Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system. The most likely reason (when combined with other observation) for seeing 1000 times more of the chemical DMS would be that exoplanet K2-18B is an ocean planet teeming with life. This ocean filled with life is causing the chemical DMS to saturate the atmosphere.
Researcher are now 99.7% certain of the detections of the key chemical signature. We need to confirm with another 24 hours of James Webb Space Telescope. If those observations were also confirmed then we would be 99.99994% certain the DMS chemical signature is good.
If we become 99.99994% certain there is DMS then scientists are convinced that DMS is there and then it needs to be explained. The leading reason is that there is the mother lode of ocean with high concentrations of marine phytoplankton on an exoplanet 120 light years away OR there is some unknown exoplanet geology or planetary mechanism that does not exist on earth that makes DMS instead of phytoplankton. Like some weird volcanos spewing DMS from a different exoplanet magma composition.
So they will first make the 24 hours of additional observations with the James Webb Telescope. They will make the theoretical and experimental work to determine whether DMS and DMDS can be produced non-biologically at the level currently inferred.
There is now a third different instrument now show that there is the DMS life signature.
Using data from the James Webb Space Telescope (JWST), the astronomers, led by the University of Cambridge, have detected the chemical fingerprints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b, which orbits its star in the habitable zone.
On Earth, DMS and DMDS are only produced by life, primarily microbial life such as marine phytoplankton. While an unknown chemical process may be the source of these molecules in K2-18b’s atmosphere, the results are the strongest evidence yet that life may exist on a planet outside our solar system.
The observations have reached the ‘three-sigma’ level of statistical significance – meaning there is a 0.3% probability that they occurred by chance. To reach the accepted classification for scientific discovery, the observations would have to cross the five-sigma threshold, meaning there would be below a 0.00006% probability they occurred by chance.
The researchers need between 16 and 24 hours of follow-up observation time with JWST may help them reach the all-important five-sigma significance.
Earlier observations of K2-18b — which is 8.6 times as massive and 2.6 times as large as Earth, and lies 124 light years away in the constellation of Leo — identified methane and carbon dioxide in its atmosphere. This was the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in the habitable zone. Those results were consistent with predictions for a ‘Hycean’ planet: a habitable ocean-covered world underneath a hydrogen-rich atmosphere.
Astronomers analyze the light from its parent star as the planet transits, or passes in front of the star as seen from the Earth. As K2-18b transits, JWST can detect a drop in stellar brightness, and a tiny fraction of starlight passes through the planet’s atmosphere before reaching Earth. The light pass throuhg the planet’s atmosphere changes the stellar spectrum that astronomers can use to determine the constituent gases of the exoplanet’s atmosphere.
The earlier weaker detection of DMS was made using JWST’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph) instruments, which together cover the near-infrared (0.8-5 micron) range of wavelengths. The new, independent observation used JWST’s MIRI (Mid-Infrared Instrument) in the mid-infrared (6-12 micron) range.
Three instruments are detecting DMS.
The concentrations of DMS and DMDS in K2-18b’s atmosphere are far higher 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.
The most likely scenario is that K@-18B is Hycean world (ocean covered) with an ocean that is teeming with life is the scenario that best fits the data we have.
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My skepticism aside, what an opportunity if there were only single celled organisms thus far on the planet!
I wonder how the big chinese rocket is coming along? Will it be the 1st country to get an 8 meter+ scope to L-1 or 2? We could do that with Star Ship or BO NG. NASA needs to send-out proposals now so it could fly by 2030. A scope for planet observation and survey only is what we need.
Let’s go!
As to the higher gravity trapping a species on their planet, a tethered ring system would work well, considering K2 is an ocean world.
https://m.youtube.com/watch?v=8B2iqiKehyM&pp=ygUbaXNhYWMgYXJ0aHVyIHRldGhldGVkIHJpbmdz
Even though K2-18b is an ocean world, it would seem likely that, if multicellular plant-like life exists, there would be rafts of vegetative matter acting as “land”.
There is also the possibility that pumice rafts serve a similar function.
https://www.abc.net.au/news/science/2020-06-03/pumice-stone-raft-transporting-marine-life/12278124
Life is everywhere.
I think the chances of a technology driven civilization evolving on an ocean planet are next to zero no matter the intelligence level. You simply cannot take any of the steps needed under water.
While going there is a little difficult, if verified, this discovery should at least boost the case for new telescopes for exoplanet imaging. Overall pretty exciting.
If DMS is really of biological origin, then why so high concentration when compared to that on Earth? Industrially, it is produced by reaction of CH3OH with H2S. When you have both CH4 and H2O, you need only sunlight to produce CH3OH, and its reaction with omnipresent H2S is trivial. And then, where is oxygen, to drive reactions in obviously reductive (H2) and neutral (CO2) atmosphere? More chemistry, less fantasy!
Yes if we are effectively an ocean planet teeming with life why not the same concentrations here?
Different planet. Different life. Different ocean. Other planet is several times bigger. Very little idea of what is happening on that other planet.
I must say that on first glance I would disagree with the 99.7 % likely hood conclusion. I quickly extracted the data and error bars and looked at the null hypothesis with a linear model and I am seeing p-values of ~ 0.14 which implies that a linear model is statistically acceptable model for the absorption data. In other words, the null hypothesis cannot be ruled out. Definitely need much tighter error bars; improved resolution would also help. But, I did not read the paper so perhaps there is much that I am missing.
They’re jumping to conclusions. A world with a hydrogen atmosphere might have unknown inorganic reactions that make DMS.
But which is more probable? The know chemical reaction of life or …?
You cannot determine which is more likely when you don’t know the likelihood of one of the options. Never mind that we don’t know how ‘likely’ life is, either.
Sadly, a planet likely so massive could never propogate a conventional rocket industry with gravity probably so high. Nukes or unconventional lift. Techno-life-type-Panspermia it is then.
Probably couldn’t support conventional, macro-scale, gas-respirating life at or locally above the liquid line either.
According to online sources, only 24% higher gravity than Earth. Less rocky than Earth, so less dense. Probably no land.
I’m amazed that they can measure the methyl sulfides levels at 10 parts per million from 120 light years away. Incredible.
I am skeptical by nature. While it would be very cool to discover cellular and multicellular life outside of our solar system, I am quick to acknowledge what we don’t know: Mainly, 99.9% of geological processes occurring throughout the trillions and trillion of planets scattered across the universe. Just because different forms of methyl sulfides are only produced by life on our planet, this does not equate to any type of assurance that it how it is produced on other planets. Or if the infrared signatures from this planet’s atmosphere isn’t produced by something we’ve never come across on our planet.
Elon Musk should be planning to go there not to Mars
120 light years away
exactly, that’s what the Super Duper Heavy Starship+ ULTRA-MAX is for.
Sure this is a long term project. Maybe they need cryogenics to put the astronauts in suspended animation. If anything happens to our sun Mars would be impacted too, we need a planet in a different solar system.
No, since the interplanetary rocket is called “Starship”, the interstellar rocket would have be called something like “Transgalactic”.
120 light years isn’t exactly infeasible, but would require either a generation ship, suspended animation, or some serious life extension tech, even at speeds that would require antimatter.
Or a robotic probe, which is far more likely in the meantime.
A robotic probe would probably face the “Far Centaurus” issue, named after a short story of that name by van Vogt.
That’s where you set out for a long interstellar trip using the best current propulsion technology, and get passed along the way by somebody who sets out later with faster propulsion.
We probably will not launch any interstellar probes at all unless we’re reasonably confident we couldn’t get them to their destination sooner by waiting on better technology. And then they’re going to be launched to much nearer stars than this one.
A star 120 light years away is probably going to be well into the 3rd generation of interstellar missions, once propulsion technology has hit some genuinely fundamental limit, and you’re confident no further significant improvements in speed are available.