Question Venus surface Lifeforms strategies/physiology

[Admiral_Ritt]

Did not want to put this question in the main spaceflight forums, since
it is entirely speculative, and hopefully avoid certain killjoys on this bbs.

It appears that Venus was more like Earth like at start.
Let make some assumptions.

If complex life up to simple animals (pre-Cambrian equivalent) arose there.
And the transformation of Venus from wet world to the present state
occurred gradually enough for life to adapt. What would they be like ?

Give a General description, and how they are able to survive on the surface
of Venus. (you may assume that Venus surface crust does partially melt over
periods of 500 Mya.


My money is on flying insect analogues. Most of the time such an insect will be in flight. Why? Because it is very easy to fly on Venus. and also at 15 km high. the Pressure is only 33 BAR. Such "insects" would have to be able descend to surface. The surface should contain compounds and chemicals OTHER than CO2, N2, SO2, such a living thing would need to harvest these Other compounds for growth, metabolic needs, reproductive needs.

So these creatures would have to figure out how to temporarily descend to
the surface, deal with the much higher temperatures and pressures there, and forage for chemical needs. They would also have to survive the melting crust that is speculated to occur over large intervals.

Let see what others can come up with.

 

[Thorsten]

Such "insects" would have to be able descend to surface.

Assuming it's supposed to be chemical life, unfortunately there's a problem.

Biochemistry requires under quite general conditions a certain combination of complexity and variability - life needs very large compounds such as proteins, but they're not supposed to be static, they need to be changeable (life needs to digest organic material and re-structure it,...)

Now the problem is that there's really no branch of chemistry which delivers such molecules at high temperatures such as at Venus surface (even the chemistries that deliver really complex molecules outside carbon are pretty rare). The reason is that hydrogen bridges in molecules just can't have arbitrary binding energies, they only come in a certain range. Which means at high temperatures they're just gone.

(That's leaving aside that biochemistry is generally agreed to pose more requirements, such as a suitable solvent, membranes to define an inside and outside of something,...) which again are difficult to meet at high temperatures.

In other words, you're hard pressed to have anything resemble bacteria, let alone higher life like insects.

 

[Hlynkacg]

...and even then, Insectoids don't seem like a particularly efficient body type for a high-temp high-press environment, flying ones with the necessary greater surface area (wings) seem even less so.

If there is life on Venus it is almost certainly some sort of airborne chemosynthetic "floater" (think jelly-fish or plankton) or crazy extremophile burrowing worms. That, or everything we thing we know about bio-chem is wrong.

 

[Urwumpe]

Maybe anorganic chemistry allows something interesting there. But I have doubts, especially since even chemists have their problems understanding unorganic chemistry.

 

[Linguofreak]

There might be some sort of unicellular life in Venus' clouds (where temperatures are somewhat earthlike) that can tolerate lots of H2SO4, but anything on the surface, or any complex life, is pretty much impossible.

 

[jedidia]

or crazy extremophile burrowing worms

Now there's a cool idea!

 

[Thorsten]

Maybe anorganic chemistry allows something interesting there

There's a surprising lack of even something like candidates. There's very few atoms from which you can build larger molecule backbones apart from carbon:

* sulfur allows long chains, but isn't particularly suitable for branching, so these are 'boring' molecules
* Silicon and Germanium are of the carbon group and so share some essential properties, but their ability to work other atoms into the molecules to form reactive centers so characteristic for carbon chemistry is absent
* Boron allows some fairly interesting structures, but it's not clear to what degree they'r flexible

(silicon also has the amusing side note that you can't have an oxygen breather, because unlike CO2 which you can exhale, SiO2 is sand which is going to clog lungs...)

... and that seems to be it - with most elements, you can't even build longer chains like hydrocarbons, let alone true biomolecules.

 

[Linguofreak]

(silicon also has the amusing side note that you can't have an oxygen breather, because unlike CO2 which you can exhale, SiO2 is sand which is going to clog lungs...)

Nothing says your energy source has to include your polymer building block.

Nothing says your oxidization has to happen in the respiratory organs either. It could happen as part of digestion and the sand could be passed in solid waste.

Not that I think surface life on Venus is at all possible.

 

[Urwumpe]

sulfur allows long chains, but isn't particularly suitable for branching, so these are 'boring' molecules

The reactions of O2F2 with sulfur are interesting though.

 

[Thorsten]

Nothing says your energy source has to include your polymer building block.

My (carefully worded) disclaimers actually do.

Besides, the argument 'it could be something we just don't know' is kind of cheap, as it's hard to refute while it's still not supported by anything. So yeah, maybe there's a complex chemistry based on X which does not require redox reactions as energy source in some corner of configuration space. There's just a complete absence of any indication that it'd be there.

But let's play this game: What energy source that happens to feed right into the excitation energies of a carbon-like chemistry do you have in mind?

The reactions of O2F2 with sulfur are interesting though.

My (very subjective and personal) bet on anything non-carbon - if anything at all - is actually sulfur - though I think bacteria-like is a stretch...

 

[Admiral_Ritt]

Remember I did not say that the originating life forms arose in Todays Venus.
It would have been a wetter Venus w/ a primordial atmosphere. I agree that
no new lifeform can arise on Venus now.

If there were enough evolutionary time, a complex lifeform that arose
in this early period, would there be a evolutionary path that allows it survive to the present day. If Venus went to a 95% SO2 Atmosphere in a few million years I would agree that there is no chance of anything escaping
extinction.

 

[Thorsten]

If there were enough evolutionary time, a complex lifeform that arose
in this early period, would there be a evolutionary path that allows it survive to the present day.

Evolution can't trick basic physics - like stability of chemical bonds.

Earth history shows that even comparatively modest change in climate were able to wipe ~70% of the lifeforms at that time - complex life is very fragile.

 

[Admiral_Ritt]

I don't think a multicellular lifeform on todays Venus. would be able to live on the surface. However the ability to "submerge" to the surface of Venus temporarily would be a matter of survival and have strong selection bias.

Any such creature would have to have a heat sink of some sort either
inorganic or organic, or some insulator.

Speaking of Extreme life:
One of the more interesting recent findings regarding extremophiles is
the discovery IN Oceanic Mud ("deep, hyper-salty basins in the Mediterranean Sea more than 10,000 feet (3,250 meters) deep. These basins are completely anoxic, or oxygen-free, and loaded with toxic levels of sulfides.")Frm LiveSci
Animals related to Loriciferans. No one expected this, since even ANIMALS
that live by hydrothermal vents rely on dissolved oxygen.

No this does not prove anything about Venus.
But it does show that there are surprises out there.

 

[Thorsten]

Yes, I know the step from 'hey, you can do without oxygen, nobody expected this' to 'why not have something that can survive 450 K' is tempting. But if you look a bit into how chemistry works, it's very different.

It's a bit aking to wondering 'Hey, there are human-powered aircraft - why not imagine a human-powered spacecraft?' Because while it seems similar if you don't know anything about flight, they're vastly different engineering regimes. You'll never launch any payload from the surface by pedaling.

Any such creature would have to have a heat sink of some sort either inorganic or organic, or some insulator.

Sit down, take a pencil and a sheet of paper, look up heat capacities of actual materials, pick the best one you can get away with. Compute how much thermal energy you need to dump dependent on your time on the surface. Compute how much of your heat sink material you need. Then compute how heavy your supposedly flying creature is going to be (I'm betting you have an 'insect' lugging around several tons of heat sink even for a short surface trip). Then argue how much energy it needs to keep this heat sink in the air. And then try to find out how a biological nuclear reactor could work, because sure chemistry isn't going to deliver it.

(I know, speculating is much nicer if nasty numbers don't interfere all the time...)

 

[Admiral_Ritt]

Throsten,
Don't go all 3rd grade remedial on me , I'm no enthusiast/fanatic.
I just wanted opinions, and wanted some alterative ideas. None came forth.

So you are willing to say for ALL planets in our galaxy that resemble Venus
and its development history in our solar system, None have extant lifeforms.

and we can leave it at that.

 

[Thorsten]

Don't go all 3rd grade remedial on me , I'm no enthusiast/fanatic.

Well, I am. I taught myself the relevant basics of biochemistry because I wanted to understand what's possible, what not and most importantly why.

I'm sorry you don't appreciate this perspective.

So you are willing to say for ALL planets in our galaxy that resemble Venus
and its development history in our solar system, None have extant lifeforms.

I'm willing to say that chemical life very likely needs a temperature region which allows hydrogen bonds to be stable.

There may be other forms of life (dependent on how you define it).

The thing that never ceases to amaze me is that despite an infinity of possibilities, nature is never 'anything goes'. Basic physics and chemistry can give us a glimpse of the shape of things we basically have no possible clue about.

How cool is that really?

 

[Admiral_Ritt]

I understand your perspective. You feel via your understanding
of physics/chemistry. That It is impossible for animal life evolve to exist on planets with the conditions of VENUS.

If you meant otherwise I don't see why your my question annoys you so much.

 

[Thorsten]

I understand your perspective. You feel via your understanding
of physics/chemistry. That It is impossible for animal life evolve to exist on planets with the conditions of VENUS.

Not... really.

My point is that speculation alone doesn't lead anywhere as long as anything goes, because whatever someone can dream up seems as valid as the next thing. But speculation augmented by understanding science basics can get to to really glimpse the shape of things. We can suddenly draw lines and say 'this speculation is impossible' - and then we can look how whatever remains looks like.

You say you wanted alternative ideas - but wouldn't you want to know which of these have a chance work?

I think that's far more interesting than just gathering ideas.

See, we can invent fusion spacecraft propulsion, antimatter propulsion, warp drive, impulse drive, you name it - yet I think it's more interesting to work out how long a fusion reactor powered craft would take to bring you to Pluto than to just say 'Fusion' and assume it's going to take a day.

I don't see why your my question annoys you so much.

You probably don't see why it annoys me because it doesn't annoy me in the first place. I just have this (given our times) funny notion that things like laws of physics and facts matter, and since this isn't a SciFi writing forum I feel perfectly justified pointing them out.