Aliens are found! Well . . . Almost.

[pood]

Not sure what else the ocean could be made of.

Titan's are methane.

But water seems most likely, given the probable temperature range.

Yeah, I agree. Titan actually has no methane/ethane ocean but rivers and lakes. However, it is believed that there is a planet-wide liquid ocean underground. I just briefly glanced at a study somewhere claiming that if there is such an ocean, it’s unlikely that thriving biosphere exists in it for some reasons. I’ll try to find the study.

 

[bilby]

Not sure what else the ocean could be made of.

Titan's are methane.

But water seems most likely, given the probable temperature range.

Yeah, I agree. Titan actually has no methane/ethane ocean but rivers and lakes. However, it is believed that there is a planet-wide liquid ocean underground. I just briefly glanced at a study somewhere claiming that if there is such an ocean, it’s unlikely that thriving biosphere exists in it for some reasons. I’ll try to find the study.

Methane is a pretty poor solvent. No other solvent compares to water. It's not even close.

The old time alchemists who were searching for a universal solvent had the closest real thing right under their noses. They also appear not to have thought through what they would keep it in if they found it...

 

[pood]

I should add the idea is that there is a water ocean underground on Titan, not just a liquid ocean.

 

[bilby]

I should add the idea is that there is a water ocean underground on Titan, not just a liquid ocean.

I had not heard that. I guess it shouldn't surprise me, but I had the impression that Titan was all about hydrocarbons and ammonia, with all the water in the form of ice.

 

[pood]

I should add the idea is that there is a water ocean underground on Titan, not just a liquid ocean.

I had not heard that. I guess it shouldn't surprise me, but I had the impression that Titan was all about hydrocarbons and ammonia, with all the water in the form of ice.

The latest study I saw was that there was a water ocean undergound that spanned all of Titan.

 

[Elixir]

Perplexity:
“Titan, Saturn’s largest moon, is thought to have a global underground ocean as salty as the Dead Sea, located beneath its icy crust and possibly above another layer of ice.
• Unlike Enceladus and Europa, Titan also has surface lakes of methane and ethane, but its subsurface ocean is likely water-based.
• The ocean is believed to be sandwiched between layers of ice, which may affect its chemistry and habitability”

I’m betting on Enceladus :

“The ocean is salty, contains organic compounds, and is in contact with the moon’s rocky core, suggesting hydrothermal vents may exist”

 

[bilby]

Perplexity:
“Titan, Saturn’s largest moon, is thought to have a global underground ocean as salty as the Dead Sea, located beneath its icy crust and possibly above another layer of ice.
• Unlike Enceladus and Europa, Titan also has surface lakes of methane and ethane, but its subsurface ocean is likely water-based.
• The ocean is believed to be sandwiched between layers of ice, which may affect its chemistry and habitability”

I’m betting on Enceladus :

“The ocean is salty, contains organic compounds, and is in contact with the moon’s rocky core, suggesting hydrothermal vents may exist”

All these worlds are ours. Except Europa; We should attempt no landing there.

 

[pood]

Reasons to be skeptical about the alleged biosignature

 

[pood]

Phil Plait is skeptical

 

[Jimmy Higgins]

Reasons to be skeptical about the alleged biosignature

Which brings us to whether the signal of a biosignature—the presence of these key wiggles in the JWST spectrum—is real. While the signal is there at three sigma, that's three sigma above a completely featureless spectrum. For its specific identity as dimethyl sulfide, we only know that it's the best fit out of the 20 chemicals considered in this paper. There are a whole host of other chemicals that could plausibly be produced on a planet like this that weren't included in this analysis. The potential presence of a dimethyl sulfide signal at other wavelengths in earlier work may seem to solidify this identification, but a reanalysis of that data found no evidence of a statistically significant signal.

This isn't be skeptical, it is being reasonable. More research is needed and no one is concluding anything here.

What this did was it verified that the original spectral information in the dimethyl sulfide side of the spectrum, where they weren't specifically looking that first time, doesn't appear to be noise. So now, this portion of the spectrum needs to be thoroughly scrutinized for all potential overlapping molecules in an attempt to confirm that this is that chemical. Then, we need to determine another way to test for other markers to test for life.

 

[Loren Pechtel]

Not sure what else the ocean could be made of.

Titan's are methane.

But water seems most likely, given the probable temperature range.

Yeah, I agree. Titan actually has no methane/ethane ocean but rivers and lakes. However, it is believed that there is a planet-wide liquid ocean underground. I just briefly glanced at a study somewhere claiming that if there is such an ocean, it’s unlikely that thriving biosphere exists in it for some reasons. I’ll try to find the study.

Methane is a pretty poor solvent. No other solvent compares to water. It's not even close.

The old time alchemists who were searching for a universal solvent had the closest real thing right under their noses. They also appear not to have thought through what they would keep it in if they found it...

Isn't alcohol a better solvent?

But the reality is that we aren't going to find intelligent methane-based life. Reaction rates are highly sensitive to temperature, evolution is going to be slow at such temperatures.

Once you consider reaction rates, elemental abundance, and silicon's inability to form long chain molecules with hydrogen you're left with a biochemistry something like ours being the only possible answer.

 

[bilby]

Isn't alcohol a better solvent?

Depends what you are trying to dissolve (and which alcohol).

Water dissolves a larger range of substances - for example, more inorganic salts dissolve in water, than in methanol or ethanol.

 

[Elixir]

All these worlds are ours.

Not if you ask barbos!

 

[lpetrich]

The very name of the field of "organic chemistry" stems from vitalism - the firm and widespread belief that certain compounds could only be produced by life. A belief that was debunked by the 1828 synthesis of Urea from Ammonium Cyanate by Friedrich Wöhler.

That was only *one* vitalist hypothesis, and that synthesis was only a tiny bit of counterevidence for that hypothesis.

• 1828 - Friedrich Wöhler - NH4-NCO to NH2-CO-NH2
• 1845 - Adolph Kolbe - CS2 to CH3-COOH in several steps
• ~ 1860 - Marcellin Berthelot - numerous organic compounds made from inorganic precursors

Even if that vitalist hypothesis was refuted by experiment, others remained. Do living things work by some vital force? No trace of one has been discovered in researches into metabolism and heredity, though genes to macroscopic features is still an unsolved problem.

About that problem, around the turn of the 20th cy., biologist Hans Driesch was experimenting with sea-urchin embryological development. Most sea urchins have a larval phase that looks like a small glass jug with spikes extending out of it and pointing in one direction. Unfolding Nature’s Patterns | The Brink | Boston University

HD decided to cut an embryo in half when it was at the 2-cell or 4-cell stage. Instead of each half developing into half of a larva, each half developed into a smaller larva. He was mystified by that, and he decided that organisms have some "entelechy" or goal-seeking tendency, a vital force under some other name.

We have not been nearly as successful with embryonic development as we have with metabolism and heredity, but we have learned enough to make HD's entelechy a superfluous hypothesis. That is from an improved understanding of cell fate, what a cell's descendants will become. At first, cells are "totipotent", able to develop into anything, but with continuing embryonic development, cells' fates become more and more restricted. Some cells continue to have a relative broad fate; those cells are stem cells.

 

[lpetrich]

 Vitalism is a very old idea, and it seems like common sense. Among notable vitalists were the Greco-Roman atomists, who believed that living things are made alive by soul atoms. Another one was Aristoteles of Stagira, better known as Aristotle. He identified three kinds of soul or vital force: the vegetable soul, which does growth and reproduction, the animal soul, which does motion and sensing, and the rational soul, which does reasoning.

It died a slow death over the 19th and early 20th centuries, and in the later part of that time, it may have seemed like a hypothesis of a "vital force of the gaps". In 1910, Jacques Loeb published The mechanistic conception of life : biological essays : Loeb, Jacques, 1859-1924 : Free Download, Borrow, and Streaming : Internet Archive and on book pages 5 - 6, he issued this challenge:

"... we must either succeed in producing living matter artificially, or we must find the reasons why this is impossible."

Where we are at now:
KEGG PATHWAY Database

1. Metabolism - Global/overview, Carbohydrate, Energy, Lipid, Nucleotide, Amino acid, Other amino, Glycan, Cofactor/vitamin, Terpenoid/PK, Other secondary metabolite, Xenobiotics, Chemical structure
2. Genetic Information Processing
3. Environmental Information Processing
4. Cellular Processes
5. Organismal Systems
6. Human Diseases
7. Drug Development

 

[Swammerdami]

Dimethyl sulfide arises on Earth only via life or human industry, but might there be non-living mechanisms due to special circumstances on another planet?

Industrial processes

In industry dimethyl sulfide is produced by treating hydrogen sulfide with excess methanol over an aluminium oxide catalyst:[19]

2 CH₃OH + H₂S → (CH₃)₂S + 2 H₂O

Dimethyl sulfide is emitted by kraft pulping mills as a side product from delignification.

What "bio-signature" chemicals present on Earth have sufficient concentration to be as detectable as that (CH₃)₂S on the alien world? IIUC O₂ suggests life because of its reactivity (i.e. impermanence).

(Disclaimer: My knowledge of chemistry is about zero; I'm probably embarrassing myself.)

 

[Bronzeage]

If we ever encounter life on another planet, we will be the aliens.