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Is it possible to colonize planetoids using breathable liquid such as perfluorocarbons (PFCs) with dissolved oxygen and filling craters and depressions with it instead of building insulated habitats?

I think this would require much less oxygen than creating a breathable atmosphere and at the same time would not limit the colonists to the inside of their dwellings.

Besides liquid breathing, fluorocarbons have other wonderful properties:

  • They are very potent dielectrics unlike water, so no short-circuit.
  • They have high weight so they can form an atmosphere where there is not enough gravity to keep an atmosphere of lighter gases.
  • For terraforming a planet: PFCs are not photodissociated, having highest lifetime in the atmosphere, they are the most potent greenhouse gases (tetraflourocarbon is 6500 times more potent than CO2), which allows to warm up planets such as Mars (this has been already suggested).
  • PFCs can be used as blood substitutes and have anestetic properties. Oxygen-rich PFCs help to heal wounds. They are also used to store living organs for transplantation.
  • Some PFCs are extremely hydrophobic

As uhoh suggests in a comment, one scenario for breathable liquid environment is "walking on the ceiling":

if the local gravity were $g′$ and the perfluorocarbon had a density of 1.6 $ g/cm^3 $ then they'd be walking on the ceiling feeling a "gravity" of 0.6 $g′$.

edit: Here is an example of such a buoyant, inverted "ice walker" - starts at 03:27:

uhoh
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Anixx
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    What about the temperature? – Organic Marble Sep 24 '16 at 01:43
  • "..would not limit the colonists to the inside of their dwellings." But they would become puddle bound. Always limits.. – Andrew Thompson Sep 24 '16 at 04:58
  • The perfluorocarbons would still need to have a high enough oxygen concentration to allow breathing - would it really require less total oxygen than a gas atmosphere with the same volume as the "puddle"? Would it also require a pressure container to keep from evaporating? (unless it's really cold, and then as @OrganicMarble already pointed out...) – uhoh Sep 24 '16 at 06:45
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    @uhoh you can make a gas atmosphere of this volume only by building closed compartments. You cannot make it in the open. The puddle can have a layer of water on the top which would be ice in the vacuum and protect the puddle. – Anixx Sep 24 '16 at 13:54
  • I like that! I've walked, ice-fished, and even driven on iced-over lakes. It can be scary and loud when it cracks, but by the time it's say 15cm or more, it's quite reliable. Since perfluorocarbons are much more dense than water, the ice/water naturally floats. So that leaves the "much less oxygen" part. Are you thinking that pfc's can be made on location, but the oxygen is hard to get? I still don't understand the advantage. – uhoh Sep 24 '16 at 14:34
  • @Andrew Thompson this is the same as being island bound on Earth. – Anixx Sep 24 '16 at 14:47
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    @uhoh besides liquid breathing, fluorocarbons have other wonderful properties. They are dielectrics unlike water, so no short-circuit. They have high weight so they can be used for artificial atmosphere on bodies that do not keep other gases. They are not photodissociated, having highest lifetime in the atmosphere, they are the most potent greenhouse gases, tetraflourocarbon is 6500 times more potent than CO2, which allows to warm up planets such as Mars (this has been already suggested). If I were writing a computer game, I would express the cost of terraforming in one resource, fluorocarbons – Anixx Sep 24 '16 at 14:56
  • Those are interesting points. Would you consider adding that to the question? People often skip reading comments so it would be more visible. – kim holder Sep 24 '16 at 15:04
  • @kim holder they are also powerful refrigirants, the most used on Earth already, so they can be used not only for warming up, but also for cooling down, albeit in a different way. Also they can serve as blood substitutes. I cannot connect it with terraforming, but imagine you have a wound and bleeding, and you take a syringe, take the surrounding liquid in it and inject into blood vessel. Everything OK. Maybe in such medium automatic injectors may make breathing not necessary at all. – Anixx Sep 24 '16 at 15:05
  • OK please order $10^6 \ kg$ for me asap! But for this question - can you be more specific? Can you propose something clearer, and ask something like "what would be the most difficult challenges..."? Right now it's hard to construct a clear answer. If your question is "would it be possible" then yes, for a quadrillion dollars, yes. But that's really not a useful question/answer. – uhoh Sep 24 '16 at 15:05
  • "this is the same as being island bound on Earth." You've never heard of 'boats'? – Andrew Thompson Sep 24 '16 at 15:08
  • @Andrew Thompson there is nothing that can prevent people making "boats" of fluorocarbons. Also expanding the habitable area would be very simple: just flood a valley or crater with this liquid and some water. Easier than building artificial islands or ships. – Anixx Sep 24 '16 at 15:10
  • "They have high weight so .." The humans with a density of around 1 gm/cc would have to work in order to leave the water ice layer at the top. "most potent greenhouse gases" Oops! There goes the ice layer. My view is that this idea creates more problems than it solves & more limitations than opportunities. – Andrew Thompson Sep 24 '16 at 15:15
  • @Andrew Thompson their effect as greenhouse gases is not connected to their use for liquid breathing. Ice (and water) are less dense than fluorocarbons, so what's the problem, it will be naturally on top. – Anixx Sep 24 '16 at 15:17
  • But once the greenhouse effect provides enough warmth for humans to survive comfortably, (e.g. 20 ℃) the ice layer (that they were 'standing on' albeit upside down) would melt. – Andrew Thompson Sep 24 '16 at 15:20
  • @Andrew Thompson fluorocarbons as greenhouse gases can be used on places like Mars. Fluorocarbons as liquid breathing can be used in places like Ceres. Fluorocarbons as refrigerants can be use in places like Mercury. They have multiple applications. – Anixx Sep 24 '16 at 15:22
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    "Fluorocarbons as liquid breathing can be used in places like Ceres." But as I've been trying to point out, they'd be utterly impractical in 'puddles'. No ice layer, they boil. Ice layer, too cold for the humans who would naturally float on the dense liquid (and thereby be pressed against the ice layer). You're either over or under thinking this, or both. But in any case, I'm sick of discussing when you obviously don't get the point. Best of luck with your puddles. I'm out of here. – Andrew Thompson Sep 24 '16 at 15:26
  • @Andrew Thompson nothing prohibits warming up local dwellings like we do on Earth. – Anixx Sep 24 '16 at 15:27
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    @AndrewThompson the humans are smart - after hitting their heads a few times the humans would rotate and then just walk on the underside of the ice. If the local gravity were $g'$ and the perfluorocarbon had a density of 1.6 $g/cm^3$ then they'd be walking on the ceiling feeling a "gravity"' 0.6 $g'$. Boats would be small crawlers/rovers that sit on the ice with rubber treads. When they want to get into a boat, they get an ice fishing hole maker and cut a hole below the rover. They "jump in" (up) until their legs are in the rover (glued to ice by oozing water) then push their way through. – uhoh Sep 26 '16 at 17:42
  • @AndrewThompson a little bit like this: http://i.stack.imgur.com/p2LXb.jpg except there'd be the perfluorocarbons, and a boat above the hole instead of water. You could wear one of those suits to keep warm (I used to, but not as nice looking) but breathing cold liquid is a lot more chilling than breathing sub-zero air. I think you'd need an external heat exchanger, or just a downward hanging hose (weighted) so you could inhale the warmer stuff below (above?) – uhoh Sep 26 '16 at 17:49
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    Buoyancy doesn't work like gravity. If you're immersed in a dense liquid, you might be able to walk on the ceiling, but the blood will still rush to your head. – Keith Thompson Oct 04 '16 at 16:27
  • @KeithThompson I need some blood to rush to my head to think about that... OK done, Nope! I think that is not right. What you described would be true if we were sealed, rigid pressure vessels, but we are very squishy ugly bags of mostly water, and the vertical pressure gradient of the perfluorcarbon (due to gravity $g'$) will exist throughout our body as well. The problem happens on Earth in air because it is less dense than we are. – uhoh Feb 11 '17 at 19:32
  • @KeithThompson When diving in water, the same density as we are, you can float upside down all day and the blood will not go to your head. In dense perfluorocarbons, it will go to the feet for sure. Imagine what would happen if one of our explorers cut their foot. Their low density blood would run out the hole and cover the underside of the ice, sitting above the perflurocarbon. We are like these guys (the hot, lower density ones), and if the outside stops moving, the insides will keep pushing up until they regain their cooler density again: https://youtu.be/jUv4Cid3OnE – uhoh Feb 11 '17 at 19:35
  • @Anixx take a look at this! It's walking on the underside of the ice! https://youtu.be/HK5qnpDClRI?t=207 – uhoh Feb 11 '17 at 19:38
  • Uh ... how common is fluorine in space compared with hydrogen, carbon, oxygen, sulfur or even nitrogen? Is there really enough anywhere to have widespread fluorocarbon lakes to begin with? – Oscar Lanzi Feb 03 '21 at 01:49
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    Minor issue: how do you eat ? and... ...drink? – JFL Sep 06 '21 at 16:45

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Intriguing idea. I looked briefly at whether Mars' lowest lowlands could contain CFC atmospheres with acceptable pressure at the bottom, plus some oxygen, CO2 and nitrogen for open-air ecosystems. (I was inspired in this partly by C.S. Lewis' Mars, which posited very deep gorges hosting reasonable atmospheric pressure at their lowest elevations; but also by the geological results from Mars rovers, which suggest lots of chlorine and fluorine minerals in the soil.) It never occurred to me that you could have lakes of a breathable liquid. This might require some modifications on people (perhaps prosthetic) to keep the liquid out of their GI tracts; maybe also some neurosurgery to suppress gag reflexes. It might make more sense for agricultural purposes, with people visiting the submerged fields in SCUBA gear and the like.

Jerard Puckett
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Michael Turner
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    Fluorocarbons are natural anestetics, they do not produce a lot of gag reflexes. Also they if contain higher concentrations of oxygen, help to heal wounds. Wounds are sometimes treated with fluorocarbons with high oxygen content. This adds to their wonderful properties. – Anixx Sep 28 '16 at 23:07
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    Being a natural anesthetic is wonderful if you're having surgery, not so much if you're breathing it 24 hours a day. – Keith Thompson Oct 04 '16 at 16:29
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Arnold Lande has patented a SCUBA diving suit that incorporates liquid perfluorocarbon breathing. At the age of 67 going on to 68 later this year, I am.up to a challenge and new adventure, so would consider trying out liquid breathing. I first heard of liquid perfluorocarbon breathing decades ago, so this is not a new concept or application [1970s].

https://scubadiverlife.com/human-fish/

uhoh
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  • Welcome to space! The structure of stack exchange is questions and answers and your answer here reads more as a comment. The question here was about the concept of having a large pool of oxygenated perfluorocarobon rather than a gaseous atmosphere in a space habitat. – GremlinWranger Mar 19 '21 at 07:19
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    I've added some supporting links including Lande's patent and some articles about it. Please feel free to edit further, and Welcome to Space! – uhoh Mar 19 '21 at 08:05
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Yes it's possible, it's even possible to colonize our own Moon with pefluorocarbons !
Perfluorononane has a melting point of -16⁰ C and a density of about 1.8 kg/L, and according to the paper Densities and Vapor Pressures of Highly Fluorinated Compounds at 60⁰ C it has a vapor pressure of about 8.5 kPa.
That means that on Earth it's liquid surface will need a water column of 85 cm to prevent it from vaporizing. On the Moon that water column would need to be 6 times higher (5.1 m.) because of the lower gravity there, but of course the water would quickly evaporate into space.

But there are also solid perfluorocarbons !
Perfluorotetradecane has a melting point of 103⁰ C and a density equal to water so a 6 m. thick solid layer of it on top of the Perfluorononane could prevent the liquid from evaporating into space.

To have a pressure of 1 atm. at the bottom of the perfluorononane lake, it would have to be 30 m. thick with on top of it the 6 m. thick solid layer of perfluorotetradecane.

Cornelis
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  • If at -16 C it will solidify, I would not like to be in the midst at the time. – Anixx Sep 06 '21 at 14:56
  • Would it help you if you are frozen in ice? – Anixx Sep 06 '21 at 15:00
  • @Anixx Of course you have to have a heat source, on our Moon it could be from batteries stored with solar energy that would need to heat the living space during the 2 weeks long, cold night. – Cornelis Sep 06 '21 at 15:28
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    One important issue that doesn't appear to be mentioned yet on this page is that liquid breathing is hard work. Your lungs need to move a fluid that's ~1000 denser than air, and doing that consumes energy. Sure, the PFC can have a high oxygen concentration, so you can reduce your breathing rate, but you still need to get rid of CO2 in a timely fashion. – PM 2Ring Sep 06 '21 at 17:34