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Venus vs Titan: which is more likely to support life?


todofwar
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Titan vs Venus  

47 members have voted

  1. 1. Which is more likely to have life on it today?

    • Venus
      6
    • Titan
      41


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Another thread got started debating searching for life on too likely candidates. I was curious, among two of the least likely candidates for harboring life, which would be more likely to have life on it? 

Venus:

Pro: 

Was habitable up until relatively recently, some form of life may have continued in the clouds

Supercritical CO2 is actually a pretty good solvent for chemistry to take place

Might still have some tectonics, and probably had tectonics long enough to develop life

Con:

Temperature closer to surface makes organics not as stable

Clouds are SO2, which can serve as a solvent but not tested

Titan:

Pro:

Liquid cycle analogous to Earth's water cycle

Plenty of organics

Radiation in upper atmosphere could provide source of energy

Con:

Nothing dissolves in liquid methane

Too cold for most chemical reactions to take place

Edited by todofwar
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2 minutes ago, Kryten said:

What is life in Venus' clouds even supposed to be made out of? Sure, you have something that might function as a solvent, but you aren't going to get organics to be in that solvent.

http://www.astrobio.net/topic/origins/extreme-life/life-on-earths-ceiling/

Life finds a way! I don't think it would evolve up there, but given Venus's past something may have survived the scorching of the surface. 

I should say, I think both candidates are highly unlikely. I just think Venus is slightly more likely. As an analogy, I wouldn't test my luck against someone with a gun or someone with a knife, but if I have to choose I'll go against the person with a knife. 

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40 minutes ago, kerbiloid said:

Titan.
Venera-4..16 and Vega-1..2 landers are already definitiely sterilized by 500 C and 90 atm.
While Titan is probably still inhabited by (sleeping) bacteria from Huygens.

Pressure is actually not a big deal. A huge fraction of life on earth lives at much higher pressures. 

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41 minutes ago, todofwar said:

Pressure is actually not a big deal. A huge fraction of life on earth lives at much higher pressures. 

Yes, higher than almost 100 times sea level pressure. The Marianas Trench doesn't have pressures nearly that high, and I doubt that any life can survive in the mantle and core, where pressures are that high...

Oh, sure, it can melt lead, it can cook a pizza in 7 seconds (Neil DeGrasse Tyson did the math), it's the hottest surface in the solar system (except for the surface of the Sun), it can vaporize DNA and organic molecules in a snap, but life is still hibernating on the now crushed and melted Venera probes. Sure...

If Venus could talk:

"That was a probe? Sorry, I thought it was space junk. It made a delicious METAL PANCAKE, though. Want a bite?"

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5 minutes ago, KAL 9000 said:

Yes, higher than almost 100 times sea level pressure. The Marianas Trench doesn't have pressures nearly that high, and I doubt that any life can survive in the mantle and core, where pressures are that high...

Oh, sure, it can melt lead, it can cook a pizza in 7 seconds (Neil DeGrasse Tyson did the math), it's the hottest surface in the solar system (except for the surface of the Sun), it can vaporize DNA and organic molecules in a snap, but life is still hibernating on the now crushed and melted Venera probes. Sure...

If Venus could talk:

"That was a probe? Sorry, I thought it was space junk. It made a delicious METAL PANCAKE, though. Want a bite?"

Uhh, not discounting the temperature issue but the Mariana Trench has pressures of 1000 atmospheres according to wikipedia, 10 times higher than the surface of Venus, and life has been found down there.  

The chemistry would have to be very different from biochemistry on earth, but the same is true of titan. No known enzymes can operate at liquid methane temperatures.

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15 minutes ago, KAL 9000 said:

Yes, higher than almost 100 times sea level pressure. The Marianas Trench doesn't have pressures nearly that high, and I doubt that any life can survive in the mantle and core, where pressures are that high...

It takes about 10m of water for 1atm of pressure, so about 1,000m for 100atm. The Marinaras trench is almost 11,000m deep.

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4 minutes ago, kerbiloid said:

In medical sterilizer temperature is 100-150° C, pressure 1-2 atm. Twice 20 min is enough for most of bacteria.

Mariana is cool. Several degrees above zero.

And they found bacteria living in autovlaves (sterilizers). But I don't really think the surface is viable. I'm thinking more acidophiles persisting in the clouds.

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While the upper atmosphere of Venus could have some form of bacterial life, I think it's more likely for Titan to have life, for one, it doesn't even need to be on the surface (Even though, we have theorized that life could exist on the surface), Titan is thought to have an underground ocean, so even if the surface doesn't have life, remember, Titan has a lot of organics, a lot could've seeped into the underground ocean, and BOOM! Life!.

 

Although, on the other hand, I think it's too early to rule anything out, we should send probes instead.

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Life on venus is quite absurd the surface temperature is nearly 470 degrees centigrade (743.1 degrees kelvin)  or 878 degrees fahrenheit, atmospheric pressure is a whopping 92.6 atmospheres (9382.69 kilopascals) besides sporting high temperature Venus has an atmosphere of Carbon Dioxide and Various Sulfuric Gases, which precipitates as a crude form of sulfuric acid. Due to possible Volcanism on the surface, and the greenhouse effect lastly the upper atmosphere of venus is electrostatically charged and gives of large amounts of electrostatic discharge in the form of lightning. Basically Venus is the astronomical equivalent of hell. 

Edited by Jeb1969
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6 hours ago, todofwar said:

http://www.astrobio.net/topic/origins/extreme-life/life-on-earths-ceiling/

Life finds a way! I don't think it would evolve up there, but given Venus's past something may have survived the scorching of the surface. 

I should say, I think both candidates are highly unlikely. I just think Venus is slightly more likely. As an analogy, I wouldn't test my luck against someone with a gun or someone with a knife, but if I have to choose I'll go against the person with a knife. 

Yes, however the bacteria don't reproduce in the stratosphere, they simply survive for some time until they die or fall down again.
On Venus you would not get resupply from the surface and anything going down would die. 
Sound unlikely that you could sustain life. 

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2 hours ago, Jeb1969 said:

Life on venus is quite absurd the surface temperature is nearly 470 degrees centigrade (743.1 degrees kelvin)  or 878 degrees fahrenheit, atmospheric pressure is a whopping 92.6 atmospheres (9382.69 kilopascals) besides sporting high temperature Venus has an atmosphere of Carbon Dioxide and Various Sulfuric Gases, which precipitates as a  crude form of sulfuric acid. Due to possible Volcanism on the surface, and the greenhouse effect lastly the upper atmosphere of venus is electrostatically charged and gives of large amounts of electrostatic discharge in the form of lightning. Basically Venus is the astronomical equivalent of hell. 

Lightning isn't a bad thing when it comes to developing life. 90 atmospheres is nothing, don't know why everyone is bringing that up when we know life can survive more than ten times that level. And sure, not all compounds are stable at 450 C, but there are plenty of strong bonds that could be operative.

No one has  yet defended the fact that on titan's surface you don't have the ability to conduct much chemistry. Too cold. And methane is an atrocious solvent for pretty much anything but hydrocarbons.

Edited by todofwar
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The basic concept of life is you have self replicating molecules that obtain energy and resources from the environment and copy their patterns before they are destroyed.  All life is like that.

The trouble with Venus is it's so hot that it's very very chaotic at the molecular level.  Anything that tries to have a pattern gets ripped apart by the heat before it can successfully copy itself.  Most substances are an energetic gas at those temperatures.

So Venus is basically impossible*, while Titan is so cold that life would be very slow - but it could work.

* "life" that would function on venus, maybe, would have to be devices that have insulated shells and a way to eject heat using pumps.  Inside the shells the machinery would be a saner temperature.  Basically self replicating robots if they were very large* might function on venus.

*the reason the machines have to be large is because insulation depends on shell thickness.  So there is no way for microorganisms to live on Venus.

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The problems with titan aren't limited to temperature. Methane is a lousy solvent, no ability to dissolve polar compounds, no ability to dissolve salts. Any large molecules will be solids and not available for chemistry. And of course chemistry is the basis for biology. There have been proposed macromolecular structures, that may even have long range order. But they won't be soluble in methane, making them as useful as regularly organized quartz.

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Titan, by far. Methane is actually the best solvent there is for cryogenic temperatures. Reason we need polar solvents at Earth temperature ranges is because you need strong hydrogen bonds to make up organic machinery in cells at 300K. Anything weaker would be too unstable, so you couldn't have things like DNA, for example. But then to build out of blocks with such strong bonds, you need polar solvents like water.

On the other hand, at 90K of Titan, you don't want such strong bonds in your organics to begin with. Instead of polar bonds, you're looking at van der Waals forces. With weaker bonds, you want weaker solvent. Non-polars like liquid methane will do just fine. With a caveat, that this does greatly limit the range of available chemistry for building life with. But you kind of expect that at such low temperatures either way.

I don't know if conditions for life to being on Titan are there, nor do I know if it's possible for something to evolve there in time that conditions were right, given how slow everything is going to be at these temperatures. But Titan has conditions compatible with a form of life that uses methane for solvent and catabolizes acetylene for food. This is a lot more than I can say for Venus.

I will say more. While I don't think Titan is the likeliest place for us to find life in the Solar System, it is the most important place for us to check. As I explained above, it is possible for a form of life to exist there, and we have some very loose tangential evidence suggesting that something like consumption of acetylene by life forms or mineral process is taking place there. Could totally be a red herring, likely even. But if we find life on Titan, it would be the most important discovery human kind has made ever. Because if life exists on Titan, it is life that definitely doesn't share origin with Earth's life. And that puts two independently evolved life forms into one star system. Not only would we have to greatly expand what we consider to be a habitable region, but we'd also know that universe is absolutely full of different kinds of life. Whereas, if we find life on Mars or Europa, it wouldn't be nearly as exciting, since we still would have to exclude common origin and it doesn't do nearly as much to expand our definition of habitable. So while it could still point to life Out There, it's not half as great a discovery.

On the balance of how likely it is, vs how important it would be as a discovery, I would mark Titan as the most important celestial body for us to study this century.

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Have many of you thought about that we might be the only life in the universe? I'm a Christian and everything but life have extremely low chances of happening, and by evolutionist standards, it takes a while for life to happen. No offense to anybody though.

Edited by Alpha 360
"Kouston, we have several problems, but that doesn't matter so we want to continue on with the mission."
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2 hours ago, K^2 said:

Titan, by far. Methane is actually the best solvent there is for cryogenic temperatures. Reason we need polar solvents at Earth temperature ranges is because you need strong hydrogen bonds to make up organic machinery in cells at 300K. Anything weaker would be too unstable, so you couldn't have things like DNA, for example. But then to build out of blocks with such strong bonds, you need polar solvents like water.

On the other hand, at 90K of Titan, you don't want such strong bonds in your organics to begin with. Instead of polar bonds, you're looking at van der Waals forces. With weaker bonds, you want weaker solvent. Non-polars like liquid methane will do just fine. With a caveat, that this does greatly limit the range of available chemistry for building life with. But you kind of expect that at such low temperatures either way.

I don't know if conditions for life to being on Titan are there, nor do I know if it's possible for something to evolve there in time that conditions were right, given how slow everything is going to be at these temperatures. But Titan has conditions compatible with a form of life that uses methane for solvent and catabolizes acetylene for food. This is a lot more than I can say for Venus.

I will say more. While I don't think Titan is the likeliest place for us to find life in the Solar System, it is the most important place for us to check. As I explained above, it is possible for a form of life to exist there, and we have some very loose tangential evidence suggesting that something like consumption of acetylene by life forms or mineral process is taking place there. Could totally be a red herring, likely even. But if we find life on Titan, it would be the most important discovery human kind has made ever. Because if life exists on Titan, it is life that definitely doesn't share origin with Earth's life. And that puts two independently evolved life forms into one star system. Not only would we have to greatly expand what we consider to be a habitable region, but we'd also know that universe is absolutely full of different kinds of life. Whereas, if we find life on Mars or Europa, it wouldn't be nearly as exciting, since we still would have to exclude common origin and it doesn't do nearly as much to expand our definition of habitable. So while it could still point to life Out There, it's not half as great a discovery.

On the balance of how likely it is, vs how important it would be as a discovery, I would mark Titan as the most important celestial body for us to study this century.

I think that's taking it a bit far. Titan has a small chance of harboring life, but that is like the odds of us finding bacteria on a comet. Possible, sure, but extremely unlikely. Saying Titan is the most important place to look for life is like saying the moon is the most important because it would show how life can develop in vacuum. 

And I can't emphasize how terrible a solvent methane is enough. It's not just bad at polar compounds, it's bad at pretty much everything except other hydrocarbons. How will you get electrochemistry going without electrolytes? How will you get energy transfer without electrochemistry? How will you get self replication without energy?

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6 minutes ago, todofwar said:

I think that's taking it a bit far. Titan has a small chance of harboring life, but that is like the odds of us finding bacteria on a comet. Possible, sure, but extremely unlikely. Saying Titan is the most important place to look for life is like saying the moon is the most important because it would show how life can develop in vacuum. 

And I can't emphasize how terrible a solvent methane is enough. It's not just bad at polar compounds, it's bad at pretty much everything except other hydrocarbons. How will you get electrochemistry going without electrolytes? How will you get energy transfer without electrochemistry? How will you get self replication without energy?

You want a solvent that's bad at everything. Because if you have a strong solvent, it will tear apart any bonds you could possibly use to organize your complex molecules at 90K without everything freezing solid. That includes the solvent, by the way.

You can do electrochemistry without ions. It sucks in comparison, and your energy storage is going to be ridiculously inefficient, but so is your energy flow to begin with, and so is the rate of every single process. And something is breaking down acetylene, releasing the stored energy, so it's clearly possible. Making use of that energy is the trick. Do I have any idea how? Nope. But I wouldn't have called ATP synthesize, either.

And it's all about the expectation on the return. A product of utility of discovery times it's likelihood. Life on mars has high likelihood, but tiny utility. We already know Terrestrial life could survive on Mars. Rest is academic. Life on an asteroid would be groundbreaking, but it's ridiculously unlikely to begin with and multiplied by our odds of finding the right asteroid. So again, very poor expectation value. Worse, we learn absolutely nothing but not finding life there. That's what we expect. Life on Titan has the right math going for it. It's certainly feasible. We see indirect evidence we expect to find, which is a good first indication. And life on Titan matches optimistic range of expectation for how life develops. Not finding life there would already be useful just to cross off the most optimistic of our expectations. But finding it there would be revolutionary and the odds of it are distinct from zero.

Think of it this way, sending a mission to Titan is like buying a lottery ticket where you are guaranteed to win at least the cost of the ticket. That would be the outcome of the study that finds no life there. It's still useful. This is the disappointing outcome, for sure, but you lose nothing. And the possibility of winning the jackpot, while somewhat remote, is definitely there, so it's just stupid not to go for it.

This is in contrast to every other destination in this Solar System. Mars is sort of a sure thing, we'll definitely get good mileage out of it, but unless we find ruins of alien civilization there, which we won't, it's not going to be anything revolutionary. And everywhere else we can go, we risk finding absolutely nothing of interest other than filling in a few checkboxes in our knowledge of the system. Titan has everything. Guaranteed payout and a chance for something great. It should be the highest priority target for this century.

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As Titan still has huge amounts of hydrocarbons and ammonia, probably they had never boiled.
If Titan has a warm and salty subsurface ocean, can't it be rich with hydrocarbons or so?

So, chances of life:
Venus: 0.
Europa: 0+.
Titan: 0+ Premium.

Titan exploration should be the main and central aim of SolSystem exploration. Not Mars or Europa.
Because it's Laythe.

Edited by kerbiloid
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