Category: Search for Life

Methanol, coming as part of the 'chemical starter kit' around young stars, has produced some unexpected surprises that could ultimately reveal some of the conditions in which planets and potentially life form around protostars.

The methanol discoveries were made by astronomers using ALMA (the Atacama Large millimeter/submillimeter Array) in the Atacama Desert in Chile, as part of a project called COMPASS (the Complex Organic Molecules in Protostars with ALMA Spectral Surveys).

"Our work provides insight into the complex chemistry of young star systems and is ultimately an important piece of the puzzle in understanding the origin of life," said University of Bern astrophysicist Maria Drozdovskaya, who leads the COMPASS project, in a statement.

Drozdovskaya's multinational team of more than 30 astronomers has been chasing down complex organic molecules, large molecules that include carbon atoms, in the planetary construction yards around eleven young stars.

These molecules form part of the chemical inventory that ultimately builds planets and, perhaps, even life that will one day live on those planets.

Methanol matters

Methanol (CH₃OH) is important because it is highly abundant in star- and planet-forming regions. In fact, it’s the most abundant complex organic molecule to be found in interstellar space, and is commonly found in planet-forming disks.

Its sheer abundance means that, of all the molecules found around young stars, methanol is the easiest in which to detect different forms where regular hydrogen atoms are replaced by a heavier isotope of hydrogen called deuterium.

How many molecules contain these heavier isotopes is highly dependent upon the conditions in which planets are forming within the disk.

That’s why the COMPASS team used ALMA to search for these forms of methanol in the gas belonging to the planet-forming disks around the 11 nearby low-mass protostars. The observations have also helped assess the general chemical diversity of these disks.

The unexpected discovery of a methanol molecule containing deuterium was made in the planet-forming disk around only one of those 11 stars, namely the young star IRAS 4A2, located about a thousand light-years away in the Perseus Molecular Cloud.

IRAS refers to the Infrared Astronomical Satellite, which was a joint NASA–UK–Netherlands mission launched in 1983 and which first detected this young star as a source of infrared light through the thick gas and dust of the molecular cloud.

The COMPASS team also discovered methanol maser emission from more than half of the 11 protostars, favoring the youngest of the stars. A maser is a microwave version of a laser in the sense that the microwave emission is being stimulated and then amplified, but astrophysical masers occur naturally, often in shock fronts as methanol molecules collide and are excited.

Methanol masers have previously been detected in planet-forming disks around turbulent high-mass protostars, but COMPASS’ observations are the first detection of them around calmer lower-mass protostars.

"The fact that it has now also been found in a low-mass protostar shows that locally extreme physical conditions can prevail there analogously to massive stars and challenges our previous understanding of the formation of sun-like stars," said Drozdovskaya.

The finding implies that methanol masers are a common product of all planet-forming discs and therefore are produced by processes that are universal in star- and planet-birth, regardless of the protostar's mass.

For example, thermal bursts from the growing star as it accumulates gas from its surroundings could generate shocks in a planet-forming disk, stimulating maser activity in the abundant methanol.

"Both results underscore how important high-performance spectroscopic measurements like those from COMPASS with ALMA are for detecting rare and previously unknown chemical phenomena," said Drozdovskaya, referring to both the methanol masers and the deuterium-rich methanol molecules around IRAS 4A2. "They show just how much we still have to learn about the chemical processes in young protostellar systems."

The new findings have at least begun to answer some questions, such as how the diversity in this 'chemical starter kit' varies from star to star, with ALMA detecting some subtle differences, such as variations in the abundance of oxygen- and nitrogen-bearing molecular species among the eleven stars.

However, questions about how the chemistry of young star systems arises and how it influences the evolution of those systems remain unanswered.

For now, the COMPASS team is painstakingly and systematically studying the data on all the different types of molecules detected in their ALMA observations, and preparing follow-up studies with other facilities including the James Webb Space Telescope (JWST).

"The analysis of all the collected data will take several more years," said Drozdovskaya.

The first results from COMPASS are published in seven papers [1, 2, 3, 4, 5, 6, 7] in the October 2026 issue of the journal Astronomy & Astrophysics.

Could we find alien technology embedded in moon dust?

The bold idea, not yet peer-reviewed, suggests checking out the lunar surface for "microscopic technosignatures." The SETI Institute — or the Search for Extraterrestrial Intelligence Institute — describes these technosignatures as "tiny engineered particles" that may have come from interstellar space before settling on the moon.

The institute recently highlighted a paper on the topic, published on arxiv in August, and added the research is undergoing peer review for consideration in the International Journal of Astrobiology. The study is led by SETI Institute Affiliate Scientist Lewis Pinault.

"The moon has been quietly accumulating material from space for billions of years, much of it likely billions of years older than the moon itself," said Pinault in a statement. "We're asking whether that ancient collection might contain microscopic traces of technologies that existed long before humans ever looked up at the sky."

Even if no aliens turn out to be there, the search could help advance models of how dust goes through interstellar space, as well as effects on lunar geology or impact science, the institute added.

"The study reports no evidence of extraterrestrial technology," the institute added in the statement. "Instead, it demonstrates that searching for these microscopic technosignatures is now scientifically testable."

That's in large part because the NASA-led Artemis program, which will ultimately bring astronauts to the moon, as well as China's Chang'e robotic series, would provide opportunities to return samples, the institute said. (China is also eyeing bringing its taikonauts to the moon by 2030.)

SETI is best known for looking for artificial radio signatures in space that may have come from extraterrestrials. This new study, the institute added, is focusing more on past alien communities that may have preserved their knowledge in "durable particles," even if the communities are no longer in existence.

The study examines how these particles could (in theory) move from star to star, stay viable over long distances and periods, embed themselves in the lunar surface and then — if humans could find them — use AI-assisted imaging, materials analysis and microscopy to take a closer look, among other techniques.

Helping in that search is the environment of the moon itself, which — compared with Earth, at least — has slow-moving geology. As the institute points out, the surface has no flowing water or substantial atmosphere like our planet does. What's more, the moon has picked up dust in its environment for about four billion years (from not long after the solar system was formed 4.5 billion years ago), presenting a potential archive of dust in the solar system and interstellar space.

"The researchers argue that if advanced civilizations produce durable microscopic debris — whether intentionally or as a byproduct of space exploration or large-scale engineering — a tiny fraction of those particles could eventually become embedded in the lunar regolith," the institute stated.

The goal is to start these studies with about 35 cubic feet (one cubic meter) of lunar regolith, which is maybe the equivalent size of a fridge. Researchers would try out a series of careful investigations using multiple tools to "begin placing meaningful limits on the amount of durable artificial material produced by technological civilizations over the history of the Milky Way."

And as mentioned, even if this small sample doesn't turn up technosignatures, the researchers say the work is still important. It's another way to search for "extraterrestrial artifacts," to look at various aspects of solar system science, and to try out newer tools for examining moon samples that weren't available in the Apollo years.

"This is a novel addition to the search methodologies applied to seeking evidence of technology as a proxy for life and intelligence beyond our solar system and we are excited at the prospect of bringing this to fruition," stated Bill Diamond, SETI Institute president and CEO.

Whatever they are and from where, UFOs, now known as Unidentified Anomalous Phenomena or UAP, are the subject of serious scrutiny at the highest levels of the U.S. government.

In June 2026, the White House established a new UAP Science Advisory Council in coordination with the Pentagon's All Domain Anomaly Resolution Office, the Office of the Director of National Intelligence and the FBI Deep diving into the UAP landscape is Avi Loeb, noted Harvard astrophysicist. He is also director of the Galileo Project at Harvard, which aims to search for signs of extraterrestrial activity here on Earth. As the council chair, Loeb said the goal of this group is to advise the U.S. government on how to resolve the nature of UAP.

Members of the UAP Science Advisory Council recently gathered at a private meeting, held on Aug. 31 at the Office of the Director of National Intelligence, Loeb told Space.com. "I cannot disclose the contents but I will say that the U.S. government is sincere in its efforts to understand UAP based on the scientific method of data collection," Loeb said.

Council membership

One of the council's members is Ben Lamm, co-founder and CEO of Colossal Biosciences. As a serial technology entrepreneur, he's no stranger to diving into complex challenges. Colossal is advancing the use of genome editing technology to "de-extinct" previously lost species such as the Wooly Mammoth.

Working along with the council's group of scientists and experts, Lamm is bullish about bringing clarity to a long-standing investigation and wonder of UAP.

"I've been fascinated by this topic for a long time, so having the opportunity to help examine the evidence firsthand and contribute to a serious scientific effort is incredibly exciting," Lamm told Space.com.

"Our mission is straightforward," Lamm added. "This is not about belief, it is about evidence. We want to apply rigorous scientific methods to both historical UAP records and new observations, collecting and analyzing data that meets today's scientific standards," he said.

Lamm said that the expectation is to bring transparency and accountability to the field by objectively evaluating credible evidence and sharing findings openly with the scientific community and the public.

"It's time to search for answers around the science because they could reshape our understanding of the world and, potentially, become one of the most significant discoveries in human history," said Lamm.

New polling data

Meanwhile, and serving as a backdrop to studying UAP, is a new Gallup poll, conducted in July. That poll found that about half of Americans, 49 percent, think all Unidentified Flying Object (UFO) sightings can be explained by human activity on Earth or natural phenomena.

The poll also found 37 percent believe at least some UFOs have been alien spacecraft visiting Earth from other planets or galaxies while another 13 percent do not have an opinion.

Interestingly, rather than becoming increasingly convinced that some sightings have been alien spacecraft, the percentage of Americans who are unsure has grown, from 7% in 2019 to 13% in 2026 the Gallup poll found.

The new poll also notes that a majority say the U.S. government is withholding UFO information. Seventy-eight percent of Americans say the U.S. government knows more about UFOs than it is telling the public, higher than the 68 percent and 71 percent who said so in 2019 and 1996, respectively.

These findings come as the Department of War continues to release a mix of UFO files under a President Donald Trump executive order.

In August 2026, the UAP Science Advisory Council announced their support for the Trump administration to provide legal assurances, including immunity where necessary, for current or former government employees and military personnel to share information with the council "regarding alleged technology from a non-human origin and help guide the council's scientific evaluation."

As "The X Files" famously told us, "the truth is out there." But at the same time, inquiring minds are immersed today in finding out whether or not the proof is out there — specifically, proof that at least some unidentified anomalous phenomena (UAP) come from somewhere beyond Earth.

The UAP acronym originally stood for "unidentified aerial phenomena," a term that itself was a rebranding of "unidentified flying object" (UFO). And UFO was a replacement of sorts for the long-lasting and stylish "flying saucers."

Whatever the terminology, truth and proof in today's fractured and somewhat conspiratorial society could be construed as strange bedfellows.

UAP study team

Mike Gold is president at Redwire Space, an innovative aerospace and defense company. In 2022 and 2023, he served on the NASA Unidentified Anomalous Phenomena Independent Study Team, a council of 16 experts across diverse areas on matters relevant to potential ways to investigate UAP.

Gold's past roles include NASA associate administrator for space policy and partnerships, acting associate administrator for the Office of International and Interagency Relations, and senior advisor to the administrator for international and legal affairs. While at NASA, he led the development and implementation of the Artemis Accords.

That past also includes 13 years at Bigelow Aerospace, during which he established the company's Washington office and oversaw the launches of Bigelow's Genesis 1 and Genesis 2 spacecraft, which showcased the use of expandable habitat technology.

Exposing the truth

Gold's ongoing UAP interests were highlighted in 2024 during a hearing of the U.S. House of Representatives' Committee on Oversight and Accountability titled "Unidentified Anomalous Phenomena: Exposing the Truth."

"We must be thorough in collecting information, fearless in making conclusions and open to following the data no matter how mundane or extraordinary the results may be," Gold told the lawmakers. "As the saying goes, the truth is out there. We just need to be bold enough and brave enough to face it."

Space.com caught up with Gold recently to discuss his current UAP views and his work with The Disclosure Foundation as an advisory board member.

Follow the data

"I would say that I came out the same way I came in," Gold said of his past work for the NASA UAP study team, "and that was objective and wanting to follow the data."

While the NASA group's final recommendations seem to be lost in the fabric of time and space, Gold said that, under the current presidential administration, NASA is taking the UAP issue quite seriously, as is the rest of the federal government.

"NASA is doing its best to contribute to the Department of War releases on UAP," said Gold. "I will note that what is being released by NASA is publicly available and has been. But I think it's beneficial for the White House to flag some of the most interesting aspects that we have from NASA archives."

Gold said, for instance, that the 1972 Apollo 17 moon landing report included imagery showing three lights in a triangular shape that was flagged in recent Department of War (DOW)/NASA-released documents.

"NASA is a proactive participant in all of this," he added, noting that having imagery identified as anomalous is "very powerful in fighting the stigma."

There are champions inside the space agency who want to pursue the UAP issue, according to Gold.

"They feel a lot more comfortable when you've got the White House putting out some of the NASA imagery and saying that this is indeed anomalous," he said.

Disclosure process

Gold brought up the fact that he is a "recovering lawyer." However, that status doesn't free him from pondering the implications of a UAP "full disclosure" — if that ever happens.

"As I think about disclosure, we are absolutely in the disclosure process. This is what the White House documents are. You have to applaud this Trump administration. This is unprecedented what's occurring. At the very least, I view this as evolutionary disclosure," Gold said.

"It's a process of looking at the information objectively," he added. "I think when others use the term 'disclosure,' it can be inherently attached to the revelation of the existence of non-human intelligence."

But that's not the way Gold views disclosure.

"It is a process where we are objectively evaluating information and then following the data and the conclusions wherever they take us," he said. "That may be something extraordinary; it may be something ordinary. The point is that we don't know."

The big reveal?

Still, if the outcome is literally out of this world, could the public handle it? Gold is optimistic on some fronts.

"I think the public could deal with the fact that extraterrestrials exist," he said. "Polls already indicate that they believe that. I also think the public can deal with the fact that we've had an extraterrestrial crash retrieval program."

Nevertheless, there are more challenging questions, Gold said, like "where we came from. Who are we? And what about the abduction phenomenon? Those secondary questions might be more difficult."

However, even if there were good reasons for keeping this issue secret, "what you can't do is keep it secret from Congress, because then we are no longer a democracy," Gold advised. "So at a minimum, our elected officials have to be briefed. They have to know. We have to have oversight."

Common sense action

Gold thinks that what's happening now is a huge shift and of great benefit to the country.

"I know that there's disappointment relative to perhaps the nature of what's being released," he said. "But you have to understand the bureaucratic process. It's what can be done immediately."

A year from now, Gold said that he anticipates even more releases from the government that will be even more interesting.

"I'd like to see NASA adopting a recommendation from the Unidentified Anomalous Phenomena Independent Study Team to include UAP and the aviation safety reporting system," he said. "That, to me, is a common-sense action that would dramatically increase the amount of UAP data that we have.

"It would not be just for science but for national security purposes. Because when I say UAP, that includes adversarial drones that are unidentified," Gold said. "Doing so could be done with little money and be so valuable," he added.

In the end, objectivity is Gold's north star when it comes to UAP.

"I am critical of people who say that this is definitely nothing extraordinary and those who say that this is definitely something extraordinary. We need to go right up the middle of this and take a look at the data. Let the data speak for itself," said Gold. "So, apologies. I am remaining violently neutral."

On Aug. 15, 1977, astronomers using Ohio State University's Big Ear radio telescope detected the famous "Wow!" signal, which to this day is one of the strongest pieces of evidence that we are not alone in the universe.

Astronomer Jerry Ehman was using the telescope to scan a region in the constellation Sagittarius when it detected a weird, 72-second-long radio burst. The signal was too strong to be explained by background noise, and researchers determined that it was very unlikely that this signal came from anything on Earth.

Despite their best efforts, astronomers have not been able to detect any other signals like it.

Why it mattered

For as long as humans have existed, we have looked up and wondered, "Are we alone?" This question remains one of the biggest mysteries across not just science but for humanity as a whole. The "Wow" signal remains an iconic and important finding in the search for life out in the cosmos.

Nearly 50 years since the "Wow!" signal, scientists have made incredible progress in the search for alien life. We have landed rovers on Mars that have found possible signs of life on the Red Planet, for example, and discovered thousands of exoplanets, or planets outside of our solar system.

The "Wow!" signal was detected nearly two decades before scientists first confirmed the existence of exoplanets. Today, we have found more than 6,000 of them and are using cutting-edge technologies to explore further and see if any of these far-off planets might contain signs of life.

When people grow impatient at the lack of success in the search for alien life, researchers often point to how few of the Milky Way's 100 billion stars or so have been searched so far. But it may be that the search for extraterrestrial intelligence (SETI) has surveyed more stars than astronomers had realized.

Louisa Mason, a PhD student at the University of Manchester, had a recent epiphany that astronomers have actually searched much more of our galaxy for radio signals than we thought. Mason came to the conclusion by using a specific simulation of the Milky Way, called the Besançon Galactic Model, and then comparing it to surveys of the sky conducted by the Green Bank and Parkes radio telescopes. Based on star catalogues, it was calculated that the two telescopes had seen 288,315 stars seen in 1,327 observations of the sky. However, by applying the Besançon Galactic Model, Mason discovered that the survey had actually included more than 6.1 million stars, most too faint to be obvious.

"One of the most exciting things about this work is realizing that we've surveyed many more stars than initially thought," Mason said in a statement. "Even a very small observation can contain a huge number and diversity of stars that we might never have intended to study." But while Mason's calculations show that we've actually surveyed many more of those stars than we realized, there's no need to grow disheartened by the lack of a detection.

When a radio telescope points towards a target star, it isn’t just listening to that star, but is also eavesdropping on all the other stars in the field of view. This is very useful for a practice called commensal SETI, whereby a SETI instrument piggybacks on a radio telescope's usual day-to-day observations.

Typically, the number of stars in a radio telescope's field of view is estimated by comparing it to detailed star catalogues such as those compiled by the European Space Agency’s Gaia mission. However, these catalogues are limited because they only include stars bright enough to be seen; there are many more stars too faint to be seen by our optical and infrared telescopes. Yet if a radio telescope is pointed in their direction, it could still detect a radio signal from them even if we cannot see the star.

Although the search may be bigger in terms of the number of stars, it is still very small in terms of the time spent listening to each star, and is still limited in the radio frequency range covered. We could very easily have missed a signal by observing between broadcasts, or at the wrong frequency.

So Mason has also looked to expand the range of radio frequencies that can be searched. Ever since modern SETI began in 1960, the bulk of SETI searches have focused on a frequency range known as the 'water hole', between the emission frequency of atomic hydrogen at 1,420 MHZ, and hydroxyl (a molecule composed of one atom of hydrogen and one atom of oxygen) at 1,666 MHz. The name 'water hole' comes about because if you combine hydrogen with hydroxyl you get a water molecule (two hydrogen atoms and one oxygen atom).

One of the reasons the water hole has been so favored is because radio waves in this frequency range are not absorbed by Earth's atmosphere. Furthermore, a lot of astronomy is conducted around the hydrogen frequency, so there's a good chance of a coincidental SETI detection. Plus, aliens might recognize the importance of water to life and the symbolism of transmitting in that frequency range.

However, there are many other frequencies that could be looked at, and in that vein Mason has conducted the first ever SETI search with ALMA, the Atacama Large Millimeter/submillimeter Array in Chile.

"For decades, SETI researchers have concentrated on a relatively small part of the radio spectrum," said Mason. "We wanted to ask what might happen if we looked somewhere very different."

Mason didn't perform new observations with ALMA, but searched a small amount of archive data for any narrowband signals that could easily have been missed. ALMA operates at shorter radio wavelengths and therefore correspondingly higher frequencies than most regular radio telescopes.

One of the advantages of looking at higher frequencies is that they suffer less from dispersion, which is when lower frequency waves interacting with electrons in space are delayed and arrive at their destination a little later than higher frequencies, therefore distorting the signal overall.

Although Mason didn't come up with any promising new signals in her ALMA search, she remains optimistic about using higher frequencies.

"The millimeter and submillimeter radio bands remain almost completely unexplored for SETI, so this is really about opening up a new area of parameter space to search," she said.

Mason presented her work at the Royal Astronomical Society’s National Astronomy Meeting in Birmingham in July. The research is also described in two papers – one on the ALMA survey, the other on the Besançon Galactic Model, in Monthly Notices of the Royal Astronomical Society.

NASA's Europa Clipper is currently on a 1.8-billion-mile journey to Jupiter, tasked with assessing whether the icy moon of its namesake, Europa, could support life.

Based on data from the historic Voyager and Galileo missions, scientists know Europa hides a global ocean beneath its frozen crust, containing more than double the water of all Earth's oceans combined. During the Europa Clipper's planned 49 close flybys of the icy moon, planetary scientists hope the spacecraft detects giant water plumes or warm surface pockets supplied by this subterranean ocean, offering a convenient way to analyze the hidden ocean's chemistry from orbit.

A new study, however, suggests any shallow water the Europa Clipper detects may not necessarily be a direct window into Europa's ocean after all.

Research led by planetary scientist Lujendra Ojha of Rutgers University indicates that Europa's icy shell acts as a far more formidable barrier than previously assumed. Computer simulations modeling the physics of water traveling through fractures in the ice reveal that liquid rising from the ocean would move turbulently, shed heat rapidly and freeze the cracks shut — often in a matter of hours — long before reaching shallow depths.

"There's an icy shell, there's water underneath, and there's all this speculation about how that water can come from deep underground and make its way all the way up without freezing en route," Ojha said in a statement. "That's really what we think we disproved."

To test this scenario, Ojha's team built computer simulations to evaluate whether ocean water could rise through fractures in the crust and collect in shallow reservoirs closer to the surface. Such reservoirs, if fed directly by the ocean, would be significantly easier for passing spacecraft to detect and analyze than an ocean buried miles below.

While earlier models assumed water would flow smoothly through these pathways, real-world physics creates a far more chaotic journey, according to the new study. Instead of a steady stream, rising water churns turbulently against the frigid walls of the fractures, rapidly losing heat.

"It's going to be left and right, it's going to be up and down, it's going to have a swirling motion," Ojha said in the statement. "And when that happens, that liquid water is going to cool very, very fast as it approaches the surface."

As the water rapidly cools, it remains liquid below its standard freezing point in a process called supercooling. This phenomenon, the study notes, triggers the formation of tiny, slushy ice crystals known as frazil ice that then quickly builds up and clogs the pathway.

While wider fractures could theoretically carry larger volumes of water, the results suggest that to prevent complete freezing, those channels would need to be "unrealistically long or occur in large numbers," the university statement read.

The findings could alter how scientists interpret incoming data from Europa Clipper, which is scheduled to arrive at Jupiter in April 2030, as well as the European Space Agency's Jupiter Icy Moons Explorer (JUICE) mission. JUICE is set to arrive in July 2031 to study Jupiter alongside three of its ocean-bearing moons, Europa, Ganymede and Callisto.

If these spacecraft do discover shallow liquid pools or similar surface features, Ojha's study suggests they are more likely created by localized melting inside the ice shell itself, rather than direct upwellings from the deep ocean.

"This helps future missions interpret what they find and better understand where to look for signs of habitability," Ojha said in the statement.

This research is described in a paper published July 23 in the journal Nature Astronomy.

The search for alien life has tended to focus on looking for either signs of extraterrestrial technology or evidence of biological processes on other worlds. But new and ongoing research suggests that scientists should start considering signs of intelligence that are not necessarily technological, but which are sufficiently complex as to be evidence of a conscious mind at work.

Biosignatures are possible signs of biology on other planets, whereas technosignatures are clues to the presence of advanced technology that might be detectable across light-years. What, though, of everything that comes between these two extremes? How do we detect life that is more complex than simple microbes and which displays intelligence that is not highly technological?

This is where the field of noosemiotics comes in, says Julia DeMarines, an American astrobiologist who has been involved in both biosignature and technosignature research. "We want to figure out if we can detect signatures of intelligence that occur before the invention of radio communication," DeMarines told Space.com. "We're looking at the ways that mind can be imprinted on matter."

Noosemiotics is derived from the Ancient Greek concept of 'nous', which refers to the theory of mind. In the 1920s the Soviet biochemist Vladimir and the French Jesuit priest Pierre Teilhard de Chardin developed the idea of the noosphere as being the sphere of human reason or thought encapsulating the Earth.

More recently, Adam Frank, David Grinspoon and Sara Imari Walker applied the noosphere to SETI by considering the collective intelligence of all the beings on a planet acting as a kind of combined planetary scale intelligence.

Therefore, according to DeMarines, a noosignature would be a sign of a noosphere, of conscious minds at work.

"Bread doesn't just pop out of a molecular cloud"

Technology is, of course, a major imprint of mind on matter, and DeMarines acknowledges that just as technosignatures can be biosignatures since they can originate from biological entities, they can also be noosignatures — for instance, gases such as nitrogen released into the atmosphere by agricultural practices. But noosignatures can be something other than biosignatures and technosignatures, too.

Which is where DeMarines’ work comes in. She had been working for a company who were looking to apply the concept of Assembly Theory, which is a chemistry theory originated by Sara Walker and Glasgow-based chemist Lee Cronin, to online data and artificial intelligence to search for thresholds that denote complex signatures of intelligence.

Assembly Theory describes the minimum number of steps required to assemble something. In chemistry it is the steps taken to assemble, for example, important biomolecules, or to facilitate evolutionary processes. The number of steps taken is referred to as the Assembly Index. As part of her work on this, as a thought exercise, DeMarines was given the task of applying assembly theory to 'bread as a technosignature'.

"I know how that sounds," she laughed. "I get weird looks when I tell people about it!"

However, bread, like anything that is made by a conscious mind be it a stone tool or a radio telescope, is a signature of intelligence. At first DeMarines approached it as a proto-technosignature before realizing that it was more appropriate to describe it as a noosignature.

"Bread doesn't just pop out of a molecular cloud, it requires technology, it requires history, it requires intelligence," said DeMarines. "Say that you have samples of bread at different human and hominin archaeological sites throughout time, dating back 14,000 years – the bread would be a signature of intelligence changing over time as the type of bread, its ingredients and how it is made also change."

How it changes over time can be measured by Assembly Theory – the number of steps taken to get from early breads made from wild grain to modern sliced white bread produced from domesticated wheat is the Assembly Index. The task is to identify how many steps it takes to get past certain thresholds that indicate change, or rather developments, in intelligence, such as new technology for farming and germinating seeds, the construction of windmills or mass production.

As such, it fills part of the space between talking about a simple biosphere and searching for a technosphere, as do things ranging from stone tools to the development of written language and everything in between.

Non-technological intelligence

The trick, though, is detecting such signatures. Archaeological finds require being present on a planet, and digging up artifacts. Are there noosignatures that could be detected on other planets remotely from Earth? DeMarines isn't sure yet, and admits that at this stage she is thinking about it from the perspectives of metrics and thresholds rather than detectability.

If there are detectable noosignatures, they could also operate as a sign to anyone watching that there is intelligence on Earth, too. DeMarines highlights the example of gases released into the atmosphere by basic agriculture. Around three-quarters of all human-made nitrogen emissions were produced before industrialization, and agriculture was the source of that, ranging from fertilizers to animal waste to microbes in the soils used, all beginning many thousands of years ago.

For example, it took human civilization 4,000 years of bread-making before they domesticated wheat over 10,000 years ago. The release of excess nitrogen into the atmosphere disrupts the planet's nitrogen cycle, creating a disequilibrium.

While thousands of years is far too long a time for humans to detect such disequilibrium on exoplanets, alien observers may have been watching Earth for a lot longer than that. Common wisdom is that while biology on Earth has been detectable for billions of years through biosignatures, intelligence only became apparent in the past 100 years or so when we began beaming radio waves out into space.

However, if we are producing noosignatures that are detectable, such as disrupting the nitrogen cycle, then that means intelligence on Earth has been visible to the rest of the universe for much longer than we realized.

Then there's the conundrum of non-technological intelligent life in the universe. Often in the past intelligence has been equated to technology, but to solely rely on technology as a measure of intelligence misunderstands what intelligence is. Technological intelligence is one form of intelligence, but there are others.

Dolphins, for instance, are greatly intelligent creatures with sophisticated social interactions, but with the best will in the world dolphins will never have technology because they do not have the dexterity in their flippers to manipulate the environment around them to the necessary degree.

However, can they imprint their minds on their environment in other ways? It has previously been speculated that the universe is silent because technological intelligence is rare, but Dolphin-like intelligence could be abundant  — yet we'd never detect it. Now, thanks to noosemiotics, perhaps a way will be found to detect signs of such life. If that can happen, maybe we will quickly discover that we are not alone after all.

You can read about DeMarines work in a paper published on the open-source arXiv repository.

A rocky planet orbiting in the habitable zone of a sun-like star may look like a perfect place for life to thrive — but not if it's too small to hold onto its atmosphere.

So, we may wonder: How much smaller Earth could be and still have its delightfully breathable atmosphere? How small could an exoplanet be to sustain life as we know it?

With these questions in mind, University of California Riverside planetary scientist Michelle Hill and her colleagues recently simulated what happens to the atmospheres of different sizes of rocky worlds. The worlds tested were similar to Earth and orbited in the habitable zones around sun-like stars. It turns out for a world to maintain an atmosphere long enough for life to gain a foothold (a few billion years at minimum), it needs to be at least as big as Mars.

Narrowing down the search for life

The habitable zone — the area around a star where temperatures are right for liquid water to exist on a planet's surface — is prime real estate in the hunt for alien life. It's also a tough neighborhood for exoplanet atmospheres, because the closer a planet is to a star, the more ways in which radiation and stellar wind will try to strip away an atmosphere.

This is why Hill and her colleagues recently simulated how long it would take rocky, Earth-like planets of various sizes, in the habitable zone of a star like our sun, to lose their atmospheres. In other words, how much smaller could Earth, or a similar planet, be and still keep an atmosphere?

The answer turns out to be that an atmosphere-sustaining planet needs to be about 80% as wide as Earth, but could technically be as small as 60%. This offers astrobiologists a clue about which planets to focus on in the search for habitable worlds and signs of alien life.

"The plethora of exoplanets creates an interesting challenge in the search for potentially habitable planets," wrote Hill and her colleagues. "Of the many targets in the habitable zones of their star, which are the best candidates for follow-up observations with the aim of detecting biosignatures?" In other words, astrobiologists now have almost too many planets to choose from and not enough telescope time to search them all. So, it's time to narrow the search.

One way to do that is to figure out which planets are most likely to be habitable — and for life as we know it, that habitability means having an atmosphere.

Modeling atmospheres — and volcanoes

Hill and her colleagues' "Smaller Than Earth Habitability Model" simulates the fate of atmospheres around digital versions of Earth. Some of the simulated worlds are exactly like ours but smaller, with the same chemical makeup and the same proportions of core, mantle and crust. Others have slightly different amounts of carbon, larger or smaller cores, or different starting temperatures. The model traces what happens to these worlds over a few billion years, based on two things: how quickly stellar wind and radiation strip away gas from the planet's atmosphere and how quickly volcanoes pump out gas (mostly carbon dioxide) to replace it.

The model is how the team realized a scaled-down version of Earth needs to be at least 80% as wide as true Earth (0.8 Earth radii) to maintain an atmosphere in the long run. Smaller planets tend to lose gas faster than volcanic eruptions can replace it.

That's because smaller planets have less gravity and weaker magnetic fields with which to hold onto their thin envelopes of gas. They also don't usually release enough gas from within to make up for the loss. Their mantles — the churning layer of magma beneath the crust — tend to release less volcanic gas over time, and their upper layers cool and harden much faster. The latter process cuts off volcanic eruptions much earlier in a planet's lifespan.

Smaller planets clinging onto atmospheres

By changing some of Earth's parameters, the team managed to get planets as small as 0.6 Earth radii to maintain a stable atmosphere. Carbon was the key: planets with more carbon in their mantles tend to release more carbon dioxide gas in eruptions, and that turns out to be the biggest factor (other than size) in whether a planet keeps its atmosphere.

"Carbon dioxide is a heavy molecule," Hill and her colleagues wrote, "which can make it a difficult molecule to lose. We focus on a pure carbon dioxide atmosphere as a best-case scenario for atmospheric retention." Of course, that's only a best-case scenario for some relatively simple forms of life, so your astrobiological mileage may vary.

It took tons more carbon than Earth contains to make a significant difference to the fate of a planet's atmosphere — but because it's theoretically possible for a planet to form with that much carbon in its makeup, that's useful knowledge. Planets with relatively smaller cores, and therefore relatively thicker mantles, also had better luck on the atmospheric retention front. Starting with a larger supply of radioactive elements, which decay and release heat into the surrounding rock, helped keep the mantle molten and the volcanic gases churning skyward.

Starting with a cooler mantle also helps — which sounds surprising. You'd think a hotter mantle would be more likely to spew volcanic gases into the atmosphere. Yet, a cooler mantle takes longer to start erupting in earnest, which means the planet gets to hold onto its reservoir of gases until its star is older and more settled.

Newborn stars are prone to violent bursts of radiation and plasma, which would sweep away the volcanic gas as fast as it erupted. With a cooler mantle and later eruptions, the planet gets to keep more of the erupted gas.

A second chance for airless worlds

There's still hope of life for smaller worlds.

Even planets that lose their initial atmospheres entirely — instead of gradually replacing them with things like carbon dioxide and methane — might have a second chance to build a new atmosphere.

Hill and her colleagues suggest that one way for a planet to regain its lost atmosphere could be comet and asteroid impacts, which might deliver volatile elements like hydrogen, oxygen and carbon. These elements can combine to form all sorts of atmospheric gases.

Such impacts could be especially helpful if they happen later in the star system's life, like after the star is past its youthful phase of intense flares.

"While smaller planets face greater challenges in retaining atmospheres, our model suggests that they can develop atmospheres under the right conditions," wrote Hill and her colleagues, so, "even those that initially lose their atmospheres should not be immediately discounted as potentially habitable worlds."

What's next?

Future simulations using the Smaller Than Earth Habitability Model could study worlds around smaller, cooler stars called red dwarfs — stars like TRAPPIST-1, which is home to at least seven rocky planets, with three of them in the habitable zone. These stars make up about 75% of the stars in our galaxy, and their relatively dim light makes it easier for telescopes like the James Webb Space Telescope (JWST) to capture images of starlight filtering through the atmospheres of planets that pass between Earth and their host stars.

Hill and her colleagues also hope to explore what happens to atmospheres around tidally-locked planets, or planets where tidal forces keep the interior hot and seismically active, similar to Jupiter's moon Io.

The researchers published their work in June in The Planetary Science Journal.

Artificial intelligence could easily fall into the trap of identifying non-life as life on other worlds, claim two researchers from Michigan State University who have tested AI on simulated life in a computer program.

"We had previously seen that AI has a big Achilles heel when it is trying to classify things that are unlike the things in its training examples," Michigan's Christoph Adami told Space.com. "We call these 'out-of-distribution' samples and it is just incredibly easy to get AI to misclassify."

Adami is a computational biologist who uses computers to apply information theory to the study of evolution and biology. One of his leading tenets is that life can be defined by its ability to encode information and replicate it. To this end, he devised the Avida computer program in 1993. It runs digital organisms written as code that can replicate by copying themselves and competing for resources — in this case, CPU time — just like real life organisms. Although the use of digital life in evolutionary studies remains controversial, what it does provide Adami with is a huge dataset of simulated lifeforms that AI can be tested on.

Spending three months of computer analysis on a thousand parallel machines, Adami and his student Ankit Gupta asked AI to determine which programs in Avida had the properties of life, and which didn't. The life and non-life programs have very similar coding, so the difference is not obvious — and this might very well be the case on another planet where life could have differences in biology to Earth life.

Adami and Gupta started out with programs representing a random sequence of molecules and asked the AI to classify them. They then set about tweaking that sequence of molecules to try and fool the AI into thinking it was seeing life, one change at a time, each time checking whether there had been a change in how confident the AI was that it was life or non-life.

"Within about 15 changes or so we can get AI to be perfectly confident of a life classification when in fact not a single time when it was being 100% confident was it actually life," said Adami.

Furthermore, no matter the sequence they started with, the AI was constantly fooled.

Many in the scientific community stand by AI as an invaluable tool because it can process huge amounts of data and search for patterns in that data. Adami himself believes that AI has an important role to play, but as we see in everyday life, AI is prone to making things up and identifying patterns that don't exist.

This really comes down to what the AI has been trained on, said Adami. If you ask an AI about data it has been trained on, it usually provides a correct answer. For example, if you train AI to identify pictures of apples and then ask it to pick out the fruit from a dataset that also includes pictures of non-food items, it will answer correctly virtually all the time. However, if you replace the apple pictures with photos of bananas and ask it to identify the fruit, it will struggle and start to misidentify things.

That's because the bananas represent "out of distribution" data. The AI wasn't trained on bananas, which are a very different shape to apples, and therefore the AI doesn't know what to make of them.

Similarly, we don't know what alien microbes will look like, and they could be quite different to the terrestrial microbes that the AI has been trained on. In other words, the alien life would be out of distribution, and the AI would have no context for saying whether any particular collection of molecules is life or not.

"You need to know your training data, and if you know that your testing data is part of the same distribution as the training data, then you'll be fine," said Adami. "But you can't guarantee that with extraterrestrial life."

This could pose a problem for missions designed to look for life.

If a Mars rover goes to the red planet and cuts open a rock and directly sees something that looks like microbial life as we know it, then the answer will be clear-cut and can be tested using traditional methods. However, many attempts to detect life will probably not be so hands-on, relying on mass spectrometry data to identify molecules and processes related to life. This could range from attempts to detect life in the atmosphere of Venus, or in the ocean of Europa, or on exoplanets via the Habitable Worlds Observatory, which NASA aims to launch in the 2040s to directly image exoplanets in the habitable zone of stars.

"This means that if there were an AI on a mission looking at particular mass spectrometry samples, then there's a very great chance that while it has been trained on the ground on a number of biotic and abiotic samples, it could still return a positive verdict when it has absolutely nothing to do with life," says Adami.

Caleb Scharf of NASA Ames, who along with Carnegie Science's Michael Wong is spearheading a NASA-sponsored five-year, $5 million project to develop AI tools to help search for life on other planets, thinks that Adami and Gupta's findings are rather interesting. However, Scharf suggests that machine-learning algorithms can be honed to avoid falling into this trap by allowing for unknown categories rather than the limited binary options of life or not life available in the Avida experiment. 

"Gupta and Adami's study points astutely to a critical challenge in life detection that might undermine the hoped-for gains from AI and machine learning: what do we do with the unknown unknowns?" Scharf told Space.com. "We think the answer may lie in allowing algorithms to notice situations where things look askew, andthere are methods from data science to tackle this very probllem, which we're actively exploring."

The next step, said Adami, is to move out of the digital world and run the same test with real-world data.

Adami and Gupta will be presenting their findings in August at the 2026 Conference on Artificial Life, which is being held in Waterloo, Canada.