Space farm creates fire hazard

[Everten P.]

What if we used a plant that adapted to the Martian environment? I can imagine a cactus like plant near the equator and grasses near the poles like in the poles of our Earth but nature works in crazy ways perhaps we could introduce life to Mars and see which direction the individuals adapt in and fill the 2000 year gap with GE?

[KerikBalm]

To be clear: I don't think this is a major problem.

Clearly, it is possible to have a balanced ecosystem with a stable O2 concentration.

Mars is a bit tricky because there's no ready source of buffer gas, and if you just concentrate martian atmosphere (the vast majority is CO2), then the plants could easily drive O2 levels very high.

Even without super concentrated CO2, plants by themselves are more than capable of driving up O2 levels well above what we are used to (both biologically, and technologically as far as fire hazards and corrosion).

A properly balanced ecosystem could avoid this, of course... the problem is getting that balance while making use of what you've got available on Mars.

As others have said, you could just do fractional distillation of the resulting atmosphere in the greenhouse, and get LOX for your rocket.

You could even use your greenhouse to make a LOX/ethanol rocket.. or some other fuel.

Of course, this is assuming you have water chemically bound in the soil, or water ice deposits just under the surface providing a ready supply of that... in which case you could just make H2-LOX fuel on site.

The plants can split the water for you, but its not very practical to collect the H2 gas before some other biological process takes it - compared ot what a solar/nuclear water splitting machine could get you - but the O2 should be easy enough to capure, as should a variety of biofuels to burn with the O2.

The greenhouse could provide all the fuel for a return, and food, *in theory*

[lajoswinkler]

http://www.hindawi.com/journals/nrp/2011/260482/

for one... I found many, but I'm at home, not at the lab, and most were hidden behind a paywall.

Exposure time, atmospheric pressure, and fraction of inspired O2 (FIO2) determine the cumulative O2 dose leading to toxicity. Oxygen is toxic to the lungs when high FIO2 (>0.60) is administered over extended exposure time (≥24 hours) at normal barometric pressure (1 atmospheres absolute (ATA)).

This says that when partial pressure of oxygen is above 60%, human lungs would experience measurable trauma after 24 hours. I assure you the concentration doesn't have to be that high if the exposure time is chronic in nature. After one year of being exposed to 40% oxygen, your body would not be healthy as before. Oxygen therapy is given when the benefit of such procedure is considerably larger than the harm.

Fail

http://en.wikipedia.org/wiki/Light-dependent_reactions#The_water-splitting_complex

http://en.wikipedia.org/wiki/Photosynthesis#Z_scheme

http://en.wikipedia.org/wiki/Light-dependent_reactions

"The net-reaction of all light-dependent reactions in oxygenic photosynthesis is:

2H_2O + 2NADP^+ + 3ADP + 3Pi → O_2 + 2NADPH + 3ATP"

Plants, and cyanobacteria, can use photosystem two to split water, generating free oxygen and free hydrogen.

Just like in mitochondria, the resulting proton gradient drives an ATP synthase.

Even when they don't fix carbon, they can release oxygen.

Lets just take the case of simple alkanes of length n - ignoring the complexities of sugar which incorporate O, and mono/poly/unsaturated fats with the double bonds.

To add 1 carbon to the chain from fixing CO2, you need to liberate the C from the O2 -> 2 O's produced... but that is not enough.

That carbon also needs 2 hydrogens - alkanes of lenght N have the simple formula CH3-(CH2)_n-CH3, or nC(n+2)H

Those two hydrogens come from H2O - 3 O's are released when you need to fix 1 C.

All those reactions are coupled. Plants don't take water and say: "Oh, now I've got me some water and I'm gonna hydrolize it!". It doesn't work that way. Every reaction in a living organism is coupled with another one. That's why it's called a metabolism.

I think you're suggesting that a plant will keep destroying water (releasing oxygen gas and accumulating hydrogen ions who knows where) if there's light available. That simply isn't true. If I'm misinterpreting your statements, I apologize.

For practical purposes, yes, but not entirely accurate.

I don't know what that even means. It either survives or it dies. In this case it dies, therefore it's accurate.

Right, it just hydrolyses water anyway to generate ATP when it doesn't need to fix carbon

Already commented.

A variety of places, a simple fate is NADP+ -> NADPH - or simply into the atmosphere where other organisms in a complex ecosystem might make use of it.

So plants release hydrogen gas? In my entire college education I've never heard of this. I admit I could be wrong, but I'd sure like to learn more about this. While it's true that some bacteria and rare algae (probably single cell phytoplankton) sometimes can produce hydrogen, I've yet have to read about salad or a pine tree releasing it.

Yea, but that depens one what the atmosphere inside these greenhouses is composed of.

If they simply run an aircompressor to raise the pressure to the point where water can exist in a liquid state, the CO2 concentration is going to be very high relative to what it is on Earth, and as explained above, basically for every CO2 you fix, you get 1.5 O2.

They can, and will, when they switch more towards photosynthesis that just makes ATP, as they use the energy for more efficient recycling of the carbon they do have, and upregulate the expression of genes needed to obtain carbon sources.

http://en.wikipedia.org/wiki/Oxygen_evolution#History_of_discovery

"He boldly proposed that, in analogy to the sulfur bacteria's forming elemental sulfur from H2S (hydrogen sulfide), plants would form oxygen from H2O (water). In 1937, this hypothesis was corroborated by the discovery that plants are capable of producing oxygen in the absence of CO2. This discovery was made by Robin Hill, and subsequently the light-driven release of oxygen in the absence of CO2 was called the Hill reaction."

Ok, you've made your point, kudos. But please explain where the hydrogen goes. NADP+ and others are just carriers and not meant to be used as longterm storage units.

What happens in such artificial conditions? Does the root system start pumping out excessive H+, acidifying the water it stands in? If it pumps H+ out, what ions does it take up? Net charge has to be zero.

I still think it will stop. Coupled systems are a mess alone, and a greater mess when one end is plucked out.

Generally, yes, but if we're just talking martian atmosphere concentration to 1 ATM, the CO2 won't be depleted until that greenhouse is awash in oxygen.

We're not talking about Martian atmosphere. This is Earth atmosphere in a sealed container on the surface of any celestial body. Closed thermodynamical system.

If you're talking about a system that collects Martian atmosphere, compresses it to 1 bar and introduces it into the habitat, then this all discussion is meaningless.

Oh, and we haven't discussed nitrogen...

Edited October 18, 2014 by lajoswinkler

[linkxsc]

I dont see why any colony wouldnt have the capability to compress its surrounding atmosphere and possibly use it for things. (In this case, to have CO2 available for adjusting the internal atmosphere)

[Leszek]

Laws don't work that way, even in law systems outside USA (in which legal precedents are common). You don't need to have a law for every specific action one might do. For example, if I stab someone dressed as a clown, there's no law that deals with "stabbing someone dressed as a clown". There is a law dealing with murder.

Mars One is using gullible people and planning to send them into certain prolonged, agonizing, media-covered deaths. Now, if you don't understand what's wrong with that, something is wrong with you. Plain and simple.

Unless we're talking about terminally ill and suffering patients which can choose medically assisted help in achieving termination of life (euthanasia), you can not make a contract with anyone which allows you to kill him or expose him to conditions where survival is barely possible. It is simply illegal.

And yes, it is illegal to stuff 100 g of chewing gum into childrens' ears. Given the low compressibility of the gum and its large volume, such amount of gum would burst their eardrums and finish inside skull, pushing against brain and killing them.

I understand where you are comming from now. However you are wrong about it being illegal. It might end up being that, but it is not clear yet. consider the following two examples:

1) You talk friends into climbing a mountain. One that is known for killing climbers. Your friends die during the attempt.

2) In Canada (and I think in the states) the price on the item in a store is what counts. The store can't mark an item for $4 and then try to charge $10 at the register. Now consider a car dealership, a car is marked $13,999 when the wind blows and all the 9's come off. The car is now marked $13.

In these two examples (and the Mars One case) a legal idea called the reasonable person applies. In the first example, if the friends are competent adults then they being reasonable persons knew the risk going in. Things get complicated though with factors such as did you try to mislead them as to the danger. But it isn't cut and dry. In the second example, a reasonable person is expected to realize the car doesn't cost $13.

Now to the Mars One case, a reasonable person is expected to realize that the trip to Mars is difficult and fraught with danger. They will have signed wavers stating as much. Should the people die and family take it to court, they would have the burden of proof to try to establish that Mars One mislead the colonists in such as way and to such an extent that a reasonable person would have been fooled. Further, exactly where that line is drawn depends on the precedent in the jurisdiction the case is tried in.

So no, it is not clearly illegal. (And good thing too, you think we have frivolous lawsuits now...)

Disclaimer: IANAL, I just had a Canadian law class in college.

Nevertheless, this falls under planning, which is the first step of acting on something. Planning does belong to crime, too. If you think it doesn't, try planning an attack on a mall. Even if you don't buy weapons and you only have blueprints on your computer, you'll can still be arrested and brought in front of a judge.

I'm not exaggerating too much here. If someone is actively persuading people to march to their certain deaths, and additionally to that, plans to make money on it, he's doing a crime.

I have read this. For the reasons stated above this doesn't apply unless it can be proved the organizers knew it was certain death. (Or perhaps nearly so.)

[Brethern]

Laws don't work that way, even in law systems outside USA (in which legal precedents are common). You don't need to have a law for every specific action one might do. For example, if I stab someone dressed as a clown, there's no law that deals with "stabbing someone dressed as a clown". There is a law dealing with murder.

Mars One is using gullible people and planning to send them into certain prolonged, agonizing, media-covered deaths. Now, if you don't understand what's wrong with that, something is wrong with you. Plain and simple.

Unless we're talking about terminally ill and suffering patients which can choose medically assisted help in achieving termination of life (euthanasia), you can not make a contract with anyone which allows you to kill him or expose him to conditions where survival is barely possible. It is simply illegal.

And yes, it is illegal to stuff 100 g of chewing gum into childrens' ears. Given the low compressibility of the gum and its large volume, such amount of gum would burst their eardrums and finish inside skull, pushing against brain and killing them.

Back in the time when oxygen was plentiful, the life on Earth was adapted to it. Nowdays not really. If pO2 would magically rise and stay at 35%, the biosphere would experience a lot of problems and, during its adaptation, many species would perish.

Where did you find the 60% value? Such high concentrations are medically prescribed to people with serious illnesses, when longterm exposure to such high partial pressures has more benefit. Cause they're like suffering and being unable to breathe which usually makes them die.

Periodic table is so condescending, true.

Oxygen gas can react with our biochemical compounds. If it can slowly oxidize simple fats on its own, then it can react with protein machines whether we're talking about plants or animals. It really is dangerous in higher concentrations.

Plants do not hydrolize water to produce oxygen. Oxygen gas is a product of a series of complex biochemical reactions which reduce carbon from its dioxide into carbon inside glucose ring. If you don't supply the plant with CO2, it will not be able to live. If you don't give it enough CO2, it won't magically start hydrolising water. Where will the hydrogen go?

With not enough CO2, the plant will wither and decrease its biomass until it adapts. In certain cases it will even die.

So if there aren't people inside the habitat and nothing (except a nonimportant amount of bacteria in the habitat) is releasing CO2, the plants can't release oxygen.

Still, if nothing is releasing CO2 which plants fix (net reaction! Plants also release CO2, but net reaction is soaking it up.), the plants will die.

If you're referring to the dark cycle, it doesn't happen at night only. It happens all the time, but it's called like that because it doesn't require light to go on.

Plants consume oxygen and release CO2 all the time, but the net effect of their total metabolism is negative amount of CO2 and positive amount of O2 in the atmosphere around them. As pCO2 drops, the plant struggles and ultimately dies.

Accounting for the plants alone, it could never be balanced because of that net effect. If there are heterotrophic organisms in the system, then it's a small ecosystem and it can work, provided input energy from outside. It's a closed thermodynamical system. Matter can't go anywhere, energy can. (In isolated systems, where even energy can't flow through the border, life can't survive.)

This is an example of a small ecosystem, a closed thermodynamical system which is in a matter ballance.

http://sphotos-a.xx.fbcdn.net/hphotos-prn1/s480x480/22113_543452615674359_680575687_n.jpg

Your comment is, as always, highly useful to the discussion.

Nevertheless, this falls under planning, which is the first step of acting on something. Planning does belong to crime, too. If you think it doesn't, try planning an attack on a mall. Even if you don't buy weapons and you only have blueprints on your computer, you'll can still be arrested and brought in front of a judge.

I'm not exaggerating too much here. If someone is actively persuading people to march to their certain deaths, and additionally to that, plans to make money on it, he's doing a crime.

People die constantly climbing Mt everest, there's an entire section of the mount covered in the corpses of the ones too weak to make it.

Yet people still go to climb it.

[Guest]

Also, FIY, "certain, prolonged death" is a pretty good description of life. I'd object to "agonizing" bit, so the only difference would be media coverage. You fail to realize that sending people to a place where they can die is not a crime. After all, people die all the time. It's true that life expectation is going to be shorter than on Earth, and that they will never return, but how does that matter? If the people don't care about dying on Earth, why stop them from living the rest of their days on Mars?

Oh, and you certainly can pay to get exposed to conditions where survival is very hard. With proper training beforehand, of course, but they will send you, say, to Siberia for a hefty fee. You'll be equipped to handle it, but it's still pretty though. Assuming it ever goes anywhere, Mars One will be nothing more than an intricate, perpetual survival holiday. People go to Arctic, Antarctic, cross deserts, climb mountains... Organizing such an expedition, even a dangerous one, is no crime.

[Dkmdlb]

There's a very easy way we could resolve the question of the illegality of the idea of Mars One:

lajoswinkler just needs to cite the statue. That's all. He's the one who made the claim, now he has to back it up. It's been 4 pages, and all we've heard is excuses about why he isn't citing it.

If his next post does not contain such a citation, I suggest we all go ahead and ignore him. Because this is a science forum, and in science, if you can't back up your claims, you get ignored.

[Kryten]

I dont see why any colony wouldnt have the capability to compress its surrounding atmosphere and possibly use it for things. (In this case, to have CO2 available for adjusting the internal atmosphere)

Using CO₂ as buffer gas would not exactly be a great idea. Concentrations above about 8% are lethal.

[NERVAfan]

Yeah, Mars One is not "certain death" except in the sense that all life is.If they could somehow get enough money to send people to Mars, it could work. I don't know how good the chances are (nor does anyone, as the on-Mars part probably hasn't been designed in all THAT much detail yet).

EDIT: I think we tend to overestimate the necessary complexity of long-term life support. The ISS water recycling breaks down a lot, but that is likely a problem with that specific design, not the general concept. And it is much easier in gravity IIRC.

Also, the NASA one is probably overengineered in terms of the standards for water quality it is designed to meet, and it has some odd choices like using really toxic stuff as biocides, that then need to be removed (why not just heat the water in a pressure cooker/autoclave instead?)

Edited October 18, 2014 by NERVAfan

[KerikBalm]

I assure you the concentration doesn't have to be that high if the exposure time is chronic in nature

A citation I saw earlier was 7 days with no ill effects in rats. I still haven't gone to the lab to get past paywalls, but I'd be fairly confident that plants would be even more tolerant, as they produce the stuff and in many cases cause elevated local concentrations (not super high, but measurable).

A week at 60% with no ill effects.... how about a month at 40?

Since we're really talking about the plants here, they may not be as healthy, but if they keep on photosynthesizing, they'll keep driving the concentration up..

All those reactions are coupled. Plants don't take water and say: "Oh, now I've got me some water and I'm gonna hydrolize it!". It doesn't work that way. Every reaction in a living organism is coupled with another one. That's why it's called a metabolism.

Strawman argument is a strawman.

The initial claim, which you disputed was: "a net O2 increase from the hydrolysis of water."

You stated: "Plants do not hydrolize water to produce oxygen. Oxygen gas is a product of a series of complex biochemical reactions which reduce carbon from its dioxide into carbon inside glucose ring"

Which is just wrong... lets go back to this source again:

http://en.wikipedia.org/wiki/Oxygen_evolution#History_of_discovery

"Ingenhousz suggested in 1796 that CO2 (carbon dioxide) is split during photosynthesis to release oxygen, while the carbon combined with water to form carbohydrates. While this hypothesis was attractive and reasonable and thus widely accepted for a long time, it was later proven incorrect. Graduate student C.B. Van Niel at Stanford University found that purple sulfur bacteria reduce carbon to carbohydrates, but accumulate sulfur instead of releasing oxygen. He boldly proposed that, in analogy to the sulfur bacteria's forming elemental sulfur from H2S (hydrogen sulfide), plants would form oxygen from H2O (water). In 1937, this hypothesis was corroborated by the discovery that plants are capable of producing oxygen in the absence of CO2."

Your inability to admit that you are wrong when you are so clearly wrong makes me wonder if its worth discussing anything further with you.

The very first step is to hydrolyze water. O2 is released then and there. That the electrons and H+ ions are then coupled to other things is irrelevant.

I think you're suggesting that a plant will keep destroying water (releasing oxygen gas and accumulating hydrogen ions who knows where) if there's light available. That simply isn't true. If I'm misinterpreting your statements, I apologize.

It simply is true. Well, as long as there is light *and* water available, obviously.

Look at the photosynthesis equation... you cannot turn CO2 into sugars without splitting water...

I don't know what that even means. It either survives or it dies. In this case it dies, therefore it's accurate.

It means its possible to keep plants alive without CO2, but its not practical for growing food.

So plants release hydrogen gas? In my entire college education I've never heard of this. I admit I could be wrong, but I'd sure like to learn more about this. While it's true that some bacteria and rare algae (probably single cell phytoplankton) sometimes can produce hydrogen, I've yet have to read about salad or a pine tree releasing it.

For the most part, the released hydrogen is recaptured by something else (like in the CO2 dark reactions, as I mentioned, generally speaking you need 2 hydrogens to add another carbon to a carbon chain), there is a miniscule amount that gets out.. but this can be tweaked.

http://onlinelibrary.wiley.com/doi/10.1002/bit.10431/abstract

Its a cyanobacteria, not a plant, but the chloroplasts are just symbiotic cyanobacteria anyway, and the photosystems and chemical reactions are the same.

"A. variabilis PK84 could produce hydrogen for prolonged periods (up to 40 days) without injection of fresh inoculum. During this period photobioreactor produced 24.5 L of H2. Possibilities for increasing the efficiency of light energy conversion are discussed."

I don't know how extensive your college education was, nor how long ago it was... but it doesn't seem to matter. The O2 is produced when water is split.

This is the very first step of photosynthesis.

But please explain where the hydrogen goes.

It can combine with oxygen, it can be added to hydrocarbons/sugars... etc. it can have many fates.

In some cases the first H20 is split, and then the 2Hs combine with O from the CO2 to make water, and you may say that CO2 is releasing its O2... but if you track where the O comes from (such as using isotopes of oxygen), all the O2 gas is coming from the isotope the water was labelled with (at least initially, as new water is produced labelled with a different isotope

The splitting of water producing O2 is directly analagous to the splitting of H2S producing sulfur as in the purple/sulfur bacteria.

You can even have a scheme where you split H2S, and fix CO2, to make water and elemental sulfur, with no O2 release.

NADP+ and others are just carriers and not meant to be used as longterm storage units.

Yea, they carry the H to other compounds(they are involved in nucleic acid, lipid, etc synthesis), and need to be reloaded with an H, and the other compounds rapidly gets very complicated.

Light reactions:

2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H+ + 3 ATP + O2

Dark Reactions:

3 CO2 + 9 ATP + 6 NADPH + 6 H+ → C3H6O3-phosphate + 9 ADP + 8 Pi + 6 NADP+ + 3 H2O

The net result is more sugar and O2, less water.

When you metabolize glucose, it is

C6H12O6+ 6O2 -> 6CO2 + 6H2O

When you synthesize glucose, it is:

6CO2 +6H20 -> C6H12O6+ 6O2

Net result is less sugar and O2, more water.

Importantly, (for the nth time), that O2 comes from the splitting of water.

I have made a misleading statement (as I don't work with plants, I was a little rusty on this)

When ATP production is desired, without generating NADPH, it mainly Photosystem I that is used, which can make ATP without splitting of water.

http://hyperphysics.phy-astr.gsu.edu/hbase/biology/etcyc.html

Both systems produce ATP, and their relative activities are modulated in response to the plants need to regenerate NADPH or ATP. NADPH is consumed in other reactions in addition to carbon fixation.

As already experimentally shown, plants will continue using photosystem II and splitting water, even when CO2 is absent.

We're not talking about Martian atmosphere. This is Earth atmosphere in a sealed container on the surface of any celestial body.

I thought we were talking about that?

Maybe I started with the wrong impression.

Still, a very basic ecosystem consisting mainly of plants will likely not have sufficient feedback loops to prevent the O2 from reaching hazardous concentrations- not that it can't be circumented.

[Armchair Rocket Scientist]

Okay... the basic idea is that a Mars colony is taking CO2 from the Martian atmosphere and using it to grow plants, but there's a problem with excess oxygen, right? And constantly venting atmosphere into space will eventually deplete the nitrogen reserves.

Honestly this doesn't really seem like a problem. If there's enough electrical power the excess oxygen can be separated out and either vented without loss of nitrogen or stored for later use. This could actually be incredibly useful, since if the colony ever wants to send anyone back to Earth they will need large quantities of liquid oxygen for rockets.

For that matter, Mar's atmosphere is about 4% nitrogen and argon, both of which are easily separated from CO2 by cooling. As long as they don't vent too much nitrogen it should be possible to constantly replenish the atmosphere.

[Raukk]

While I'm unsure of the energy budget or the resources required; it would be possible to use Electrolysis to split water into Hydrogen and Oxygen and collect them in separate containers before feeding the Hydrogen into a fuel cell supplied with O2 from the green house, the excess oxygen from the Electrolysis could be stored or vented. I assume the fuel cell power and H2O products would be recycled back into the closed system.

I have no idea if this would be a better or worse solution than the other ones stated in this thread.

[KerikBalm]

I think the easiest solution, if oxygen was building up, due to an unbalanced ecosystem inside the greenhouse (as it is likely to be initially), would just be to fractionally distill the O2 out of it, and then you've got a ready made supply of oxidizer for future landings.

[KSK]

I think the easiest solution, if oxygen was building up, due to an unbalanced ecosystem inside the greenhouse (as it is likely to be initially), would just be to fractionally distill the O2 out of it, and then you've got a ready made supply of oxidizer for future landings.

Or you could use a little MAGIC. (http://en.wikipedia.org/wiki/Magnesium_injection_cycle). Alternative link here (http://www.technologyreview.com/news/408698/solar-powered-laser/). Burn magnesium to make magnesium oxide, take the magnesium oxide outside your habitat, zap it with laser to release oxygen, take regenerated magnesium back inside. Repeat, wash, zap.

[KSK]

Wikipedia has a decent article on the Calvin cycle or Light Independent Reactions which fix atmospheric CO2. Better description of the key reaction here.

Key reaction: Ribulose-1-5-bisphosphate + CO2 + H2O --------> 2x 3-phosphoglycerate + 2 H+

Or: C5H8P2O11 + CO2 + H20 ----------> 2x C2H3PO7 + 2H+

Note that all the oxygen winds up in the phosphoglycerate and is not released as molecular oxygen.

[Kryten]

What's that got to do with anything? It's not like you can uncouple the light-driven and light-independent reactions.

[KSK]

What's that got to do with anything? It's not like you can uncouple the light-driven and light-independent reactions.

Depends what you mean by uncouple. They're coupled in plants but other organisms use different energy sources to drive the Calvin cycle and fix carbon. But my point was just to add to what KerikBalm was saying about CO2 not being reduced to oxygen during photosynthesis.