from transpiration to cell wall covering, enzymes synthesis etc etc.
No real research here yet, but when it arrives i bet its not what we hope for.
Some 0G experiments have been done with mixed results, but 0G and 1/3 G are two very different beasts.
Water species might be the exception.

3. Rainfall patterns, to begin with a terraformed Mars should be a very wet planet with lots of rain from atmospheric dust.
After the initial rain out of the dust Mars will settle into more like desert rain conditions on Earth.
The rain and cloud patterns might be very un energetic since Mars has about 1/2 the solar energy of earth and no volcanic activity to help seed rain.
Water species will be the exception.

Not trying to be to negative here or trying to pick on you personally.
Just being more realistic about what to expect on Mars.

I question the entire teraform idea for Mars when we could teraform sections with a large sheet of clear UV protected plastic like material, a compressor, a few bars and a snow shovel.
If we choose to make a pete bog or tropical jungle or salt ocean with fish in one, then why not build it and not have to wait for the entire planet.

What benefit does terraforming surface Mars have over west Edmonton Mall Mars?


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.

Offline

#46 2007-07-26 22:47:54

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

Sigh! Nay sayer.

First, the triple point of water is 6.1173 mbar. The pressure recorded by Mars Pathfinder never got that low, it varied from 6.77 to 7.08 mbar. That means liquid water can exist on the surface of Mars right now. The rivulets imaged by Mars Global Surveyor are evidence that water does flow on Mars today, it just doesn't last long. We need more heat for water to stay liquid for more that a couple hours.

Second, acid converts feldspar to clay at a fixed rate. It doesn't matter how active the moss is, once strong acid is formed it will act on its own. A long year on Mars means long summer as well as long winter. That means twice as many days of winter between summers, but summer also lasts twice as long. So the number of Earth years to completion actually stays the same. Light intensity doesn't matter, the moss may take longer to form but once acid is formed the reaction will proceed at full speed.

Next, you keep forgetting this thread is about an advanced stage of terraforming. It's about building deep soil to grow crops like wheat outdoors without a greenhouse. At first colonists will use pressurized greenhouses to grow food. Then we build chemical plants to spew greenhouse gasses at industrial rates. Since extracting carbon from calcite and dolomite releases oxygen, so we'll release a little oxygen as well. We'll probably also need a space mirror to focus light on the poles. Note I said poles; that's where you need heat to sublimate CO2. Once all the dry ice is sublimated, the thick atmosphere and warm conditions will start to melt all that water ice.

Initial terraforming organisms on Mars will be sturdy plants that produce oxygen from CO2, don't require atmospheric O2 or soil carbon compounds, can live on Mars soil without conditioning, and grow rapidly. That may mean moss or fungus or cyanobacteria, I don't know, but this thread is about building deep soil.

One rational for study space settlement that the average public can relate to is applying those techniques right here on Earth. I found one; terraforming can convert Canada shield to deep arable soil. I spoke to a teacher to worked in northern Manitoba; he claims all this isn't necessary, that there are patches of deep black soil now, and they're relatively level. If so I keep asking why they don't grow their own vegetables, and build cold storage to keep them over winter. Perhaps set-up a canning business. My mother pickled cucumbers to make pickles, stored in mason jars. She grew up on a subsistence farm, but we lived in a suburb. I also mentioned a berry that's native to Manitoba but considered a delicacy in Scandinavia, served fresh or as jam or liqueur; great export opportunity. But they don't. Sigh.

Another reason to settle is to grow the economy. Gamers know you don't wait for current resources to run out before expanding. Ever play a strategy game like Star Craft? You have to establish a second base to harvest resources long before your first base runs out. As long as you have more than one, your economy ticks along nicely. If you wait for the first to run out, everything stagnates and you struggle to get the second one. In fact, you probably won't have enough resources to build a second base once your first base is running out. Limited resources is very dangerous. That's a war game, the opposition will kill you if you run out, but in real life there are natural disasters that stress the economy.

So let's see, Mall Word. Is that what you're arguing for? That requires a massive roof. Do you realize how big a planet is? Mars has as much surface area as all the dry land on Earth combined. Requiring a roof is very expensive, it greatly limits growth. Besides, didn't you read the thread where we calculated there's more than enough CO2 to create sufficient pressure for both humans and plants outdoors? We don't need a roof, just enough heat to sublimate all the CO2.

Offline

#47 2007-07-27 06:23:30

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

RobertDyck,

I have no problem with the Pete bog on Mars or any other echo system we choose to seed.

The trouble i have is the in between point, getting from the now Mars to the green world Mars is not going to be very straight forward.
The unknowns of plant and animal life on a early teraformed mars might be so insurmountable that we abandon the idea before it begins.
Or Mars never goes beyond the bacteria phase because nothing else can adapt.

The data for Mars having water right now seems pretty good, as you point out it doesn't stay long.

If the pressure was say 50mb a water/snow cycle would start with that escaping water.
Snow would fall on the ground and cool Mars, the more water we have in that cycle the more snow cover the cooler mars gets from reflected light.

At around 100mb of pressure all the planet starts to melt.
100mb becomes 300mb in a few decades.

Trouble here is how to get to 100mb without turning Mars into a global snowball that needs 150mb or 200mb to escape from?
Getting Mars to the 100mb at a very fast pace is no easy trick.
I have only one clean way that will work to get an atmosphere beyond the 100mb key in short term, but we end up with a 500-600 mb co2 atmosphere.
The other ways using large impactors will work but cause nearly as much disaster to mars as well.

Any solution to warm mars will leave us an atmosphere mostly made of c02 that takes epochs to convert to 02 and carbon products.

If we ended up with a Mars of 250mb of near all co2 that would be about the same amount that earth had to convert over the epochs.

I haven't forgotten the theme of advance teraforming here, but to do that we need a convincing route to that goal with no skip step jumps and no forgetting the rules at mars.

West Edmonton mall mars wont be as difficult to build as expected.
Mars has all the raw materials to build it all.
Not sure i would want to live in a immense mall that makes west Edmonton look like a tiny section, but i think its the future of mars settlement.


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.

Offline

#48 2007-07-28 20:27:37

RickSmith
Banned
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: Building soil

1/2 the light on Mars =1/3 the growth rate. ...

This is not at all what I understand.  There are two types of plants, the C3 and C4 plants (refering to the chemical path followed by the carbon atom in photosynthesis.)

There are about 300,000 species of C3 plants with only ~3,000 species using C4 photosynthesis.  The C4 plants are newcomers (mostly grasses but including sugar cane and maize). 

If you plot the rate of photosynthesis to CO2 level, you find that as you raise the amount of light at a given CO2 level, the growth rate rapidly flattens out.  This point is called the light saturation which begins at >200 micro moles of photons / m^2 / second.

TABLE OF INCREASING LIGHT LEVELS AND CO2 UPTAKE
..........................Light Level
..........................100.........200..........300..........400........500........1000.......1500.........2000
C3 Plant uptake:....4..............7............8..............9...........9.5.........10............10.............10
C4 Plant uptake:....3..............7..........10.............15...........20.........35............42.............47

Light levels measured in micromoles of photons /m^2/s of Photosynthetically Active Radiation (PAR)

CO2 uptake measured in micomoles of CO2 / m^2/s.

By the way, the levels reach about 2000  micromole/m^2/s of PAR photons on the Earth's surface.

Note that at higher CO2 levels, the C3 plants close much the gap between them and the C3 plants.

(This data comes from page 103 of Terraforming by Fogg and I am reading the values off of a graph with out a grid so the values are a bit approximate.)

Anyway, at about 1/4 Earth's light levels, C3 plants have maxed out their growth.  C4 plants do much better but even they grow more slowly as you increase the light level. 

In fact many C4 plants have light colored leaves to reduce the amount of light absorbed (and heat).  The light level does not matter to them; it is the CO2 level that limits their growth.

So to first and second approximation it would be more correct to say, 1/2 the light = 100% of the growth.  (At least for C3 plants.)  In the asteroids the light should still be enough.  At Jupiter orbit your plants are beginning to starve for light and would grow faster with more. 

Warm regards, Rick.

Offline

#49 2007-07-29 18:45:47

nickname
Banned
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Building soil

RickSmith,

Almost all  the group of plants you are referring to are very poor in UV, most are under canopy plants and most tropical species.
Only a very small handful would be useful for Mars.

No matter how you select plants the production at 1/2 light will be about 1/3 the 02 production VS Earth.

Even with temperatures and rain fall patterns identical to earth the echo system wouldn't be as productive on Mars with 1/2 the available energy to plants.

Main difference in c3 and c4 plants is the way they take in c02, the c3 group does this in a near automatic procedure in an inefficient manner, c4 plants can control its intake in a more robust  efficient fashion.
It is believed that c4 plants came into existence when the available c02 levels on earth were at the lowest.

That one fact about 3c plants might rule out the entire group with an atmosphere of much higher co2 content than earth ever had and no control over its intake.

A good selection of plants for Mars might be cacti, they are c02 controlling plants, can withstand long droughts, endure higher UV amounts than most plants and a few species grow happily in places that the night time temperature drops well below 0c.

In all honesty i can't see how any land plants will survive on Mars surface with such a high c02 atmospheric count and virtually no free Oxygen.
We might have a very long wait for the cyano family to convert c02.

Even with that we are converting c02 to free oxygen, at around 40% it would ignite.
Even at 40% Oxygen atmosphere we would still have 60% co2, a level to high for any land plants.
No need to mention the time scale to convert 100mb of the initial 300mb of co2 to oxygen even at earth echo system levels.

For a useful echo system we will need vast amounts of nitrogen or another inert gas in the atmosphere so c02 and Oxygen levels can both be safe.

This is a regularly overlooked detail on the road to a terraformed Mars.

A water terraformed Mars is slightly different, most of the hurdles on land disappear in the water.
Maybe a better strategy on Mars is to just terraform the water and forget the land.
Build our cities on the land and learn to live with oxygen masks.
We can grow our terrestrial crops in greenhouses under controlled conditions on the land.
If we want open green spaces we can build and plant them indoors.

Mall mars starting to sound pretty good now eh? smile


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.

Offline

#50 2007-07-29 22:32:24

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Building soil

C3 plants convert carbon dioxide into monosaccharide directly using the Calvin-Benson cycle. Each step in the Calvin-Benson cycle has a specific enzyme that catalyzes the reaction. The problem is one of the enzymes, ribulose diphosphate carboxylase, is sensitive the ratio O2:CO2. It is supposed to combine CO2 with ribulose diphospate and water to form two molecules of 3-phosphoglycerate and 2 H+ ions. However, if the concentration of O2 is too high it will instead combine O2 with ribulose diphospate to form one molecule of 3-phosphoglycerate, 2 H2+ ions, and one molecule of phosphoglycolate. There's a long chain of reactions to convert it into 3-phosphoglycerate, at which point it re-enters the Calvin-Benson cycle. Rebuilding this intermediate takes a lot of energy.

The C4 or Hatch-Slack pathway has specialized cells to concentrate CO2. The mesophyll cell combines pyruvate (a 3 carbon molecule) with CO2 to form malate (a 4 carbon molecule). That is transported to a bundle-sheath cell where decomposition of NADP+ into NADPH removes one CO2 molecule, changing malate back into pyruvate. This pumps CO2 into bundle-sheath cells where photosynthesis happens. It takes energy (NADP+ is a chemical formed in the light reaction), but photorespiration is practically stopped. As a result C4 plants produce more carbohydrate for a given amount of sunlight than C3 plants.

Evolution happens for a reason. This demonstrates the Calvin-Benson cycle evolved at a time when CO2 concentration was several times what it is today.

The biochemistry text book I get this from says:

In a field of C3 crop plants during the course of a hot windless day, the concentration of CO2 in the air over the plants decreases from its normal level of about 0.03 percent to as low as 0.005 percent because of the rapid use of CO2 for photosynthesis.

I have to say Rick Smith is right on this issue.

Offline

Board footer

Powered by FluxBB