One of the biggest challenges in the search for alien life is that Earth remains the only example of life we know. As a result, nearly every attempt to identify biology elsewhere starts, at least partly, by looking for chemistry that resembles life here.

Researchers at the University of Glasgow are exploring a different strategy. Rather than asking whether an alien molecule looks biological by Earth standards, they propose asking a more fundamental question: How difficult was that molecule to make?

In a new study published in the Proceedings of the National Academy of Sciences, researchers demonstrate a method that combines mass spectrometry with machine learning to estimate what researchers call “molecular assembly,” or MA.

The concept comes from Assembly Theory, which attempts to quantify molecular complexity by identifying the minimum number of construction steps needed to build a molecule. Researchers argue that when highly complex molecules appear repeatedly and in abundance, their existence may point to a process that is consistently steering chemistry down particular pathways.

That could make molecular assembly useful as an “agnostic” biosignature—one that does not depend on alien life sharing Earth’s chemistry.

“There is a growing interest in ‘agnostic’ life detection strategies: methods that can identify molecular signs of life without needing an exact understanding of what that life might look like, or how it might interact with a complex, poorly characterized environment,” the researchers write. “The measured assembly index, defined as the number of steps along the shortest construction pathway, is fixed for each molecule and does not depend on external conditions, such as the environment in which the molecule might be detected or the specific ‘alien’ biochemistry from which it might arise.”

The researchers’ proposed “agnostic” approach could become increasingly important as scientists encounter tantalizing, but often ambiguous, chemical signals in the search for alien life.

Methane on Mars, phosphine reported in Venus’s atmosphere, and dimethyl sulfide proposed as a possible biosignature within exoplanet atmospheres have all attracted attention because living organisms can produce those compounds.

However, biology is not the only way to make them. Methane, for example, can emerge from geologic processes. Dimethyl sulfide is strongly associated with life on Earth, yet it has also been detected in cometary material and produced in laboratory experiments simulating primordial chemistry.

The presence of a particular molecule, in other words, does not necessarily tell scientists what produced it. Molecular assembly approaches the problem from a different angle. Under Assembly Theory, researchers calculate the shortest possible pathway for constructing a molecule from simpler building blocks. A molecule with an MA of 40, for example, has a shortest construction pathway twice as long as one with an MA of 20.

The reasoning is rooted in probability. Undirected chemistry has an enormous range of possible molecular structures. As molecules become more complex, the odds of repeatedly producing the same highly elaborate structure shrink unless something constrains the process.

Biological systems store and use information to direct chemical reactions toward particular outcomes, permitting organisms to manufacture the same complicated molecules again and again instead of wandering randomly through the immense space of possible chemistry.

Previous experiments cited in the study found an approximate dividing line between abiotic and biological samples at an assembly index of around 15.

Perhaps more importantly, in the search for alien life, scientists would not necessarily need to know what a molecule is before recognizing that it is unusually complex.

That could be especially useful on worlds such as Mars, Europa, Enceladus, or Titan, where spacecraft may encounter compounds unlike anything commonly found on Earth.

Several proposed planetary missions use, or could use, mass spectrometers. These instruments analyze molecules by measuring ions’ mass-to-charge ratios.

More sophisticated multistage mass spectrometers can repeatedly break molecules apart, giving indications of their structure and assembly history. But spacecraft operate under severe limits on power, mass, computing capacity, and instrument complexity. Many planetary missions, therefore, rely on simpler, single-stage mass spectrometry.

To close that gap, the researchers trained an XGBoost model on standardized mass spectra from the National Institute of Standards and Technology Chemistry WebBook. The model learned to estimate molecular assembly directly from single-stage spectra.

According to the study, it reduced relative mean squared error threefold compared with the best-performing baseline model, cutting the figure from 0.12 to 0.04.

The model also tended to underestimate molecules with especially high MA values. For a life-detection system, that bias could be preferable. It means the model was more likely to be conservative than to classify a molecule as an unusually strong biosignature mistakenly.

Researchers envision future spacecraft using this kind of analysis autonomously. A rover or lander that detects molecules with unusually high assembly scores might flag the surrounding area for closer inspection, prioritize certain samples, or identify material worth returning to Earth.

The study explicitly evaluated conditions designed to resemble instruments proposed for missions to Titan and Europa.

The same framework also raised another, more speculative possibility: when the researchers compared very large molecular databases, they identified several medical compounds with unusually high MA values. Their complexity was not the product of biology alone, but of deliberate human synthesis.

That led the team to suggest that particularly complex artificial molecules might serve as “molecular technosignatures”—chemical evidence oftechnology, rather than life itself.

For now, however, the method remains far from being a ready-to-fly alien-life detector. Instrument settings strongly affected performance. In simulated experiments, changing impact energies could nearly double prediction error, while one comparison increased it by more than 2.3 times. Molecules that break apart unusually easily can also cause the model to overestimate assembly, while molecules that resist fragmentation may be underestimated.

The researchers therefore describe the study as a proof of concept. Turning the approach into an effective tool for planetary investigation would require standardized databases, careful instrument calibration, and chromatographic separation to isolate individual molecules before analysis.

Future versions could also combine mass spectrometry with other techniques, including nuclear magnetic resonance or infrared spectroscopy. Infrared measurements, the researchers suggest, extend aspects of the approach to the remote study of exoplanet atmospheres.

Yet the wider goal is significant. Instead of deciding beforehand what alien biology should produce, scientists could search for evidence that a process has persistently directed chemistry toward highly specific, complex outcomes.

“In this work, we presented a proof-of-concept demonstrating the potential use of ML to predict the MA molecular complexity as a biosignature from in situ mass spectrometers during future space missions,” the researchers write. “Although the application of ML in life detection remains a nascent endeavor, it holds significant promise.”

The recent study, “Molecular Assembly as a Universal Biosignature Measurable by Mass Spectrometry,” appeared in Proceedings of the National Academy of Sciences.

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

Researchers have detected a sugar in the interstellar medium for the first time. Sugars are central to life. They help form the structural backbone of DNA and RNA and participate in essential metabolic reactions. They are also thought to have been necessary for the formation of the earliest nucleic acids. Yet researchers studying life’s origins [...]

Researchers have detected molecules containing rings and chains of carbon atoms in the vicinity of a rare pair of quasars. The trends in the distribution of these molecules are unexpected, suggesting that more work is needed to understand the conditions surrounding active supermassive black holes.

Infrared Eyes on Molecules in Space

Across the universe, atoms are combining to form molecules, and our ability to study molecules in distant realms has never been better. JWST is particularly attuned to emissions from molecules engaged in a kind of chemical yoga, stretching their bonds and flexing the angles between their atoms.

JWST’s sensitive infrared eyes have allowed researchers to study the distribution, creation, and destruction of both aromatic (containing one or more rings of carbon atoms in which certain electrons spread out within the ring) and aliphatic (containing chains of carbon atoms) hydrocarbons. These molecules have been spotted in a wide array of environments, and now, astronomers are finding them in more distant and more extreme environments than ever before.

Distant Discovery

SDSS J074922.96+225511.7, or J0749+2255 for short, is a quasar pair seen 3 billion years after the Big Bang. The two feasting supermassive black holes are roughly 12,000 light-years apart, giving researchers a glimpse into the late stages of a galaxy merger and a harsh environment in which to study the survival and destruction of molecules.

Researchers studying J0749+2255 with JWST have previously reported the detection of a 3.3-μm emission feature from aromatic molecules. Now, C. E. Mentzer (University of Missouri), Aigen Li (University of Missouri), and Xuejuan Yang (Xiangtan University) have analyzed JWST spectra of J0749+2255 and found not just widespread aromatic emission at a rest-frame wavelength of 3.3 μm, but also aliphatic emission at 3.4 μm, which they attribute to carbon chains branching off from the aromatic molecules. This likely makes J0749+2255 the most distant galaxy in which both aromatic and aliphatic emission has been detected.

Unexpected Trends

Mentzer, Li, and Yang subdivided the observations into 47 regions and measured the strength of the 3.3- and 3.4-μm features in each region. This analysis found strong aromatic emission nearest the quasars and showed that the fraction of carbon atoms bound up in aliphatic chains is highest close to the quasars.

Both of these findings are unexpected: the harsh radiation environment near the two active black holes is thought to break apart chains of carbon atoms attached to aromatic rings (which should decrease the 3.4-μm emission) and possibly destroy small aromatic molecules (which should decrease the 3.3-μm emission) — yet both of these features are strongest near the quasar cores where the radiation should be most capable of molecular destruction.

The authors speculated that the analysis regions centered on the quasars are large enough that they contain gas that hasn’t been pummeled by the quasars’ intense radiation and outflows, leaving molecules intact and able to produce the observed emission. However, this doesn’t explain the trend of stronger 3.3- and 3.4-μm emission closer to the quasars — necessitating further research into the emitting behavior of aromatic and aliphatic molecules under the extreme conditions of a dual quasar’s neighborhood.

Citation

“Widespread Detection of Aromatic and Aliphatic Emission in the Dual Quasar J0749+2255 at Cosmic Noon,” C. E. Mentzer et al 2026 ApJL 1005 L38. doi:10.3847/2041-8213/ae7e86

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Scientists have discovered an abundance of molecules in the cosmos, but for the first time ever, they were able to detect one in interstellar space very familiar to us here on Earth: sugar. 

The discovery, made in the vast clouds of gas and dust between stars, could help scientists better understand how some of the chemical ingredients necessary for life formed long before Earth existed.

Researchers at the Centro de Astrobiología, part of the Spanish National Research Council (CSIC), identified the sugar molecule erythrulose within the interstellar medium.

Sugars are considered fundamental building blocks of life. On Earth, they play vital biological roles, including forming the backbone of RNA and contributing to the chemistry that ultimately supports DNA, while also serving as an important source of energy. Scientists studying the origins of life have long sought to understand how the first sugars formed, since they are essential ingredients in the molecules associated with life’s earliest development.

“The detection of erythrulose is very exciting because it opens up the possibility of discovering in space other sugars such as ribose, which is part of RNA, and other important molecules for the origin of life,” says Carlos Briones, co-author of the study, in a statement. 

Even so, one major question remains: where did the first biologically important sugars originate?

Previous studies have identified sugars such as ribose and glucose in meteorites and asteroid samples, suggesting that some organic compounds may have been delivered to the early Earth from space. Until now, however, no sugar had been directly detected in the cold molecular clouds where stars and planets form.

The newly identified molecule, erythrulose, was found in the molecular cloud G+0.693−0.027 near the center of the Milky Way. On Earth, erythrulose is a naturally occurring four-carbon ketose sugar.

The discovery was made using highly sensitive radio astronomy observations from the Yebes Observatory’s 40-meter radio telescope and the 30-meter telescope operated by the Institute for Radio Astronomy in the Millimeter Range. Researchers analyzed the unique radio signatures, or spectral fingerprints, emitted by molecules in space.

The team identified 12 spectral lines matching laboratory measurements of erythrulose, confirming the molecule’s presence.

The findings also challenge some existing ideas about how complex molecules form in space. Scientists have generally proposed that interstellar chemistry builds larger molecules by gradually adding carbon atoms. Yet erythrulose proved to be more abundant than related three-carbon sugars that researchers expected would appear first.

“This finding was unexpected, as the prevailing view in astrochemistry is that interstellar molecules grow in size through the sequential addition of carbon atoms,” said Izaskun Jimenez Serra (CAB), the lead author of the recent study. 

Instead, the researchers found that erythrulose could form inside icy dust grains from simpler two-carbon alcohols and aldehydes. These frozen environments may function as natural chemical laboratories, allowing increasingly complex organic molecules to develop over time.

The team estimates that during the Late Heavy Bombardment—roughly 4.1 to 3.8 billion years ago, when Earth experienced intense asteroid and comet impacts—between 500,000 and 50 million tonnes of erythrulose may have been delivered to the planet’s surface.

The discovery adds another piece to the puzzle of life’s origins, suggesting that some of its essential ingredients may have arrived with something surprisingly sweet.

This paper was published in the journal Nature Astronomy.

Chrissy Newton is a PR professional and the founder of VOCAB Communications. She currently appears on The Discovery Channel and Max and hosts the Rebelliously Curious podcast, which can be found on YouTube and on all audio podcast streaming platforms. Follow her on X: @ChrissyNewton, Instagram: @BeingChrissyNewton, and chrissynewton.com. To contact Chrissy with a story, please email chrissy @ thedebrief.org.

The discovery hints that life’s ingredients may form before planets exist.

Fullerenes — a class of molecules composed entirely of interconnected carbon atoms — are the largest molecules definitively detected in space. Researchers using JWST to study a planetary nebula have found new spectral features from a fullerene composed of 60 carbon atoms, offering another way to study how these molecules form and survive in space.

Full of Fullerenes

The planetary nebula Tc 1 holds special significance in the field of astrochemistry. More than a decade ago, researchers using the Spitzer Space Telescope studied this wispy nebula illuminated by the core of a dead star. These observations led to the first confident identification of molecules called fullerenes in space. Fullerenes are large molecules constructed from interconnected rings of carbon atoms, forming hollow spheres, rugby-ball shapes, and long tubes. Spheroidal fullerenes, especially C₆₀, are commonly referred to as buckyballs.

Since that discovery, Tc 1 has been a hot spot for studies of buckyballs. However, researchers are still puzzling over how these large molecules form and survive in harsh space environments.

From Spitzer to JWST

Morgan Giese (The University of Western Ontario) and collaborators recently reported on the results of a JWST observing program that aimed to understand how fullerenes respond to changes in their environment. The team mapped the distribution of C₆₀ molecules at varying distances from the powerful ionizing radiation of Tc 1’s central star.

The team successfully spotted the emission features from the fullerene C₆₀ seen in earlier observations, but they also turned up something unexpected: a handful of prominent emission features from 3.5 to 5.2 microns that had not been reported previously.

Feature Presentation

What’s the source of these emission features? The distribution of the emission provides a strong clue: known spectral features from fullerenes C₆₀ and C₇₀ are concentrated in a narrow, bright ring around the center of the nebula, with diffuse emission suffusing the rest of the nebula — and the newfound spectral features follow the same distribution.

This evidence hints that C₆₀ or C₇₀ is the source of these new features, but Giese’s team took the investigation a step further. Using anharmonic quantum chemical calculations, they computed the spectrum of C₆₀‘s combination bands, which arise when multiple vibrational modes are excited at the same time. This is the first time this type of spectrum has been calculated for C₆₀, and the authors found good agreement between their computed spectrum and the JWST spectrum, providing further evidence that C₆₀ is the source of these bands.

Giese and coauthors found that 17% of the energy emitted by the C₆₀ molecules in Tc 1 is released in these  combination bands, suggesting that these features must be taken into account when modeling the cooling of C₆₀ molecules. The discovery of new fullerene spectral features also has implications for future studies of these molecules: since these features appear in a wavelength range where features from other complex molecules like polycyclic aromatic hydrocarbons are weak, these newly identified bands provide a promising way to spot and study fullerenes across space environments.

Citation

“Detection of C₆₀ Combination Bands in the Near-IR Spectrum of Tc 1,” Morgan M. Giese et al 2026 ApJL 1004 L32. doi:10.3847/2041-8213/ae76d5

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Astronomers have found that interstellar comet 3I/ATLAS contains an unusually large amount of methanol. Every interstellar object that passes through our solar system offers a rare chance to sample material forged around another star. Now, new observations of comet 3I/ATLAS using the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed a chemical surprise: the comet is [...]

Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.

Title: Protostars at Subsolar Metallicity: First Detection of Large Solid-State Complex Organic Molecules in the Large Magellanic Cloud
Authors: Marta Sewiło et al.
First Author’s Institution: NASA Goddard Space Flight Center
Status: Published in ApJL

Stars and planets form when clouds of molecules collapse in on themselves due to the overwhelming force of gravity (which, relatable). This process is quite mysterious, as these clouds will only live for a couple million years before collapsing, and the newly forming protostars only live for about half a million years before becoming main-sequence stars.

But we are able to find some protostars in the Milky Way and in the Small and Large Magellanic Clouds near us, and observing the molecules around these protostars can help us understand how protostars form.

To look for molecules around protostars, astronomers take spectra of the protostars in the infrared, which is a wavelength region where molecules emit a lot of light. As better instruments are being built, astronomers are more often able to look for what are called complex organic molecules, which are carbon-bearing molecules with at least six atoms.

These complex organic molecules can be detected in different states: most detections have been of gaseous molecules in and around protostars or planet-forming disks, but they can also be found in a solid state on the surfaces of dust grains in the interstellar medium in a galaxy. In this state, they are called complex organic molecule “ices.” These “ices” were rarely found pre-JWST, but since its launch, detections have been more numerous, mainly in the Milky Way. Observing these complex molecules on the surfaces of dust grains tells us more about protostellar dust chemistry, which is an important but still mysterious aspect of star formation.

In this study, researchers look outside of our own galaxy to explore the complex organic molecules in the Large Magellanic Cloud (LMC). The LMC is an interesting place to look for these molecules because it has lower metal content (i.e., elements heavier than hydrogen and helium) than the Milky Way, as well as a harder radiation field. This means photons flying around in the LMC generally have higher energies than photons flying around in the Milky Way, and elements like carbon, oxygen, and nitrogen are less abundant. This is important because these conditions are more similar to what typical galaxies were like in the early universe. Thus the LMC is a better test bed to look at protostars than the Milky Way if we want to understand how stars formed in the early universe.

The authors of this study have found signatures of complex organic molecules in protostars forming in the LMC. They focus on the protostar ST6 in the LMC, shown in the right image in Figure 1. They used JWST’s Mid-Infrared Instrument to take spectra of the region around ST6.

Spectroscopic Signatures of Molecules on Dust Grains

The researchers used the Python tool called dEcompositioN of Infrared Ice features using Genetic Modelling Algorithms (ENIIGMA) to fit the spectroscopy. This code compares the spectra to laboratory data of these complex organic molecules at the temperatures we see in the LMC. The authors fit for complex organic molecules they might expect to see, and they detect methanol (CH₃OH), acetaldehyde (CH₃CHO), ethanol (CH₃CH₂OH), methyl formate (HCOOCH₃), and acetic acid (CH₃COOH); of these, acetaldehyde, ethanol, and methyl formate have never before been detected outside of the Milky Way. Interestingly, this is the first time acetic acid has been definitively detected in any astrophysical environment. The spectral contribution from each molecule is shown in Figure 2; all the individual contributions added together make up the observed spectrum.

These detections provide evidence that these complex organic molecules can be produced on the surfaces of dust grains. Further, their detection in the LMC provides evidence that these molecules can be produced in “harsh” environments like the LMC, with lower metal content and harder radiation fields.

When the authors compared the abundances of these ices to other protostars in the Milky Way galaxy, they found that the abundances are slightly lower around the LMC protostar. This may happen because the dust temperatures are generally higher in the LMC due to the higher-energy photons, which affect the chemistry happening on the dust. Some species they found, however, do have similar abundances to the Milky Way protostars, indicating that the harder radiation field of the LMC does not affect how these species form. Finding more complex organic molecules in the Magellanic Clouds will help us understand further how these compounds form on dust grains and how the galactic environment may affect their formation.

Original astrobite edited by Shalini Kurinchi-Vendhan.

About the author, Caroline von Raesfeld:

I’m a third-year PhD student at Northwestern University. My research explores how we can better understand high-redshift galaxy spectra using observations and modeling. In my free time, I love to read, write, and learn about history.

The post Detecting New Icy Molecules Around a Newly Forming Star with JWST appeared first on AAS Nova.

To probe the chemistry of cold pre-stellar cores, researchers investigated Lynds 1544 and made the first-ever spatially resolved map of methanimine — a simple molecule that may be involved in the formation of amino acids in space — in this environment.

Astrochemistry at Work

Peering across the galaxy, astronomers have discovered a broad and growing array of molecules, revealing the rich chemistry taking place everywhere from molecular clouds to protoplanetary disks. A central question in astrochemistry is where, when, and how molecules form in space, and how molecules might survive the various phases of star formation and be incorporated into newborn planetary systems, where they could play a role in the construction of complex organic molecules necessary for life.

Today’s research article, led by Yuxin Lin (Max Planck Institute for Extraterrestrial Physics), focuses on a molecule called methanimine (CH₂NH). CH₂NH is the simplest molecule in a class of nitrogen-containing compounds called imines, and it’s thought to be an important stepping-stone in the creation of amino acids.

First Spatially Resolved Map

Lin and collaborators searched for CH₂NH within Lynds 1544 (L1544), a pre-stellar core in the nearby Taurus Molecular Cloud. Pre-stellar cores — condensed, gravitationally bound clumps of cold gas within a molecular cloud — represent an early stage in the process of star formation, just before the gas collapses to form a protostar.

L1544 has been the subject of many astrochemical investigations, and previous studies have revealed that it contains a complex, chemically differentiated envelope surrounding a dense core in which many chemical species have frozen out onto dust grains, leaving the gas depleted of these species.

Using the Institute for Radio Astronomy in the Millimetre Range 30-meter radio telescope, Lin’s team mapped the distribution of CH₂NH across L1544. This isn’t the first time that CH₂NH has been detected in a cold pre-stellar core, but it’s the first time that the molecule has been mapped in a spatially resolved way in such an environment. This allows researchers to compare the distribution of CH₂NH to other molecules in the core and build an understanding of the chemistry behind its formation.

The Chemistry of CH₂NH

The new observations show that CH₂NH can be found throughout L1544, with clear spatial trends in the molecule’s abundance: higher near the outer layers of the core, lower near the center. Using chemical models to aid their analysis, Lin’s team showed that the observed distribution suggests formation pathways driven by moderate amounts of ultraviolet radiation.

In the outer layers of the core, where the gas is less dense, ultraviolet light creates reactive chemical species called radicals that can spur the formation of CH₂NH. In the interior of the core, dense gas prevents the incursion of ultraviolet light. This means that few radicals are created that can help form CH₂NH molecules, and the molecules that do form tend to freeze out onto dust grains, disappearing from the gas.

The discovery of CH₂NH throughout L1544 suggests that the precursors to complex organic molecules can form during the cold, calm pre-stellar core phase of star formation, allowing these molecules to be inherited by nascent planetary systems.

Citation

“First Mapping of Prebiotic Molecule CH₂NH in a Prestellar Core,” Yuxin Lin et al 2026 ApJL 996 L32. doi:10.3847/2041-8213/ae2c76

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