Breathing Carbon Dioxide

[shardsofnarsil]

Hey! I'm preparing to write a science fiction novel. A central part of it involves a race of humans genetically altered to breathe carbon dioxide instead of oxygen so they could live on planets like Venus.

 

I'm curious as to what conjectures, ideas, or theories any of you could present on how CO2 would affect the body differently than oxygen. Would it affect skin color? blood color? how long they could hold their breath?

 

I'm not interested in whether it's possible or not. After all, this is science fiction. But assuming it was possible, what would it be like? Any ideas, from the mundane to the far-fetched, will be very appreciated.

 

Thanks

 

Josh

[Cap'n Refsmmat]

Providing you made it so these humans would separate the carbon from the oxygen, and then breathe the oxygen, they probably would have a much better respiratory system. This is because normal air is only 21% oxygen. However, on planets like Venus, they are 95% carbon dioxide, and carbon dioxide is [math]\frac {2}{3}[/math] oxygen. So there would be 61% oxygen, making it much easier to breathe.

They would certainly be able to hold their breath longer with more oxygen, but I'm not sure about skin color and such.

[Tesseract]

Hey! I'm preparing to write a science fiction novel. A central part of it involves a race of humans genetically altered to breathe carbon dioxide instead of oxygen so they could live on planets like Venus.

 

I'm curious as to what conjectures' date=' ideas, or theories any of you could present on how CO2 would affect the body differently than oxygen. Would it affect skin color? blood color? how long they could hold their breath?

 

I'm not interested in whether it's possible or not. After all, this is science fiction. But assuming it was possible, what would it be like? Any ideas, from the mundane to the far-fetched, will be very appreciated.

 

Thanks

 

Josh[/quote']

 

You would be fried alive on Venus before you could take one breath...

[Cap'n Refsmmat]

I'm not interested in whether it's possible or not. After all' date=' this is science fiction. But assuming it was possible,[/quote']

[Tesseract]

Just wanted to make sure he knew that...

[shardsofnarsil]

Thanks, I am aware that temperatures on Venus go into the eight and nine hundreds, and that the atmospheric pressure is about 90 times that of Earth's. But I'm trying to be creative and work around those obstacles.

[J'Dona]

I think that what they were getting at is that for it to be "science fiction", the science in your story has to be realistic or at least scientifically grounded, otherwise it would only be fantasy.

 

Assuming that your GE humans are only splitting apart the CO₂ into O₂ and not actually using the CO₂ to breathe with like plants, then provided you can find some way for them to do that they shouldn't be too different from normal humans as they would be using the same chemicals in their body. Otherwise their bodies would need to incorporate some way to use CO₂ directly, like a form of concentrated phtotosynthesis in their lungs (although then they'd need some way to the get light onto the cells, so the cells might need to be on the outside of their body, thus altering their skin color and anatomy and causing problems of actually getting the O₂ once it's produced into their lungs.)

 

Some of the problems with living on Venus could be countered with genetic engineering in the humans as they would have. Their skin cells may have been altered to be able to withstand a greater atmospheric pressure, like on Venus, although this might mean that they can't survive in "normal" atmospheric pressure like on Earth, just as we can't survive on a planet with a similarly lower atmospheric pressure like Mars. I don't know what you could do about heat... just about all organic molecules would combust and burn at that temperature if there was oxygen in the air to let them, and if these humans used oxygen in their bodies then it would probably get it from there as they melted. Some form of space-suits might protect them from the heat and the pressure as well, but then it's not quite as natural as I believe you're trying to go for. Another problem is the abudance of nasty things like sulphuric acid in the atmosphere, mostly higher up mind you, and liquid metals on the ground. On a planet like Venus, your humans would have to contend with a certain amount of metals and acids that they'll be breathing in, so they'll need some decent way of filtering those out of their system. I don't know much about biology so I can't offer anything there.

 

Another possibility I'm sure you may have thought of is Mars. Its temperature range is certainly more hospitable to humans (sometimes up to 20 degrees Celsius) and the atmosphere is still about 95% CO₂. The atmospheric pressure is less so instead of needing humans genetically engineered to withstand 9 MPa of pressure (Venus), 8.9 MPa higher than Earth, they would just need to be able to survive under the near-vacuum conditions on Mars (only 100 kPa different from Earth). That should be easier and might provide some useful abilities later on in the story, like space-walking. Of course, the much lower atmosphere on Mars would be a problem as people would not be able to get very much oxygen from the converted CO₂, so these humans might be restricted to the lowest points on Mars (like of the bottom of the Valles Marineris canyon where pressure might be a little higher). This would mean that they are unable to holdtheir breath for very long, for sure, and would probably need some form of breathing equipment to help them collect CO₂. Of course, this is just for Mars and if you would rather that your humans lived on Venus, that's fine. It's certainly much more interesting than just another Martian colony!

 

Whereas this is fiction and you can do anything you want in it, whether possible or impossible, you have to bear in mind that if you want it to be considered "science fiction" the reader has to believe that it is possible. I would recommend, though, that you continue to ask questions about any parts of the science in your story that you're uncertain about. I do some writing as well, and whereas I'm not ready to start a novel yet (though I have a fixed idea for one that I spend a LOT of time thinking about and sorting out the details in for when I do), I understand what it takes to do all the research and try to make interesting situations work out, however difficult the science behind it might be. I've heard of one case where a guy wrote a story based inside a neutron star, in a layer between the outer crust shell and the core, so gravity was similar to Earth. If someone can call that science fiction, then humans on Venus certainly can be as well.

 

 

EDIT: In response to Cap'n Refsmmat's post in #2:

 

I think it works out a little differently to that due to the different RAM's of carbon and oxygen. 95% CO₂ would be more like the equivalent of (16+16)/(12+16+16) x 95% = 69.1% or so oxygen, as compared to Earth's 21%. Since Venus also has 90 times the atmospheric pressure and so - I would assume - 90 times the atmosphere at ground level, the actual oxygen they would be getting would be 90 x 69% = 622% as compared to Earth's 21%, so about 29.6 times as much oxygen as on Earth. (edited again to fix typo)

[shardsofnarsil]

Thanks a lot. I definitely want to get as much science right as possible, which is why I'm asking questions on here.

 

It's not imperative that they can live on the planet completely naturally, without space suits. In my story, humans need to live on Venus because there's a special element there that facilitates hyperspace travel and is in high demand in the solar system. So it's fine if they wear space suits, they just have to be able to live there so they can set up a colony and mine the metal.

 

I'm cordially avoiding Mars simply because I've read a number of science fiction stories that take place on Mars, but none on Venus, and I want to try something a little different.

 

Shards'

[LucidDreamer]

Animals use oxygen as a powerful electron acceptor in the final stage of the electron transport chain. The electron transport chain is a series of protein complexes that pass the electron down the line until it reaches oxygen. The purpose of this is to create energy for the cells many chemical reactions.

 

Plants use CO2 as a source of carbon to make 6-carbon sugars to store energy. These two gases are used for different purposes in biological systems. Some bacteria species use nitrogen instead of oxygen as the final carbon acceptor, so you could consider changing it to nitrogen because it might be scientifically more plausible. The others suggestion that CO2 could just be used as a source of O2 might also be possible.

 

However I do have a suggestion that might solve some of your problems. Not only would the environment of Venus make it difficult for humans to exist it would also make it difficult for them to grow or raise any form of food. If you want them to breath carbon dioxide why not make them plant-like. This would solve two of your problems at once. Your genetically engineered humans would breathe carbon dioxide, using the oxygen in their electron-transport chain and using the carbon in a photosynthetic process to create a fuel source. They would likely have green skin because it is saturated with chlorophyll and require large amounts of water. They might also have a pre-lung filtration organ to filter out the nasty gases the others mentioned.

 

I'm not sure how your genetically engineered humans would deal with the incredible pressure and intense heat of Venus. I would suggest you take the easy way out, having your humans establish some sort of environmental change system to convert Venus’s very inhospitable environment into a more pleasant one. If you make your humans too bizarre your readers will no longer relate to them. Well anyway, good luck. Hope to see your book on the shelves of Barnes and Nobles.

[JaKiri]

not actually using the CO_{2[/sub'] to breathe with like plants}

 

_{Plants breath Oxygen you doofus.}

[J'Dona]

That's at night though, if you're taking about inhaling and using it. Obviously they breathe CO₂ it in the sense that they use it during photosynthesis. They only breathe O₂ during day in the sense that it's waste product. I'm not sure how the reactions work at night but it's the reverse, so in that case they would certainly be breathing oxygen and using it and expelling CO₂. I was only referring to breathing case of reactants during day, which is what mattered. Surplus oxygen (which there should be if I was right in there being 29.6 as much "oxygen" once converted on Venus than on Earth) might just be stored for use at night.

[Sayonara]

"Breathing" is usually associated with respiration.

 

Does anyone know how much useful light makes it to the surface of Venus? Those clouds are pretty thick.

[JaKiri]

That's at night though, if you're taking about inhaling and using it. Obviously they breathe CO_{2[/sub'] it in the sense that they use it during photosynthesis.}

 

_{That's not 'breathing'.}

 

_{They only breathe O2[/sub'] during day in the sense that it's waste product.}

 

_{I don't know what this means.}

 

_{I'm not sure how the reactions work at night but it's the reverse, so in that case they would certainly be breathing oxygen and using it and expelling CO2[/sub']. I was only referring to breathing case of reactants during day, which is what mattered. Surplus oxygen (which there should be if I was right in there being 29.6 as much "oxygen" once converted on Venus than on Earth) might just be stored for use at night.}

 

_{Most adult trees use more oxygen than they produce.}

 

_{Almost all the oxygen production in the world is done by plankton.}

[J'Dona]

Yeah, I guess I should have been more specific in my first post. I think shardsofnarsil was more concerned with extracting oxygen from carbon dioxide though, so I didn't think it was necessary to go into exhalation and nighttime reactions since the use of the exhaled oxygen in the body was implied and the storage during night shouldn't be a problem. These humans do have technology, after all.

 

I've tried looking up on the light intensity on the surface of Venus, but I couldn't find much statistics. Apparently, based on the pictures from the Venera 13, it is "as bright as an overcast day on Earth". The heat and high levels of CO₂ might help to counteract that, but it's certainly a restricting condition.

 

This is of course completely ignoring the sulphuric acid and trace amounts of water on the planet.

 

 

EDIT: Sorry, just saw your post JaKiri, I'll edit in a sec...

 

Okay, I think I must be misunderstanding you. Could you please give me the correct definition of "breathing" in the terms we're talking about so that I can find where my explanation doesn't apply?

[J'Dona]

Ah, I've just looked up on the definitions in the Oxford Science Dictionary, and apparently breathing relates to the muscular movement, whereas respiration relates to the actual chemical processes involved. So, whereas I was mainly referring to the intake of atmosphere rather than the chemical reactions, since they had to be separated anyway and the physical process seemed more important than the chemical reactions about which we already know, then "breathing" and "breathes" could be replaced with "respiration" and "respires" and it might come across better. As Sayonara said, they are usually associated with one another.

 

I'll be sure to make the distinction in the future, now that I know the difference.

[Leison]

Hey! I'm preparing to write a science fiction novel. A central part of it involves a race of humans genetically altered to breathe carbon dioxide instead of oxygen so they could live on planets like Venus.

 

I'm curious as to what conjectures' date=' ideas, or theories any of you could present on how CO2 would affect the body differently than oxygen. Would it affect skin color? blood color? how long they could hold their breath?

 

I'm not interested in whether it's possible or not. After all, this is science fiction. But assuming it was possible, what would it be like? Any ideas, from the mundane to the far-fetched, will be very appreciated.

 

Thanks

 

Josh[/quote']

 

 

I appreciate your ideas of CO2 .

My thoughts:

O2 is the most important gas for our body.Without it no respiration and no energy so no life. And as far as your story, You should mould your story by stating " human injects some kind of chemicals(vaccine) in the body and it has some period of it working time .By doing this,human could inhale CO2 and in the lungs the O2 would be seperated by that injected chemical and Carbon would be by-product.So, when exhaling the breathe would be black smoke."This would add a interesting part in your story.But while writing the novel, you should also take care of other aspects like at. pressure, temperature ,what to eaT etc

 

I think my thoughts would be helpful to you.

[YT2095]

geneticaly engineer them to have Chloroplasts and Chlorophil in each cell, their color would be a deep green/brown (the red in the blood would make it dark and red and green= brown).

they would breathe out O2 (that would be toxic to them). but they would also need copious amonts of Light and certain minerals and trace elements as a supplementary diet.

 

potassium nitrate and ammonium phosphate would be good additions if you wanted them to grow and have seedlings (children).

 

anyway, I refuse to write your book for you! )

[YT2095]

well (s)he could be busy writing p`haps?

 

not only that but it`ll go into the archives for the next person that asks

[Martin]

hey shards

 

venus surface doesnt get enough light besides being too hot (like the others said)

 

so put these CO2-users on MARS! Mars atmosphere is mostly C02.

 

the sunlight on mars is roughly 500 watts per square meter

 

and human metabolism is roughly 200 watts

 

so if you had a big green ass and went sunbathing like Earth people do on the beach

you could soak up a good meal of energy

 

If mobile green plants were engineered to handle the low pressure (one percent of earth normal) and severe cold, then they might run around happily, grubbing for subsurface ice to eat, visiting the famous polar caps and canyons.

 

they could build greenhouses to live in that would help provide a better temperature and retain moisture-----the main thing is to tolerate low pressure and to have chlorophyl in your skin. Maybe they should grow leaves for extra area.

[SketchTurner]

So in a sense you'd have to have genetically modified 'little green men'. Hmm sounds familiar. Well they'd be slow due to the lack of energy (notice how plants don't actually do much?) but if they were little (maximise 'surface area:volume' ratio) and green (to photosynthesise) then you could have men. Well men with tough skin who moved very little and didn't think much.

[dagaz]

Both plants and animals require oxygen for cellular respiration which involves the breakdown of sugars into ATP which can then be broken down to release energy. Plants also require CO2 for photosynthesis in which they produce the sugars, but they still need oxygen for respiration so they can get energy from the food they make.

[Ophiolite]

hey shards

 

venus surface doesnt get enough light besides being too hot (like the others said)

 

I think the light levels would be more than adequate.

 

Venera 8' date=' for example, ….. [i']confirmed the earlier data on the high Venus surface temperature and pressure returned by Venera 7, and also measured the light level as being suitable for surface photography, finding it to be similar to the amount of light on Earth on an overcast day. [/i]

 

 

Extracted from:

 

http://www.solarviews.com/eng/venera8.htm

 

 

 

Shardsofnarsil, you may already have found this one, but it might be generally useful on the Venusian environment

http://www-mars.lmd.jussieu.fr/mars/esadoc/aopp/venus.pdf