Category: 7. Science

You are what you eat, it turns out—even if your last meal was 150 million years ago, according to new research.

While the grub itself may be long gone, a record of dinosaurs’ favorite foods has been stowed away in their ancient tooth enamel over the last eon.

“It’s really just more proof that this ecosystem was as spectacular as we thought it was.”

When researchers at The University of Texas at Austin took a close look, they discovered that some dinosaurs were discerning eaters, with different species preferring different plant parts.

Tooth enamel contains calcium isotopes that reflect the range of foods the dinosaurs ate; different types of plants have different chemical signatures, and discrete parts of trees—from buds to bark—can also have unique signatures.

According to the study’s lead author Liam Norris, the results help explain how so many behemoth creatures all lived together in the same area at the same time.

“The ecosystem that I studied has been a mystery for a long time because it has these giant herbivores all coexisting,” says Norris, a recent doctoral graduate at UT’s Jackson School of Geosciences.

“The idea is that they were all eating different things, and now we have found proof of that.”

The findings appear in Palaeogeography, Palaeoclimatology, Palaeoecology.

Norris inspected teeth from four dinosaur species and one crocodyliform, both herbivores and carnivores, that roamed the Western US during the Late Jurassic. The plant-eaters are the long-necked Camarasaurus; the short-armed Camptosaurus; and the trunk-legged Diplodocus. The meat-eaters are the bipedal Allosaurus and the comparatively small, crocodile-like Eutretauranosuchus.

The bones and teeth of these ancient creatures were all found in the Carnegie Quarry deposit in northeast Utah, which is thought to have formed during an extreme drought in as little as six months to a few thousand years.

“We were very lucky to be able to study fossils of dinosaurs that lived together and were all rapidly preserved in a single deposit,” says Rowan Martindale, an associate professor at the Jackson School’s earth and planetary sciences department.

“The Jurassic tomb preserved a unique paleontological gem and these skeletons are beautifully displayed at Dinosaur National Monument.”

Norris, who now works at the Texas Science & Natural History Museum, studied teeth from 17 individual animals across these five species. The specimens were loaned by the Utah Field House of Natural History State Park Museum or accessed in the field at Dinosaur National Monument. He shaved off a dusting of their enamel, which he took back to the Jackson School for calcium isotope analysis. Jackson School Professor John Lassiter and Radiogenic Isotope Laboratory Manager Aaron Satkoski, both coauthors on the paper, helped to analyze and interpret these data.

Previously, scientists believed that large herbivorous dinosaurs coexisted by munching on different levels of the tree canopy according to height. However, Norris’s research shows that plant height wasn’t the only factor driving the differentiation of their diets—instead, it was specific plant parts.

For example, Norris found that the Camptosaurus was a rather discerning eater, preferring softer, more nutritious plant parts such as leaves and buds. The Camarasaurus ate mostly conifers, with a preference for woody plant tissues. The Diplodocus ate more of a mixed diet that included soft ferns and horsetail plants lower to the ground, as well as tougher plant parts.

“This differentiation in diet makes sense with what we see from the morphology of these animals: the different height, the different snout shape. Then, we bring in this geochemical data, which is a very concrete piece of evidence to add to that pot,” Norris says.

This research also provides interesting food for thought to a theory about long-necked dinosaurs having flexible necks that could be used to reach many areas of vegetation without having to expend the energy to move the rest of their body. This research, which shows that the dinosaurs ate from different levels of the tree canopy, furthers that line of thinking.

The carnivores in the study—the Allosaurus and Eutretauranosuchus—had an overlap in calcium isotope values, which could mean that they ate some of the same things. However, the results also showed that the Eutretauranosuchus is more likely to have eaten fish, while the Allosaurus primarily ate herbivorous dinosaurs—possibly including the three other dinosaur species mentioned in this study.

For this ancient ecosystem to have supported so many enormous dinosaurs with such specific dietary proclivities helps to paint a picture of the vegetation and plant productivity of the time.

“It’s really just more proof that this ecosystem was as spectacular as we thought it was,” Norris says.

Henry Fricke of Colorado College also coauthored the study.

Source: UT Austin

The controversial claim of microbes that exhibit arsenic rather than phosphorus in their biochemistry has been retracted by the journal Science 15 years after it was first published — but while most in the research community are pleased by the decision, the retraction has angered the authors of the original study.

Arsenic, as we know from its use as a poison, is a toxic substance. Thus, life as we know it of course would not include arsenic in its biochemistry. Yet, because the search for alien life is, by its very definition, a search for life as we don‘t know it, astrobiologists like to consider the possibility of organisms that have a different biochemistry to the one we’re familiar with.

Limb-resolved transmission spectroscopy has the potential to transform our understanding of exoplanetary atmospheres. By separately measuring the transmission spectra of the evening and morning limbs, these atmospheric regions can be individually characterized, shedding light into the global distribution and transport of key atmospheric properties from transit observations alone.

In this work, we follow up the recent detection of limb asymmetry on the exoplanet WASP-107 b (Murphy et al. 2024) by reanalyzing literature observations of WASP-107 b using all of JWST’s science instruments (NIRISS, NIRCam, NIRSpec, and MIRI) to measure its limb transmission spectra from ∼1-12 μm.

We confirm the evening–morning temperature difference inferred previously and find that it is qualitatively consistent with predictions from global circulation models. We find evidence for evening–morning variation in SO₂ and CO₂ abundance, and significant cloud coverage only on WASP-107 b’s morning limb.

We find that the NIRISS and NIRSpec observations are potentially contaminated by occulted starspots, which we leverage to investigate stellar contamination’s impact on limb asymmetry measurements.

We find that starspot crossings can significantly bias the inferred evening and morning transmission spectra depending on when they occur during the transit, and develop a simple correction model which successfully brings these instruments’ spectra into agreement with the uncontaminated observations.

A Panchromatic Characterization Of The Evening And Morning Atmosphere Of WASP-107 b: Composition and Cloud Variations, and Insight into the Effect of Stellar Contamination

Matthew M. Murphy, Thomas G. Beatty, Everett Schlawin, Taylor J. Bell, Michael Radica, Thomas D. Kennedy, Nishil Mehta, Luis Welbanks, Michael R. Line, Vivien Parmentier, Thomas P. Greene, Sagnick Mukherjee, Jonathan J. Fortney, Kazumasa Ohno, Lindsey Wiser, Kenneth Arnold, Emily Rauscher, Isaac R. Edelman, Marcia J. Rieke

Comments: Currently under review with the Astronomical Journal. Comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2505.13602 [astro-ph.EP] (or arXiv:2505.13602v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2505.13602
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Journal reference: AJ 170 61 (2025)
Related DOI:
https://doi.org/10.3847/1538-3881/addf38
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Submission history
From: Matthew Murphy
[v1] Mon, 19 May 2025 18:00:03 UTC (6,001 KB)
https://arxiv.org/abs/2505.13602
Astrobiology,

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The controversial claim of microbes that exhibit arsenic rather than phosphorus in their biochemistry has been retracted by the journal Science 15 years after it was first published — but while most in the research community are pleased by the decision, the retraction has angered the authors of the original study.

Arsenic, as we know from its use as a poison, is a toxic substance. Thus, life as we know it of course would not include arsenic in its biochemistry. Yet, because the search for alien life is, by its very definition, a search for life as we don‘t know it, astrobiologists like to consider the possibility of organisms that have a different biochemistry to the one we’re familiar with.

This, in fact, led to NASA, — and with great razzamatazz, one might add — holding a press conference in 2010 that declared the supposed discovery of arsenic-based microbial life in Mono Lake, which is a heavily salt-rich body of water in California.

NASA claimed this discovery would forever change the search for life beyond Earth.

Life’s chemical details

Consider that all life as we know it, including human life, exclusively uses six key elements in its biochemistry: carbon, hydrogen, nitrogen, phosphorus, oxygen and sulfur.

Take phosphorus as an example. In our biochemistry, phosphorus, in the form of phosphate, is crucial for forming the sugar-phosphate backbone of molecules of RNA and DNA, as well as storing and delivering metabolic energy through adenosine triphosphate (ATP).

Astronomical observations, however, suggest phosphorus might not be evenly distributed across the Milky Way galaxy. And it has been posited that life in those phosphorus-depleted regions of space might survive by substituting phosphorus with another element, such as arsenic. It was this possibility that, 15 years ago, prompted a team led by Felisa Wolfe–Simon of NASA’s Astrobiology Institute to search for possible arsenic-based life in the extreme alkaline conditions within Mono Lake.

Then, in that 2010 press conference, the discovery team revealed they had found it in the form of a bacterium known as GFAJ-1 present in supposedly phosphorus-free samples from Mono Lake. The discovery was hailed as a revolutionary development in astrobiology — for all of about five minutes.

Despite all the hullaballoo of the press conference, when Wolfe–Simon and her team’s work was published online by the journal Science, other biochemists quickly came out to argue there were serious flaws in the research. Specifically, they argued that swapping out phosphorus for arsenic would cause DNA to dissolve within a second when exposed to water. More damning was the claim from the critics that the samples used by Wolfe–Simon’s team were contaminated by phosphorus from the lake. The life in those samples, the critics argued, was probably still just using the phosphorus within those samples.

When Science finally published the research paper in print a year later, it was appended by eight technical comments from other researchers highly critical of the findings, plus two extra papers from independent teams who tried to replicate the results but failed to find any evidence for arsenic-based life in Mono Lake. Wolfe–Simon and her colleague also published a response to the criticisms, in which they wrote that “we maintain that our interpretation of As [arsenic] substitution, based on multiple congruent lines of evidence, is viable.”

Not many people believed them, and Wolfe–Simon’s team have never published the results of any follow-up experiments that try to address some of the points in the criticism; they also declined to respond to any criticism other than through the medium of peer-reviewed letters. The blowback against Wolfe–Simon’s team was fierce and, at times, unsightly, with some abusive comments being leveled directly at Wolfe–Simon, who was still a young researcher. As a consequence, Wolfe–Simon opted to drop out of active research.

Now, 15 years later, Science’s Editor-in-Chief Holden Thorp and the journal’s Executive Editor Valda Vinson have reopened the can of worms by deciding to retract the paper. Why has it taken so long for them to do so?

“Science did not retract the paper in 2012 because at that time, Retractions were reserved for the Editor-in-Chief to alert readers about data manipulation or for authors to provide information about post-publication issues,” Science’s editors wrote in their official retraction notification. “Our decision then was based on the editors’ view that there was no deliberate fraud or misconduct on the part of the authors. We maintain this view, but Science’s standards for retracting papers have expanded. If the editors determine that a paper’s reported experiments do not support its key conclusions, even if no fraud or manipulation occurred, a Retraction is considered appropriate.”

The other side of the story

Traditionally, papers were only retracted if evidence of fraud or misconduct came to light, or if a paper’s authors requested that it be retracted, perhaps if new evidence disproved their results. However, the Retraction Watch website reports that, since 2019, Science has retracted 20 papers from its various publications, mostly on the basis of what the journal believes to be innocent errors.

Suffice to say, Wolfe–Simon and her team-members do not agree with Science’s decision. In their response, published in the interests of fairness along with the retraction by Science, the team stated their disappointment.

“We do not support this retraction,” they wrote. “While our work could have been written and discussed more carefully, we stand by the data as reported. These data were peer-reviewed, openly debated in the literature, and stimulated productive research.”

Moreover, the team argues that Science’s decision-making process was flawed and that it contravenes the guidelines of the Committee on Publication Ethics, or COPE. Those guidelines state that retraction is only warranted when there is clear evidence of major errors, the fabrication of data, or falsification that damages the reliability of a paper’s findings.

“In going beyond COPE, the editors of Science explain that ‘standards for retracting papers have expanded’,” the team wrote. “We disagree with this standard, which extends beyond matters of research integrity. Disputes about the conclusions of papers, including how well they are supported by the available evidence, are a normal part of the process of science. Scientific understanding evolves through that process, often unexpectedly, sometimes over decades. Claims should be made, tested, challenged, and ultimately judged on the scientific merits by the scientific community itself.”

Thorp and Vinson went further in a blog post on Science’s website, where they were clearer on the reason for the retraction and arguing that COPE’s guidelines allow them to retract the paper. “Given the evidence that the results were based on contamination, Science believes that the key conclusion of the paper is based on flawed data,” they said.

The Retraction Watch website reports that Wolfe–Simon’s team said that when they had been told about the retraction, they were not told that it was because of the claimed contamination. In fact, they only heard that from a second-hand source who had seen the blog post. Even so, contamination had been the number one criticism going all the way back to 2010, and was not a new or surprising accusation.

Thorp and Vinson ended their blog post by saying “we hope this decision brings the story to a close.”

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It remains to be seen whether this will be the case. However, what is clear is that there are serious lessons to be learned by both sides about how to present controversial results and how to both give and receive scientific criticism — Thorp and Vinson made a point in saying they condemn verbal abuse and ad hominem attacks that had been directed towards Wolfe–Simon and her team by other researchers. It also sheds light on the intricacies of when and how papers should be retracted.

In recent years, we have seen how claims of phosphine in the atmosphere of Venus and dimethyl sulphide, which is a potential biosignature, in the atmosphere of the exoplanet K2-18b have sparked debate and argument. It is to be hoped that scientists in the research community can remember to not take disagreements too far when debating these and other claimed discoveries in the future.

This study uses methods from futures studies to develop a set of ten self-consistent scenarios for Earth’s 1000-year future, which can serve as examples for defining technosignature search strategies.

We apply a novel worldbuilding pipeline that evaluates the dimensions of human needs in each scenario as a basis for defining the observable properties of the technosphere. Our scenarios include three with zero-growth stability, two that have collapsed into a stable state, one that oscillates between growth and collapse, and four that continue to grow. Only one scenario includes rapid growth that could lead to interstellar expansion.

We examine absorption spectral features for a few scenarios to illustrate that nitrogen dioxide can serve as a technosignature to distinguish between present-day Earth, pre-agricultural Earth, and an industrial 1000-year future Earth.

Three of our scenarios are spectrally indistinguishable from pre-agricultural Earth, even though these scenarios include expansive technospheres. Up to nine of these scenarios could represent steady-state examples that could persist for much longer timescales, and it remains possible that short-duration technospheres could be the most abundant.

Our scenario set provides the basis for further systematic thinking about technosignature detection as well as for imagining a broad range of possibilities for Earth’s future.

Jacob Haqq-Misra, George Profitiliotis, Ravi Kopparapu

Comments: Published open access in Technological Forecasting and Social Change
Subjects: Physics and Society (physics.soc-ph); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Popular Physics (physics.pop-ph)
Cite as: arXiv:2409.00067 [physics.soc-ph] (or arXiv:2409.00067v3 [physics.soc-ph] for this version)
https://doi.org/10.48550/arXiv.2409.00067
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Journal reference: Technological Forecasting and Social Change (2025) 218: 124194
Related DOI:
https://doi.org/10.1016/j.techfore.2025.124194
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Submission history
From: Jacob Haqq-Misra
[v1] Fri, 23 Aug 2024 12:55:19 UTC (570 KB)
[v2] Mon, 5 May 2025 15:08:04 UTC (593 KB)
[v3] Thu, 22 May 2025 17:15:48 UTC (2,696 KB)
https://arxiv.org/abs/2409.00067
Astrobiology,

With around 200 detections of exoplanets around giant stars to date, our knowledge of the population of exoplanets orbiting evolved hosts more massive than the Sun remains limited.

The CORALIE radial-velocity search for companions around evolved stars (CASCADES) was launched in 2006 with the aim of improving our understanding of the demographics of exoplanets around intermediate-mass stars, by studying them once they have evolved off the main sequence.

We intend to refine the current sample of known exoplanets orbiting intermediate-mass (1.5 – 5 M⊙) giant stars of spectral types G and early K. We searched for exoplanets orbiting the four stars HD 87816, HD 94890, HD 102888, and HD 121056. We used data obtained with the CORALIE spectrograph, mounted on the Leonhard Euler Swiss telescope located at La Silla Observatory in Chile. We gathered high-precision radial-velocity measurements over more than ten years for each of the aforementioned targets. We started by performing a search for periodic signals in the radial-velocity time series of the four targets by using periodograms.

Following this, we fit for a Keplerian model using the significant peak with the highest power of the periodogram as the starting guess for the period. We then subtracted this model and repeated the procedure iteratively on the residuals until no significant peaks were found. Finally, to explore the posterior distribution of our models, the final solution was determined using a Markov chain Monte Carlo approach.

We report the discovery of five new massive planets around HD 87816, HD 94890, and HD 102888 as well as the presence of a distant, potentially substellar, companion around HD 102888. We confirm the presence of a previously announced exoplanet orbiting the HD 121056 multi-object system with a period of 89 days and propose an update to the period of the outer companion.

al-velocity Search For Companions Around Evolved Stars (CASCADES) IV: New Planetary Systems Around HD 87816, HD 94890, and HD 102888 And An Update On HD 121056

E. Fontanet, S. Udry, D. Ségransan, P. Figueira, J. A. Acevedo Barroso, B. Akinsanmi, M. Attia, M. Battley, S. Bhatnagar, M. Bugatti, Y. Carteret, H. Chakraborty, A. Deline, C. Farret Jentink, Y.G.C. Frensch, M. Houelle, B. Lavie, C. Lovis, M. Mayor, A. Nigioni, G. Ottoni, F. Pepe, D. J. M. Petit dit de la Roche, M. Shinde, N. C. Santos, S. Tavella, N. Unger, G. Viviani

Comments: Accepted for publication in A&A. Main text: 10 pages, 14 figures, 8 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2505.14317 [astro-ph.EP] (or arXiv:2505.14317v2 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2505.14317
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Submission history
From: Emile Fontanet
[v1] Tue, 20 May 2025 13:03:40 UTC (6,466 KB)
[v2] Mon, 23 Jun 2025 12:55:08 UTC (6,466 KB)
https://arxiv.org/abs/2505.14317
Astrobiology,

Abu Dhabi, UAE, July 28, 2025: A new study from NYU Abu Dhabi has found that high-energy particles from space, known as cosmic rays, could create the energy needed to support life underground on planets and moons in our solar system.

The research shows that cosmic rays may not only be harmless in certain environments but could actually help microscopic life survive. These findings challenge the traditional view that life can only exist near sunlight or volcanic heat. Published in the International Journal of Astrobiology, the study is led by the Principal Investigator of the Space Exploration Laboratory at NYUAD’s Center for Astrophysics and Space Science (CASS), Dimitra Atri.

The team focused on what happens when cosmic rays hit water or ice underground. The impact breaks water molecules apart and releases tiny particles called electrons. Some bacteria on Earth can use these electrons for energy, similar to how plants use sunlight. This process is called radiolysis, and it can power life even in dark, cold environments with no sunlight.

Using computer simulations, the researchers studied how much energy this process could produce on Mars and on the icy moons of Jupiter and Saturn. These moons, which are covered in thick layers of ice, are believed to have water hidden below their surfaces. The study found that Saturn’s icy moon Enceladus had the most potential to support life in this way, followed by Mars, and then Jupiter’s moon Europa.

“This discovery changes the way we think about where life might exist,” said Atri. “Instead of looking only for warm planets with sunlight, we can now consider places that are cold and dark, as long as they have some water beneath the surface and are exposed to cosmic rays. Life might be able to survive in more places than we ever imagined.”

The study introduces a new idea called the Radiolytic Habitable Zone. Unlike the traditional “Goldilocks Zone” — the area around a star where a planet could have liquid water on its surface — this new zone focuses on places where water exists underground and can be energized by cosmic radiation. Since cosmic rays are found throughout space, this could mean there are many more places in the universe where life could exist.

The findings provide new guidance for future space missions. Instead of only looking for signs of life on the surface, scientists might also explore underground environments on Mars and the icy moons, using tools that can detect chemical energy created by cosmic radiation.

This research opens up exciting new possibilities in the search for life beyond Earth and suggests that even the darkest, coldest places in the solar system could have the right conditions for life to survive.

Methane is a potent greenhouse gas, an important energy source, and an important part of the global carbon cycle. The relative abundances of doubly substituted (“clumped”) methane isotopologues (¹³CH₃D and ¹²CH₂D₂) offer important information on the sources and sinks of methane.

However, the clumped isotope signatures of microbially produced methane from different methanogenic pathways lack a systematic investigation. In this study, we provide a data set encompassing isotopic signatures of hydrogenotrophic, methylotrophic, acetoclastic, and methoxydotrophic methanogenesis.

We find that a statistical “combinatorial effect” generates significant differences in ¹²CH₂D₂ compositions between hydrogenotrophic methanogenesis and the other pathways, while variations in the fractionation factors of clumped isotopologues result in differences in ¹³CH₃D compositions between the methylotrophic, acetoclastic, and methoxydotrophic pathways.

The energy yield of methanogenesis and the energy conservation approaches implemented by different microbial strains may also influence the isotope values of methane. Further analysis suggests that previously observed isotopic signatures of methane in freshwater environments are potentially due to mixing between hydrogenotrophic and other methanogenesis pathways.

This study provides new experimental constraints on the isotope signatures of different microbial methanogenic pathways and evidence of the mechanisms responsible for the observed differences. This enables a better understanding of the sources and sinks of methane in the environment.

Astrobiology

Water is detected in environments representing every stage of star and solar system formation, but its chemical evolution throughout these stages remains poorly constrained.

Deuterium ratios offer a means of probing chemical links between water in different cosmic regions because of their sensitivity to physicochemical conditions.

Here, we present the first detection of the 4.1 μm HDO ice feature with JWST toward a low-mass protostar, L1527 IRS, which may eventually grow to a sun-like mass. We measure an ice HDO/H₂O ratio of 4.4+3.7−1.7×10⁻³, where the reported error is dominated by uncertainties in continuum definition and ice band strengths.

This fraction is similar to the gas HDO/H₂O ratios measured in the warm (>100 K) inner cores of other low-mass protostellar envelopes and protoplanetary disks found in comparably isolated star-forming regions.

Such a similarity tentatively supports the assumption that water vapor detected in these regions is not significantly altered by gas-phase reactions following ice sublimation. It also supports the hypothesis that pre- and protostellar water ice is largely inherited in a chemically unaltered state by outer protoplanetary disks.

However, the fraction is a factor of ∼4-10 times higher than the gas HDO/H₂O ratios measured toward comets and low-mass protostars in clustered star-forming regions. This difference may be due to either gas-phase water reprocessing in protostellar envelopes and protoplanetary disks, or differences between prestellar conditions of isolated dense cores and the clustered star-forming regions that are more analogous to the environment in which our Sun formed.

Katerina Slavicinska, Łukasz Tychoniec, María Gabriela Navarro, Ewine F. van Dishoeck, John J. Tobin, Martijn L. van Gelder, Yuan Chen, A. C. Adwin Boogert, W. Blake Drechsler, Henrik Beuther, Alessio Caratti o Garatti, S. Thomas Megeath, Pamela Klaassen, Leslie W. Looney, Patrick J. Kavanagh, Nashanty G. C. Brunken, Patrick Sheehan, William J. Fischer

Comments: Accepted for publication in ApJL. 10 pages, 4 figures, 1 table (+14 pages, 10 figures, 2 tables in appendix)

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2505.14686 [astro-ph.SR] (or arXiv:2505.14686v3 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2505.14686
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Related DOI:
https://doi.org/10.3847/2041-8213/addb45
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Submission history
From: Katerina Slavicinska
[v1] Tue, 20 May 2025 17:59:58 UTC (11,976 KB)
[v2] Mon, 26 May 2025 10:38:16 UTC (11,976 KB)
[v3] Tue, 3 Jun 2025 16:07:37 UTC (11,977 KB)
https://arxiv.org/abs/2505.14686

Astrobiology,