B Strongest hints yet of biological activity outside the solar system

[Cerenkov]

TL;DR Summary

New JWST data strongly suggests that it has detected two gases in the atmosphere of exoplanet K2-18b that are considered to be biomarkers.

https://hycean.group.cam.ac.uk/articles/hints-of-biological-activity-outside-the-solar-system/

https://hycean.group.cam.ac.uk/

This new data follows up on what was hinted in earlier observations.

https://www.nasa.gov/universe/exopl...hane-carbon-dioxide-in-atmosphere-of-k2-18-b/

Thank you,


Cerenkov.

 

[Lnewqban]

Another opportunity for human kind to destroy a place that has been functioning without our influence for millions of years.

 

[FactChecker]

Another opportunity for human kind to destroy a place that has been functioning without our influence for millions of years.

I wouldn't worry too much about that. At the fastest speed that we have ever got a spaceship to go, it would take over 200 thousand years to get there.

 

[Orodruin]

it would take over 200 thousand years to get there.

Remind me of the half-life of Cs-135 and I-129 …

 

[fresh_42]

Remind me of the half-life of Cs-135 and I-129 …

You are already planning the batteries?

 

[DaveC426913]

But back on-topic. This is seriously dammed cool.

 

[Cerenkov]

This caught my eye...


"However, the concentrations of DMS and DMDS in K2-18b’s atmosphere are very different than on Earth, where they are generally below one part per billion by volume. On K2-18b, they are estimated to be thousands of times stronger – over ten parts per million."


If this holds up it would be fascinating.

Perhaps this is just what we would expect from a water world several times Earth's size, completely covered with a deep ocean? A vast surface area to collect sunlight, giving rise to floating masses of primitive organisms? With a biomass far in excess of Earth's wouldn't we expect to see a much larger biomarker signal like this?

Speculation? Yes. But informed by the data. So surely, not just a flight of fantasy?


Thank you,


Cerenkov.

 

[Filip Larsen]

As far as experimental indications go the probability of this signal being caused by presence of biological life (as we know it) seems rather slim.

https://arstechnica.com/science/202...f-a-possible-biosignature-on-a-distant-world/

To be compelling, a biosignature from an exoplanet has to clear several hurdles that can be broken down into three key questions:

• Is the planet what we think it is?
• Is the signal real?
• Is life the only way to produce that signal?

At present, none of those questions can be answered with a definitive yes.

 

[RiScJ]

Is dimethylsulfide a good biomarker?

We inspected data collected by the high-resolution mass spectrometer DFMS (Balsiger et al. 2007) onboard ESA’s Rosetta spacecraft, which was studying comet 67P/Churyumov-Gerasimenko (hereafter 67P) for two years from up close, for the signature of DMS. Our detailed analysis of the sulfur-bearing hydrocarbon signals detectable in 67P’s coma yields strong evidence for the presence of DMS and thus provides the basis to argue that this molecule might not be a robust indicator of extraterrestrial life.

 

[Cerenkov]

Ok, so I've read the two linked articles from Filip Larsen and RiScJ (thanks guys!) and on the back of these I now have a question.

Is it viable to say that when it comes to looking for indications of life, is the situation re K2-18b at all similar to that of Mars?

In both cases there are hints of what could be biomarkers in the atmospheres of both bodies, with methane in the case of Mars. But an inorganic origin for both the DMS on K2-18b and the Martian methane could also be the case.

Is that a fair summary?


Thanks,

Cerenkov.

 

[Ken G]

It's part of a fair summary. But it only touches on whether the signal is a biomarker, there are also the other two issues mentioned above: is the planet really an ocean world, or just a mini Neptune? (It's more likely just a mini Neptune, so the assumption of what the world is like could be totally wrong). Also, is the signal real? (The data is based on some 3-sigma and 1-sigma detection levels, when scientists really like to get 5-sigma before they get too excited.) So the problem here is, there are "three hoops" that this system must get though with high confidence for any level of excitement to be justified, and so far it has not passed even one of those hoops. So all we can say is, "this system merits further study." That much is similar to Mars-- the chance of life of on Mars merits further study, that's all.

 

[Ken G]

But back on-topic. This is seriously dammed cool.

And there lies the problem. The pressure on astronomers to achieve "cool" results can lead to them overstate their claims, as happened here. Maybe this isn't bad for astronomy, since people like the headlines and aren't bothered by (or never even hear) the retractions later. It's a sticky issue, if astronomy exists purely to entertain and fascinate (which is kind of true), does it matter if there's a high level of reliability, or is it enough just to keep people on the edge of their seats?

 

[DaveC426913]

Publish or perish.

No, I am not saying it's cool because they might have found life. It's just cool to be in on the journey. I like to keep abreast of exo-planetary developments.

 

[Cerenkov]

I thank Ken G and DaveC426913 for their replies and input...

...but in the light of the original article by Prof Nikku Madhusundhan I find myself somewhat bemused and at a loss.

If there are doubts about the role of DMS as a biomarker, why would the JWST, which first discovered hints of it in the atmosphere of K2-18b a few years ago, be tasked with further, more lengthy observations? Telescope time on that probe must be at a premium. So what's the justification for this?

And why would K2-18b be treated as a Hycean world in all but name in the article when, as Ken G writes, it is more likely to be a mini-Neptune? If there's reasonable doubt about the status of this planet, shouldn't the author make this clear? Or at least be more even-handed about it?

Lastly, if there are these doubts about DMS and the planet itself, why compare the DMS concentrations of Earth with K2-18b, like this?

However, the concentrations of DMS and DMDS in K2-18b’s atmosphere are very different than on Earth, where they are generally below one part per billion by volume. On K2-18b, they are estimated to be thousands of times stronger – over ten parts per million.

I was sucked in by this comparison, thinking that if something associated with organic life on Earth was estimated to be thousands of times stronger on that exoplanet, then it must logically follow that this ocean world must be teeming with abundant life.

And lo and behold, what does the article itself say?

Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have.”

On the face of the comments made in this thread, the two above quotes seem very misleading. Like DaveC426913, I keenly watch for news about the possibility of life on exoplanets, so it's somewhat disappointing, if not galling, to be lead up the garden path like this.

Now, if I'm doing anyone an injustice here by not fully understanding something or not appreciating some subtlety I'll certainly apologise and retract my comments.

Thank you,


Cerenkov.

 

[DaveC426913]

If there are doubts about the role of DMS as a biomarker, why would the JWST, which first discovered hints of it in the atmosphere of K2-18b a few years ago, be tasked with further, more lengthy observations? Telescope time on that probe must be at a premium.

What JWST tasks do you think would supersede the search for exo-life?

Lots of research is important, sure, but surely unanswered questions about a possible exo-life candidate warrants a high priority, no?

And why would K2-18b be treated as a Hycean world in all but name in the article...

What do you mean "treated as"? We're researching it. That's how we treat such things. "Treated as" means we give it the attention (scope time, research time, etc.) that is warranted to a possible exo-life candidate, until such time as that is ruled out.

It's not like they've starting sending out forms for volunteer colonists.

when, as Ken G writes, it is more likely to be a mini-Neptune? If there's reasonable doubt about the status of this planet, shouldn't the author make this clear? Or at least be more even-handed about it?

Just because something is "more likely" to be mundane doesn't mean you abandon it.

Your lottery ticket is almost certainly not a winner, but you don't throw it in the trash without checking it, do you? You treat it as a potential winner until such time as that treatment is no longer warranted, no?

However, the concentrations of DMS and DMDS in K2-18b’s atmosphere are very different than on Earth, where they are generally below one part per billion by volume. On K2-18b, they are estimated to be thousands of times stronger – over ten parts per million."

"Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have.”

On the face of the comments made in this thread, the two above quotes seem very misleading. Like DaveC426913, I keenly watch for news about the possibility of life on exoplanets, so it's somewhat disappointing, if not galling, to be lead up the garden path like this.

Sorry, I don't follow. What is misleading?

I interpret it as "There is hope, but don't bet the farm just yet." - which is exactly what I'd expect at this stage.


I'm not sure what you mean by "galling" and "garden path". It sounds like you are expecting black-and-white, hard yes/no announcements about a subject that is only in the early stages of research.

I don't know about you, but I don't want to wait in silence for years while they hone their confidence levels, and then only get an answer once they're certain. I want to be along for the ride. Especially since it'll be years.

In my opinion, that's exactly why they publish these preliminary reports. For people like me.

Am I misunderstanding your position?

 

[Cerenkov]

If there are doubts about the role of DMS as a biomarker, why would the JWST, which first discovered hints of it in the atmosphere of K2-18b a few years ago, be tasked with further, more lengthy observations? Telescope time on that probe must be at a premium.

What JWST tasks do you think would supersede the search for exo-life?

Lots of research is important, sure, but surely unanswered questions about a possible exo-life candidate warrants a high priority, no?


Yes. You've misunderstood my position here, Dave.

The doubts expressed by others about the viability of DMS as a biomarker make me wonder why the precious JWST observing time was committed to K2-18b. If DMS is as doubtful a biomarker as Filip Larsen and RiScJ suggest then why was so much telescope time given to such a doubtful search? So I'm not actually questioning the importance of using the JWST for searching for alien life. On that score we are in agreement.

And why would K2-18b be treated as a Hycean world in all but name in the article...

What do you mean "treated as"? We're researching it. That's how we treat such things. "Treated as" means we give it the attention (scope time, research time, etc.) that is warranted to a possible exo-life candidate, until such time as that is ruled out.

It's not like they've starting sending out forms for volunteer colonists.

Again, you've misunderstood.

I was focusing on the wording of the article itself and the way it appeared to 'treat' K2-18b as, at least, a good candidate for a Hycean world. Nothing at all about the scope time or the research time. It was the wording of the article I was focusing on.

when, as Ken G writes, it is more likely to be a mini-Neptune? If there's reasonable doubt about the status of this planet, shouldn't the author make this clear? Or at least be more even-handed about it?

Just because something is "more likely" to be mundane doesn't mean you abandon it.

I didn't say or even imply that. Of course you don't abandon it. You are taking entirely the wrong meaning from my words.

I was comparing the doubts expressed by Ken G in this thread with (once again) the words of the article's author. My focus is the article, ok?


Your lottery ticket is almost certainly not a winner, but you don't throw it in the trash without checking it, do you? You treat it as a potential winner until such time as that treatment is no longer warranted, no?


We agree. But you've put a slant on what I wrote that simply isn't there. In no way did I imply giving anything up. My focus was on the wording of the article.

However, the concentrations of DMS and DMDS in K2-18b’s atmosphere are very different than on Earth, where they are generally below one part per billion by volume. On K2-18b, they are estimated to be thousands of times stronger – over ten parts per million."

"Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have.”

On the face of the comments made in this thread, the two above quotes seem very misleading. Like DaveC426913, I keenly watch for news about the possibility of life on exoplanets, so it's somewhat disappointing, if not galling, to be lead up the garden path like this.

Sorry, I don't follow. What is misleading?

The comparison of the DMS levels on Earth and on K2-18b is misleading IF the doubts expressed by Filip Larsen, RiScJ and Ken G about that chemical are true. Those doubts should also have been detailed in the article, for the sake of balance, so that naïve amateurs like myself won't take away the wrong meaning.


I interpret it as "There is hope, but don't bet the farm just yet." - which is exactly what I'd expect at this stage.

That's my position too. But the article goes further and suggests more.


I'm not sure what you mean by "galling" and "garden path". It sounds like you are expecting black-and-white, hard yes/no announcements about a subject that is only in the early stages of research.

No. I'm well aware that this is not b&w. I'm just taking issue with the tone of the article.

I don't know about you, but I don't want to wait in silence for years while they hone their confidence levels, and then only get an answer once they're certain. I want to be along for the ride. Especially since it'll be years.

Me too. But I would also want any significant doubts about DMS or the status of the planet (Hycean or not?) to be given in the article, for the sake of balance. Which was not done.


In my opinion, that's exactly why they publish these preliminary reports. For people like me.

Am I misunderstanding your position?


Yes, I'm afraid so - about almost everything I said.

I hope my comments in this post will correct that.



Cerenkov.

 

[DaveC426913]

Oh, I see. The article has too hopeful a spin.


I think this is par for the course. The article will generate interest wide and far. That's it's primary purpose.

Guileless folk will become interested in a subject because of what they see as possibilities, whereas skeptical people will take the article, as with all pop articles, with a healthy pinch of salt.

We know there are hoops to jump through, and we know that (for example) a 1% chance is "a good chance"; it doesn't have to be a (say) 40% chance to be good.

Those who want the facts will skim the article and go read the published paper.

Sorry, but that's the way of the world. Even NASA lives and dies on public sentiment. They won't get funding if their articles say "well it's extremely unlikely, but we think it warrants another zillion dollars in funding." ¯\_(ツ)_/¯

 

[FactChecker]

If there are doubts about the role of DMS as a biomarker, why would the JWST, which first discovered hints of it in the atmosphere of K2-18b a few years ago, be tasked with further, more lengthy observations? Telescope time on that probe must be at a premium. So what's the justification for this?

It narrows down the search drastically. It has picked one a possible planet out of a billion.

 

[Cerenkov]

Ok Dave, I think I get it now.

Thanks,

Cerenkov.

 

[Cerenkov]

It narrows down the search drastically. It has picked one a possible planet out of a billion.

I'm sorry FactChecker, but in the light of the doubts about DMS already expressed in this thread I can't see how pursuing an earlier tentative detection with more telescope time narrows down anything.

If DMS is not a trustworthy and reliable biomarker, then how have you gained anything by finding a stronger DMS signal after using more telescope time to find it?

If there's something I'm missing here could you please unpack the details for me.

Thank you,

Cerenkov.

 

[DaveC426913]

I'm sorry FactChecker, but in the light of the doubts about DMS already expressed in this thread I can't see how pursuing an earlier tentative detection with more telescope time narrows down anything.

If DMS is not a trustworthy and reliable biomarker, then how have you gained anything by finding a stronger DMS signal after using more telescope time to find it?

You appear to be assumimg that the only further information that could be gathered is 'a stronger signal' i.e. the same thing we have, only stronger.

I think that is an oversimplification.

No single marker is, in itself, strongly reliable (Excepting perhaps a radio message or giant welcome sign).

I am pretty confident there are a host of factors that would refine the confidence in the finding - either for or against.

That being said, here is another (pop sci) article that foes into a little bit more detail about what they might learn with a closer look.

https://scitechdaily.com/are-we-fin...ects-lifes-signature-on-distant-ocean-planet/

Basically, better data, matching the model better, could push the confidence level up. It is currently "3 sigma". The better the data matches the model, the higher the confidence.

 

[ketoenol]

I'm sorry FactChecker, but in the light of the doubts about DMS already expressed in this thread I can't see how pursuing an earlier tentative detection with more telescope time narrows down anything.

If DMS is not a trustworthy and reliable biomarker, then how have you gained anything by finding a stronger DMS signal after using more telescope time to find it?

If there's something I'm missing here could you please unpack the details for me.

Thank you,

Cerenkov.

I think whether Dimethylsulfide is a good biomarker is still up in the air a bit too. The paper looking at the Rosetta data is one piece of that conversation, but it's not a nail in the coffin or anything. They didn't actually detect DMS, and if it is on the comet it's in a lot lower concentrations than on this planet (well, if the signal is being properly assigned).

Like the methane on Mars, even if there are plausible abiotic methods to create some of the chemical, it's hard to understand how it would survive in as large of concentrations as it is if it wasn't being constantly generated at rates that seem pretty hard to explain without life. But right now we have a sample size of basically 1 for what life looks like, so there's lots we don't know.