Space farm creates fire hazard

[Aghanim]

http://www.space.com/27451-private-mars-colony-feasibility-study.html?adbid=10152399793041466&adbpl=fb&adbpr=17610706465&cmpid=514630_20141016_33770217

Yes, we all know that Mars One is a scam, talk about that in the Mars One is a scam thread. But here is what interests me:

Furthermore, the new analysis suggests that growing crops within settlers' habitats, as Mars One envisions, would generate enough oxygen to make the living spaces a fire hazard.

Piping in nitrogen could lower the oxygen to safe levels, researchers said, but this fix would likely deprive the colony of a vital gas needed to compensate for leakage into the surrounding Martian atmosphere. The possible end result? A space that would quickly become unlivable, suffocating colonists after about 10 weeks, the study found.

There are ways to prevent this scenario  growing food in isolated greenhouses, for example, or implementing an oxygen-extraction system. But the best alternative is to nix the idea of Mars farms and bring all the colony's food from Earth, the study determined.

Is it even possible for a space farm to produce enough oxygen to significantly increase flammability?

[lajoswinkler]

Today's plants don't work that way. If they're put into an atmosphere with significantly higher partial pressure of oxygen, it will harm them. So they don't to that to themselves.

Plants consume CO2 and O2, but their net production gives excess O2. You'll never get an increasingly higher partial pressure of oxygen no matter how many salad you plant in the habitat.

Yes, Mars One is a media scam and a very stupid, illegal idea, but the plants wouldn't cause a fire hazard.

[Dkmdlb]

illegal idea

Citation needed.

[KerikBalm]

Today's plants don't work that way. If they're put into an atmosphere with significantly higher partial pressure of oxygen, it will harm them. So they don't to that to themselves.

citation needed

Plants consume CO2 and O2, but their net production gives excess O2. You'll never get an increasingly higher partial pressure of oxygen no matter how many salad you plant in the habitat.

If there is net O2 production, I don't see why the O2 levels wouldn't continue to increase until they reach toxic levels.... which could be well after the conditions become dangerously flammable (as its thought they were at various times in the past when O2 concentration was higher)

But then again.... shouldn't they be trying to use that O2 to supply the habs, where you'll have humans consuming O2?

[lajoswinkler]

Citation needed.

Would you like me to cite a law which says that stuffing exactly 100 g of chewing gum into kids' ears is illegal, too? Come on.

citation needed

Oxygen gas is a corrosive and toxic substance if applied in higher than normal concentrations during enough time. It works like that for all living beings. Look at it on the periodic table. It's next to the halogen group. Next to fluorine which is the most electronegative element in existence.

Living beings deal with excess oxygen in various ways, usually by employing enzymes to catalyze and divert the reactions into less harmful ones.

Source: my college and knowledge.

If there is net O2 production, I don't see why the O2 levels wouldn't continue to increase until they reach toxic levels.... which could be well after the conditions become dangerously flammable (as its thought they were at various times in the past when O2 concentration was higher)

But then again.... shouldn't they be trying to use that O2 to supply the habs, where you'll have humans consuming O2?

The total plant made waste O2 is consumed by heterotrophic organisms like animals, fungi, some bacteria. Our biosphere is in a state of dynamic equilibrium between producers and consumers of oxygen gas.

Even if you don't have people in the habitat, the plants won't make the atmosphere with a high pO2. It's plant physiology, all understood. If you want them to produce more O2, you need to give them more CO2. Otherwise they work with what they've got.

[Dkmdlb]

Would you like me to cite a law which says that stuffing exactly 100 g of chewing gum into kids' ears is illegal, too? Come on.

No I want you to cite the law that says Mars One is an illegal idea. There is no such law. Obviously. You can't just make stuff up and expect everybody to believe it. Mars One might be a scam, but that doesn't mean you can just heap a bunch of false criticisms on it. And when someone calls you out you don't get to brush it off as if it's a silly objection.

And for what it's worth, it is not illegal, per se, to stuff chewing gum in the ears of children.

Edited October 17, 2014 by Dkmdlb

[linkxsc]

And for what it's worth, it is not illegal, per se, to stuff chewing gum in the ears of children.

Fine, then go find a kid, shove some gum in their ear while their parents are around. When you post bail 2moro or whenever, come back, tell us which law you were breaking so we can all know.

[Dkmdlb]

Do you know what per se means?

[linkxsc]

Yeah. I was being sarcastic. Just like you were. Just like the guy before you were too. Because even though there may not be laws directly against it. There is probably something wrong being done.

[Leszek]

Dkmdlb is right.

lajoswinkler has made a lot of naked assertions and then in the second post failed to explain them. I am not saying he is wrong. I don't know. I am saying he hasn't explained his ideas properly. Some of what he is saying is either wrong or explained wrong.

For example, if you increase the amount of O2 in the air, you MUST be increasing the partial pressure of O2. Either that or you are reducing the total pressure of gas in total in the enclosure. Either by leaking it out or by removing it somehow. There is no two ways about it. That is how partial pressure works. So either he is wrong or he said it wrong when he asserted:

Today's plants don't work that way. If they're put into an atmosphere with significantly higher partial pressure of oxygen, it will harm them. So they don't to that to themselves.

Plants consume CO2 and O2, but their net production gives excess O2. You'll never get an increasingly higher partial pressure of oxygen no matter how many salad you plant in the habitat.

Further his next post after that failed to elucidate. It reads fine, I am reasonable confident he knows what he is talking about in the second post, but he didn't answer any of the objections raised in any useful way.

It is not obvious why it is or would be an illegal idea. He implies that it is illegal in the same way putting bublegum in the kids ears would be. But as pointed out, the bublegum isn't illegal per se, it falls under assault. But how is that in any way analagous to the OP topic or Mars One in general?

And O2 is highly reactive and his spiel about how plants and animals cope with it are correct, but plants can and do raise the partial pressure of O2 in their environment. This is a fact, and it is WHY we have O2 in earths atmosphere at all above trace levels. Why should they fail to do it again in an enclosed environment?

He then moves on to what happens in earths biosphere. Great, but how does this apply to the mars farm?

lajoswinkler seems to know in part at least what he is talking about, but he isn't explaining himself properly and what he is saying can't be right as said.

[Starman4308]

http://www.space.com/27451-private-mars-colony-feasibility-study.html?adbid=10152399793041466&adbpl=fb&adbpr=17610706465&cmpid=514630_20141016_33770217

Yes, we all know that Mars One is a scam, talk about that in the Mars One is a scam thread. But here is what interests me:

Is it even possible for a space farm to produce enough oxygen to significantly increase flammability?

I don't know the numbers, but I do know the theory of what's going on. There's a closed loop: the plants take in carbon dioxide and produce an equivalent quantity of oxygen and fixed carbon. The colonists and various decomposers will consume the fixed carbon and oxygen and produce carbon dioxide. At excess oxygen, CO2 is depleted and the plants stop growing. At excess CO2, the plants love it, and the colonists die, leaving the hardier decomposers to survive. If well-planned, there will be a sufficient buffer of CO2 and O2 such that, between planting and consuming crops, neither O2 nor CO2 is dangerously excessive or depleted. This could be assisted by using staggered plantings, such that only a fraction of your crops are just being planted or being harvested at any given time.

Granted that this is Mars One, in the absurd off-chance it actually gets to Mars, it probably will not be so planned, and will quite possibly be the cause of their eventual demise. Mars One was never a good idea.

[Kryten]

The scenario is that the plants, due to needing to reach a minimum size before being harvested, and being nourished with water gathered from outside, produce excess O₂. The life support system, to prevent excessively high oxygen levels while being unable to filter it out selectively, vents air and pumps in nitrogen. Nitrogen tank runs out on day 60, astros become deceased. Seems like it could pretty easily be solved by growing in smaller batches and fiddling with ECLSS parameters.

[Nuke]

what if you make the grow domes co2 rich, and then make the habitable sections low pressure oxygen? obviously the co2 rich atmosphere would be somewhat toxic to humans, but i suppose they can work with a co2 scrubber mask or something. it would definitely help if you could find a source of inert gas on mars.

on mars you have a whole atmosphere of co2 at your disposal, surplus oxygen can be used to make rocket fuel. just to feed the colonists would take much more plant matter than is needed for o2 production. then you have foliage which can be either composted (not sure what thats doing to your air) or fed to livestock. the latter helps to consume the surplus o2 if rocket fuel production is not required, and produces manure. otherwise you would either need to store it or vent it.

Edited October 17, 2014 by Nuke

[Tommygun]

This is interesting and strange at the same time.

NASA has been doing greenhouse experiments for a long time, but I have never heard of this problem.

I remember Biosphere 2 problems with too little oxygen due to several causes, but nothing like this.

[Brethern]

I don't know the numbers, but I do know the theory of what's going on. There's a closed loop: the plants take in carbon dioxide and produce an equivalent quantity of oxygen and fixed carbon. The colonists and various decomposers will consume the fixed carbon and oxygen and produce carbon dioxide. At excess oxygen, CO2 is depleted and the plants stop growing. At excess CO2, the plants love it, and the colonists die, leaving the hardier decomposers to survive. If well-planned, there will be a sufficient buffer of CO2 and O2 such that, between planting and consuming crops, neither O2 nor CO2 is dangerously excessive or depleted. This could be assisted by using staggered plantings, such that only a fraction of your crops are just being planted or being harvested at any given time.

Granted that this is Mars One, in the absurd off-chance it actually gets to Mars, it probably will not be so planned, and will quite possibly be the cause of their eventual demise. Mars One was never a good idea.

Allot of plants reverse their cycle at night. They take in oxygen and output co2. So it could balance itself if self contained.

I have a solution for this problem. Let's set up a greenhouse base on the moon and do field testing.

[NERVAfan]

This study is too strict on the limits of what's an acceptable oxygen level IMO (30% as maximum?).

And if you have too much oxygen, light a candle. This is something that can be dealt with.

- - - Updated - - -

Allot of plants reverse their cycle at night. They take in oxygen and output co2. So it could balance itself if self contained.

Plants still have a net production of oxygen, though.

I have a solution for this problem. Let's set up a greenhouse base on the moon and do field testing.

It can be tested easily enough on earth in a sealed habitat.

[Aghanim]

Allot of plants reverse their cycle at night. They take in oxygen and output co2. So it could balance itself if self contained.

I have a solution for this problem. Let's set up a greenhouse base on the moon and do field testing.

But plants produce net oxygen, but that depends on the lighting conditions. Still, if we somehow replaces all of the CO2 with oxygen in normal air, will things become easier to burn?

Look at this graph:

Increasing oxygen by 0.04% shouldn't increase flammability too mucch

[Alchemist]

First, the plants won't produce oxygen if they run out of CO2. So, unless you start pumping large amounts of CO2 into the greenhouse from the martian atmosphere you won't get uncontrolled amounts of O2.

Second, you don't really need nitrogen in the breathable air - living in 21 kPa of pure oxygen is not a big problem. Of course, there is the question of nitrogen for the crops, but plants don't absorb it directly from air, maybe it's possible to modify soil bacteria for using reduced concentrations of N2. Or there's always the option of using some physically chemical equipment to produce nitrogen fertilizer from the atmospheric nitrogen.

[Brotoro]

The study mentioned in the first post sounds like nonsense to me.

Anyway, extra oxygen would be great. Just have an air liquification unit handy and separate out any extra oxygen for use elsewhere if you don't want it in the air.

[Tommygun]

First, the plants won't produce oxygen if they run out of CO2. So, unless you start pumping large amounts of CO2 into the greenhouse from the martian atmosphere you won't get uncontrolled amounts of O2.

Second, you don't really need nitrogen in the breathable air - living in 21 kPa of pure oxygen is not a big problem. Of course, there is the question of nitrogen for the crops, but plants don't absorb it directly from air, maybe it's possible to modify soil bacteria for using reduced concentrations of N2. Or there's always the option of using some physically chemical equipment to produce nitrogen fertilizer from the atmospheric nitrogen.

Can a plant survive at 21 kPa without the low pressure dehydrating it?

I know they can compensate some with plant hormones.

The study mentioned in the first post sounds like nonsense to me.

Anyway, extra oxygen would be great. Just have an air liquification unit handy and separate out any extra oxygen for use elsewhere if you don't want it in the air.

I was thinking about that too, if they have the power for it.

Edited October 18, 2014 by Tommygun

[KerikBalm]

Oxygen gas is a corrosive and toxic substance if applied in higher than normal concentrations during enough time.

That depends entirely on how much higher the concentration is.

We know that Oxygen once reached 35% of our atmosphere. That would pose a fire risk in many situations.

Furthermore, you haven't cited anything as to the maximum tolerable concentration for various plants: hint, it is even higher.

For mammals, it is about 60% for long term exposure.

It works like that for all living beings. Look at it on the periodic table. It's next to the halogen group. Next to fluorine which is the most electronegative element in existence.

Condescend much?

Living beings deal with excess oxygen in various ways, usually by employing enzymes to catalyze and divert the reactions into less harmful ones.

Source: my college and knowledge.

Most of those enzymes you refer to are for ROS, which are not pure molecular oxygen, but rather compounds produced by the ETC when doing oxidative phosphorylation.

Plants produce a net O2 increase from the hydrolysis of water.

O2 would build up to significantly unless O2 was again reacting with the sugars/hydrocarbons to again produce CO2 and H20.

If the biomass increasess, the excess O2 increases...

Of course, this is assuming only biological processes... if you can find some unoxidized chemical compounts on mars, and put them in the greenhouse, tey could soak up the excess O2, but it would be hard to have the reaction rate by high enough, yet not a fire hazard . Ie aluminum will oxidize in O2, an aluminum poweder, when given a source of heat... will rapidly oxidize and make a lot of heat...

Edited October 18, 2014 by KerikBalm

[Alchemist]

Can a plant survive at 21 kPa without the low pressure dehydrating it?

I know they can compensate some with plant hormones.

Unless the total pressure approaches saturated vapor pressure (thus getting boiling effect) the rate of evaporation is almost fully governed by vapor partial pressure and is almost unaffected by having or not having some extra amount of nitrogen.

Yet again, if you need 100 kPa there's not too much problem of getting nitrogen-argon mixture from martian atmosphere since CO2 is easy to separate (of course, you can purify nitrogen even further, but that would require much more expensive compressor). And extra argon is completely harmless inert gas.

[jwenting]

illegal idea

Didn't know we had a thought police yet...

Ideas aren't illegal, only acting on them may be.

[lajoswinkler]

No I want you to cite the law that says Mars One is an illegal idea. There is no such law. Obviously. You can't just make stuff up and expect everybody to believe it. Mars One might be a scam, but that doesn't mean you can just heap a bunch of false criticisms on it. And when someone calls you out you don't get to brush it off as if it's a silly objection.

And for what it's worth, it is not illegal, per se, to stuff chewing gum in the ears of children.

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.

That depends entirely on how much higher the concentration is.

We know that Oxygen once reached 35% of our atmosphere. That would pose a fire risk in many situations.

Furthermore, you haven't cited anything as to the maximum tolerable concentration for various plants: hint, it is even higher.

For mammals, it is about 60% for long term exposure.

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.

Condescend much?

Periodic table is so condescending, true.

Most of those enzymes you refer to are for ROS, which are not pure molecular oxygen, but rather compounds produced by the ETC when doing oxidative phosphorylation.

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 produce a net O2 increase from the hydrolysis of water.

O2 would build up to significantly unless O2 was again reacting with the sugars/hydrocarbons to again produce CO2 and H20.

If the biomass increasess, the excess O2 increases...

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.

Of course, this is assuming only biological processes... if you can find some unoxidized chemical compounts on mars, and put them in the greenhouse, tey could soak up the excess O2, but it would be hard to have the reaction rate by high enough, yet not a fire hazard . Ie aluminum will oxidize in O2, an aluminum poweder, when given a source of heat... will rapidly oxidize and make a lot of heat...

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.

Allot of plants reverse their cycle at night. They take in oxygen and output co2. So it could balance itself if self contained.

I have a solution for this problem. Let's set up a greenhouse base on the moon and do field testing.

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.

Didn't know we had a thought police yet...

Ideas aren't illegal, only acting on them may be.

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.

Edited October 18, 2014 by lajoswinkler

[KerikBalm]

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.

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.

Periodic table is so condescending, true.

Strawman argument is a strawman.

Plants do not hydrolize water to produce oxygen.

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.

If you don't supply the plant with CO2, it will not be able to live.

For practical purposes, yes, but not entirely accurate.

If you don't give it enough CO2, it won't magically start hydrolising water.

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

Where will the hydrogen go?

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.

With not enough CO2, the plant will wither and decrease its biomass until it adapts.

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.

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.

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."

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.

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.

Edited October 18, 2014 by KerikBalm