Let’s suppose I want to create a lifeform that could survive unprotected on Venus.

It couldn’t contain any water of course. But it could be carbon-based. Instead of water, perhaps the lifeform could use soap as its solvent.

Could it be DNA-based?

ATP melts at 187 °C and boils above 951 °C (above because it boils at a higher temperature when the atmospheric pressure is higher). Venus average temperature is 462 °C so having an ATCG genetic code still looks possible.

If not, Robert L Forward suggested a genetic code consisting of liquid crystals (though that was for a cold planet).

So few organic materials are liquid at Earth surface temperatures, far more are liquid at Venus surface temperatures. Wouldn’t that make life easier on Venus than on Earth?

On the surface or underground unprotected ?

I can imagine it would almost need to be two dimensional in shape as height would be detrimental due to the extreme pressures

Cymek said:

On the surface or underground unprotected ?

I can imagine it would almost need to be two dimensional in shape as height would be detrimental due to the extreme pressures

The pressure on the surface of Venus is about the same as at 900 m depth in the oceans, so that should be a great impediment to carbon based life.

The Rev Dodgson said:

Cymek said:

On the surface or underground unprotected ?

I can imagine it would almost need to be two dimensional in shape as height would be detrimental due to the extreme pressures

The pressure on the surface of Venus is about the same as at 900 m depth in the oceans, so that should be a great impediment to carbon based life.

… where “should” = “should not”

The Rev Dodgson said:

The Rev Dodgson said:

Cymek said:

On the surface or underground unprotected ?

I can imagine it would almost need to be two dimensional in shape as height would be detrimental due to the extreme pressures

The pressure on the surface of Venus is about the same as at 900 m depth in the oceans, so that should be a great impediment to carbon based life.

… where “should” = “should not”

Thank you. Pressure doesn’t become a significant worry for life until 7.39 MPa which is the triple point of carbon dioxide. Even above that, carbon based life would still be possible, it would just be breathing supercritical carbon dioxide (high density and viscosity) instead of gaseous carbon dioxide.

mollwollfumble said:

The Rev Dodgson said:

The Rev Dodgson said:

The pressure on the surface of Venus is about the same as at 900 m depth in the oceans, so that should be a great impediment to carbon based life.

… where “should” = “should not”

Thank you. Pressure doesn’t become a significant worry for life until 7.39 MPa which is the triple point of carbon dioxide. Even above that, carbon based life would still be possible, it would just be breathing supercritical carbon dioxide (high density and viscosity) instead of gaseous carbon dioxide.

I can’t imagine you get life forms that are very tall though, wouldn’t they evolve to be short, squat and dense

Cymek said:

mollwollfumble said:

The Rev Dodgson said:

… where “should” = “should not”

Thank you. Pressure doesn’t become a significant worry for life until 7.39 MPa which is the triple point of carbon dioxide. Even above that, carbon based life would still be possible, it would just be breathing supercritical carbon dioxide (high density and viscosity) instead of gaseous carbon dioxide.

I can’t imagine you get life forms that are very tall though, wouldn’t they evolve to be short, squat and dense

It took about 275 million years on Earth before life here ceased to be short, squat and dense.

Because organics are more easily liquid on Venus, an ocean of tar is possible.

How about a silicon-based life-form?

Silicon requires greater temperature, time and pressure to react than carbon. It is the element below carbon on the periodic table so behaves similarly in some chemical senses. It forms long chain and flat-sheet molecules. It forms weak acids and many of its compounds are relatively unreactive to strong mineral acids.

Michael V said:

How about a silicon-based life-form?

Silicon requires greater temperature, time and pressure to react than carbon. It is the element below carbon on the periodic table so behaves similarly in some chemical senses. It forms long chain and flat-sheet molecules. It forms weak acids and many of its compounds are relatively unreactive to strong mineral acids.

I’d really love to do that. The relative absense of oxygen would help stop the organism from accidentally ending up as a silicate or silicone. Any idea about how to make a genetic code for a silicon-based lifeform?

mollwollfumble said:

Let’s suppose I want to create a lifeform that could survive unprotected on Venus.

It couldn’t contain any water of course. But it could be carbon-based. Instead of water, perhaps the lifeform could use soap as its solvent.

Could it be DNA-based?

ATP melts at 187 °C and boils above 951 °C (above because it boils at a higher temperature when the atmospheric pressure is higher). Venus average temperature is 462 °C so having an ATCG genetic code still looks possible.

If not, Robert L Forward suggested a genetic code consisting of liquid crystals (though that was for a cold planet).

So few organic materials are liquid at Earth surface temperatures, far more are liquid at Venus surface temperatures. Wouldn’t that make life easier on Venus than on Earth?

Found a technical hitch.

“We find that under dry conditions, complete DNA degradation occurs at above 190°C. In addition, as the boiling temperature of water is pressure dependent, we have investigated the thermal degradation of the DNA in water for different applied partial pressures.Apr 27, 2013
Thermal degradation of DNA. – NCBI”.

“under dry conditions, at gradual temperatures, DNA degradation occurs in a linear manner, with complete degradation at around 190°C. In addition, we found that pressure itself negatively affects DNA thermal degradation in water.Again, we would like to stress that we do not discuss the denaturation of DNA, that is, separation between the two strands by breaking the hydrogen bonds between them, but rather we refer to DNA degradation, that is, breaking the covalent bonds within each strand.”

At atmospheric pressure there’s already a 25% breakdown at 130°C. At a pressure of 10 bar, things get worse, a 70% breakdown at 110°C.

So it looks like DNA is not a feasible genetic code on Venus, unless it can be stabilised somehow by for example dissolving it in tar or attaching polymers to it.