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Would it be possible, given many advances in genetic engineering that today remain speculative, to design a lifeform capable of withstanding the hostile conditions of the Venusian atmosphere?

I'm picturing something akin to a tree. Its crown is made of branches and leaves, and where the roots would be we find another, inverted crown with branches and leaves. In the Venusian atmosphere, the sunlight bounced back from the clouds below is almost as bright as direct sunlight, so this is a way to capture and use as much light as possible. The branches in the upper crown have many small bubbles  of transparent membrane attached that hold air (nitrogen and oxygen) inside. These bubbles are what make the tree buoyant (breathable air is a lifting gas on Venus). The branches in the lower crown hold water distilled from the sulfuric acid and lower its center of mass, making it more stable. These trees bound themselves to others via their branches, forming great clusters that resemble floating forests. This is how they manage to survive the hurricane winds present in the atmospheric layer around 55 kilometers above the surface.

What would its basic biochemistry look like? I'm thinking it would breathe in CO2, fix the carbon and release the oxygen, which it uses together with nitrogen extracted from the atmosphere to fill the bubbles in its upper crown. It uses sulfuric acid as biosolvent, and this is where things get funky and murky for me. I don't know how different its biochemistry would have to be compared to a typical Earth tree in order to be able to use sulfuric acid and also be able to survive its acidity in the first place. This is where I'm most looking for input.

I don't expect this lifeform to be able to survive long-term without human care and intervention. It is also not meant to pave the way for terraforming, but to provide an abundant and easy to use resource for human settlers. Humans collect its air and water bubbles. They give its biomass many industrial and agricultural uses (assuming its acidity doesn't preclude them from doing so). These forests represent the basic economic foundation upon which Venusian settlements survive and thrive.

Anything I'm missing? Anything I should keep in mind or include? I'm not looking to come up with a perfectly realistic bioengineered tree, but I'd like it to be as plausible as possible.

EDIT I should clarify. This is asked in the spirit of soft sci-fi, perhaps dipping into science-fantasy. I don't expect this to be something that could plausibly happen in real life, it's a concept I've been toying with that I'd like to incorporate into my setting, but I won't do it if it requires magic to work. Think the Dune sandworms. Some details of their biology can be iffy at best, but the author handwaves the issues away and the story is all the more richer for having them.

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    $\begingroup$ In what realm do you mean "feasible", "plausible" and "possible"? Is your world a hard sci-fi, a soft sci-fi, science-fantasy, pure fantasy, surreal fantasy, etc? In other words, the kind of realism you're working with in your setting will guide us in responding yes, no, or maybe. $\endgroup$
    – elemtilas
    Commented Apr 9 at 16:33
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    $\begingroup$ I would expect biggest issue to be those elements that are needed such as magnesium but are not in the atmosphere. It would be more plausible to start with algae, simpler life forms so faster easier to iterate. $\endgroup$ Commented Apr 9 at 20:41
  • $\begingroup$ I should clarify. It's in the realm of soft sci-fi, perhaps dipping into science-fantasy. I don't expect this to be something that could plausibly happen in real life, it's a concept I've been toying with that I'd like to incorporate into my setting, but I won't do it if it requires magic to work. Think the Dune sandworms. The details of their biology are iffy at best, but the author handwaves the issues and the story is all the more richer for having them. $\endgroup$
    – Aeolian
    Commented Apr 10 at 0:37
  • $\begingroup$ Okay --- please edit your question with that information! Comments can be deleted at any time and are not considered part of the question. $\endgroup$
    – elemtilas
    Commented Apr 10 at 2:58
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    $\begingroup$ Have you read Larry Niven's The Integral Trees and The Smoke Ring? They are about life in a gas torus. They may give you some ideas. $\endgroup$ Commented Apr 10 at 13:01

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I worry that something the size of a tree may be very fragile. If it has a tiny leak it may start to fall.

How about something smaller? How about an aerial version of a volvox colony. This would be a globe of little epiphytes that form into spheres. These will intercept light, become warm, and become buoyant. They can reproduce as volvox colonies do by growing smaller spheres within themselves, and releasing them when they burst. The spheres do not have to be airtight: if the gaps between the algae are small, the air will be contained well enough.

What happens at night? They will cool. They will lose their buoyancy. They will fall, but they will only fall slowly. Maybe they will not fall too far before the light comes back. The night at the surface of Venus is longer than the year, but there are huge winds in the atmosphere that circle Venus in about 4 Terran days.

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    $\begingroup$ Thanks for your comment. I wasn't aware of volvox colonies. That's interesting! $\endgroup$
    – Aeolian
    Commented Apr 10 at 0:53
  • $\begingroup$ If it has a lot of separated lift-bubbles (which I'd imagine it have) it would merely drop a bit towards denser air, so not a critical issue. That being said: the trees would definitely break $\endgroup$
    – Hobbamok
    Commented Apr 10 at 14:33
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Extracting water from the ambient sulfuric acid would be an incredible feat. Concentrated sulfuric acid will rip the water right out of carbohydrates, leaving a pile of carbon soaked with somewhat more dilute acid. The problem is not just that you need to biologically tear the water away from the sulfuric acid without being destroyed by that acid, you then need to somehow separate it from whatever material you concocted that was able to do this.

This also poses obvious issues for using it as a biosolvent. Realistically, what you'd actually use would be highly diluted with water, or the range of biochemistry you can use is extremely limited. The problem remains the same, you need to get water from the environmental sulfuric acid to dilute what you're using as a solvent.

The most straightforward way to separate water from sulfuric acid is distillation, which requires temperatures and materials unlikely for a biological system. Additionally, water is a lot more useful to you than sulfuric acid, and you can get more by decomposing the sulfuric acid itself, but this requires even more extreme temperatures. This system becomes a lot more plausible if it isn't entirely biological, for example if the trees incorporate mechanical components to perform the industrial processes that extract the needed water. And you're going to need to supplement and tend the forest anyway, since the atmosphere simply doesn't have everything needed.

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    $\begingroup$ Thanks for your insight. This gives me food for thought. How about this? In this setting, humans inhabit many diverse aerostats that incorporate all the necessary systems to support life, including equipment that distills water from sulfuric acid. They then use some of this water to nurture the floating forests. They also seed these forests with minerals that are non-existent in the atmosphere and necessary for the trees to survive. The trees have been engineered to be acid-resistant, which makes them a vital source of acid-resistant materials. $\endgroup$
    – Aeolian
    Commented Apr 10 at 0:51
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    $\begingroup$ The relationship between humans and the forests is symbiotic. Both need each other to survive. $\endgroup$
    – Aeolian
    Commented Apr 10 at 0:52
  • $\begingroup$ There are sulphur oxidising bacteria that produce sulphuric acid. Clearly it can be handled to at least some degree by biological organisms. $\endgroup$ Commented Apr 10 at 10:26
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    $\begingroup$ @Hobbamok that reaction seems overly complicated...I see no reason to involve sodium chloride, electrolysis, or elemental sodium, for example. Stripping out the unnecessary bits, you could just react it with an alkali metal hydroxide to produce a sulfate and water, thermally decompose the sulfate to produce an alkali metal oxide, SO2, and some oxygen, and react the alkali metal oxide with water to produce the hydroxide again. $\endgroup$ Commented Apr 10 at 16:00
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    $\begingroup$ And there are sulfate-reducing bacteria that consume sulfates and produce elemental sulfur, so this could be done biologically, but on Earth this requires some source of organic materials to oxidize in place of the sulfur being reduced. It'd be quite energy intensive, which would limit the rate at which a plant could recover water from the sulfuric acid. The cyborg-trees route would probably be more productive. $\endgroup$ Commented Apr 10 at 16:04
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Where does the mass come from? A tree cannot grow on CO2 and water alone, it actually needs nutrients from the soil as well.

The tree does not need to worry about acid: at the level of atmosphere where it would operate, clouds are mostly just water. It is seemingly a perfect aeroponic environment, one made almost entirely out of CO2, trace N2 and water vapor. But even if the tree was a perfect gas-to-biomass converter, it would not be able to survive on such a dilute "diet".

Least silly way to achieve that, is to park the trees over one of the many Venusian volcanoes. the volcano would belch out clouds of ash particles, which are rich in sulfur, sodium, magnesium, etc that the plant needs to survive. It would be effectively dusted with ash as fertilizer.

Of course, this kind of place would be even more dangerous to humans than regular Venusian atmosphere is.

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  • $\begingroup$ There are many volcanoes on Venus, but very little volcanic activity, to the point that until recently it was debated whether there was any current activity, and the atmospheric superrotation means hovering over one would mean fighting hurricane force winds. $\endgroup$ Commented Apr 10 at 14:53
  • $\begingroup$ Trace (!) minerals are just a small fraction of the overall mass though. And since OP explicitly stated that some upkeep is a fair caveat, I would assume fertilizing to be fair game. Especially if/since we're engineering the whole thing from scratch anyway. On top of that the number one (or #2) trace mineral is sulphur once again, and oh boi do we have enough of that. So we can realistically get it down to 0.01% or so of product mass in required fertilizer which is fair and far below irl farming (all numbers made up, including the number one) $\endgroup$
    – Hobbamok
    Commented Apr 10 at 14:53
  • $\begingroup$ The nutrients are seeded by the humans themselves. They keep stockpiles of fertilizer for that. I don't expect these minerals to amount to a huge part of the tree's mass but yes, it's something to keep in mind. Sadly, I don't think volcanoes would work. Like Christopher said, staying fixed in place above a volcano would require fighting winds that would tear the forest apart. $\endgroup$
    – Aeolian
    Commented Apr 10 at 16:49
  • $\begingroup$ Note that it's not at all easy or without significant limitations, but even current technology is capable of building hardware that can operate indefinitely on the surface. It's not an utterly inaccessible environment, just much, much harder than the alternatives, and not something that you're going to do with any sort of biotech. $\endgroup$ Commented Apr 10 at 18:57

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