But Not Life as We Know It*

The Webb Space Telescope has detected an exoplanet with water, methane, and traces of a chemical that only arise from life on earth.

That chemical, dimethyl sulfide (DMS), is produced by phytoplankton, basically algae, on earth.

Needless to say, this could be yet another false alarm. There may be other golological or astronomical processes that can produce DMS, but I am a bit excited about this.

Also, this gives me the opportunity to quote Star Trek ……… Sort of.

It turns out that the line comes from a Star Trek filk, but still, I'm stoked to say the line:

A new investigation with NASA’s James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

The first insight into the atmospheric properties of this habitable-zone exoplanet came from observations with NASA’s Hubble Space Telescope, which prompted further studies that have since changed our understanding of the system.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system. This lack of equivalent nearby planets means that these ‘sub-Neptunes’ are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers.

The suggestion that the sub-Neptune K2-18 b could be a Hycean exoplanet is intriguing, as some astronomers believe that these worlds are promising environments to search for evidence for life on exoplanets.

"Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere," explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results. "Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations."

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

Spectra of K2-18 b, obtained with Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph), display an abundance of methane and carbon dioxide in the exoplanet’s atmosphere, as well as a possible detection of a molecule called dimethyl sulfide (DMS). The detection of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. K2-18 b, 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth.

Credits: Illustration: NASA, CSA, ESA, R. Crawford (STScI), J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)

The inference of DMS is less robust and requires further validation. “Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” explained Madhusudhan.

While K2-18 b lies in the habitable zone, and is now known to harbor carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet's large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface. Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

"Although this kind of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy," explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Characterizing the atmospheres of exoplanets like K2-18 b — meaning identifying their gases and physical conditions — is a very active area in astronomy. However, these planets are outshone — literally — by the glare of their much larger parent stars, which makes exploring exoplanet atmospheres particularly challenging.

The team sidestepped this challenge by analyzing light from K2-18 b's parent star as it passed through the exoplanet's atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star. This is how the exoplanet was first discovered in 2015 with NASA’s K2 mission. This means that during transits a tiny fraction of starlight will pass through the exoplanet's atmosphere before reaching telescopes like Webb. The starlight's passage through the exoplanet atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet's atmosphere.

"This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits," said Madhusudhan. "For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years and in a relatively narrow wavelength range."

"These results are the product of just two observations of K2-18 b, with many more on the way,” explained team member Savvas Constantinou of the University of Cambridge. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

The team’s results were accepted for publication in The Astrophysical Journal Letters.

The team now intends to conduct follow-up research with the telescope's MIRI (Mid-Infrared Instrument) spectrograph that they hope will further validate their findings and provide new insights into the environmental conditions on K2-18 b.

"Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe," concluded Madhusudhan. "Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest."

Yeah, I know, it's not supposed to be about my ability to pseudo-quote Star Trek, but it IS about about my ability to pseudo-quote Star Trek for me.

Don't mock me for this.

OK, you can mock me for this.

^*I've been waiting my whole life to say that.

Scientists Gaslight Snails

As Anna Russel would say, "I'm not making this up, you know."

A group of neuroscientists have implanted memories in snails. 

This is a highly complex biochemical procedure, using RNA to transfer memories from a trained snail to an untrained sale, but to the layman, this is chemically assisted gaslighting.

Also, who trains snails?

Transferring memories from one living thing to another sounds like the plot of an episode of “Black Mirror.” But it may be more realistic than it sounds — at least for snails.

In a paper published Monday in the journal eNeuro, scientists at the University of California-Los Angeles reported that when they transferred molecules from the brain cells of trained snails to untrained snails, the animals behaved as if they remembered the trained snails’ experiences.

David Glanzman, a professor of neurobiology at U.C.L.A. who is an author of the new paper, has been studying Aplysia californica, a sea snail, and its ability to make long-term memories for years. The snails, which are about five inches long, are a useful organism for studying how memories are formed because their neurons are large and relatively easy to work with.

In experiments by Dr. Glanzman and colleagues, when these snails get a little electric shock, they briefly retract their frilly siphons, which they use for expelling waste. A snail that has been shocked before, however, retracts its siphon for much longer than a new snail recruit.

Recently, the scientists realized that even when they interfered with their trained snails’ brain cells in a way that should have removed the memory completely, some vestige remained. They decided to see whether something beyond the brain cells’ connections to each other — namely, RNA — could be hanging on to the memory.

………

To understand what was happening in their snails, the researchers first extracted all the RNA from the brain cells of trained snails, and injected it into new snails. To their surprise, the new snails kept their siphons wrapped up much longer after a shock, almost as if they’d been trained.

Next, the researchers took the brain cells of trained snails and untrained snails and grew them in the lab. They bathed the untrained neurons in RNA from trained cells, then gave them a shock, and saw that they fired in the same way that trained neurons do. The memory of the trained cells appeared to have been transferred to the untrained ones.

Importantly, when the researchers gave the new snails a drug that keeps chemical tags from being added to DNA, the memory did not transfer. That is in line with other experiments that have suggested that blocking the formation of such tags blocks the formation of long-term memory in snails and some rodents, said Dr. Glanzman. That suggests that what they are seeing is in fact related to memory, and not something else to do with the influx of new RNA.

Science was glorious, isn't it?

All Your Bases Are Belong to Us

We have now discovered that, "All of the bases in DNA and RNA have now been found in meteorites," which means that arguments supporting the extraterrestrial origins of life have become far more persuasive:

More of the ingredients for life have been found in meteorites.

Space rocks that fell to Earth within the last century contain the five bases that store information in DNA and RNA, scientists report April 26 in Nature Communications.

These “nucleobases” — adenine, guanine, cytosine, thymine and uracil — combine with sugars and phosphates to make up the genetic code of all life on Earth. Whether these basic ingredients for life first came from space or instead formed in a warm soup of earthly chemistry is still not known (SN: 9/24/20). But the discovery adds to evidence that suggests life’s precursors originally came from space, the researchers say.

Scientists have detected bits of adenine, guanine and other organic compounds in meteorites since the 1960s (SN: 8/10/11, SN: 12/4/20). Researchers have also seen hints of uracil, but cytosine and thymine remained elusive, until now.

………

A few years ago, geochemist Yasuhiro Oba of Hokkaido University in Sapporo, Japan, and colleagues came up with a technique to gently extract and separate different chemical compounds in liquefied meteorite dust and then analyze them.

We may all be descending from extraterrestrial chemistry.

Interesting Chemisty? Yes. Life? No.

Not Life as We Know It

The fact that the Royal Astronomical Society has announced that the atmosphere of Venus contains significant amounts of phosphine (PH₃), a substance that, on earth at least, is only produced through the action of anaerobic life and complex industrial processes, where it is a precursor to a number of organophosphorus compounds.

It could be a sign of life, but with no free liquid water, and atmosphere that is largely CO₂, Nitrogen, and Sulfuric Acid, I'm dubious.

On the other hand, it is clear that Venus has been the red-headed stepchild of planetary studies, with Mars getting most of the attention, so if we see a few more probes sent to Venus as a result of this finding, I'll take it.

Their press release is after the break: