Scientists find strongest evidence yet of life on an alien planet; Webb sees 3-sigma evidence for dimethyl sulfide

[essentialsaltes]

In a potential landmark discovery, scientists using the James Webb Space Telescope have obtained what they call the strongest signs yet of possible life beyond our solar system, detecting in an alien planet's atmosphere the chemical fingerprints of gases that on Earth are produced only by biological processes.

The two gases - dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS - involved in Webb's observations of the planet named K2-18 b are generated on Earth by living organisms, primarily microbial life such as marine phytoplankton - algae.

Scientists have hypothesized the existence of exoplanets called hycean worlds - covered by a liquid water ocean habitable by microorganisms and with a hydrogen-rich atmosphere.

Earlier observations by Webb, which was launched in 2021 and became operational in 2022, had identified methane and carbon dioxide in K2-18 b's atmosphere, the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in a star's habitable zone.

DMS and DMDS, both from the same chemical family, have been predicted as important exoplanet biosignatures. Webb found that one or the other, or possibly both, were present in the planet's atmosphere at a 99.7% confidence level, meaning there is still a 0.3% chance of the observation being a statistical fluke.
The gases were detected at atmospheric concentrations of more than 10 parts per million by volume.

"For reference, this is thousands of times higher than their concentrations in the Earth's atmosphere, and cannot be explained without biological activity based on existing knowledge," Madhusudhan said.

 

[SelfSim]

"For reference, this is thousands of times higher than their concentrations in the Earth's atmosphere, and cannot be explained without biological activity based on existing knowledge," Madhusudhan said.

Err .. more accurately speaking, should read: '.. cannot be explained on Earth without biological activity based on existing knowledge which has been acquired from Earth's biosphere'

These dudes need to start thinking outside of the Earthly box!

The information he has, means not much in an environmental context never before documented or analysed.

 

[SelfSim]

Err .. more accurately speaking, should read: '.. cannot be explained on Earth without biological activity based on existing knowledge which has been acquired from Earth's biosphere'

These dudes need to start thinking outside of the Earthly box!

The information he has, means not much in an environmental context never before documented or analysed.

Further, (and for the sake of fairness), from the pre-release paper on ArxiV, here:

A conclusive identification of a biosignature necessitates a robust assessment of various factors, including the robustness of the detections, the environmental context, and potential false positives (e.g. Meadows et al. 2022; Schwieterman et al. 2018). It is widely recognized that the detection of a biosignature is unlikely to be instantaneous or unambiguous in the first instance, rather relying on continued accumulation of evidence and addressing the above factors (Meadows et al. 2022). Our study is the first formal step in this direction, building on the first possible hints of DMS reported in our previous work (Madhusudhan et al. 2023b) and further evidence of DMDS and/or DMS with a higher significance seen in the present observations. Finally, our present detection based on multiple spectral features with a different instrument in a different spectral range from previous work provides an important independent line of evidence in this direction.

 

[BukiRob]

The media writes sensational headlines that are not justified by the findings. The evidence of those 2 elements do not prove life. It merely proves that some of the KNOWN elements required for life have been discovered and NOTHING MORE

 

[essentialsaltes]

It merely proves that some of the KNOWN elements required for life have been discovered and NOTHING MORE

While certainly the result can't be taken for more than what it is, these gases are not required for life, but are products of life (on Earth). And they have been previously discussed as potential biosignatures in exoplanets.

4.2.5. Sulfur gases (DMS, DMDS, CH3SH) and relation to detectable C2H6​

Biology produces several sulfur-bearing gases as direct or indirect products of metabolism. The direct products of metabolism tend to be simple sulfur gases such as H2S, carbon disulfide (CS2), carbonyl sulfide (OCS), and SO2, although these are also produced in abundance by abiotic volcanic and hydrothermal processes and thus are not strong biosignature gas candidates [e.g., see Arney et al. (2014), for an analysis of these gases in the Venusian atmosphere]. More complex sulfur gases such as CH3SCH3or DMS, CH3S2CH3 or DMDS, and CH3SH (also known as methyl mercaptan) are produced as indirect products of metabolism but have few if any known abiotic sources on modern Earth.

 

[SelfSim]

While certainly the result can't be taken for more than what it is, these gases are not required for life, but are products of life (on Earth). And they have been previously discussed as potential biosignatures in exoplanets.

4.2.5. Sulfur gases (DMS, DMDS, CH3SH) and relation to detectable C2H6​

Biology produces several sulfur-bearing gases as direct or indirect products of metabolism. The direct products of metabolism tend to be simple sulfur gases such as H2S, carbon disulfide (CS2), carbonyl sulfide (OCS), and SO2, although these are also produced in abundance by abiotic volcanic and hydrothermal processes and thus are not strong biosignature gas candidates [e.g., see Arney et al. (2014), for an analysis of these gases in the Venusian atmosphere]. More complex sulfur gases such as CH3SCH3or DMS, CH3S2CH3 or DMDS, and CH3SH (also known as methyl mercaptan) are produced as indirect products of metabolism but have few if any known abiotic sources on modern Earth.

In general I agree with what you're saying there .. (ie: no problems).

I have some further comments:

i) Life as a phenomenon, here on Earth, is one thing .. extant life elsewhere, is currently always speculative.

ii) We don't know what 'life elsewhere' means, until we understand the measurement models required to support the diagnosis of 'Earth-life' from an isolated remote sensing viewpoint. There are some published hypothetical reference models for this .. but they, themselves, require more statistical observational evidence which, at the moment, is far from sufficient to cover the uncertainties implicit to time based deep space observations.

iii) So-called 'biosignatures' has meaning in the context of extant Earth-life. Applying the term to observations elsewhere, demands more evidence in support of terms like 'Earth-like planet', where evidence of 'Earth-like' there is, itself, also still subject to significant uncertainties. (eg: Venus, Mars, etc).

My degree of scepticism here might seem overly high, but extraordinary claims are scepticism's playground .. especially when it comes to 'exo-life'.

 

[BukiRob]

Pretty sure that Sulfer gases can occur by other means than just life

In general I agree with what you're saying there .. (ie: no problems).

I have some further comments:

i) Life as a phenomenon, here on Earth, is one thing .. extant life elsewhere, is currently always speculative.

ii) We don't know what 'life elsewhere' means, until we understand the measurement models required to support the diagnosis of 'Earth-life' from an isolated remote sensing viewpoint. There are some published hypothetical reference models for this .. but they, themselves, require more statistical observational evidence which, at the moment, is far from sufficient to cover the uncertainties implicit to time based deep space observations.

iii) So-called 'biosignatures' has meaning in the context of extant Earth-life. Applying the term to observations elsewhere, demands more evidence in support of terms like 'Earth-like planet', where evidence of 'Earth-like' there is, itself, also still subject to significant uncertainties. (eg: Venus, Mars, etc).

My degree of scepticism here might seem overly high, but extraordinary claims are scepticism's playground .. especially when it comes to 'exo-life'.

The size of the known Universe is something like 93,000,000,000 light years accross and is likely far bigger than that. I know in the last 20 years we though that our galaxy had fewer stars than our current understanding and the milky way is not a particularly large galaxy. Their is a nearly uncountable number galaxies with between 100-400 million stars to extrapolate find these gases and ASSUMING that life is responsible form them is the very epitome of foolishness. Sure, it could be a sign of life it could also be the result of other things. We have toddlers not a week goes by when cosmology discovers thing that shouldnt be because it is contrary to our current understanding

 

[SelfSim]

Pretty sure that Sulfer gases can occur by other means than just life

The size of the known Universe is something like 93,000,000,000 light years accross and is likely far bigger than that. I know in the last 20 years we though that our galaxy had fewer stars than our current understanding and the milky way is not a particularly large galaxy. Their is a nearly uncountable number galaxies with between 100-400 million stars to extrapolate find these gases and ASSUMING that life is responsible form them is the very epitome of foolishness. Sure, it could be a sign of life it could also be the result of other things. We have toddlers not a week goes by when cosmology discovers thing that shouldnt be because it is contrary to our current understanding

Umm .. would you care to correct the grammar in that post, as its almost impossible to figure out what you are saying.

 

[BukiRob]

Umm .. would you care to correct the grammar in that post, as its almost impossible to figure out what you are saying.

I have absolutely NO use for grammer nazi's not my problem if you cant figure out what Im saying too bad for you

 

[SelfSim]

I have absolutely NO use for grammer nazi's not my problem if you cant figure out what Im saying too bad for you

Lovely .. .. one asks for clarity and one is accused of being a 'nazi'.

From what I can make out, you're trying to communicate a numbers based argument.

i) Firstly, numbers based arguments are statistically irrelevant when there is only one data point in hand.

ii) Secondly, the life is everywhere argument is just a valid as is the single instance of life argument. Better than both however, is that we simply don't know .. because there is no objective evidence either way.

iii) Thirdly, 'epitomes of foolishness' is merely your unsupported opinion .. which can be tossed on the big pile of all the other unsupported opinions .. on your way out the door.

 

[Hans Blaster]

Pretty sure that Sulfer gases can occur by other means than just life

The origins of these specific sulfur compounds was covered in post #5 (a reply to you).

The size of the known Universe is something like 93,000,000,000 light years accross and is likely far bigger than that.

Visible Universe, and it isn't relevant to this discovery.

I know in the last 20 years we though that our galaxy had fewer stars than our current understanding and the milky way is not a particularly large galaxy. Their is a nearly uncountable number galaxies with between 100-400 million stars to extrapolate find these gases and ASSUMING that life is responsible form them is the very epitome of foolishness.

Also irrelevant. Chemistry is chemistry. This paper does not claim or assume these gases come from life on this planet (K2-18 b). Life isn't even mentioned in the title:

New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI

Sure, it could be a sign of life it could also be the result of other things.

Which are discussed in section 4 (summary and discussion). At no point to do the authors claim "we have found life".

We have toddlers not a week goes by when cosmology discovers thing that shouldnt be because it is contrary to our current understanding

What on Earth does this mean? What do "toddlers" have to do with any of this?

 

[sjastro]

Here is the relevant paper in draft version but not peer reviewed on the atmosphere of the exoplanet K2-18b.

https://arxiv.org/pdf/2504.12267

Unlike the wild comments made in this thread involving toddlers, the authors have adopted a very cautious approach.

Overall, our findings present an important step forward in the search for signatures of life on exoplanets. However, robustly establishing both the veracity of the present findings and their possible association with life on K2-18 b needs a dedicated community effort in multiple directions — observational, theoretical and experimental. Observations with JWST are already demonstrating that possible hycean worlds indeed significantly expand and accelerate the search for life elsewhere. The central question now is whether we are prepared to identify the signatures of life on such worlds. The opportunity is at our doorstep.

The paper is further work based on the 2023 paper where DMS was found in K2-18b's atmosphere at a 2.4σ level which is a 1 in 66 chance of a statistical anomaly resembling a real signal.
The 3σ level for DMS (dimethyl sulfide) and DMDS (dimethyl disulfide) represents a 1 in 370 chance and constitutes evidence rather than discovery, whereas the presence of CH₄ (methane) at a 5σ level or a 1 in 1.7 million chance is a discovery.

 

[trophy33]

Interestingly, we do not see any signs of developed civilizations, anywhere in the universe. However, it would be useful for our own future civilization to find planets supporting at least microbial life or plant-like life.

 

[David Lamb]

We have toddlers not a week goes by when cosmology discovers thing that shouldnt be because it is contrary to our current understanding

I expect it's a typo, but I have no idea what having toddlers has to do with cosmology (unless in American English, "toddlers" as some other meaning than "very young children".)

 

[SelfSim]

I expect it's a typo, but I have no idea what having toddlers has to do with cosmology (unless in American English, "toddlers" as some other meaning than "very young children".)

I think it was meant to be:
'We have are toddlers. Not a week goes by when cosmology discovers thing{s} that shouldnt be because it is contrary to our current understanding'.

 

[David Lamb]

I think it was meant to be:
'We have are toddlers. Not a week goes by when cosmology discovers thing{s} that shouldnt be because it is contrary to our current understanding'.

Thanks. That sounds more likely. I was led astray by thinking that "toddlers" was the typo word.

 

[SelfSim]

So back onto the main topic, I recently found this interesting development proposal (see ExoLife Finder here) for a new ground-based Fizeau-interferometric array telescope, designed specifically for detecting 'the energy signatures of life or its optical fingerprints, on nearby exoplanets' (targetted to commence at the Teide observatory Tenerife, Canary Islands, in 2026):
(Website link with images here).

The ExoLife Finder (ELF) telescope is an under-development hybrid interferometric telescope being designed at the (IAC) for the direct detection and imaging of exoplanets and potentially water-bearing exoplanets. Developed by a collaboration of scientists and engineers including the PLANETS Foundation, the ELF aims to analyze the surfaces and atmospheres of exoplanets for evidence of life, focusing on nearby star systems within 25 light years of Earth

It looks to be a way of overcoming the extensively repetitious time-based observational requirements currently imposed by Astrobiology research on JWST:

To achieve its imaging and detection goals, the ELF utilizes the so-called vortex nulling properties of its Fizeau interferometry. These optics create what is called a coronagraph from the telescope primary optics alone. The use of complex inversion algorithms that depend on repeated observations of the exoplanet systems over months then samples the exoplanetary rotation and orbit to reveal details of its surface structure like oceans, continents, forests, deserts, or even city complexes.

Looking for known Earth-life 'signatures':

The telescope's primary focus is on detecting molecules such as water, oxygen, methane, carbon dioxide and ozone, which are commonly associated with life on Earth. Additionally, the ELF is capable of detecting photosynthetic bio-pigments on the surface of exoplanets, which could indicate the presence of photosynthetic organisms

I suppose even if it doesn't find any of those, it will help to delineate what is worthwhile looking for and what isn't, in this hunt for the evidence to justify Astrobiology's existence.

PS: Note its observational range, (of ~25 lyr), is about 1/5 less than K2-18 b's lofty 124 lyr distance!

 

[SelfSim]

Wiki's page on K2-18b here, provides some interesting commentary about its potential shortcomings on its being a host for exo-life.

One interesting analysis aspect centers around the separation between any potential ocean and the atmosphere, because: 'JWST observations were initially considered to be more consistent with a fluid-gas interface and thus a liquid ocean'. It goes on to discuss the uncertainties of a separate ocean.

Nonetheless, yet another paper suggests:

.. that a liquid water ocean model requires the presence of a biosphere in order to produce sufficient amount of methane.

This announcement seems to have caused a big swelling up of speculative planetary modeller interests!

 

[Bob8102]

The existence of life on other worlds is not evidence for evolution, but for creation. The chances that life evolved on earth are effectively zero; life on earth is evidence for creation. Ditto for any other worlds. From my POV, the God of the Bible may have created life all over the universe, just not human-equivalent beings. Here's what creationists might expect that would be different from what evolutionists might expect: No life in early stages of evolution. For example, we would not expect to find a world with a few struggling microbes around hydrothermal vents. We would expect to find complete ecosystems. No human equivalent or superior aliens. There are too many biblical problems with human-equivalent aliens. Hebrews says that Christ died ONCE for sins. He did not go and die on other worlds for aliens' sins. The curse on nature due to the sin of Adam and Eve affected the entire universe, not just the earth or solar system. That curse is why stars explode and why galaxies collide, for example. What if the people of an alien world never sinned? What are they doing in a cursed universe of stellar and biological death, disease and disaster?

Therefore, if God created life on other worlds, this life exists solely of lesser-than-human life forms. In the original plan of creation, we were supposed to subdue and have dominion over the entire universe, not just the earth. Earth is the capital of the cosmos. But sin and the curse changed the plan of history. The concept of life on other worlds fires the imagination.

 

[AV1611VET]

The two gases - dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS - involved in Webb's observations of the planet named K2-18 b are generated on Earth by living organisms, primarily microbial life such as marine phytoplankton - algae.

So if scientists create dimethyl sulfide in a laboratory, have they created evidence of life?

If a planet has a pocket of carbon dioxide, nitrogen, oxygen, and water vapor in it, does that mean that planet has life on it?

Methinks finding gas on another planet that is a byproduct of life doesn't mean that planet has life.

Can you go into a house that hasn't been inhabited for years and smell flatlulence?

(I should make this into a challenge thread.)