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 

Deep within ancient chamber tombs where elite members of society in ancient Greece and Crete were once laid to rest, new evidence has emerged that these high-status individuals wore some out-of-this-world iron jewelry.

Among the most coveted jewelry worn in the Bronze Age Mediterranean world were rings that were likely made from extraterrestrial iron, according to a new study published in the Journal of Archaeological Science.

Researchers Matthieu Gounelle and Eleni Mantzourani used chemical analysis to examine more than 90 iron objects from the Bronze Age and Early Iron Age, uncovered from 33 archaeological sites, revealing that about one-third of the artifacts were likely crafted using iron that fell from space.

Although iron harvested from ancient meteorites accounted for at least 10 of the rings the researchers examined, another three “might deserve further examination,” the study’s authors say, in new observations that indicate these ancient extraterrestrial adornments “may have been popular power symbols among prominent individuals” that included the Mycenaean and Minoan palatial elite.

Yet despite their apparent significance, the otherworldly fashion trend involving these otherworldly rings seems to have mysteriously vanished by the 12th century BCE, for reasons that remain unclear to researchers.

Meteoritic Iron as a Status Symbol

Using portable X-ray fluorescence, or XRF, to assess these rare artifacts in various museums where they are kept, most of the objects were found to contain very little nickel, if any at all. This is consistent with iron produced using smelting processes from the periods in question, which relied on terrestrial ores.

However, 13 of the objects possessed elevated levels of nickel, which hinted at the likelihood that some of these ancient rings had been crafted with metal originating in meteorites, which contain far more nickel than smelted varieties of iron do.

Another intriguing discovery the researchers made was that each artifact suspected of being made from meteoritic iron was either a whole or fragmentary signet or bezel ring, combining the suspected meteoritic iron with gold, silver, or bronze. Most were also found in various chamber tombs alongside other luxury goods, adding to the likelihood that these unique artifacts may have been considered symbols of status or authority.

Where Did Ancient Greeks Obtain Extraterrestrial Iron?

However, another mystery involves the source of the meteoritic material, which remains uncertain since extraterrestrial iron was uncommon in ancient Greece. Because of this, the team suspects that one reason for this material’s role as a status symbol may have been not just its otherworldly nature, but also the fact that it was likely imported.

“Given the rarity of meteorites in Greece and the established trade networks during the Bronze Age, we propose that the source of the raw meteoritic material was Egypt,” the team writes, “where meteorites are numerous due to the abundance of deserts.”

Several famous examples of meteoritic iron have been recovered from Egypt, which include a dagger found among the items entombed with the Pharaoh Tutankhamun.

The abundance of rings made from this extraterrestrial metal contrasts with the more common iron objects that appear to have been made from smelted material. This suggests that ancient metalworkers recognized the distinction between the materials, and ascribed higher value to the far rarer meteoritic forms of iron.

An Otherworldly Fashion Trend Goes Missing

Curiously, the researchers also found that by around the 12th century BCE, this otherworldly fashion trend appears to have almost completely vanished, and for reasons that remain unclear.

Possible reasons for this may include interruptions to trade networks, political upheaval, or simply changes in trends from the period. However, one potential clue is that the ancient Greeks’ production of meteoritic iron rings seems to have ended coinciding with the collapse of the Mycenaean palace system.

“Such a development could be related to economic, social or political changes,” the team speculates, although they also acknowledge more mundane possibilities.

“It is also possible that the meteoritic finger ring fashion, almost exclusive to Minoan and Mycenaean Late Bronze Age, has ‘naturally’ faded away as does any fashion,” the researchers write.

The recent study, “Iron in Greece in the second millennium B.C.E.,” appeared in the Journal of Archaeological Science. 

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

Astronomers searching for extraterrestrial intelligence have traditionally focused on a specific, narrow band of the radio spectrum. However, a new survey presented at the Royal Astronomical Society‘s National Astronomy Meeting (NAM2026) in Birmingham suggests that this approach may overlook a significant portion of the available frequencies.

The frequencies most often investigated by SETI (Search for Extraterrestrial Intelligence) programs are those between 1.42 and 1.66 GHz. This range, known as the ‘water hole’, is situated between the natural radio emissions of hydrogen and hydroxyl, the two molecules that make up water. Astronomers have regarded this quiet section of the spectrum as a reasonable place for interstellar communication, because any civilization acquainted with these molecules would probably also decide to send and receive signals in search of in that specific region.

Louisa Mason, who is carrying out research as a PhD student at the University of Manchester, focused on investigating frequencies outside the water hole range. To carry out the first SETI survey with that telescope, she used archived data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. She analyzed data originally collected for other astronomical studies instead of requesting new observation time.

Hunting for Signals in Unclaimed Territory

Mason focused on two narrow frequency bands in the ALMA Band 3 data, looking for narrowband signals that might be the result of technology rather than natural astrophysical origins. In the four observations that she examined, she did not discover any candidates for technosignatures above her detection threshold.

“For decades, SETI searches have concentrated on a relatively small part of the radio spectrum. We wanted to ask what might happen if we looked somewhere very different,” Mason said. “The millimetre and submillimetre radio bands remain almost completely unexplored for SETI, so this is really about opening up a new area of parameter space to search.”

A lack of results does not rule out the possibility of alien transmitters. It only means that none appeared in this specific region of the sky and frequency range. Mason describes the survey as a proof of concept, showing that high-frequency telescopes like ALMA could play a much larger role in future SETI efforts.

A Much Bigger Haystack Than Anyone Realized

The research also revealed a gap in how astronomers count the stars they have actually examined. Each time a telescope observes a single target, it also collects light from many other stars in the same field of view. Researchers refer to this as “stellar bycatch.”

Previous SETI surveys have made this bycatch estimate based on the Gaia catalog, which is the European Space Agency‘s survey of the stars. However, Gaia has certain limitations such as its magnitude cutoffs, uncertainties when measuring distant stars, and difficulties in crowded areas. To overcome these limitations, Mason used the Besançon Galactic Model, a simulation of the Milky Way’s stellar population that includes stars that are too faint or too far away for Gaia to detect.

When Mason applied the model to a previous survey of 1,327 telescope observations, the estimated number of stars observed increased from about 288,000 with Gaia to over 6.1 million with the galactic simulation.

“One of the most exciting things about this work is realizing that we’ve surveyed many more stars than initially thought,” Mason said. “Even a very small observation can contain a huge number and diversity of stars that we might never have intended to study. By combining high-frequency observations with galactic simulations, we can better understand exactly what we’ve searched and where we should look next.”

Recommendations for SETI

Mason carried out this research in collaboration with Professor Michael Garrett, Dr. Andrew Siemion, and Dr. Kelvin Wandia. The team argues that expanding both the radio frequencies searched and the number of stars included could reduce the influence of human assumptions on SETI strategies. Whether these broader searches will detect technosignatures missed by traditional water-hole surveys remains unknown.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.

Interdimensional beings are extradimensional beings, as distinct from extraterrestrials are perceived as entities in realms beyond our physical universe, governed by different principles. These beings may exist as energy or abstract forms and are common in science fiction and spiritual demonic contexts. Modern scientific language is used to make them acceptable.