All of this aerial weirdness involves unidentified anomalous phenomena, or UAP for short. Whatever they are, UAP continue to be seen, reported and even documented through various sensor technologies. However, despite years of whistleblowers testifying before Congress, there seems to have been a bottleneck in getting to the bottom of the UAP issue in 2025. Why so?

Key specialists appraising the issue UAP have yet to untangle the mystery, but do appear to agree on what needs to be done now to further resolve what UAP are and from where they might originate.

Plurality of minds

The UAP phenomenon benefits from having a plurality of minds engaged in disciplined debate, suggests Michael Cifone, founding executive director and President of the Society for UAP Studies, based in Los Angeles, California.

Today, there's a division emerging between classical Unidentified Flying Object (UFO), aka "flying saucer," incidents and studying UAP from the point of view of observational and experimental science. But engaging scientific methods and instruments turns out to be neither trivial nor cheap, Cifone said.

"Perhaps the holdup is reluctance to dump time, energy and money into what looks to some like a wild goose chase," said Cifone.

Cold cases

"Like any other scientific venture, both funding and institutional support is required," Cifone said. "Given the historical stigma associated with the topic that has been hard to achieve. But now with the emphasis no longer on chasing forensic cold cases, and relying on reports of UAP, serious scientists and student researchers are getting involved."

The upshot is to deploy scientific methodology to establish the observational framework with the proper instrumentation, Cifone added, "in order to generate the data on UAP from which more secure conclusions can be derived."

Cifone said that progress, like in any other science or research area, will be slow but hopefully steady, albeit incremental.

"What will likely happen is that there will be downstream benefits that aren't foreseeable exactly now. Maybe new sciences will break away. So it will be a win for the growth of knowledge and for science in particular," Cifone senses.

For Cifone, his view is to keep the eye on the ball and work out the observational framework design and required instruments and observational modalities before we can have the reliable datasets we need. "But science doesn't always go as planned. In any case, there's a lot of work to be done."

Cifone points to an increasing number of institutions that are studying UAPs. Indeed, work underway on UAP has blossomed into a world-wide field of research, he said.

All sky, all the time

To Cifone's point, there's the University of Würzburg in northern Bavaria, one of the oldest universities in Germany. An Interdisciplinary Research Center for Extraterrestrial Studies (IFEX) has been established.

One effort the university is developing is an "AllSkyCAM" able to capture UAP. An automated reporting system is currently under construction with the university cooperating with the Luftfahrt-Bundesamt, the national civil aviation authority of Germany, to research unusual phenomena in the country's airspace.

Then there's the Galileo Project led by astrophysicist Avi Loeb of Harvard University. They have designed and built an array of sensors to scan the sky for aerial phenomena and assess atmospheric anomalies that may not be of terrestrial origin.

This type of research can produce data on UAP, Cifone said, "then we need to experiment with the data and produce theories, or what you call explanations, and perhaps even understanding! We're only at the observational framework design and testing phase. Then we need to let the systems run, probably for many years."

Test a hypothesis

There's need to be able to scientifically test a hypothesis that some UAP are potentially extraterrestrial craft, said Robert Powell, executive board member of the Scientific Coalition for UAP Studies (SCU).

"I consider extreme acceleration to be the best characteristic that has the potential to eliminate a terrestrial explanation for a UAP," said Powell. But measurement of high accelerations of UAP, he said, requires high-precision scientific gear and data.

"The cost of putting out a network of calibrated and characterized equipment, maintaining it, obtaining placement rights on land, and analyzing the data will cost tens to hundreds of millions of dollars," said Powell.

Military systems

One estimate by an engineer in SCU forecasts that given 300 "actual" UAP sightings per year — and assuming random distribution of sightings — that with 930 automated camera systems distributed across the U.S., one would have a 95% chance of detecting a UAP of 50 foot or larger size within a year.

"To date, the financial resources to achieve this are not available," said Powell. "The military has the capability with radar, satellite, and optical systems, but the scientific community does not have access to these systems." He thinks the work ahead could be done now via military systems, but only if there were no national security concerns.

"I think it will take many years to do it through privately-financed civilian systems but that doesn't mean we shouldn't continue working at it," Powell concluded.

Ignore, rationalize away

Ryan Graves is chair of the American Institute of Aeronautics and Astronautics (AIAA) Unidentified Anomalous Phenomena Integration Committee. He is also director of Americans for Safe Aerospace, a military pilot group devoted to aerospace safety and national security, but focused on UAPs.

"Highly credible people and professional observers are seeing objects that appear to exhibit capabilities beyond the state of the art," Graves told Space.com. "In the data received, there seems to be this core anomalous aspect that we can't just ignore or rationalize away."

Graves speaks with UAP eye-witness authority as a former Lt. U.S. Navy and F/A-18F pilot. He was the first active-duty pilot to publicly point to his own encounters and spotlights his military colleagues regarding their UAP sightings.

In July 2023, Graves testified about UAPs before the House Oversight Committee's National Security Subcommittee in Congress, a hearing centered on UAP and the implications for national security, public safety, and how best to attain government transparency on the issue.

Pay attention

"We need to pay attention to this and recognize the national security implications," Graves said. Objects are operating in sovereign air space, he said, potentially collecting intelligence and trying to break into or set the stage to counter our defenses and set the country up for strategic surprise.

In blunt talk, Graves said UAP are engaged in actions "that would be recognized as acts of war or at the minimum preparation for an attack."

For its part, the AIAA UAP Integration & Outreach Committee is a strictly agnostic, science-first committee inside the AIAA.

"Our remit is to bring aerospace rigor to an area with real safety-of-flight implications," Graves said. The committee has been convening experts across AIAA's technical committees, publishing peer-reviewed and conference papers, and producing policy guidance that standardizes how aviation professionals document and share safety-relevant observations, Graves added.

Retention of data

While AIAA provides technical expertise rather than lobbying, Graves said the work on UAP has helped clarify best-practice reporting standards as well as set standards for retention of data on what's being reported.

One early payoff is that AIAA's UAP effort parallels what Congress has been considering in the standalone bill "Safe Airspace for Americans Act," introduced in January 2024 and reintroduced in September of this year. "Our focus remains the same," said Graves, "and that is credible data, clear procedures, and aviation safety."

That bipartisan Act is championed by U.S. representatives Robert Garcia of California and Glenn Grothman of Wisconsin, legislation crafted to support civilian UAP reporting.

"Transparency surrounding UAP is crucial for national security, public safety, and making sure people trust that our government is taking these reports seriously," Congressman Garcia said in a statement. "This bill creates a clear, protected pathway for pilots and other aviation professionals to report UAP incidents without having to fear stigma or worry about retaliation. This is a vital step forward to make sure our skies are safe and our government is responsive."

Closure on the topic?

Graves also points to the current leadership of the Department of Defense All-domain Anomaly Resolution Office, or AARO. It too is established to minimize technical and intelligence surprise by "synchronizing identification, attribution, and mitigation of UAP in the vicinity of national security areas," the AARO states.

"I'm optimistic. There is significant organizational change across the government that I think will bare fruit. There process is maturing to the point where they can start delivering on their expectations," said Graves.

Overall, Graves is heartened by current UAP interest and on-going activities.

"I don't know if there's been a better time to hope for closure on this topic. I don't think we've ever been in quite the situation we're in today," Graves said.

Titan is the largest of the 274 known moons orbiting Saturn. In fact, Titan is bigger than the planet Mercury.

"I love Titan — I think it's one of the most interesting worlds in the solar system," study lead author Flavio Petricca, a planetary scientist at NASA's Jet Propulsion Laboratory in Southern California, told Space.com. "It's the only moon in our solar system with an atmosphere, and it's the only body with liquid on its surface other than Earth."

Scientists have long suspected that seas might also lurk under Titan's icy shell. For instance, the way Titan flexes under Saturn's gravity suggests that the moon is home to a vast underground ocean.

In the new study, Petricca and his colleagues wanted to reexamine Titan using new, improved methods to analyze radio tracking data. These new techniques greatly reduced uncertainties regarding data gathered by NASA's Cassini mission of Titan's interior.

Unexpectedly, the scientists discovered that Titan's interior is resisting distortion from Saturn's gravitational pull to a much greater degree than previously thought. This suggests Titan likely does not have a hidden ocean, but instead a layer of ice close to its melting point that is kept from liquefying by high pressure. This slushy icy likely hosts pockets of liquid water, the researchers added.

Titan may once have had an underground ocean near the beginning of its history, Petricca said. There may not have been enough heat from radioactive elements in its core to keep this ocean from freezing, he noted. "It may be going through a phase again where heating is increasing again," Petricca added.

All in all, ocean worlds may be less common than recently thought, the scientists noted. "We're not certain if having widespread liquid pockets instead of a global ocean makes Titan more or less habitable," Petricca said. "It will be interesting to find out."

NASA's upcoming Dragonfly mission to Titan can help scan the moon to better understand its geology. "We'll better understand the conditions for habitability there," Petricca said.

The scientists detailed their findings online Dec. 17 in the journal Nature.

The findings challenge the prevailing wisdom that relatively small planets orbiting extremely close to their stars cannot sustain atmospheres.

The ultra-hot super-Earth, TOI-561 b, is the innermost of at least three planets circling a 10-billion-year-old star located about 280 light-years from Earth. The planet orbits at just one-fortieth the distance between Mercury and the sun, completing a full orbit in under 11 hours.

That extreme proximity places it in a class of ultra-short-period super-Earths that are heated to temperatures high enough to melt rock. Under such conditions, scientists generally expect planets to lose any atmosphere due to intense stellar radiation, leaving behind bare, airless rock. But observations from NASA's TESS space telescope have shown TOI-561 b has an unusually low density for a purely rocky world, suggesting that another explanation may be needed.

"It must have formed in a very different chemical environment from planets in our own solar system," Johanna Teske, a staff scientist at the Carnegie Earth and Planets Lab in Washington D.C. who led the new paper, said in a statement.

To test whether the planet has an atmosphere, the team used the JWST's NIRSpec instrument to measure the temperature of TOI-561 b's dayside. In May 2024, JWST observed the planet–star system continuously for more than 37 hours, capturing four full orbits. Scientists focused on moments when the planet passed behind its star, events known as "secondary eclipses" when the planet's own light briefly disappeared. By measuring the tiny drop in the system's total brightness during each eclipse, the team could isolate the planet's infrared glow and directly determine its dayside temperature.

If TOI-561 b had no atmosphere, its dayside should reach roughly 4,900 degrees Fahrenheit (2,700 degrees Celsius). Instead, the JWST measured a temperature much cooler, around 3,100 degrees Fahrenheit (1,700 degrees Celsius). To understand why, the researchers tested a range of possible surfaces and atmospheric types to see which could reproduce the signal observed by JWST.

"We really need a thick volatile-rich atmosphere to explain all the observations," study co-author Anjali Piette of the University of Birmingham said in the statement. "Strong winds would cool the dayside by transporting heat over to the nightside."

The team suggests the planet may maintain a balance between its molten surface and its atmosphere, allowing gases to cycle between them and potentially replenishing its atmosphere.

"While gases are coming out of the planet to feed the atmosphere, the magma ocean is sucking them back into the interior," study co-author Tim Lichtenberg of the University of Groningen in the Netherlands said in the statement. "It's really like a wet lava ball."

The results open the door to probe the interiors and geological activity of such extremely hot rocky planets by studying their atmospheres, the researchers note.

The findings were published on Dec. 11 in the The Astrophysical Journal Letters.

That's the overarching conclusion of an in-depth report about human Mars exploration from the U.S. National Academies of Sciences, Engineering and Medicine that came out today (Dec. 9).

"The detection of life on Mars is a persistent top priority for explorers of many disciplines, and it is the top science objective in this report," states the 240-page document, which is called "A Science Strategy for the Human Exploration of Mars."

The National Academies prepared the report for NASA, which wants to send astronauts to the Red Planet as soon as the mid-2030s. The document offers recommendations for how the agency can maximize the science gains of its planned crewed Mars campaign.

Those recommendations are extensive and detailed. For example, the report lays out 11 science objectives that such a campaign should pursue, with the search for signs of life (as well as indications of "indigenous prebiotic chemistry" and a broad assessment of habitability) at the top of the list.

The other 10 objectives, listed in order of descending priority, are:

• Characterize Mars' water and carbon dioxide cycles
• Map Martian geology in detail
• Determine how the Martian environment affects the physical and psychological health of astronaut explorers
• Figure out what starts and drives Martian dust storms
• Determine the availability and accessibility of Martian resources that could "support permanent habitation"
• Discover if exposure to the Martian environment affects DNA and reproduction
• Learn about the population dynamics of microbes on Mars, and if microbial species from Earth could adversely affect astronauts' health and performance on the Red Planet
• Determine how Martian dust affects astronauts and their hardware
• Learn how the Martian environment affects a transplanted ecosystem of Earth microbes, plants and animals
• Gain a better understanding of the Martian radiation environment and how it may affect crewmembers and their missions

"A Science Strategy for the Human Exploration of Mars" also proposes four possible three-mission campaigns, the top-ranked of which could achieve all 11 of the above objectives.

That campaign would send all three missions to "a low- to mid-latitude site with near-surface glacier ice and diverse geology," the report states. "The search for prebiotic chemistry and life would focus on near-surface niche environments, such as geologically recent transiently habitable zones, and/or ice, including layered ice."

Another possible campaign would target the deep subsurface, establishing a powerful drilling operation that could get 1.2 to 3 miles (2 to 5 kilometers) beneath the red dirt, where pockets of liquid water are thought to exist.

Both of those proposed campaigns would feature an initial 30-sol crewed surface mission, an uncrewed cargo delivery flight and then a 300-sol astronaut mission on the surface. (One sol, or Martian day, is slightly longer than an Earth day — about 24 hours and 40 minutes.) So would a third proposed campaign, though a fourth would launch three crewed 30-sol missions to three different sites on the Red Planet.

There is some commonality across all the proposed campaigns. For example, according to the report, no matter how NASA's crewed Mars plans take shape, the agency should aim to build a science lab on the Red Planet's surface, haul Mars samples home from every astronaut mission and set up a recurring "Mars Human-Agent Teaming Summit" to maximize and coordinate the efforts of robotic missions, astronauts and artificial intelligence.

In addition, the report notes, a concerted search for Mars life will be constrained by current "planetary protection" guidelines, which aim to minimize the chances that our exploration efforts contaminate other worlds with Earth microbes or bring alien life to our shores.

Therefore, the document states, "NASA should continue to collaborate on the evolution of planetary protection guidelines, with the goal of enabling human explorers to perform research in regions that could possibly support, or even harbor, life."

TRAPPIST-1e is one of seven Earth-size exoplanets tightly packed around a cool red dwarf star smaller and dimmer than our sun that's about 40 light-years away. It orbits in the system's "habitable zone," where temperatures could allow liquid water to exist — but that's only if the planet has an atmosphere. Early James Webb Space Telescope (JWST) observations even hinted at a possible atmosphere, revealing faint signatures of methane, which, on Earth, results from living organisms and is tied to complex chemistry on Saturn's haze-shrouded moon Titan.

But those first glimmers, scientists now say, were likely misleading.

"Based on our most recent work, we suggest that the previously reported tentative hint of an atmosphere is more likely to be 'noise' from the host star," Sukrit Ranjan, an assistant professor at the University of Arizona Lunar and Planetary Laboratory, said in a statement. "However, this does not mean that TRAPPIST-1e does not have an atmosphere — we just need more data."

The new paper uses detailed computer simulations to test whether TRAPPIST-1e could realistically maintain a methane-rich, Titan-like atmosphere. The results suggest methane on a world orbiting a small, active red dwarf star like TRAPPIST-1 would be destroyed much faster than on Titan — too quickly for any plausible geological process to replenish it.

The latest findings build on two papers published in September that analyzed the JWST's 2023 observations of TRAPPIST-1e. During four separate transits when the planet crossed the face of its star, the JWST's Near-Infrared Spectrograph (NIRSpec) instrument recorded subtle changes in starlight that could, in principle, reveal atmospheric chemicals. The data were consistent with an atmosphere dominated by nitrogen and methane and lacking carbon dioxide, effectively ruling out a Venus- or Mars-like atmosphere.

But the signals varied significantly from transit to transit, hinting that the measurements were being contaminated by the star itself. TRAPPIST-1 is smaller, cooler and far dimmer than our sun, cool enough that gas molecules, including methane, can form in the star's own atmosphere.

"We reported hints of methane, but the question is, 'is the methane attributable to molecules in the atmosphere of the planet or in the host star?'" Ranjan said in the statement.

In the paper, Ranjan and his team modeled how long methane could realistically survive in TRAPPIST-1e's environment. They found that while Titan's methane can persist for 10 million to 100 million years, methane on TRAPPIST-1e would last only about 200,000 years. The planet receives far more ultraviolet radiation than Titan, causing methane to be broken apart thousands of times faster, the study notes.

That makes it extraordinarily unlikely that scientists would catch the planet during a methane-rich phase unless methane were being replenished at extreme, continuous rates, the researchers say. Maintaining Titan-like levels would require TRAPPIST-1e to outproduce Titan in methane generation, an implausible scenario that would demand nonstop global volcanism, catastrophic methane release from an icy interior, or constant planetary resurfacing. Even under generous assumptions, these processes cannot fully account for the required methane supply, the study notes.

As a result, the team concludes that more rigorous analysis and additional observations are needed to determine whether TRAPPIST-1e has any atmosphere at all, and whether the JWST's tentative methane hints originate from the planet or are simply artifacts of the star.

"The basic thesis for TRAPPIST-1e is this: If it has an atmosphere, it's habitable," Ranjan said in the statement. "But right now, the first-order question must be, 'Does an atmosphere even exist?'"

Despite the challenges, TRAPPIST-1e remains one of the most promising potentially habitable worlds beyond our solar system. However, JWST, designed before the first exoplanet was discovered, is operating at the limits of its sensitivity when probing the atmospheres of Earth-sized planets.

Future instruments may help disentangle the confusing signals. NASA's upcoming Pandora mission, scheduled for launch in 2026, will observe stars and planets simultaneously to better separate stellar and atmospheric features.

The researchers are also planning a rare dual-transit observation in which TRAPPIST-1e and the innermost planet TRAPPIST-1b cross the star together. TRAPPIST-1b is known to lack an atmosphere, so comparing its "clean" signal to TRAPPIST-1e's could reveal which features belong to the star and which — if any — arise from TRAPPIST-1e's atmosphere, scientists say.

"These observations will allow us to separate what the star is doing from what is going on in the planet's atmosphere — should it have one," said Ranjan.

The paper about these results was published on Nov. 3 in The Astrophysical Journal Letters.

TRAPPIST-1 is an ultracool red dwarf, located about 40 light-years away in the constellation Aquarius. It hosts seven Earth-size planets, three of which orbit in the so-called "habitable zone" where liquid water might exist. However, the small star is notoriously active, erupting with energy bursts roughly six times per day, which can threaten planetary atmospheres within the system and obstruct observations, according to a statement from the University of Colorado Boulder.

Using data from the James Webb Space Telescope (JWST), researchers tracked six flares observed in 2022 and 2023. These flares appear as a big flash detectable by the JWST's infrared sensors, revealing how much heat the star releases during an outburst. By combining these observations with computer simulations, the team reconstructed the physical processes driving each flare, allowing them to estimate the properties of the electron beams that trigger these stellar tantrums.

"If we can simulate these events using a computer model, we can reverse engineer how a flare might influence the radiation environment around each of these planets," Ward Howard, lead author of the study, said in the statement. This, in turn, can help determine which worlds might retain atmospheres capable of supporting life.

Surprisingly, the electron beams powering these flares appear about ten times weaker than those seen in similar stars. That doesn't mean they're harmless — each flare emits radiation across the spectrum, from visible light to ultraviolet radiation and powerful X-rays, all of which can erode or alter planetary atmospheres over time.

As a result, the researchers suggested that the innermost TRAPPIST-1 planets may have lost their atmospheres, potentially leaving them as bare rocks, while one planet in the habitable zone, TRAPPIST-1e, could still retain a thin, Earth-like atmosphere — a tentative sign that it might support conditions favorable to life.

By decoding TRAPPIST-1's flare behavior, scientists can refine predictions about which planetary atmospheres might survive its constant outbursts. Rather than mere observational nuisances or purely destructive forces, these eruptions can be read as messages from the star, offering key insights into the potential habitability of its planets and informing the broader search for life beyond Earth.

Their findings were published Nov. 20 in the Astrophysical Journal Letters.

When astronomers search for planets that could host liquid water on their surface, they start by looking at a star's habitable zone. Water is a key ingredient for life, and on a planet too close to its star, water on its surface may "boil"; too far, and it could freeze. This zone marks the region in between.

But being in this sweet spot doesn't automatically mean a planet is hospitable to life. Other factors, like whether a planet is geologically active or has processes that regulate gases in its atmosphere, play a role.

The habitable zone provides a useful guide to search for signs of life on exoplanets – planets outside our solar system orbiting other stars. But what's in these planets' atmospheres holds the next clue about whether liquid water — and possibly life — exists beyond Earth.

On Earth, the greenhouse effect, caused by gases like carbon dioxide and water vapor, keeps the planet warm enough for liquid water and life as we know it. Without an atmosphere, Earth's surface temperature would average around zero degrees Fahrenheit (minus 18 degrees Celsius), far below the freezing point of water.

The boundaries of the habitable zone are defined by how much of a "greenhouse effect" is necessary to maintain the surface temperatures that allow for liquid water to persist. It's a balance between sunlight and atmospheric warming.

Many planetary scientists, including me, are seeking to understand if the processes responsible for regulating Earth's climate are operating on other habitable zone worlds. We use what we know about Earth’s geology and climate to predict how these processes might appear elsewhere, which is where my geoscience expertise comes in.

Why the habitable zone?

The habitable zone is a simple and powerful idea, and for good reason. It provides a starting point, directing astronomers to where they might expect to find planets with liquid water, without needing to know every detail about the planet's atmosphere or history.

Its definition is partially informed by what scientists know about Earth's rocky neighbors. Mars, which lies just outside the outer edge of the habitable zone, shows clear evidence of ancient rivers and lakes where liquid water once flowed.

Similarly, Venus is currently too close to the sun to be within the habitable zone. Yet, some geochemical evidence and modeling studies suggest Venus may have had water in its past, though how much and for how long remains uncertain.

These examples show that while the habitable zone is not a perfect predictor of habitability, it provides a useful starting point.

Planetary processes can inform habitability

What the habitable zone doesn't do is determine whether a planet can sustain habitable conditions over long periods of time. On Earth, a stable climate allowed life to emerge and persist. Liquid water could remain on the surface, giving slow chemical reactions enough time to build the molecules of life and let early ecosystems develop resilience to change, which reinforced habitability.

Life emerged on Earth, but continued to reshape the environments it evolved in, making them more conducive to life.

This stability likely unfolded over hundreds of millions of years, as the planets surface, oceans and atmosphere worked together as part of a slow but powerful system to regulate Earth’s temperature.

A key part of this system is how Earth recycles inorganic carbon between the atmosphere, surface and oceans over the course of millions of years. Inorganic carbon refers to carbon bound in atmospheric gases, dissolved in seawater or locked in minerals, rather than biological material. This part of the carbon cycle acts like a natural thermostat. When volcanoes release carbon dioxide into the atmosphere, the carbon dioxide molecules trap heat and warm the planet. As temperatures rise, rain and weathering draw carbon out of the air and store it in rocks and oceans.

If the planet cools, this process slows down, allowing carbon dioxide, a warming greenhouse gas, to build up in the atmosphere again. This part of the carbon cycle has helped Earth recover from past ice ages and avoid runaway warming.

Even as the sun has gradually brightened, this cycle has contributed to keeping temperatures on Earth within a range where liquid water and life can persist for long spans of time.

Now, scientists are asking whether similar geological processes might operate on other planets, and if so, how they might detect them. For example, if researchers could observe enough rocky planets in their stars' habitable zones, they could look for a pattern connecting the amount of sunlight a planet receives and how much carbon dioxide is in its atmosphere. Finding such a pattern may hint that the same kind of carbon-cycling process could be operating elsewhere.

The mix of gases in a planet's atmosphere is shaped by whats happening on or below its surface. One study shows that measuring atmospheric carbon dioxide in a number of rocky planets could reveal whether their surfaces are broken into a number of moving plates, like Earth's, or if their crusts are more rigid. On Earth, these shifting plates drive volcanism and rock weathering, which are key to carbon cycling.

Keeping an eye on distant atmospheres

The next step will be toward gaining a population-level perspective of planets in their stars' habitable zones. By analyzing atmospheric data from many rocky planets, researchers can look for trends that reveal the influence of underlying planetary processes, such as the carbon cycle.

Scientists could then compare these patterns with a planet's position in the habitable zone. Doing so would allow them to test whether the zone accurately predicts where habitable conditions are possible, or whether some planets maintain conditions suitable for liquid water beyond the zone’s edges.

This kind of approach is especially important given the diversity of exoplanets. Many exoplanets fall into categories that don't exist in our solar system — such as super Earths and mini Neptunes. Others orbit stars smaller and cooler than the sun.

The datasets needed to explore and understand this diversity are just on the horizon. NASA's upcoming Habitable Worlds Observatory will be the first space telescope designed specifically to search for signs of habitability and life on planets orbiting other stars. It will directly image Earth-sized planets around sun-like stars to study their atmospheres in detail.

Instruments on the observatory will analyze starlight passing through these atmospheres to detect gases like carbon dioxide, methane, water vapor and oxygen. As starlight filters through a planet's atmosphere, different molecules absorb specific wavelengths of light, leaving behind a chemical fingerprint that reveals which gases are present. These compounds offer insight into the processes shaping these worlds.

The Habitable Worlds Observatory is under active scientific and engineering development, with a potential launch targeted for the 2040s. Combined with today's telescopes, which are increasingly capable of observing atmospheres of Earth-sized worlds, scientists may soon be able to determine whether the same planetary processes that regulate Earth’s climate are common throughout the galaxy, or uniquely our own.

The announcement was made at the European Space Agency's (ESA) Ministerial Council — a high-level meeting of the agency's 23 member states — on Wednesday (Nov. 25).

"I've got yesterday a letter from the NASA administration to confirm the contributions of NASA to Rosalind Franklin," ESA Director General Josef Aschbacher told reporters at the opening of the meeting. "So, this is certainly something that is good news."

The ExoMars Rosalind Franklin rover is a 660-pound (300 kilograms) Mars exploration robot fitted with a 6.6-foot (2 meters) drill to search for signs of life below the Red Planet's radiation-battered surface.

The project, conceived in the early 2000s, has faced multiple setbacks on the way to the launch pad. The mission was originally planned in cooperation with NASA, but the American agency withdrew in 2012 after budget cuts imposed by the Obama administration, forcing ESA to seek support from Russia.

The rover, which is named after a British chemist who played a key role in discovering the structure of DNA, was supposed to lift off atop a Russian Proton rocket from the Baikonur Cosmodrome in Kazakhstan in September 2022 and descend to the Martian surface atop a Russian-made landing platform a year later. But that plan changed in early 2022: ESA severed ties with the Russian space agency Roscosmos in response to Russia's invasion of Ukraine.

NASA then came back into the picture. In late 2022, ESA member states agreed to invest an additional 360 million Euros ($417 million US) to build a new landing platform for the rover. NASA offered to provide a rocket, radioisotope heaters needed to protect the rover's technologies in the frigid Martian weather, and braking retrorockets to safely lower the landing platform to the ground. With new developments needed, ESA established a new launch date for the rover in 2028.

But Donald Trump's election victory last year nearly thwarted those plans, as Rosalind Franklin was among 20 science collaborations between ESA and NASA that Trump's fiscal year 2026 budget proposal eliminated. Since then, speculation has swirled about whether ESA would have to seek additional funding to complete the mission on its own. The NASA contribution to ExoMars is estimated at $375 million, according to the nonprofit space exploration advocacy group Planetary Society.

Speaking at the ESA Ministerial Council, Aschbacher confirmed that NASA will provide all of the three elements it had previously committed to.

"These confirmations have been given to us in writing, so this is a very important step," Aschbacher said.

He added that NASA had already delivered a science instrument to be carried by Rosalind Franklin — the Mars Organic Molecule Analyzer-Mass Spectrometer (MOMA-MS), which will be able to detect the tiniest traces of organic materials in the samples drilled up by the rover. The instrument, ESA's spokesperson said, is currently undergoing integration, testing and verification in Europe.

ExoMars is only one of Europe's flagship science space missions caught in the NASA budget drama. The Laser Interferometer Space Antenna (LISA) gravitational wave observatory comprising three innovative spacecraft is a joint project worth an estimated $3 billion. NASA was to provide about $1 billion worth of technology for the mission, including onboard telescopes and lasers, according to the Planetary Society. The Venus exploration probe EnVision also relies on NASA's help. The American agency was supposed to build an innovative synthetic aperture radar instrument worth an estimated $300 million. That contribution has also been cut by the Trump administration.

Further planned missions, including the X-Ray telescope New Athena and exoplanet watcher Ariel, will be hit if the Trump budget proposal is approved. Both the U.S. House of Representatives and Senate, however, are working to reinstate at least some of that funding. ESA member states will be negotiating ESA's future direction and funding on Nov. 26 and Nov. 27, not knowing how the situation in the U.S. will resolve.

Earlier, a source familiar with the situation inside ESA told Space.com that the agency is working on a rescue plan for LISA and EnVision and believes that Europe could go it alone if need be.

"We are discussing with our member states about their ambition to take responsibility for one or more of the NASA elements should we need to take recovery actions," the source said. "By the middle of next year, we expect to be in a position to decide on the way forward, with clarity on NASA funding and member state ambition and funding."

Aschbacher previously unveiled bold plans to secure a record-breaking budget of over 22 billion Euros ($25 billion) for ESA's next three-year period, up 5 billion from the last budget agreed in 2022. The negotiations, however, come in a tense time period for Europe with countries pressed to increase their defense spending due to worsening tensions with Russia.

"With the expected technological advances in the coming decades, if missions are specifically designed for these targets, we believe that in situ exploration of Martian karstic caves is an achievable goal," said Chunyu Ding, of the Institute for Advanced Study at Shenzhen University in China, in an interview with Space.com.

The caves, in the Hebrus Valles region between the extinct volcano Elysium Mons and Utopia Planitia in Mars' northern mid-latitudes, are revealed by eight skylights, which are holes in the ceiling of the caves that are visible on the surface as pits ranging from tens to over 100 meters across. The skylights are distinguishable from craters because they don't possess raised walls or splashes of ejecta around them. It is thought that the skylights form when the surface partially collapses into the empty cave below it.

Caves and skylights have been found on Mars before, but as lava tubes formed in volcanic regions. Hebrus Valles, on the other hand, is not a volcanic region; it displays ancient river channels and copious hydrated minerals and sediments deposited by bodies of liquid water on the surface long ago.

These features were identified by scientists led by Ding and his Shenzen colleague Ravi Sharma. Their team used archive data from a variety of Mars missions, including mineralogical maps based on observations by the Thermal Emission Spectrometer on NASA's now-defunct Mars Global Surveyor, hydrogen detections (as a proxy for water) from the Gamma-Ray Spectrometer on the agency's Mars Odyssey, and models of the Martian terrain built around data from the HiRISE camera on NASA's Mars Reconnaissance Orbiter.

They determined that the skylights and their surroundings are consistent with what's termed "karstic" caves. Karstic refers to the dissolution of carbonate- and sulfate-bearing bedrock. While we find karstic caves in many locations on Earth, this is the first time that they have been identified on Mars.

The observations show that the Hebrus Valles region is rich in carbonate rock such as limestone and sulfate rock such as gypsum. Over 3.5 billion years ago, when Mars was warmer and wetter, these carbonate and sulfate sediments were laid down by large pools of liquid water, such as lakes and seas. When Mars grew cold, the surface water went away, much of it forming sub-surface ice and frozen brines.

Indeed, the Gamma-Ray Spectrometer data from Mars Odyssey points to water ice possibly still existing there in some quantity. At some point, local heating events, perhaps from distant volcanoes, impacts or long-term orbital variations, would have melted the subsurface ice and brines, and the liquid water would have run through cracks and fractures in the ground, dissolving the rock and turning those cracks into large caves.

Not all regions of Mars meet the requirements to form karstic caves, since for one thing carbonate and sulfate rocks are not omnipresent. Nor do all locations, particularly lower-latitude areas, host subsurface ice and frozen brines or have been geologically stable for long enough to allow the caves to form and their rocky ceiling to collapse and form the skylights.

"Our results suggest that Hebrus Valles is unlikely to be a completely isolated case, but these caves also will not be everywhere on Mars," said Ding. "They are likely concentrated in a limited set of regions that satisfy the necessary depositional and hydrological conditions. It is quite reasonable to expect more karstic caves to be discovered in other, similar environments in the future."

Indeed, more than just the eight caves may be present in Hebrus Valles; there could be others that have not yet experienced a ceiling collapse and revealed themselves. Of those known so far, the skylights appear to be several tens to over 100 meters across, and underground the cavities could be several times larger still, and tens of meters deep.

Karstic caves are the perfect location to preserve ancient biosignatures. The watery and stable microclimate within the caves long ago could have hosted microbial colonies, and today the caves are protected from the extreme conditions on Mars' surface, such as wildly different diurnal temperatures, dust storms and solar ultraviolet and cosmic-ray radiation. Hence future life-seeking missions may seek to explore them.

However, the surrounding rock will limit the transmission of radio signals from inside the caves to orbiting spacecraft, making exploration of the caves more difficult, but not impossible, said Ding.

"From an engineering standpoint, directly entering these caves is a major challenge," he said. "However, our geomorphological analysis suggests that not all candidate caves are simple vertical shafts. In our paper, we use the term 'accessible potential karstic caves.'"

Most of the skylights are characterized by steep walls descending down into the darkness of the caves, but among the eight Hebrus Valles caves there is evidence for slopes made by rocky debris in multiple, step-like formations that might allow a staged descent.

This could be accomplished by multiple robotic explorers forming a communications chain down into the caves, ranging from wheeled rovers that carefully navigate down each step, to climbing robots lowered by winches or aerial rotorcraft that can fly in and out of the skylights.

The cave's rocky shielding might not only lend itself to preserving biosignatures, but could also offer protection to future Mars astronauts, shielding them and their outposts from the hazards of radiation and dust storms on the surface. If so, it could be that humanity's future on Mars is to be found underground.

The conclusions of Ding's team were published on Oct. 30 in The Astrophysical Journal Letters.

As humans began to explore outer space in the latter half of the 20th century, radio waves proved a powerful tool. Scientists could send out radio waves to communicate with satellites, rockets and other spacecraft, and use radio telescopes to take in radio waves emitted by objects throughout the universe.

However, sometimes radio telescopes would pick up the artificial radio signals from telecommunications. This interference threatened sensitive astronomy observations, causing inaccurate data and even damaging equipment. While this interference frustrated scientists, it also sparked an idea.

During the Cold War, a new field emerged at the intersection of radio astronomy and radio communications. It put forward the idea that astronomers could search for radio communications from possibly existing extraterrestrial civilizations. Astronomy usually dealt with observing the universe’s natural phenomena. But this new field made the detection of technologically, or artificially produced radio waves, the object of a natural science.

This field has continued today and is now called the search for extraterrestrial intelligence, or SETI. SETI encompasses all that scientists do to search for intelligent life beyond Earth. It includes one of the original uses of radio telescopes: to study signals from across the galaxy in hopes of detecting intelligent messages.

When the idea behind SETI was first proposed and pursued in the 1960s, only two countries, the U.S. and the USSR, had the technical capability for it. As the only space powers at the time, they were the key actors affected by radio frequency interference.

As a historian of science, I've worked to make sense of what happened throughout the history of Soviet SETI during the space race by analyzing a range of primary sources. SETI captured the scientific imagination of many prominent Soviet astronomers in the 1960s and early 1970s.

Astronomers have not yet confirmed any detection of radio signals – or any other kinds of signs – from extraterrestrial civilizations. But many scientists are still searching, even as their bold ideas run into obstacles. Some evidence suggests humans might be the only intelligent life in the universe.

Soviet SETI: The golden age of radio astronomy

SETI is intertwined with the profound changes brought by radio astronomy. Up until the second part of the 20th century, scientists could see astronomical objects and phenomena only in optical or visible light. Optical light is the same kind of light that the human eye is sensitive to.

After World War II, scientists figured out that they could peacefully use radar antennas, developed for use in that war, to detect radio signals coming from objects out in the universe. Deciphering these signals allowed researchers to study astronomical objects in the universe. They learned, for example, about the most abundant element: hydrogen.

In the former Soviet Union, the prominent radio astronomy pioneer Iosif Samuilovich Shklovsky played a key role in detecting radio signals from hydrogen.

Scientists knew that every chemical element would absorb certain wavelengths of light and reflect others, and the light signals that an object absorbed or reflected could tell astronomers what element it was. Most hydrogen could not be observed directly in optical light, so astronomers didn’t spot it out in space until they started looking beyond the visible light spectrum.

Shklovsky figured out how to detect hydrogen with radio waves, which helped astronomers map the distribution and motion of hydrogen gas in and between galaxies.

Historians generally consider the year 1960 the start of the golden age of radio astronomy. After the detection of hydrogen, astronomers discovered previously unknown types of stars, such as pulsars and quasars. These phenomena offered scientists new insights into the nature of astrophysical phenomena and fundamental physics.

Shklovsky later grew fascinated with the possibility of using radio waves to contact other intelligent beings in the universe. In 1960, he published an article on this topic in one of the country’s most prestigious scientific journals.

Shklovsky's article soon expanded into a widely popular book called "Universe, Life, Intelligence," published in 1962. That same year, the USSR's Academy of Sciences sent its first radio message in the direction of Venus from a radar in Crimea.

The experiment involved bouncing radio signals off the surface of Venus to transmit the following words using Morse code: Lenin, USSR and mir, which in Russian means both world and peace. Even though statistically increasing radio interference risk, this message was mainly symbolic. The Soviet Union wanted to depict its technological might and wasn't expecting to communicate with extraterrestrials. Soviet SETI was thus not yet a real pursuit.

Starting an organized search

Shklovsky and the majority of other radio astronomers pursuing the search for extraterrestrial intelligence were all located in central Russia at the time. The USSR Academy of Sciences was also located there. But this group needed more formal measures to move their search from a few initiatives into a coordinated effort.

Due to concerns over unwanted public attention, the scientists organized a conference far from Moscow, at the Byurakan Astrophysical Observatory in the Soviet Republic of Armenia, in 1964. At this conference, researchers formed a group specifically dedicated to studying artificial radio signals from space. With this group, SETI became a top-down, state-led activity.

With this validation, scientists could now theoretically look for artificial signals, potentially from an alien origin. However, any discussions about artificial radio signals were subject to strict government surveillance, given the fact that military satellites depended on them, too.

Soviet scientists faced several obstacles. For example, their own government's secrecy made coordination difficult. The Cold War also set limits on developing SETI internationally. However, they had a green light to search and study peculiar signals they suspected had artificial origin.

International collaboration

Efforts to collaborate internationally on artificial signals culminated in 1971 with a symposium, again at Byurakan. There, about 50 scientists – the majority from the U.S. and the USSR, but also some from Czechoslovakia, Hungary, the U.K. and Canada – agreed to disagree on how to best conduct SETI.

Some in attendance compared this gathering to Noah's Ark, because an almost equal number of prominent scientists from East and West of the Iron Curtain managed to meet that year. And the gathering took place in Armenia at the foot of Mount Ararat, located in neighboring Turkey. This mountain is where archaeologists believe Noah's Ark may have beached.

After almost a week of discussion at Byurakan, the two geopolitical blocks designated an official SETI group. That group still exists today, and it still connects researchers all around the world who conduct SETI research. Given the secrecy around radio signals in space, this international SETI group marked a momentous diplomatic achievement at the height of the Cold War.

SETI started in the Soviet Union with a few strong Moscow-based initiatives. It continued through group events in Armenia – from the first state-level Soviet conference to the international one.

SETI is the first and only domain of astronomy to study artificial radio signals themselves. It indirectly addressed radio frequency interference during a time when these frequencies were highly unregulated.

Stakeholder countries eventually addressed their radio frequency interference issues with international agreements on radio frequency usage and allocation. An international committee approved a feasible and comprehensive radio frequency allocation plan for the first time in the 1970s. This plan has been revised and renewed ever since. Today, space scientists and astronomers use an internationally agreed upon plan to minimize this interference.

Remarkably, SETI began even before this allocation plan. SETI continues its rich legacy today by continuing to search for signals – and along the way discovering new astrophysical objects and phenomena.

Read the original article here.

Binary star system Eta Cassiopeiae, located just 19 light-years away, could be a good target in the search for habitable exoplanets, according to a recent study. University of California, Riverside astronomer Stephen Kane and his colleagues simulated the orbital dynamics of the star system and concluded that it's not home to any giant planets – or any planets farther than 8 astronomical units (8 times Earth's distance from the Sun) away from its main star.

But small, Earth-like planets might still be hanging out in the main star's habitable zone, waiting for astronomers to find them.

An empty planetary neighborhood

From Earth, Eta Cassiopeiae looks like a bright point of light in the night sky, but it's really two stars locked together in an endless orbital waltz, circling a shared center of gravity once every 472 years. The larger of the pair is a G-type star just a smidgen more massive than our sun, and its smaller partner is a K-type star which weighs in at just 57% of our sun's mass.

Recently, the European Space Agency's Gaia mission provided astronomers with much more precise measurements of the two stars’ masses and orbits. Kane and his colleagues used that data, along with new observations from a high-resolution spectrometer at the Keck Observatory, to build computer simulations of the star system.

It turns out that the outer reaches of the star system are probably pretty empty. The team of astronomers simulated the orbits of hypothetical planets orbiting Eta Cassiopeiae A, the larger of the two stars, and they found that planets orbiting farther than 8 astronomical units away were just too vulnerable to getting pushed and pulled around by Eta Cassiopeiae B – and ending up in wildly unstable orbits. All of those simulated outer worlds got kicked out of the star system to begin new lives as rogue planets, leaving the outer reaches of the Eta Cas system eerily vacant.

"Inside of 8 AU, the situation is more complicated," wrote Kane and his colleagues in their recent paper.

The enormous mass of Eta Cassiopeiae B makes itself felt even close to the larger star; some of the simulated planets got nudged into long, narrow eccentric orbits even when they started in about the same position as Mars. But despite that, most of the planets in the larger star's habitable zone ended up on stable orbits (even if some of those orbits were eccentric ones, which might have caused some wild seasonal swings on the planets’ surfaces). That raises the intriguing possibility that the real Eta Cassiopeiae A might have some Earth-sized worlds orbiting in its habitable zone.

Kane and his colleagues say it's definitely worth a look with future telescopes like the European Southern Observatory's Extremely Large Telescope. As we speak, astronomers are working to pinpoint — and rule out — star systems where newer, bigger telescopes might capture direct images of potentially habitable worlds. Eta Cassiopeiae might be one of those star systems, if Kane and his colleagues are right.

Complicated, But not impossible

One of the things that makes Eta Cassiopeiae so interesting for future exoplanet searches is that, according to Kane and his colleagues’ recent study, the system has no giant planets at all: no alien versions of Uranus or Neptune on the outskirts of the system, and no hot Jupiters whizzing dangerously close to the main star, either. In their simulations, Kane and his colleagues modeled whether today’s telescopes could detect giant planets, orbiting Eta Cassiopeiae A at various distances, using the radial velocity method. (Radial velocity looks for slight wobbles in a star that reveal the gravitational pull of an orbiting planet.)

If any giant planets orbited Eta Cassiopeiae A within about 8 AU, astronomers could spot their telltale signature in the spectrum of light from the star. And since no planets at all can survive the binary star system’s constantly-shifting gravity beyond 8 AU, the system must be totally giantless.

That may actually be good news for life, or at least for the presence of planets in the habitable zone around Eta Cassiopeiae A. If there were giant planets orbiting the larger star, their orbits would be as eccentric as those of comets in our own solar system – and having a gas giant swooping through the inner star system every few decades or centuries would be a nightmare for rocky little worlds just trying to stay in their orbital lanes. It would, in Kane and his colleagues’ words, "effectively eliminate these systems as viable search targets for habitable zone terrestrial planets."

There's no guarantee that Eta Cassiopeiae is home to any potentially habitable planets, or even any planets at all, but Kane and his colleagues' recent study suggests it could be worth a look.

Kane and his colleagues published their work in October in The Astronomical Journal.

Researchers at Cornell University have developed the first-ever reflectance spectra — essentially a color-coded key — of the colorful microorganisms that live in Earth's clouds. Now, astronomers can potentially use this key to identify similar organisms in the clouds of exoplanets, if they exist.

"We thought clouds would hide life from us, but surprisingly, they could help us find life," Lisa Kaltenegger, professor of astronomy at Cornell and the director of the Carl Sagan Institute, said in a statement.

The idea for the work came from astrobiologist Ligia Coelho, an astronomy postdoctoral fellow at Cornell University. "There is a vibrant community of microorganisms in our atmosphere that produces colorful biopigments, which have fascinated biologists for years. I thought astronomers should know about them," she said.

Biopigments are quite common in Earth's organisms. "Biopigments have a universal character on our planet. They give us tools to fight stresses like radiation, dryness and lack of resources," said Coelho. "We produce them, and so do bacteria, archaea, algae, plants, other animals." The cloud microorganisms produce biopigments for protection from ultraviolet rays, which are abundant high in the atmosphere where they reside.

Running the spectra through models, Coelho and her collaborators determined that exoplanet clouds with the colorful microorganisms would look different from exoplanet clouds without them. Thus, astronomers can use them as a potential biosignature.

Of course, we don't know that similar microorganisms even exist anywhere else in the universe. But if they do, we'll be able to use upcoming telescopes like NASA's Habitable Worlds Observatory and the European Southern Observatory’s Extremely Large Telescope to look for them.

"Finding colorful life in Earth’s atmosphere has opened a completely new possibility for finding life on other planets," said Kaltenegger. "Now, we have a chance to uncover life even if the sky is filled with clouds on exoplanets."

Research on the biopigment spectra was published in the Astrophysical Journal Letters on Nov. 11.

For decades, scientists have debated the origin of Earth's water. One long-standing theory suggests that it was delivered by icy bodies from the outer solar system after Earth formed, while another proposes that the raw materials that make up our planet already held the ingredients necessary to generate water internally. Until now, however, this second hypothesis had never been tested under realistic laboratory conditions.

In a series of high-pressure, high-temperature experiments designed to mimic the fiery beginnings of a young planet, scientists recreated the extreme environment where such worlds' molten rock and hydrogen gas interact. These tests revealed that liquid water can, in fact, form naturally during the early stages of planet formation.

The new findings, published Oct. 30 in the journal Nature, offer a fresh perspective on one of planetary science's oldest questions and expand the possibilities for where life-sustaining water might arise in the cosmos.

"This work demonstrates that large quantities of water are created as a natural consequence of planet formation," Anat Shahar, a scientist at the Carnegie Institution for Science in Washington D.C., who co-led the study, said in a statement. "It represents a major step forward in how we think about the search for distant worlds capable of hosting life."

Of the more than 6,000 exoplanets discovered so far in our Milky Way galaxy, worlds larger than Earth but smaller than Neptune, known as sub-Neptunes, are the most common. Although no such planet exists in our solar system, scientists suspect these worlds possess rocky interiors enveloped by thick, hydrogen-rich atmospheres. That combination makes them ideal analogues for testing how water might form during the earliest stages of planetary evolution, the study notes.

To explore this process, Shahar and her team built a miniature version of a sub-Neptune in the lab. Using a device called a diamond anvil cell, they compressed samples of molten, iron-rich rock to nearly 600,000 times Earth’s atmospheric pressure between the tips of two diamonds and heated them to more than 7,200 degrees Fahrenheit (4,000 degrees Celsius) — temperatures comparable to those found deep within a molten planet, according to the statement.

Scientists say this setup simulated a crucial phase in planet formation, when newly formed worlds orbiting young stars are shrouded in thick blankets of hydrogen gas. That hydrogen acts like a "thermal blanket," trapping heat and keeping magma oceans molten for millions — or even billions — of years, during which the gas and molten rock can interact.

Under these hellish conditions, the researchers found that hydrogen dissolves easily into molten rock, where it reacts with iron oxides to produce substantial amounts of water. The results show that water can arise as a natural byproduct of rock-and-gas chemistry, without requiring delivery from comets, asteroids or other external sources.

The findings imply that, rather than a rare cosmic accident, water may be an inevitable outcome of how planets form, making it far more common across the galaxy than scientists once thought.

One of Saturn's moons, Enceladus has been known to be an active ocean world ever since 2005, when the Cassini mission found giant plumes of water vapour squirting up from the ocean deep below through huge fractures in the surface. These plumes are powered by energy from tidal interactions with Saturn, which flex the moon's interior, subtly squeezing and stretching it and ultimately keeping its interior warm enough for liquid water.

The question of how long Enceladus' ocean has existed is an unanswered one, but with water, heat and the right organic chemistry for life, Enceladus is viewed as a prime target for the search for life beyond Earth.

"Enceladus is a key target in the search for life outside the Earth, and understanding the long-term availability of its energy is key to determining whether it can support life," said study leader Georgina Miles, of the Southwest Research Institute and a Visiting Scientist at the University of Oxford, in a statement.

If Enceladus didn't continually receive enough energy from tidal heating, its ocean would gradually freeze. If it received too much energy, the activity in the ocean would increase, altering its environment perhaps to the detriment of its habitability. Therefore, a careful balance between the energy deposited into the moon by the tidal interaction, and the energy that leaks away through convection up to the surface and into space, is required to ensure stability over hundreds of millions or even billions of years.

Planetary scientists know that heat flows out from the south pole, where the fractures, known as tiger stripes, that produce the plumes are located. However, they thought that Enceladus' north pole was inert.

It seems that they were wrong.

By comparing measurements from Cassini's Composite Infrared Spectrometer (CIRS) of the temperature of Enceladus' north pole during Saturnian winter in 2005 and what passes for summer on the icy moon in 2015, and then comparing it to predicted temperatures based on modeling, Miles' team found that Enceladus' north pole was seven degrees Celsius (45 degrees Fahrenheit) warmer than expected. This excess heat is flowing out from the ocean that is measured to be 12 to 14 miles (20 to 23 kilometers) beneath the surface at the north pole, and averaging 15.5 to 17.4 miles (25 to 28 kilometers) deep globally. This thick ice shell will make it difficult for any future mission to drill down to the ocean; entering via the tiger stripes might be the best bet, even if it might be more dangerous. A mission to launch in the 2040s is currently being considered by the European Space Agency.

The measured heat flow is 46 milliwatts per square meter, which compared to Earth is two-thirds the heat loss through our continental plates. When measured for the entirety of Enceladus, including the heat flow towards the south pole, the moon is losing 54 gigawatts across its entire surface area, which is a close match for the amount of energy that tidal heating puts into the moon. This careful balance is no coincidence, and implies the ocean has been stable, without freezing solid, for a very long time.

"Understanding how much heat Enceladus is losing on a global level is crucial to knowing whether it can support life," said Carly Howett of both the University of Oxford and the Planetary Science Institute in Arizona. "It is really exciting that this new result supports Enceladus' long-term sustainability, a crucial component for life to develop."

Although Cassini ended its 13-year mission in 2017 when it plunged into Saturn to prevent it from crashing onto and contaminating any of Saturn's moons, it seems that the spacecraft is still making discoveries.

"Eking out the subtle surface temperature variations caused by Enceladus' conductive heat flow from its daily and seasonal temperature changes was a challenge, and was only made possible by Cassini's extended missions," said Miles. "Our study highlights the need for long-term missions to ocean worlds that may harbor life, and the fact the data might not reveal all its secrets until decades later after it has been obtained."

The findings were published on Nov. 7 in Science Advances.

The Japanese Aerospace Exploration Agency's Akatsuki mission orbiting Venus was declared dead last week after engineers spent more than a year trying to get in touch with the silent spacecraft. Akatsuki spent a decade orbiting the planet and was well beyond its design lifetime when its mission ended, giving unprecedented looks at the hellish atmosphere of Venus.

While this Venus mission is gone, more are on the books. But some of them are hanging by a thread, as they depend on NASA support at a time when the agency is facing unprecedented budget cuts. The Trump administration proposed a 24% reduction to the agency's fiscal 2026 budget, from $24.8 billion to $18.8 billion. While the U.S. House of Representatives and Senate have proposed more money for NASA, the U.S. budget is still in limbo as the government enters its second month of shutdown after the fiscal year began on Oct. 1.

Here is a list of proposed missions to Venus.

NASA's DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging)

The $500 million DAVINCI mission is slated to launch in the early 2030s as a combination orbiter and descent probe. The orbiter will look at the clouds of Venus, as well as the planet's mountains, during two flybys. The 3-foot-wide (1 meter) descent probe will fall to the surface of Venus and catalog its punishingly thick atmosphere and sulfuric acid-laden clouds along the way, as well as take some images of Venus' surface terrain.

NASA says the spacecraft together will achieve several firsts, including looking for traces of any ancient water cycle on Venus. The mission will focus on Alpha Regio, a "tessera" highland region that has only been imaged through orbital radar instruments. These types of terrain may be billions of years old, making the region one of the oldest surfaces on Venus.

DAVINCI will also be the first mission to chart the chemical composition of the lower atmosphere of Venus, between 17 miles (27.5 kilometers) and the surface, which will allow scientists to learn more about how gases and chemical compounds work on the surface — and perhaps even the subsurface — of Venus. But that's assuming the spacecraft goes forward, as it is on the list of canceled missions in the Trump administration's 2026 NASA budget.

NASA's VERITAS (Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy)

VERITAS will launch no earlier than 2031 to learn more about how Venus and Earth, which are roughly the same size, diverged so greatly in their planetary histories. Aims of the science include learning how the oceans and magnetic field of Venus disappeared, and how plate tectonics changed the terrain. Like DAVINCI, however, VERITAS will be canceled if Trump's 2026 NASA budget is enacted.

VERITAS, a half-billion-dollar mission, is based on the design of NASA's MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft that has been orbiting Mars since 2014. The spacecraft is supposed to orbit around the poles of Venus to allow for views of the entire planet below. Initially the orbit will be 120 hours and highly elliptical, but managers plan a second burn of the engines that will allow VERITAS to circle the planet in only 10 hours.

VERITAS will then use a technique called "aerobraking," using the drag of the upper atmosphere of Venus to lower its orbit by reducing the speed of the spacecraft. This is a lengthy procedure, expected to last several months, but will allow the spacecraft to carry less fuel to Venus and prioritize that mass instead for instrumentation. Once that is finished, VERITAS will be able to go around the planet in 1.6 hours, for a mission expected to last for 2.5 Earth years.

European Space Agency's Envision

Envision is slated to lift off no earlier than November 2031 aboard an Arianespace Ariane 6 rocket. Led by the European Space Agency (ESA), the mission will include a synthetic aperture radar from NASA as well as support from the American agency's Deep Space Network, which is a group of three large radio dishes that communicate with spacecraft across the solar system. NASA's contribution, however, is under threat following proposed cuts to its fiscal 2026 budget, ESA officials confirmed to Nature earlier this year.

The €610 million ($705 million) mission will cruise to Venus for 15 months, then aerobrake in the atmosphere for 11 months before reaching its science orbit, which will circle the planet in roughly 90 minutes. ESA says the mission will focus on the origins of habitability in the solar system, as Venus may have had a climate similar to that of Earth for billions of years before something triggered its oven-like conditions at the surface. The mission aims to spend four Earth years examining Venus from its subsurface to its upper atmosphere, including learning more about the planet's history while charting its current climate and activity.

The spacecraft will be an orbiter with several instruments: an S-band radar/microwave radiometer and altimeter that will map the surface of the planet; three optical spectrometers aiming to examine trace gases (including volcanic gases) as well as the composition of the surface; a subsurface radar sounder to examine the subsurface as far as 0.6 miles (1 km) below the surface; and a radio science experiment to look at Venus' gravity field, as well as atmospheric composition and structure.

Rocket Lab's Venus Life Finder

Billed as the first private mission to explore Venus, Rocket Lab is partnering with the Massachusetts Institute of Technology (MIT) to launch a small spacecraft to Venus in search of the building blocks of life, organic compounds, in the cloud layers of Venus. The Venus Life Finder mission is expected to use Rocket Lab's Electron rocket and Photon spacecraft, which will orbit the planet roughly 30 miles (48 km) above the surface. It was originally slated to fly in early 2025, but after a delay the spacecraft may lift off in summer 2026.

The mission (pegged at just $10 million in media reports) includes a probe that is expected to fall into the atmosphere of Venus, taking data primarily at altitudes between 37 and 28 miles (60 to 45 kilometers). This region was chosen because there have been suggestions of phosphine there, and temperatures and pressures in this altitude range are similar to those on Earth.

During a science collection phase lasting only between three and five minutes, according to the Planetary Society, the mission's laser science instrument (an autofluorescence nephelometer) will strike cloud molecules in the atmosphere. The instrument will then examine the scattered light for more information about the size, shape and concentration of the molecules. If the molecules are organic, they may glow or autofluoresce.

Indian Space Research Organisation's Venus Orbiter Mission

India plans to send its first mission to Venus no earlier than 2028, following several missions looking to compare planets in the solar system: three Chandrayaan space missions to the moon (2008, 2019 and 2023) and the Mars Orbiter Mission to the Red Planet in 2014. The Venus Orbiter Mission, nicknamed Shukrayaan, costs $147 million (12.36 billion rupees) and has been delayed from a launch in 2023.

In background information about the mission, the Indian Space Research Organisation says that Venus is particularly interesting because of its thick carbon dioxide atmosphere, high-pressure surface and active ionosphere (upper atmosphere) that's influenced by the solar wind, or constant stream of particles from the sun.

The Venus Orbiter Mission is supposed to orbit the planet to study its surface, atmosphere, and solar interactions, and will also test aerobraking in the atmosphere. Some of the science objectives of its 16 payloads include high-resolution mapping of the surface, looking at dust and "airglow" in the atmosphere, examining below the surface and looking at the X-ray spectrum of solar rays near the planet.

When scientists dream of exploring the hidden oceans beneath the icy crusts of moons like Jupiter's Europa or Saturn's Enceladus — or other icy regions, such as permanently shadowed lunar craters or ice-bearing soils near the Martian poles — one major problem stands in the way: drilling through the ice.

Traditional drills and melting probes are heavy, complex and consume vast amounts of power. Now, researchers at the Institute of Aerospace Engineering at Technische Universität Dresden in Germany have developed a promising new solution — a laser-based ice drill that can bore deep, narrow channels into ice while keeping both mass and energy requirements low.

"We've created a laser drill that enables deep, narrow and energy-efficient access to ice without increasing instrument mass — something mechanical drills and melting probes cannot achieve," Martin Koßagk, lead author of the study, told Space.com in an email.

Mechanical drills become heavier with depth as they extend rods downward, and melting probes rely on long, power-hungry cables. The laser drill sidesteps both problems by keeping all instruments at the surface. This tech sends a concentrated beam into the ice, vaporizing it rather than melting it — a process known as sublimation.

The resulting vapor escapes upward through a narrow borehole just wide enough for gas and dust samples to be collected. Instruments on the surface can then analyze these samples for chemical composition and density, providing valuable clues about the thermal properties and formation history of the cosmic body being explored.

While lasers aren't the most energy-efficient tools, the beam vaporizes a mere pinhole of ice, meaning the drill uses far less total power than electric heaters. It also works faster in dust-rich layers that slow traditional melting probes, allowing it to bore much deeper without added mass or energy.

Therefore, a laser-based instrument "makes subsurface exploration of icy moons more realistic, allowing high-resolution analysis of ice composition and density, improving models of heat transport and ocean depth on bodies like Europa and Enceladus, and supporting studies of crust formation," Koßagk said. "On the moon or Mars, the laser drill can also extract subsurface material such as dust from ice-bearing craters or soils, enabling geological reconstruction beyond the surface layers."

The team's laser drill concept operates at roughly 150 watts (W), with a projected mass of about 9 pounds (4 kilograms), remaining constant regardless of depth — whether 33 feet (10 meters) or 6 miles (10 kilometers). However, Koßagk noted that a mass spectrometer for analyzing the gas and instruments for dust separation and analysis would increase the power requirement and mass.

Early tests show promise. The prototype drilled through ice samples about 8 inches (20 centimeters) long under vacuum and cryogenic conditions during laboratory experiments, and at greater depths in field tests in the Alps and Arctic, reaching depths of more than a meter in snow. In tests with 20 watts of laser power, the system reached drilling speeds near 1 meter per hour, and up to 3 meters per hour in loose or dusty ice.

A laser-based concept is not without limitations. In stone or layers of dust in which there is no ice that could be vaporized, the drilling process would be stopped. And, in those cases, a new borehole would need to be drilled from the surface that bypasses the obstacle.

"It is therefore important to operate the laser drill in conjunction with other measuring instruments," Koßagk told Space.com. "Radar instruments could look into the ice and locate larger obstacles, which the laser drill could then drill past."

Water-filled crevasses would also pose a challenge. When one is drilled into, the laser drill would have to pump out water as it flows in before it could continue to drill deeper. However, drilling into these areas could help to identify the chemistry of potential habitats for past or present microbial life. If bacteria ever existed, their remains might be detectable in the samples collected from a laser-drilled borehole.

To make this type of laser drill possible, next steps would be miniaturizing the system, developing a dust-separation unit and completing space-qualification tests. A compact payload version could one day ride aboard a lander to an icy moon, bringing scientists closer to decoding the secrets frozen beneath alien surfaces, Koßagk said.

Meanwhile, back on Earth, the same tool could even help predict avalanches. Field tests in cooperation with the Austrian Research Centre for Forests and Department of Natural Hazards in the Alps and the Arctic showed that the laser drill can measure snow density without digging a pit — and, mounted on a drone, it could collect data from dangerous slopes where humans can't safely go, Koßagk said.

Whether on Earth or in deep space, the goal is the same: to look beneath the surface and understand what's hidden in the ice.

The team's initial findings were published Sept. 8 in the journal Acta Astronautica.

Young stars can be much more tumultuous than older stars. Stellar physics predicts that in our sun's formative years it was throwing off flares of radiation and coronal mass ejections (CMEs) far more powerful and more frequent than what the sun can manage today.

Yet no one had actually seen a young sun-like star being so energetic — until now.

A coronal mass ejection and its accompanying flare occur when taut magnetic field lines on the sun or another star snap, releasing a huge burst of energy before the field lines reconnect. This energy manifests as a brightening on the surface of the sun or star, while it can lift a huge plume of plasma straight from the corona, which is the ultra-hot outer layer of a star's atmosphere.

We're familiar with observing CMEs on our sun, but extraterrestrial CMEs are more difficult to spot. Nevertheless, ground-based telescopes observing at the hydrogen-alpha wavelength have detected cool, lower-energy plasma being burped off young stars during CMEs. The next step was to search for the higher-energy release of energy that stellar physicists believe characterizes the frequent CMEs from young stars.

To that end, a multi-national team of astronomers led by Kosuke Namekata of Kyoto University in Japan have made a breakthrough by targeting the young sun-like star EK Draconis, which is 112 light-years away from Earth in the constellation of Draco, the Dragon. The star is thought to be 50 million to 125 million years old, which is considered very young for a star that will exist for billions of years, and has a mass (0.95 solar masses), radius (0.94 solar radii) and surface temperature (5,560 to 5,700 kelvin) that are very close to the values for our sun.

"What inspired us most was the long-standing mystery of how the young sun's violent activity influenced the nascent Earth," said Namekata in a statement. "By combining space- and ground-based facilities across Japan, Korea and the United States, we were able to reconstruct what may have happened billions of years ago in our own solar system."

Namekata's team performed simultaneous observations of EK Draconis with the Hubble Space Telescope, NASA's Transiting Exoplanet Survey Satellite (TESS) and three ground-based telescopes in Japan and Korea. The Hubble observations were in ultraviolet light, which enabled the detection of the higher-energy components of a CME, while the ground-based telescopes tracked the cooler plasma via its hydrogen-alpha emission and TESS watched for brightening caused by the accompanying flare.

Together, Hubble and the ground-based telescopes detected the spectral lines from the emission of a CME on EK Draconis. Hubble's ultraviolet vision detected a cloud of hot plasma with a temperature of 100,000 kelvin (180,000 degrees Fahrenheit). The amount of Doppler shifting in the ultraviolet spectral lines from the star indicated that the hot plasma had been ejected at a velocity of 300 to 550 kilometers per second (670,000 to 1.2 million mph). Ten minutes later, a plume of cooler gas at 10,000 kelvin (18,000 degrees Fahrenheit) appeared, moving more slowly at 70 kilometers per second (157,000 mph). Together, the hot and fast component and cool and slow component were both two sides of the same CME.

The hot component of the CME carried much more energy than the cooler plasma. This much energy released on a regular basis, researchers said, would be significant enough to drive chemical reactions in a planetary atmosphere, producing greenhouse gases that could keep a planet warm, as well as breaking atmospheric molecules apart so they can reform as complex organic molecules that could potentially act as the building blocks of life. (No exoplanets have been detected orbiting EK Draconis yet, but it does have a probable red dwarf companion star.)

The observations therefore are a rare insight into the role that stars can play in the origin of life, a role that our sun may have played 4.5 billion years ago and which other stars may be doing today.

The findings were published on Oct. 27 in the journal Nature Astronomy.

For the past few years, astronomers including Beatriz Villarroel, of Nordita, Stockholm University, have been scrutinizing photographic plates exposed in the years before the Space Age began, as part of the Vanishing and Appearing Sources during a Century of Observations (VASCO) project. The aim of VASCO is to use archival data, now digitized, to search for new astrophysical transients, which are objects that brighten or fade, sometimes dramatically. These objects can appear as a spot of light in one image of the sky or space, only to vanish in the next.

Villarroel and study co-author Stephen Bruehl, a professor of anesthesiology from the Vanderbilt University School of Medicine, say their data show a statistical correlation between these flashes of light and reported sightings of unidentified objects. “We speculate that some transients could potentially be UAP in Earth orbit that, if descending into the atmosphere, might provide the stimulus for some UAP sightings,” they write in one of the new studies.

When VASCO launched, it had the stated aim of looking for stars that had vanished, which could for example signal a massive star collapsing into black hole without exploding as a supernova. VASCO could potentially also reveal new types of variable stars, active galactic nuclei, stellar flares or even brand new phenomena.

Sometimes the transients VASCO studies are unexplained, which has previously led Villarroel to a startling conclusion: that some of the objects detected on the plates are metallic objects in high Earth-orbit, before the launch of Sputnik 1 in 1957.

“Today we know that short flashes of light are often solar reflections from flat, highly reflective objects in orbit around the Earth, such as satellites and space debris, but the photographic plates analyzed in VASCO were taken before humans had satellites in space,” Villarroel said in a statement.

VASCO researchers analyzed 106,000 transients that look like stars that appeared and swiftly disappeared in a single exposure between the years 1951 and 1957. In particular, the appearance of the unidentified transients were 68% more likely to occur the day after a nuclear weapons test in Earth’s atmosphere than on other day, Bruehl added in the statement.

“The magnitude of the association between these flashes of light and nuclear tests was surprising, as was the very specific time at which they most often occurred – namely, the day after a test,” said Bruehl. “What they might represent is a very fascinating question that needs further investigation.”

In their study, Villarroel and Bruehl also found that the transients captured by the photographic plates increased by an average of 8.5% for each UAP sighting that was reported.

In a second study, which also included researchers from Algeria, India, Nigeria, Spain, Switzerland, Ukraine and the United States, they found that one anomalous transient coincided with a cluster of flying saucer sightings over Washington, D.C., on 27 July 1952. This particular transient, along with several others, was an instance where multiple flashes of light were seen along a narrow band. This, says Villarroel, suggests flat, reflective objects in motion high above Earth that were reflecting sunlight – a hypothesis supported by the fact that the number of mystery transients drops off in parts of the sky in Earth’s shadow, where sunlight can’t reach.

“You don’t get those kinds of solar reflections from round objects like asteroids or dust grains in space, which leave streaks during a 50-minute exposure, but only if something is very flat and very reflective and reflects the sunlight with a short flash,” said Villarroel.

Villarroel and Bruehl propose another possible explanation, however: that nuclear weapons tests triggered some unknown atmospheric phenomenon that went unnoticed at the time. But Villarroel and Bruehl are skeptical that such a phenomenon would stand still in the atmosphere for 24 hours between the weapons test and when the plate was exposed at Palomar in California. The transients do not seem to be particles of nuclear fallout that have drifted down onto the photographic plate either, since such particles would produce foggy, diffuse spots, not pinpoint, star-like objects.

The explanation Villarroel and Bruehl focus on most in their papers is that these transients are UAP of some kind. Their study connects the nuclear tests to sightings, which have been reported in the vicinity of nuclear sites for decades. "Significantly more UAP sightings were reported within nuclear weapons testing windows (test date + /- 1 day) than outside of testing windows," they report in their study.

There are, of course, many caveats. Critics have claimed that the transients could be photographic defects, or contamination, especially as the plates are quite old and were stored away for many decades before being digitized.

Villarroel and Bruehl perhaps also give too much credit to reports of UFO sightings. Their reported correlation of 8.5% between the appearance of the transients and flying saucer sightings is only relevant if it can be assumed those UAP sightings are credible in the first place. There may also be an observation bias – the 1950s were the heyday of UFO sightings, so it is perhaps not too surprising that there were sightings coinciding with the appearance of transients, since UAP sightings were reported on many different days.

Ultimately, correlation does not necessarily mean causation, and Villarroel and Bruehl do acknowledge this in their study.

In SETI, the search for extraterrestrial intelligence, researchers tend to assume that any unexplained phenomena isn’t aliens, and to exhaust every possible natural explanation before invoking an extraterrestrial one. This approach would be helpful here, although what those alternative explanations might be are not yet certain.

Because of the nuclear test-ban treaty there is, quite rightly, no way to test the hypothesis that the transients are related to atmospheric phenomena caused by nuclear explosions, of which there were at least 124 above the ground between 1951 and 1957.

For now, the discovery of the transients remains an intriguing puzzle. One possible way forward that has been suggested is to try and repeat the observations on the modern day sky. If geosynchronous satellites that we know about produce similar patterns of transients on photographic plates, then that would strengthen the hypothesis that the transients on the Palomar plates could depict metallic objects reflecting sunlight in high orbit.

The two studies are published in Scientific Reports and Publications of the Astronomical Society of the Pacific.

Over centuries, this curiosity evolved into a scientific pursuit, blending astronomy, biology, chemistry, and philosophy into a single, thrilling endeavor: to find life elsewhere in the cosmos.

From Galileo's telescope to the James Webb Space Telescope, each technological leap has brought us closer to answering that age-old question. We've sent probes to Mars, listened for alien signals through SETI, and discovered thousands of exoplanets orbiting distant stars. Along the way, we've refined our understanding of what life is, how it might arise, and where it could thrive — even in the most extreme environments.

This quiz explores the milestones, theories, and missions that have defined the search for extraterrestrial life.

Whether you're a space science enthusiast or just curious about the universe's biggest mystery, this challenge will stretch your mind across time and space.

Try it out below and see how well you score!

New laboratory research suggests that some organic molecules previously detected in plumes erupting from Saturn’s moon Enceladus may be products of natural radiation, rather than originating from the moon’s subsurface ocean. This discovery complicates the assessment of the astrobiological relevance of these compounds.

Enceladus hides a global ocean buried beneath its frozen crust. Material from this liquid reservoir is ejected into space from cracks in the ice near the south pole, forming plumes of dust-sized ice particles that extend for hundreds of kilometers. While most of this material falls back onto the surface, some remains in orbit, becoming part of Saturn’s E ring, the planet’s outermost and widest ring.

Between 2005 and 2015, NASA's Cassini spacecraft flew repeatedly through these plumes and detected a variety of organic molecules. The detection was viewed as evidence of a chemically rich and potentially habitable environment under the ice, where molecules essential to life could be available. However, the new study offers an explanation in which radiation, not biology, is behind the presence of at least some of these organic molecules.

To test the role of space radiation, a team of researchers led by planetary scientist Grace Richards, a postdoc at the National Institute for Astrophysics in Rome, simulated conditions near Enceladus's surface by creating a mixture of water, carbon dioxide, methane, and ammonia, the main expected components of surface ice on Enceladus. They cooled the concoction to −200°C inside a vacuum chamber and then bombarded it with water ions, which are an important component of the radiation environment that surrounds the moon.

The radiation induced a series of chemical reactions that produced a cocktail of molecules, including carbon monoxide, cyanate, ammonium, and various alcohols, as well as molecular precursors to amino acids such as formamide, acetylene, and acetaldehyde. The presence of these simple molecules indicates that radiation could induce similar reactions on Enceladus.

Richards presented these findings at the Europlanet Science Congress–Division for Planetary Sciences Joint Meeting (EPSC-DPS 2025) in Helsinki, Finland. She and her coauthors also published a detailed report in Planetary and Space Science.

Enceladus and beyond

The new research raises the question of whether the organic molecules detected in Enceladus's plumes truly come from the moon's buried ocean, whether they are formed in space, or whether they form close to the surface after the plumes leave the Enceladean interior.

While the finding doesn't exclude the possibility of a habitable ocean on Enceladus, Richards urges caution in assuming a direct link between the presence of these molecules in the plumes, their origin, and their possible role as precursors to biochemistry.

"I don’t necessarily think that my experiments discredit anything to do with Enceladus's habitability," Richards said.

However, she added, "when you're trying to infer this ocean composition from what you’re seeing in space, it's important to understand all the processes that go into modifying this material." Apart from radiation, these processes include phase changes, interactions with the moon's ice walls, and interactions with the space environment.

"We need a lot of experiments of that type," said planetary scientist Alexis Bouquet, a French National Centre for Scientific Research (CNRS) researcher at L'Université d’Aix-Marseille who wasn't involved in the study. "They demonstrated that you can produce a certain variety of species in conditions that are relevant to the south pole of Enceladus."

Bouquet highlighted the importance of simulating these environments in a lab for planning future missions to Enceladus and for interpreting the much-anticipated data from current missions to Jupiter's icy moons. These missions are NASA's Europa Clipper, which will explore Europa, and the European Space Agency's (ESA) JUICE (Jupiter Icy Moons Explorer), which will visit all three of the giant planet's moons with subsurface oceans: Ganymede, Calisto, and also Europa.

The intense radiation around Jupiter makes these experiments especially relevant. "Radiation chemistry for Europa or the Jovian moons in general [is] a big deal, a bigger deal than in Enceladus," Bouquet says.

Another Story Completely

As Richards's work questions the origin of organic compounds around Enceladus, researchers keep adding more molecules to the puzzle.

After a new analysis of data gathered during one of Cassini's close approaches to Enceladus in 2008, researchers led by planetary scientist Nozair Khawaja at the Freie Universität Berlin and the University of Stuttgart reported the discovery of new types of organic molecules, seemingly emanating from the icy vents. They include ester and ether groups and chains and cyclic species containing double bonds of oxygen and nitrogen.

On Earth, these molecules are essential links in a series of chemical reactions that ultimately produce complex compounds needed for life. And while these molecules could have an inorganic origin, "they increase the habitability potential of Enceladus,"
Khawaja said. The findings appeared in Nature Astronomy.

Khawaja's team's analysis suggests that complex organic molecules are present in fresh ice grains just expelled from the vents. During its last flyby, Cassini got as close as 28 kilometers to the moon's surface.

After modeling the plumes and the icy grains' residence times in space, they think that the ice grains sampled by Cassini did not spend a lot of time in space, likely just "a few minutes," Khawaja said. "It is fresh."

This short duration in space questions whether space radiation had enough time to produce the organic molecules Khawaja detected. Just a few minutes would not be long enough for such complex chemistry to take place, even in a high-radiation environment.

"Big grains coming from the surface full of organics? That is much harder to explain through radiation chemistry," Bouquet said.

While the types of experiments performed by Richards "are valuable and take the science to the next level," Khawaja said, "our results tell the other story completely."

Back to Enceladus

Both studies reinforce the complexity of Enceladus's chemistry, upholding it as a prime target in the search for extraterrestrial life, or at least life's building blocks. Enceladus has all three prerequisites for life: liquid water, an energy source, and a rich cocktail of chemical elements and molecules. Even if the subsurface ocean is out of reach—it lies at least a few kilometers beneath the ice close to the poles—the plumes offer the only known opportunity to sample an extraterrestrial liquid ocean.

Studies for a potential ESA mission dedicated to Enceladus are already underway, with plans that include high-speed flybys through the plumes and, potentially, a lander on the south pole. The insights from both recent studies will help researchers design the instrumentation and guide the interpretation of future results.

"There is no better place to look for [life] than Enceladus," Khawaja said.

The planet, known as GJ 251c, orbits a red dwarf star 18.2 light-years away in the constellation of Gemini, the Twins. The planet's mass is four times greater than that of Earth, making it a 'super-Earth' — a rocky planet larger and more massive than our own.

"While we can't yet confirm the presence of an atmosphere or life on GJ 251c, the planet represents a promising target for future exploration," said Suvrath Mahadevan, who is a professor of astronomy at Penn State University, said in a statement.

In the habitable zone, sometimes referred to as the Goldilocks zone, conditions are just right for liquid water to exist on the surface of a planet with an appropriate atmosphere.

GJ 251c was discovered thanks to observations spanning over 20 years, during which scientists looked for a slight wobble of the world's parent star incurred by the planet's gravity. As the star wobbles ever so slightly toward and away from us, we see a Doppler shift in its radial velocity that can be measured with a spectrograph.

One other planet is known to exist in the system, GJ 251b, which was discovered in 2020 and orbits its star every 14 days at a distance of 7.6 million miles (12.2 million kilometers). Using archive data from telescopes worldwide, a team of astronomers, including Mahadevan, was able to refine the accuracy of the radial velocity measurements for planet GJ 251b

The team then combined this refined data with brand new, high-precision observations from the Habitable-Zone Planet Finder (HPF), which is a near-infrared spectrograph on the Hobby-Eberly Telescope at McDonald Observatory in Texas. This revealed a second planetary signal belonging to a four-Earth-mass world orbiting the star every 54 days. That was then confirmed by measurements with the NEID spectrograph on the 3.5-meter WIYN telescope at Kitt Peak National Observatory in Arizona.

Though it may sound straightforward, in reality, the challenge of detecting the planet was formidable.

Stars are constantly roiling and churning as convective bubbles burst through to their visible surfaces and prominences splutter into space. This creates a noisy background of what's called asteroseismic activity that manifests as Doppler shifted lines in the star's spectrum. Picking out the Doppler shifted radial velocity signals from this noise is tricky, requiring a great deal of modeling what a planetary signal should look like.

"This is a hard game in terms of trying to beat down stellar activity as well as measuring its subtle signals, teasing out slight signals from what is essentially this frothing, magnetospheric cauldron of a star-surface," said Mahadevan.

Now that we know about the planet, astronomers can plan future observations.

GJ 251c is probably a little bit too far away from its star for the James Webb Space Telescope (JWST) to search for signs of an atmosphere around it. The next generation of 30-meter-class telescopes might be able to detect the planet's atmosphere via a method of searching for light reflected off its surface or atmosphere, but it will likely require the Habitable Worlds Observatory, which is a planned giant space telescope that is hoped to launch in the 2040s, to fully characterize GJ 251c.

"We are at the cutting edge of technology and analysis with this system," said Corey Beard of the University of California, Irvine, who participated in the research. "We need the next generation of telescopes to directly image this candidate."

Although GJ 251c is described by Mahadevan as being "one of the best candidates in the search for an atmospheric signature of life," referencing how we will search for biosignatures in the planet's atmosphere, there remains an elephant in the room: its star.

At 36% of the mass of our sun, the star GJ 251 is a red dwarf. Astronomers have now found numerous rocky planets in the habitable zone of red dwarfs, including Proxima Centauri b, TRAPPIST-1e and f, and Teegarden's Star b. However, red dwarfs are notorious for having violent tempers that bely their diminutive stature, releasing regular powerful flares that can over time strip a planet of its atmosphere. For example, the JWST's observations of the inner three planets of TRAPPIST-1 find no evidence for an atmosphere, while its observations of the fourth planet, e, are so far inconclusive. Some astronomers are now growing skeptical that Earth-like worlds can thrive around red dwarfs.

What GJ 251c has going for it is that it is slightly farther away from its star than habitable zone planets found around other red dwarfs are. This is thanks to its star being a little more massive than those other stars and therefore hotter, pushing the habitable zone farther out. It is possible that GJ 251c is far enough away from its star to have avoided the worst of its temper tantrums, and, if armed with a thick atmosphere and strong planetary magnetic field, it could have resisted the star's stellar wind from stripping its atmosphere away.

However, at present, this remains guesswork. "We made an exciting discovery," said Mahadevan, "But there’s still much more to learn about this planet."

The findings were reported on Oct. 23 in The Astronomical Journal.

A new study from NASA and Penn State University suggests fragments of biomolecules from ancient microbes could survive in Martian ice for tens of millions of years — long enough for future missions to potentially find them, according to a statement from the university.

In laboratory experiments simulating Mars conditions, researchers froze samples of E. coli bacteria in two different environments: pure water ice and a mixture of water and ingredients found in Martian soil, including silicate-based rocks and clay. The samples were cooled to minus 60 degrees Fahrenheit (minus 51.1 degrees Celsius) — the temperature of icy regions on Mars — and then exposed to radiation levels equivalent to what they would experience over 20 million years on Mars. The results were extended through modeling to represent 50 million years of exposure, according to the statement.

"Fifty million years is far greater than the expected age for some current surface ice deposits on Mars, which are often less than two million years old, meaning any organic life present within the ice would be preserved," Christopher House, co-author of the study and professor of geosciences, said in the statement. "That means if there are bacteria near the surface of Mars, future missions can find it."

The researchers found that the amino acids — the building blocks of proteins — survived far better in pure ice than in ice mixed with sediment. More than 10% of the original amino acids remained intact after the simulated 50-million-year exposure, while those in the soil mixture degraded 10 times faster and did not survive. When tested under even colder temperatures similar to those on Europa, an icy moon of Jupiter, and Enceladus, an icy moon of Saturn, the researchers found it further reduced the rate of deterioration.

Therefore, the researchers suggest that in pure ice, radiation byproducts such as free radicals become trapped and immobilized, slowing the chemical breakdown of biological molecules. In contrast, the minerals in Martian soil appear to create thin films of liquid that allow destructive particles to move and cause more damage.

"These results suggest that pure ice or ice-dominated regions are an ideal place to look for recent biological material on Mars," Alexander Pavlov, lead author and a space scientist at NASA Goddard Space Flight Center, said in the statement.

This can help better plan which areas to target during future Mars missions and how to design tools capable of drilling into subsurface ice deposits — most of which are believed to be less than two million years old, meaning any biomolecular traces from a more recent habitable period could be preserved in the frozen ice.

Their findings were published Sept. 12 in the journal Astrobiology.

This new detection on a brown dwarf is predicted by models that simulate alien atmospheres and is a reminder that phosphine is not necessarily a biosignature. However, astronomers remain puzzled about why some objects contain phosphine and others do not, even though theory says it should be there.

The phosphine was identified in the cold atmosphere of a brown dwarf called Wolf 1130C, which exists in a triple system along with a low-mass red dwarf star and a white dwarf. The phosphine exists with an abundance of 0.1 parts per million, which matches what models of the atmosphere of gas giant planets and brown dwarfs predict. Indeed, both Jupiter and Saturn contain a similar abundance of phosphine to Wolf 1130C.

The problem has been that many brown dwarfs that are expected to show detectable abundances of phosphine do not, and scientists don't know why.

Phosphine is a phosphorus-based molecule, composed of one atom of phosphorus and three hydrogen atoms. It is also pretty unstable in atmospheric conditions, and chemical reactions can easily break phosphine molecules apart. We see phosphine in Jupiter and Saturn's clouds because it is formed deep within the hot interiors of the giant planets, and then convection currents carry the phosphine to higher altitudes faster than the rate at which it is destroyed.

This is one of the reasons why the claimed detection of phosphine on Venus is so controversial.

It was in 2020 that a team led by Jane Greaves of the University of Cardiff in Wales detected phosphine in Venus' atmosphere using the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. On Earth, phosphine occurs naturally as a product of biological processes, and Greaves' team strongly pushed the biological angle to explain their discovery, leading to speculation that there could be microbes living in Venus' toxic clouds.

However, a large section of the astronomical community differed with the team's findings, arguing that there were flaws in the analysis, and other groups have struggled to replicate the findings. In spite of this, Greaves' team has doubled down on their conclusions, and the presence of phosphine on Venus remains fiercely debated and controversial.

Part of scientists' disagreement with the discovery is that they find it hard to see how the phosphine could survive in Venus' atmosphere.

Nevertheless, phosphine is still considered a potential biosignature by astrobiologists in their search for alien life.

However, its existence in the clouds of Jupiter and Saturn, and now on Wolf 1130C, is a reminder that non-biological chemical processes can also produce phosphine. The question is why Jupiter, Saturn and Wolf 1130C have detectable levels of phosphine while other brown dwarfs that have been studied by JWST do not, or at least are so depleted in it that the molecule is not detectable.

There are several possible explanations. One is unique to the Wolf 1130 system. Before it evolved into a white dwarf, Wolf 1130B was a large star with a mass between six and eight times that of our sun. Such stars aren't quite massive enough to go supernova, so they end their lives much in the same way as our sun will — by expanding to become a red giant and then puffing off their outer layers to form a planetary nebula, while leaving behind their inert core as a white dwarf the size of Earth which, in the case of Wolf 1130B, packs in 1.24 solar masses.

Stars in the six-to-eight solar mass range can produce significant amounts of phosphorus in the latter stages of their life, which they can then belch out into space as the red giant shrugs off its outer layers. If this phosphorus-rich material was spewed all over Wolf 1130C, then it would explain where the phosphorus to form phosphine came from.

It's a nice theory, but unfortunately it doesn't pass muster. The white dwarf in the Wolf 1130 system forms a close binary with the low-mass star, Wolf 1130A, while the brown dwarf orbits the pair of them from a distance. A and B are so close that they are tidally locked to each other, meaning they show each other the same face constantly. Their relationship is even more involved than that — the gravitational pull of the white dwarf is actually stretching Wolf 1130A into an egg shape toward it.

When the star that formed the white dwarf died, the outer layers of the red giant would have engulfed Wolf 1130A. If the death of the star that became the white dwarf had deposited phosphorus onto the brown dwarf, then we'd also expect to see an over-abundance of phosphorus on Wolf 1130A, but we do not.

Another possibility is that the presence of phosphine is somehow related to the intrinsic chemical composition of the brown dwarf. Some models predict that atmospheres that contain very few elements heavier than helium have a preponderance for more phosphine. Indeed, 1130C does appear to have a very low abundance of these heavier elements, which astronomers refer to collectively as "metals." Similarly, Jupiter and Saturn also have low "metallicities."

The exact reason why a lack of heavy elements promotes phosphine is multifaceted: Not only does it help create the conditions in which phosphine can form and survive longer than it normally would, but the relative lack of other molecules present in the atmosphere means that there is less to interfere with the phosphine signal in the brown dwarf's spectrum, causing it to stand out more.

The problem is that other brown dwarfs observed by JWST also have low metallicities, but they don't show the expected amounts of phosphine.

These ambiguities prompt the authors of the new research, led by Adam Burgasser of the University of California, San Diego, to question how useful a biosignature phosphine is when we cannot even say for sure how it forms on distant planets and brown dwarfs.

"The inability of models to consistently explain all these sources indicates an incomplete understanding of phosphorus chemistry in low-temperature atmospheres," the authors said. "We therefore caution against the use of phosphine as a biosignature until these discrepancies are resolved."

If nothing else, the new study reminds us that, even if the detection of phosphine on Venus turns out to be real, its origin could very well be abiotic rather than biologically related. It's not time to get excited about life on any of these worlds just yet.

The findings were published on Oct. 2 in the journal Science.

On the western edge of Jezero Crater, NASA's Perseverance rover has been exploring Neretva Vallis, a river-carved valley that once fed a vast Martian lake. There, in an outcrop of ancient mudstone called the Bright Angel formation, the rover found one of its most intriguing targets yet: an arrowhead-shaped rock nicknamed Cheyava Falls, flecked with tiny black "poppy seeds" and ringed "leopard spots."

Closer analysis revealed that the strange markings are rich in organic carbon, iron, phosphorus and sulfur. More strikingly, scientists recently reported signs of vivianite (an iron phosphate) and greigite (an iron sulfide). On Earth, both minerals typically form through redox reactions — the electron-swapping processes that underpin all life. Plants rely on redox in photosynthesis, humans and other animals use it to extract energy from food during respiration, and microbes employ it to "breathe" metals in oxygen-starved settings such as deep-sea vents.

On our planet, such signatures are often the fingerprints of biology. On Mars, they remain a tantalizing "maybe" — chemical traces that could point to life, or could also arise from purely non-living processes. Either way, they mark a departure from the chemistry that scientists are used to seeing on the Red Planet.

"Whatever their origin, this is a very distinct chemistry than anything we've seen in ~20-25 years of roving the planet," Joel Hurowitz, a geoscientist at Stony Brook University in New York who led the recent study, told Space.com.

Even if the reactions turn out to be non-biological, he added, they could reveal "prebiotically useful chemistry we haven't thought about before," while also serving as a reminder of the ways that abiotic nature can mimic life's signals — false positives for biosignatures "that we'll have to do some really hard thinking about."

A window into Mars' past

Mars' surface usually tells a story of oxidation: iron reacting with oxygen billions of years ago, when liquid water and a thicker atmosphere were still present, leaving behind the global blanket of rust that earned Mars its enduring nickname, the Red Planet. At Cheyava Falls, however, Perseverance identified minerals that formed through the other half of the equation, known as reduction, where iron and sulfur gained electrons instead of losing them.

Redox reactions are especially compelling because, left to themselves, they proceed only sluggishly at low temperatures. That slow pace, and the energy locked within it, makes them an excellent fuel source for life. Life fast-forwards these reactions with enzymes, enabling microbes to seize the energy that would otherwise dissipate.

"All living things need to get energy from their environment. Life on Earth figured out how to do that very early by taking advantage of redox reactions," study co-author Mike Tice, a geobiologist at Texas A&M University in College Station, told Space.com.

Seeing evidence of redox chemistry on Mars, then, raises the possibility that similar processes could once have supported any life that may have emerged there.

"Based on what we know of life on Earth as well as some other theoretical factors, we think that life almost anywhere will probably wind up using redox reactions to get energy," said Tice. Searching ancient rocks for the chemical fingerprints of redox reactions, particularly cases where they appear to have unfolded faster than non-biological chemistry alone could explain, "is a key strategy for finding past life," he added.

That's what makes the minerals Perseverance spotted — particularly greigite in the leopard spots — so compelling. Abiotic sulfide production at low temperatures is extremely sluggish, according to Tice.

"They basically don't happen at the temperatures that we think these rocks experienced," he said. "So, the very things that make this particular redox reaction useful to some living organisms are the things that make it useful as potential evidence for life."

With rocks more than 3.5 billion years old, non-biological processes have had plenty of time to leave behind features that mimic biosignatures. At Cheyava Falls, though, the rocks show no signs of being altered by heat or pressure that could have driven fast chemical reactions, yet sulfides are present in notable amounts. For scientists, that discrepancy keeps open — but does not confirm — the possibility of a biological origin.

"It's very indirect evidence for life," Chris Impey, an astronomer at the University of Arizona who was not involved in the study, told Space.com. "It's not going to convince anyone that there's life on Mars beyond a reasonable doubt, which is at this point where the game is."

Gerard van Belle, the director of science at Lowell Observatory in Arizona, who was also not involved in the study, agreed. "It's not a smoking gun," he told Space.com. "The $100,000 question here is, Are those things something that would come from a uniquely biotic source, or are there abiotic ways?"

Still, these redox reactions intrigue scientists because they leave behind minerals that act like time capsules. Their chemistry and abundance preserve clues about the environment in which they formed — whether water once moved through the rocks, how oxygen-rich or oxygen-poor the environment was, and whether energy sources existed that microbes might have tapped.

The Bright Angel mudstone also looks chemically distinct from other Jezero rocks. It is unusually oxidized and stripped of elements like magnesium and calcium, a profile that Hurowitz said resembles soils on Earth that have been heavily weathered by long exposure to rain. That distinction likely reflects shifts in Mars' climate and atmosphere as Jezero Crater filled with sediment, the researcher said.

"The Bright Angel formation adds new dimensions to the overall picture of Mars' past environments," Hurowitz said. It tells scientists that the planet's climate and atmosphere may have varied considerably through time, "but also [have been] capable of supporting habitable environments while all of that variation was occurring."

Perseverance has already drilled a core from Cheyava Falls and cached it for eventual return to Earth. If all goes to plan with NASA's Mars Sample Return (MSR) mission campaign, scientists are eager to analyze the rock in ways impossible aboard the rover. (That's far from guaranteed, however; MSR has been plagued by delays and cost overruns, and President Donald Trump's 2026 proposed federal budget would cancel the project.)

Hurotwiz said he would "want to go right to work" on isotopic measurements of the Cheyava Falls sample — comparing lighter and heavier versions of iron, sulfur and carbon in the rock, particularly between the original mudstone and the newer minerals, vivianite and greigite, that crystallized within it. Differences in isotopic compositions between these reactants and products, he noted, "can be diagnostic in determining whether or not biology was involved in the redox reactions that formed them."

Van Belle said that returning pristine samples to Earth would make "a big difference" in the search for fossil-like structures — the kind of evidence that has long fueled debates, such as those over the famous Mars meteorite Allan Hills 84001, but this time without the uncertainty of contamination.

Tice said that, if someone had asked him two years ago whether life ever existed on Mars, his answer would have been that scientists simply didn't know enough to have a meaningful discussion. Previous NASA missions had shown that the Red Planet's surface could have supported life billions of years ago but didn't offer evidence for or against its habitation during that time.

Now, Perseverance is beginning to change that.

"We now have the first hints," he said, "and we can have real arguments and plan new observations constrained by the reality of actual rocks and minerals — that excites me!"

He likened the moment to treasure hunting. "This is the moment where the metal detector has gone off and you've dug up something shiny," he said. "You still need to find out exactly what you've got — but you've got something to work with."

"It's arguably the best evidence that we have so far for microbial life on early Mars," Oleg Abramov of the Planetary Science Institute told Space.com.

A rover and a rock

When Perseverance, trundling through an ancient river delta in Jezero crater on Mars, came across a large sedimentary rock that mission scientists have nicknamed "Cheyava Falls," it found something highly unusual, or at least unusual for Mars: light spots on the red rock, each spot ringed by dark material. Because of the way these features appear, scientists have referred to them as "leopard spots," and indeed we see similar spots on rocks on Earth.

Here, they can form in one of two ways.

One way is when iron-rich rock is exposed to high temperatures and acidic conditions, but neither are evident in the area around Cheyava Falls.

The other way? Life.

The rock Perseverance found appears to be rich in hematite, a common iron oxide that forms in liquid water — which makes sense because the rover is exploring an old, dried-up river valley and delta. Chemical reactions involving the hematite can turn the rock from red to white and produce iron rich minerals, in this case an iron phosphate called vivianite and an iron sulfide called greigite.Both are associated with microbial life on Earth in that they are useful energy sources. There's also organic material present (organic in this sense means molecules with at least one carbon atom, but not necessarily part of something that was living), preserved in the clay sediments, although Perseverance’s instruments are unable to determine what kind of organic molecules they are.

To be clear, Cheyava Falls is not confirmation that there was life on Mars. "But," Abramov says, "it's intriguing, and definitely worth further study."

The controversial Mars meteorite

However, this is not the first time the question of life on Mars has come up.

"There have been some hints of biological activity on Mars reported previously," said Abramov.

Back in 1996, NASA scientists led by David McKay claimed they had found minerals associated with life and even possible microfossils in a meteorite named ALH84001. It was located in Antarctica in 1984, but came from Mars. The discovery caused quite a stir, and the hype only increased when the finding was announced by former U.S. president Bill Clinton.

It didn't take long for the excitement to falter, however. Other researchers took a look at the data and found that inorganic processes or terrestrial contamination could replicate all the evidence from the meteorite.

Abramov points out that this does not disprove the Mars life explanation, but rather just presents an alternative, albeit much more probable, explanation for the evidence.

"It hasn't been ruled that what was observed in ALH84001 was a consequence of Martian biology — it may very well be," he said. "But while at the time it seemed fairly compelling evidence, in retrospect it was probably hyped up more than it should have been."

Abramov feels the astrobiology and planetary science communities have learned some lessons from the Martian meteorite saga in terms of how these discoveries, which carry with them a degree of ambiguity, are presented.

"ALH84001 actually shares some similarities with this new finding in Jezero," he said. "Both cases involve organic material and minerals that are generally precipitated by life. But this new finding in Jezero is arguably stronger evidence, but it's not being hyped up the way that ALH84001 was."

Methane on Mars

Another intriguing biosignature that is less controversial but still unexplained is the anomalous plumes of methane gas on Mars, first found by astronomers using ground-based telescopes in 2003, followed by the European Space Agency's Mars Express orbiter in 2004, and most recently by NASA's Curiosity rover and Europe's Trace Gas Orbiter. Unlike the uncertainty regarding the contents of the ALH84001 meteorite, the methane is definitely there, but where is it coming from?

Methane is easily destroyed by solar ultraviolet light, so something must be replenishing it on Mars. The methane plumes are also highly localized. On Earth, methane is largely produced by life, but there are also geophysical sources of the gas too, such as reactions between water and rock, or "serpentinization, "which is a chemical reaction involving carbon dioxide, water and olivine, which is a common mineral on Mars.

"The plumes are intriguing but ambiguous," said Abramov. "The levels of methane in the Martian atmosphere do seem to fluctuate, but they are very small amounts at the parts per million level, and we're not sure what the source is. It could be biological activity in the subsurface or maybe a hydrothermal-type environment, but it could also be something abiological."

Biosignatures beyond Mars

Furthermore, researchers are not only looking for and finding biosignatures on Mars; there is evidence for them elsewhere, too.

In 2020, astronomers led by Jane Greaves of the University of Cardiff claimed to have detected the gas phosphine in the atmosphere of Venus. The second planet from the sun has a completely inhospitable surface, with temperatures reaching 863 degrees Fahrenheit (462 degrees Celsius) and a crushing pressure underneath an oppressively thick atmosphere. There is, however, a region in its atmosphere at an altitude of over 31 miles (50 kilometers), where the temperature and pressure are almost Earth-like. On our planet, phosphine is produced only by life. Could its detection on Venus mean there is life in its clouds, or is some inorganic chemistry, unknown on Earth, producing it?

The discovery is controversial, however, because many other scientists have argued against the analysis of the data by Greaves' team and have mostly failed to detect the specific gas in their own observations, although there are claims of detecting phosphine on Venus by two instruments now: the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The issue might not get cleared up until new missions go to Venus; unfortunately, NASA's planned Venus missions are possible casualties of budget cuts facing NASA in the next financial year — although a European mission, named EnVision, is still set for launch in 2031.

More recently, there is the claim for the detection of a biosignature gas, dimethyl sulfide, in the atmosphere of an exoplanet called K2-18b. Some models suggest that K2-18b is a hycean world — an ocean planet with a thick atmosphere of hydrogen — and the signature of dimethyl sulfide was detected by the James Webb Space Telescope. However, just as with phosphine on Venus, the claimed detection has been strongly disputed. It is right at the limits of the JWST's abilities to detect, so we might not get confirmation one way or another until a larger space telescope is launched.

We don't necessarily have to face that problem for Mars and Cheyava Falls. Perseverance has taken a sample of the rock, stowing it away in a protective canister for a future mission to pick up and return to Earth.

"It would be great to get those samples back to Earth and into a terrestrial laboratory," says Abramov. "Then we could analyze those samples to high resolution, and we might find other lines of evidence such as potential microfossils and other minerals."

However, those waiting for a eureka moment, a definite discovery, might still be in for disappointment. It's easy to forget that the biosignature on Cheyava Falls is billions of years old, and what we're seeing is a trace, of a trace, of a trace, of what might have been connected to microbial life in the past.

"In terms of a definitive answer, the way I look at it is, as scientists, we get closer and closer to the truth without quite getting there," says Abramov. "So in terms of saying definitively whether it is life or not, that is going to be very difficult if not impossible."

Unfortunately, NASA's planned Mars Sample Return mission to collect Perseverance's sample canisters is under threat. Technical and cost problems have seen NASA turn to private aerospace companies to see if they can come up with a solution to making the mission successful, but even if they can, it might not survive the cost-cutting facing NASA in the Trump Administration's planned budget for the 2026 financial year.

"Getting those samples to Earth and analyzing them in proper labs is going to be our best chance of understanding what's happening," says Abramov.

Only then could scientists make possibly the greatest discovery in history: the discovery of life, past or present, on another planet.

Enceladus is one of the most intriguing moons in the solar system due to the discovery by NASA's Cassini probe of plumes of water ice erupting from the moon's south polar region. The find indicates geological activity on Enceladus, along with a subsurface ocean of liquid water — and perhaps even an environment capable of sustaining life.

ESA is now targeting a mission to study enigmatic Enceladus as part of its Voyage 2050, the agency's long-term plan for space science activities, according to ESA officials at the Europlanet Science Congress (EPSC) and Division for Planetary Sciences (DPS) joint meeting, which was held in Helsinki in early September.

The Enceladus mission, though in its earliest stages, will need both an orbiter and a lander to answer major science questions, with the orbiter to be designed to sample material in the plumes emanating from the "tiger stripes" at the south pole.

An early mission configuration following first industrial studies calls for two launches of the largest variant of the Ariane 6 rocket, with spacecraft to dock in Earth orbit. Next, approval is needed at the ESA ministerial meeting in Bremen, Germany, in November, allowing a mission definition phase, leading to mission adoption in 2034 and a launch around 2042. The spacecraft would then arrive in the Saturn system in 2053, starting a tour of Enceladus and other moons, collection of plume material and preparation for a landing around 2058.

Jörn Helbert of ESA's European Space Research and Technology Centre (ESTEC) stated in a presentation at EPSC-DPS that, since March of this year, the ESA study team has been working with a newly selected payload working group and an expert committee to refine the science requirements and identify key technologies.

The Enceladus mission aims to advance European expertise in several scientific and technological fields, including in-orbit assembly, operating in extreme environments, landing technologies and novel scientific instrumentation, according to Helbert. He added that the development of these technologies will have wide-ranging applications beyond ESA's space science program.

Helbert noted that Enceladus has three necessary conditions for supporting life as we know it: the presence of liquid water, a source of energy and a specific set of chemical elements. An answer to the question of whether or not life exists below Enceladus's icy shell may, however, require decades of efforts in terms of planning, resources and innovation.

Planets lacking plate tectonics and sufficient carbon dioxide and oxygen could make advanced civilizations like ours extremely rare, Manuel Scherf and Helmut Lammer of the Austrian Academy of Sciences suggested during a presentation at the Europlanet Science Congress and the Division for Planetary Science (EPSC-DPS) in Helsinki earlier this month.

According to their research, for a biosphere to persist long enough to allow for the evolution of complex life and subsequent advanced technology, an Earth-like planet needs to meet certain criteria.

First, there must be enough carbon dioxide to sustain photosynthesis and prevent atmospheric escape — but not too much that the atmosphere becomes toxic or traps too much heat. The key to this balance is plate tectonics, which regulate the amount of atmospheric carbon dioxide via the carbon-silicate cycle.

But plate tectonics won't maintain the biosphere forever. "At some point, enough carbon dioxide will be drawn from the atmosphere so that photosynthesis will stop working. For the Earth, that's expected to happen in about 200 million to roughly one billion years," Scherf said in a statement. Thus, a planet would also need a life-sustaining biosphere that lasts longer than the time it takes for technologically intelligent life to evolve. On Earth, that evolution took 4.5 billion years.

Second, a world must have a nitrogen-oxygen dominant atmosphere to develop an advanced civilization. Oxygen, in particular, is crucial not only for biology but also for technological advancement. For example, levels below about 18% oxygen could prevent the use of fire, which historically has been essential for metalworking and thus the development of advanced tools.

The team created models to compare the lifespans of biospheres with various atmospheric compositions to the amount of time it might take advanced civilizations to evolve. They concluded that if an advanced technological civilization were to exist in our Milky Way galaxy, the closest it would be to Earth is likely about 33,000 light-years away. Such a civilization would also have to survive for at least 280,000 years — and possibly much longer — for there to be any chance it overlaps with ours in time.

In other words, the odds are very slim that we coexist with another intelligent civilization in the Milky Way.

Despite the grim outlook, the authors encourage continued efforts, especially through SETI (the search for extraterrestrial intelligence). "Although ETIs [extraterrestrial intelligences] might be rare, there is only one way to really find out, and that is by searching for it," said Scherf. "If these searches find nothing, it makes our theory more likely, and if SETI does find something, then it will be one of the biggest scientific breakthroughs ever achieved, as we would know that we are not alone in the universe."

For years, scientists thought these planets, which are larger than Earth but smaller than Neptune, could form far from their stars, sweeping up ice beyond the so-called "snow line." As the planets migrated inward, scientists have thought that ice might melt into oceans hidden beneath hydrogen skies. Such hypothetical worlds were dubbed "Hycean planets," a blend of "hydrogen" and "ocean."

"Our calculations show that this scenario is not possible," Caroline Dorn, an assistant professor of Physics at ETH Zürich in Switzerland who co-led the new study, said in a statement.

The results come just months after high-profile claims about K2-18b, an exoplanet about 124 light-years away, made global headlines as a likely ocean world "teeming with life." A team of scientists studying James Webb Space Telescope (JWST) observations had reported hints of a possible biomarker gas, dimethyl sulfide, on K2-18b — fueling speculation that the planet might be cloaked in a hydrogen-rich atmosphere above a vast global ocean. These are conditions that could potentially support life (as we know it).

But those claims were quickly met with pushback. Independent analyses of the same JWST data suggested the team's evidence for DMS was weak at best, while other experts cautioned that sub-Neptunes may not be ocean-bearing worlds at all, but rather volatile-rich planets wrapped in thick, hostile atmospheres.

In the new study, Dorn and her team modeled how sub-Neptunes evolve during their early lifetimes, when they are thought to be blanketed by hydrogen gas and covered for millions of years by molten rock. Unlike earlier studies, the researchers included chemical interactions between magma and the atmosphere, according to the statement.

Of the 248 model planets the team studied, "there are no distant worlds with massive layers of water where water makes up around 50 percent of the planet's mass, as was previously thought," Dorn said in the statement. "Hycean worlds with 10-90 percent water are therefore very unlikely."

The team found that hydrogen and oxygen — the building blocks of H2O — tend to bind with metals and silicates in the interior, effectively sequestering water deep in the interior. Even planets that began with abundant ice ended up with less than 1.5% of their mass as water near the surface, the new study reports, far less than the tens of percent envisioned for Hycean planets.

"We focus on the major trends and can clearly see in the simulations that the planets have much less water than they originally accumulated," Aaron Werlen, a researcher on Dorn's team at ETH Zürich who co-led the new study, said in the same statement. "The water that actually remains on the surface as H2O is limited to a few per cent at most."

The researchers also found that the most water-rich atmospheres did not appear on planets formed far from their stars, where ice is plentiful, but rather on planets formed closer in. In these cases, water was generated chemically, as hydrogen in the atmosphere reacted with oxygen from the molten rock.

The implications are sobering for astrobiology. If Hycean planets do not exist, the most promising havens for liquid water, and potentially life, may lie on smaller, rocky worlds more akin to Earth.

Still, K2-18b remains a captivating target, scientists say. As a sub-Neptune, a type of planet missing from our own solar system but common across the galaxy, it could reveal fundamental insights into how planetary systems form and why ours turned out the way it did.

The new results also suggest that Earth may not be exceptional, with many distant worlds veiled in similarly modest traces of water.

"The Earth may not be as extraordinary as we think," Dorn said in the statement. "In our study, at least, it appears to be a typical planet."

The research was published on Sept. 18 in The Astrophysical Journal Letters.

In the study, scientists identified 24 minerals that chart Jezero's changing environment, highlighting both the volcanic origins of rocks in the crater and a long history of their interaction with water. Although the research does not analyze the Sapphire Canyon sample directly, it shows the crater as a whole experienced multiple episodes of water activity, each with conditions that could have supported life (as we know it).

"There were several times in Mars' history when these particular volcanic rocks interacted with liquid water," study lead author Eleanor Moreland of Rice University in Texas said in a statement, "and therefore more than one time when this location hosted environments potentially suitable for life."

The study draws on three years of data collected by Perseverance, which has been exploring Jezero since landing on Mars in 2021. Using the rover's X-ray instrument (PIXL) and a newly developed algorithm called MIST, researchers were able to identify the minerals and assemble a so-called "mineralogical archive" of the crater, according to the statement.

Minerals are natural storytellers, forming under specific combinations of temperature, chemistry and pH. At Jezero, they reveal three stages of water-rock interaction, each with different implications for habitability, the new study notes. To ensure accuracy, the team ran their identifications through thousands of statistical simulations — a process likened to how meteorologists model hurricane tracks — to account for instrument error and assign confidence levels to each match, according to the statement.

The oldest rocks on the crater floor bore signs of hot, acidic fluids, recorded in minerals such as greenalite, hisingerite and ferroaluminoceladonite. These conditions would have been least favorable for life, scientists say, as high temperatures and low pH are known to damage biological structures.

"These hot, acidic conditions would be the most challenging for life," study co-author Kirsten Siebach, who is an assistant professor of Earth, environmental and planetary sciences at Rice University, said in the statement. "But on Earth, life can persist even in extreme environments like the acidic pools of water at Yellowstone, so it doesn't rule out habitability."

Later episodes of water activity left behind minerals such as minnesotaite and clinoptilolite, which formed in cooler, more neutral waters that would have been friendlier to microbes, the study reports.

Finally, researchers found widespread deposits of sepiolite, a mineral that forms in low-temperature, alkaline waters considered highly hospitable from an Earth perspective. Its presence across all regions Perseverance has explored suggests a broad episode of habitable conditions, scientists say.

"These minerals tell us that Jezero experienced a shift from harsher, hot, acidic fluids to more neutral and alkaline ones over time — conditions we think of as increasingly supportive of life," Moreland said in the statement.

Alongside these alteration minerals, the team also confirmed the presence of volcanic building blocks such as pyroxene, feldspar and olivine, reinforcing the prevailing view that Jezero's floor was formed by ancient lava flows later transformed by water.

The new findings also add context to last year's headlines, when Perseverance's work at Cheyava Falls — where Sapphire Canyon was sampled — revealed intriguing signs of conditions often linked to microbial life. At the time, scientists described it as the strongest evidence yet that Mars may once have hosted primitive organisms, though they stressed that nonbiological explanations, such as certain mineral reactions from heating, could not be ruled out.

Follow-up analyses have since found no evidence the rock was heated, but researchers caution that only laboratory studies on Earth can settle the biological-versus-nonbiological debate.

"We're pretty close to the limits of what the rover can do on the surface," Katie Stack Morgan, Perseverance Project Scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said during a press conference last week on Sept. 10. "That was by design. The payload of the Perseverance rover was selected with a Mars sample return effort in mind; the idea was for our payload to get us just up to the potential biosignature designation and have the rest of the story told by instruments here on Earth."

Each tube cached on Mars could hold a crucial piece of the puzzle — and perhaps, the first direct evidence of life beyond Earth. But the path to bringing them home continues to remain uncertain. After years of cost overruns, NASA announced in January that it would study cheaper alternatives for its proposed Mars Sample Return (MSR) program, which would aim to deliver samples by 2035. The agency's 2026 budget proposal, however, calls for canceling the program.

"We believe there is a better way to do this, a faster way to get these samples back," Sean Duffy, NASA's acting administrator, said during the press conference last week, , though he offered no details on cost, timing, or technical approach.

Meanwhile, China is pushing ahead with its own Mars sample-return mission. The Tianwen-3 mission aims to collect at least 500 grams of Martian rock and soil as early as 2028 and return them to Earth by 2031 — potentially beating NASA to the milestone. If successful, China would secure the first Mars samples and perform a dramatic leap in planetary science leadership.

In addition to revealing Mars' mineral story, the new MIST algorithm developed by the study authors could prove critical in deciding which rocks to return to Earth, the new study notes. By identifying minerals and assigning confidence levels to each detection, it helps mission scientists prioritize the most valuable samples. Such a catalog, tied to specific sampling sites, would be vital when selecting which sealed cores to bring back under the MSR program.

"The results reported here can be crucial when down-selecting which samples, if not all, are returned to Earth," the researchers wrote in the study.

The study was published on Sept. 11 in the Journal of Geophysical Research.

The first planets studied by the ATREIDES program, the two worlds of the TOI-421 system, demonstrate misaligned orbits, hinting that this system experienced a more chaotic evolution than our solar system. Studying it could help astronomers figure out why these "hot Neptunes" appear to be so rare in the cosmos, as well as teach us about how planets form elsewhere in the universe.

"The complexity of the exo-Neptunian landscape provides a unique window onto the processes involved in the formation and evolution of planetary systems," ATREIDES Principal Investigator and University of Geneva (UNIGE) researcher Vincent Bourrier said in a statement describing the ATREIDES program.

To understand why this class of extrasolar planet, or "exoplanet," is missing from close orbits around other stars, ATREIDES scientists investigated the TOI-421 planetary system. Located around 244 light-years from Earth, TOI-421 is an orange dwarf or "K-type" star orbited by two exoplanets, TOI-421 b and TOI-421 c. What this investigation revealed is a surprisingly tilted orbital situation in TOI-421 that implies that this system experienced a chaotic history, one which may help explain why hot Neptunes are so rare.

TOI-421 b is a scorching hot sub-Neptune planet with a mass around 7 times that of Earth that orbits its star at a distance equivalent to around 6% of the distance between our planet and the sun. TOI-421 c is larger, with a mass of around 14 times that of Earth, which orbits its star at a distance equivalent to around 12% the distance between Earth and the sun, making it a hot Neptune and putting it in a region adjacent to the Neptunian desert called "the savanna."

"A thorough understanding of the mechanisms that shape the Neptunian desert, savanna, and ridge will provide a better understanding of planetary formation as a whole ... but it's a safe bet that the universe has other surprises in store for us, which will force us to develop new theories," Bourrier said.

Mapping the Neptunian desert

Over the last 10 years of exoplanet observations, the Neptunian desert has become increasingly complex. Areas further out from stars than the Neptunian desert have been found to be more generously populated with Neptune-sized worlds. This more temperate realm with more Neptune-like exoplanets has come to be known as the "savanna" of the Neptunian desert.

Astronomers have also defined a region between the Savanna and the Neptunian desert, which they call the "Neptunian ridge." This region is more densely populated by Neptune-like worlds than both the desert and the savanna. The scientists of the ATREIDES program aim to understand these three distinct regions by identifying the processes that lead to the relative planetary populations.

The team wants to test the hypothesis that the Neptunian landscape is created as a result of the way that planets migrate from their birthplaces to the orbits we observe them in.

Some exiled planets would migrate slowly through the disk of gas and dust that exists in these systems during their infancy. This sedate migration should produce planets in orbits aligned with their star's equator and the orbits of the other planets in their home system. That is similar to the orbits of the planets in the solar system, which are aligned almost to the equatorial plane of the sun.

However, some other planets would be violently thrown from their site of formation via a chaotic process called "high-eccentricity migration." That should result in those planets falling into highly misaligned orbits.

That means the alignment between a star's orbital plane and the orbital plane of its planets is key to investigating this migration hypothesis.

The team can't yet say anything conclusive yet about the Neptunian desert, its neighboring regions, or planetary evolution in general. Many more observations of more planetary systems with hot Neptunes will be needed for that.

However, this research successfully demonstrates the effectiveness of the ATREIDES program and the techniques it has developed and employed.

The team's research was published on Tuesday (Sept. 16) in the journal Astronomy & Astrophysics.

But new research presented this week at a planetary science conference in Finland shows that many of the organic molecules detected in these plumes could also form right on the moon's surface, driven by relentless radiation from Saturn's magnetic field. The results cast doubt on whether the plumes truly carry whispers of alien life, or merely echoes of lifeless chemistry on the frozen shell.

"Although this doesn't rule out the possibility that Enceladus' ocean may be habitable, it does mean we need to be cautious in making that assumption just because of the composition of the plumes," study lead Grace Richards of Italy's National Institute for Astrophysics said in a statement.

For their experiment, Richards and her colleagues recreated conditions on Enceladus in miniature inside a specialized laboratory in Hungary. Using an ice chamber, the team froze mixtures of water, carbon dioxide, methane and ammonia to a bone-chilling –420 degrees Fahrenheit (-253 degrees Celsius), mimicking frigid conditions near the moon's surface. The ices were then bombarded with high-energy "water-group ions," the same charged particles trapped around Saturn that constantly irradiate Enceladus.

To monitor the chemical changes induced by radiation, the researchers used infrared spectroscopy to observe the molecular "fingerprints," or spectra, of the ices. As radiation interacted with the samples, the spectra shifted, signaling the formation of new molecules.

Each of the five experiments produced carbon monoxide, cyanate, and ammonium — compounds that were detected in Enceladus' plumes by NASA's Cassini spacecraft in 2005. When the samples were gently warmed, more complex organics appeared, including carbamic acid, ammonium carbamate and potential amino acid precursors including methanol and ethanol, as well as molecules like acetylene, acetaldehyde and formamide, which are building blocks that could contribute to the chemistry of life.

"Although many of these products have not previously been detected on Enceladus' surface, some have been detected in Enceladus' plumes," Richards and her colleagues wrote in the paper. This leads to "questions about whether plume material is formed within the radiation-rich space environment or whether it originates in the subsurface ocean."

Crucially, the timescales necessary for radiation to drive these chemical reactions are comparable to how long ice remains exposed on Enceladus' surface or in its plumes, so distinguishing ocean-sourced organics from surface-born ones may be difficult, the study notes.

"It is likely that the composition of the subsurface ocean may not be accurately reflected by the composition of the emergent plume, or by material deposited on the surface immediately adjacent to the plume," the paper reads.

For astrobiologists, the results are both sobering and exciting. On one hand, they complicate the story that organics in the plumes are definitive signs of a life-friendly ocean. On the other, they highlight that rich, potentially life-relevant chemistry can thrive even in extreme, radiation-battered environments, thereby expanding the ways scientists think about where prebiotic molecules might form and why Enceladus remains a prime target for exploration.

NASA's Cassini mission, which ended in 2017 with a dramatic plunge into Saturn's atmosphere, gave humanity its first and only direct "taste" of Enceladus' geysers. But instruments onboard the spacecraft weren't designed to distinguish between molecules forged in the moon's presumably deep ocean and those cooked up in the icy shell.

These answers could come in the coming decades with future missions. One concept under consideration as part of the European Space Agency's Voyage 2050 program envisions a dedicated probe that could land on the surface and collect material ejected from the moon's hidden ocean. NASA has also previously studied an "Orbilander" concept designed to sample Enceladus' plumes from orbit.

Meanwhile, China is exploring a multi-part mission architecture that would include an orbiter, a lander and a deep-drilling robot that would attempt to reach the subsurface ocean to search for potential biosignatures.

This research is described in a paper published in the October 15 edition of the journal Planetary & Space Science.

Since February 2021, NASA's Perseverance rover has been exploring a region on Mars known as Jezero Crater, a huge cavity believed to have once hosted a lake. It's considered one of the most promising places to look for evidence of ancient life on the Red Planet (life as we know it, at least) — and there has been an update in the search.

On Wednesday (Sept. 10), researchers presented a study that describes how Perseverance found intriguing minerals on the western edge of Jezero Crater, in the clay-rich, mudstone rocks of a valley called "Neretva Vallis."

"When we see features like this in sediment on Earth, these minerals are often the byproduct of microbial metabolisms that are consuming organic matter," Joel Hurowitz, a planetary scientist at Stony Brook University in New York and lead author of the new study, said during a NASA press conference held on Wednesday.

So, could this mean we've finally found proof of aliens? Well, not quite. The authors stress that further analysis is necessary to identify the true origin of the minerals and determine whether they are indeed markers of life, otherwise known as "biosignatures," or the result of some other inorganic processes.

"I want to remind everyone that what we're describing here is a potential biosignature that is a characteristic element, molecule, substance or feature that might have a biological origin but requires more data or further study before reaching a conclusion about the presence or absence of life," Lindsay Hayes, Senior Scientist for Mars Exploration in the Planetary Science Division at NASA Headquarters, said during the conference.

Either way, the findings do demonstrate that notably complex reactions once occurred on Mars — organic or not — adding yet more layers to the planet humans have been trying to decode since the dawn of astronomy.

To get into some specifics, the samples Perseverance collected that appear to harbor those exciting minerals were found in what's known as the "Bright Angel" formation within the northern margin of Neretva Vallis. Within that formation, one particular rock is of great interest to researchers. It's named "Cheyava Falls."

Not too long ago, when Cheyava Falls was first presented to the public, it made headlines around the world because scientists were openly fawning over the specimen's peculiar, dotty features that resembled "poppy seeds" and "leopard spots." The latter, which are millimeter-size blobs, are each surrounded by black rings that scientists determined contain iron and phosphate after studying them with Perseverance's toolkit. Both substances can result from chemical processes on Earth that are driven by microbes.

"These spots are a big surprise," David Flannery, an astrobiologist and member of the Perseverance science team from the Queensland University of Technology in Australia, said at the time. "On Earth, these types of features in rocks are often associated with the fossilized record of microbes living in the subsurface."

"What we saw in this rock were these layers of very fine-grained, rusty red mud stone that had in them these incredible features," Hurowitz said. "These textural features told us that something really interesting had happened in these rocks, some set of chemical reactions occurred at the time they were being deposited."

The natural next step was to have Perseverance examine Cheyava Falls (and other specimens associated with Bright Angel) a little more closely. On July 21, 2024, the rover even drilled into Cheyava Falls and collected a sample. This sample, the 25th that Perseverance had grabbed, is named Sapphire Canyon.

"I would describe the Sapphire Canyon sample as mysterious," Morgan Cable, a research scientist for Perseverance, previously said in a video about the core sample that NASA posted on April 10. "We see these signatures that tell us chemistry has happened, potentially involving organics — but what does that mean? Could life have been involved, or something that didn't involve life at all?"

That's sort of where the tale left off.

Now, what the new study appears to add to the story is a very detailed analysis of the Bright Angel bunch. Sure enough, the researchers found evidence that this outcrop really could be a solid lead in the quest to find proof of life beyond Earth. According to a release about the results, the team "identified tiny nodules and specks enriched in iron phosphate and iron sulfide. These features are associated with organic carbon and appear to have formed after sediment deposition, under low-temperature conditions."

The key seems to be the result that certain "redox" reactions could have occurred to give rise to these minerals. A redox reaction is a chemical reaction in which electrons are transferred between two substances; one of the substances is oxidized and the other is reduced.

"This organic carbon appears to have participated in post-depositional redox reactions that produced the observed iron-phosphate and iron-sulfide minerals," the study authors wrote.

"The exciting discovery of reduced iron phosphates and sulfides associated with organic compounds in the clay-rich mudstones of Jezero Crater suggests that the organic material might have been involved in the unusual redox reactions," states a News and Views article, written by Janice Bishop of SETI Institute in Mountain View, California and Mario Parente of the University of Massachusetts, Amherst. This article was published in tandem with the study results.

"On Earth, microorganisms commonly interact with minerals and have been observed to convert sulfates (which contain oxidized sulfur atoms) to sulfides (which contain reduced sulfurs) in cold, oxygen-free Antarctic lakes," the News and Views article continues. "There is no evidence of microbes on Mars today, but if any had been present on ancient Mars, they too might have reduced sulfate minerals to form sulfides in such a lake at Jezero crater."

A few other results presented in the team's paper strengthen the case of a possible biosignature existing in Mars' Bright Angel formation as well. For instance, the new findings suggest the green-toned specks in muddy clay found in the outcrop could contain the mineral vivianite, which the News and Views authors say can specifically shed light on certain kinds of redox reactions that may have taken place on Mars.

All in all, however, there is one major underlying elephant in the room: For any further confirmation of whether evidence of Mars life lies in Perseverance's sample tubes, those sample tubes need to be returned to Earth. Unfortunately, as of now, NASA's Mars Sample Return program remains in limbo due to budget constraints, priority shifts since the Trump administration took the White House and a highly complicated blueprint for the mission.

Still, scientists continue to stress that there is only so much one can do when analyzing tiny rock samples while separated by a 140-million-mile (225-million-kilometer) stretch of the vacuum of space.

"We're pretty close to the limits of what the rover can do on the surface," Katie Stack Morgan, Perseverance Project Scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said during the conference. "That was by design. The payload of the Perseverance rover was selected with a Mars sample return effort in mind; the idea was for our payload to get us just up to the potential biosignature designation and have the rest of the story told by instruments here on Earth."

"Laboratory analyses of samples returned from Mars could also cast light on the potential for prebiotic — and even biological — chemistry to occur on worlds beyond Earth," the News and Views authors write.

UFOs are coming back to Washington, D.C. tomorrow.

A hearing titled "Restoring Public Trust Through UAP Transparency and Whistleblower Protection" will be held by the Task Force on the Declassification of Federal Secrets, a task force established in January 2025 by the House Committee on Oversight and Government Reform. At the hearing, three U.S. military veterans will share their experiences witnessing UAP, or unidentified anomalous phenomena, a new term for UFOs that encompasses strange objects or events not only in the sky but also in water or space, or that appear to travel between these domains.

The hearing begins at 10 a.m. ET (1400 GMT) on Tuesday (Sept. 9). Watch it live here courtesy of the House Committee on Oversight and Reform.

The Task Force is chaired by Representative Anna Paulina Luna (R-Fla.), who has alleged that the U.S. government is hiding the truth about many other conspiracies. "It is time to give Americans the answers they deserve, which is why I am honored to lead this bipartisan task force that seeks truth and transparency," Luna said in a House statement announcing the task force. "We will also investigate UAPs/USOs, the Epstein client list, COVID-19 origins, and the 9/11 files."

Luna says tomorrow's hearing is intended to compel Congress to reexamine what types of information should be classified and which should be available to the public, mostly when it comes to UAP. "The American people deserve maximum transparency from the federal government on sightings, acquisitions, and examinations of UAPs and whether they pose a potential threat to Americans' safety," Luna said in a House statement announcing the hearing.

In addition to the three military veterans who claim to have witnessed UAP, the hearing will also include longtime investigative journalist George Knapp. For decades, Knapp has claimed the U.S. government is hiding evidence of UFOs and/or alien life. In the late 1980s while working as anchor for KLAS-TV in Las Vegas, Knapp rose to fame helping popularize the claims of UFO-lore stalwarts Bob Lazar and John Lear.

Lazar claims to have worked at the U.S. Air Force's infamous Area 51 facility where he helped reverse engineer crashed flying saucers. His claims have never been substantiated.

Lear, meanwhile, was a former CIA pilot who promoted theories that the U.S. government was involved in a long-term conspiracy to hide the fact that it colluded with extraterrestrial beings.

Ultimately, Tuesday's hearing is intended to send the message that "whistleblowers who provide details on spending information and policies and procedures regarding the classification and declassification of UAPs should be able to do so without retribution," according to Luna's statement.

We've heard similar sentiments in previous congressional hearings. In November 2024, former U.S. counterintelligence officer Luis Elizondo, who claims to have investigated UAP while working for secret Pentagon program, testified that we are "in the midst of a multi-decade, secretive arms race  — one funded by misallocated taxpayer dollars and hidden from our elected representatives and oversight bodies."

Elizondo, who has shared easily debunked imagery as proof of UAP in other congressional briefings, suggested the U.S. government should offer protections to UAP whistleblowers so those who are "desperate to do the right thing can come forward without fear."

For decades, purported whistleblowers have argued that classified military and intelligence sensors and satellites regularly record evidence of unexplained phenomena or advanced craft, potentially piloted by alien beings.

But because those records are classified by the U.S. government in order to not reveal the full extent of its surveillance or sensing capabilities, these whistleblowers argue, the truth is being withheld from the American public and the world.

The planet in question is TRAPPIST-1e, an Earth-sized rocky exoplanet that's located around 40 light-years away from our planet.

TRAPPIST-1e is the fourth planet in orbit around a red dwarf star called TRAPPIST-1. It sits well within the "habitable zone" or Goldilocks zone, the region of space around a star that is neither too hot nor too cold to allow liquid water to exist on the surface of a planet.

However, just existing in the habitable zone of a star isn't sufficient to guarantee the existence of liquid-water oceans or indeed the conditions needed to support life. After all, Earth, Mars, and Venus are all in our solar system's habitable zone, but only one of these planets has water oceans and supports life today (as far as we know). One of the key differences is the atmosphere of our planet, and that is what astronomers are searching for around TRAPPIST-1e.

"TRAPPIST-1e has long been considered one of the best habitable zone planets to search for an atmosphere," study team member Ryan MacDonald, a researcher at the University of St. Andrews in Scotland, said in a statement. "But when our observations came down in 2023, we quickly realized that the system’s red dwarf star was contaminating our data in ways that made the search for an atmosphere extremely challenging."

The JWST data indicate several possible scenarios for TRAPPIST-1e and its potential atmosphere. That makes this research a significant step forward in the search for life beyond the solar system.

To examine the potential atmosphere of TRAPPIST-1e, the team had to wait until it crossed or "transited" the face of its parent star. This reveals details of the chemical composition of a planet's atmosphere because chemicals absorb light at characteristic wavelengths. That means when starlight passes through a planetary atmosphere, the chemicals in that atmosphere leave their characteristic "fingerprints" in the spectrum.

This isn't as straightforward as it may initially sound. Astronomers have to account for factors like starspots across the face of the red dwarf star. So the team has spent the last year carefully removing contamination from the TRAPPIST-1e data to hone in on the planet's atmosphere, or lack thereof.

"We are seeing two possible explanations," MacDonald said. "The most exciting possibility is that TRAPPIST-1e could have a so-called secondary atmosphere containing heavy gases like nitrogen. But our initial observations cannot yet rule out a bare rock with no atmosphere."

The indeterminate nature of the team's results means that JWST is far from finished with TRAPPIST-1e. The researchers hope to perform a deeper search for the planet's atmosphere, with each subsequent transit potentially presenting a clearer picture of its atmospheric contents.

"In the coming years, we will go from four JWST observations of TRAPPIST-1e to nearly 20," MacDonald concluded. "We finally have the telescope and tools to search for habitable conditions in other star systems, which makes today one of the most exciting times for astronomy."

The team's research was published as two papers on Monday (Sept. 8) in The Astrophysical Journal Letters

The sun will someday die. This will happen when it runs out of hydrogen fuel in its core and can no longer produce energy through nuclear fusion as it does now. The death of the sun is often thought of as the end of the solar system. But in reality, it may be the beginning of a new phase of life for all the objects living in the solar system.

When stars like the sun die, they go through a phase of rapid expansion called the Red Giant phase: The radius of the star gets bigger, and its color gets redder. Once the gravity on the star’s surface is no longer strong enough for it to hold on to its outer layers, a large fraction – up to about half – of its mass escapes into space, leaving behind a remnant called a white dwarf.

I am a professor of astronomy at the University of Wisconsin-Madison. In 2020, my colleagues and I discovered the first intact planet orbiting around a white dwarf. Since then, I've been fascinated by the prospect of life on planets around these, tiny, dense white dwarfs.

Researchers search for signs of life in the universe by waiting until a planet passes between a star and their telescope's line of sight. With light from the star illuminating the planet from behind, they can use some simple physics principles to determine the types of molecules present in the planet's atmosphere.

In 2020, researchers realized they could use this technique for planets orbiting white dwarfs. If such a planet had molecules created by living organisms in its atmosphere, the James Webb Space Telescope would probably be able to spot them when the planet passed in front of its star.

In June 2025, I published a paper answering a question that first started bothering me in 2021: Could an ocean – likely needed to sustain life – even survive on a planet orbiting close to a dead star?

A universe full of white dwarfs

A white dwarf has about half the mass of the Sun, but that mass is compressed into a volume roughly the size of Earth, with its electrons pressed as close together as the laws of physics will allow. The sun has a radius 109 times the size of Earth's – this size difference means that an Earth-like planet orbiting a white dwarf could be about the same size as the star itself.

White dwarfs are extremely common: An estimated 10 billion of them exist in our galaxy. And since every low-mass star is destined to eventually become a white dwarf, countless more have yet to form. If it turns out that life can exist on planets orbiting white dwarfs, these stellar remnants could become promising and plentiful targets in the search for life beyond Earth.

But can life even exist on a planet orbiting a white dwarf? Astronomers have known since 2011 that the habitable zone is extremely close to the white dwarf. This zone is the location in a planetary system where liquid water could exist on a planet’s surface. It can’t be too close to the star that the water would boil, nor so far away that it would freeze.

The habitable zone around a white dwarf would be 10 to 100 times closer to the white dwarf than our own habitable zone is to our Sun, since white dwarfs are so much fainter.

The challenge of tidal heating

Being so close to the surface of the white dwarf would bring new challenges to emerging life that more distant planets, like Earth, do not face. One of these is tidal heating.

Tidal forces – the differences in gravitational forces that objects in space exert on different parts of a nearby second object – deform a planet, and the friction causes the material being deformed to heat up. An example of this can be seen on Jupiter's moon Io.

The forces of gravity exerted by Jupiter's other moons tug on Io's orbit, deforming its interior and heating it up, resulting in hundreds of volcanoes erupting constantly across its surface. As a result, no surface water can exist on Io because its surface is too hot.

In contrast, the adjacent moon Europa is also subject to tidal heating, but to a lesser degree, since it's farther from Jupiter. The heat generated from tidal forces has caused Europa's ice shell to partially melt, resulting in a subsurface ocean.

Planets in the habitable zone of a white dwarf would have orbits close enough to the star to experience tidal heating, similar to how Io and Europa are heated from their proximity to Jupiter.

This proximity itself can pose a challenge to habitability. If a system has more than one planet, tidal forces from nearby planets could cause the planet’s atmosphere to trap heat until it becomes hotter and hotter, making the planet too hot to have liquid water.

Enduring the red giant phase

Even if there is only one planet in the system, it may not retain its water.

In the process of becoming a white dwarf, a star will expand to 10 to 100 times its original radius during the red giant phase. During that time, anything within that expanded radius will be engulfed and destroyed. In our own solar system, Mercury, Venus and Earth will be destroyed when the Sun eventually becomes a red giant before transitioning into a white dwarf.

For a planet to survive this process, it would have to start out much farther from the star — perhaps at the distance of Jupiter or even beyond.

If a planet starts out that far away, it would need to migrate inward after the white dwarf has formed in order to become habitable. Computer simulations show that this kind of migration is possible, but the process could cause extreme tidal heating that may boil off surface water – similar to how tidal heating causes Io’s volcanism. If the migration generates enough heat, then the planet could lose all its surface water by the time it finally reaches a habitable orbit.

However, if the migration occurs late enough in the white dwarf's lifetime – after it has cooled and is no longer a hot, bright, newly formed white dwarf – then surface water may not evaporate away.

Under the right conditions, planets orbiting white dwarfs could sustain liquid water and potentially support life.

Search for life on planets orbiting white dwarfs

Astronomers haven't yet found any Earth-like, habitable exoplanets around white dwarfs. But these planets are difficult to detect.

Traditional detection methods like the transit technique are less effective because white dwarfs are much smaller than typical planet-hosting stars. In the transit technique, astronomers watch for the dips in light that occur when a planet passes in front of its host star from our line of sight. Because white dwarfs are so small, you would have to be very lucky to see a planet passing in front of one.

Nevertheless, researchers are exploring new strategies to detect and characterize these elusive worlds using advanced telescopes such as the Webb telescope.

If habitable planets are found to exist around white dwarfs, it would significantly broaden the range of environments where life might persist, demonstrating that planetary systems may remain viable hosts for life even long after the death of their host star.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

That strong, baffling radio episode was captured by Ohio State University's Search for Extraterrestrial Intelligence (SETI) project, also known as the "Big Ear." It has been viewed by some as one of the oddest radio transmissions from afar ever detected, also cited as compelling evidence for extraterrestrial intelligence.

The outburst was a strong narrowband radio signal received on Aug. 15, 1977 by Ohio State University's Big Ear radio telescope. Astronomer Jerry Ehman discovered the anomaly a few days later while reviewing the recorded data — writing on a computer printout "Wow!"

Unpublished observations, archival data

Jump ahead to today. Researchers from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo are proposing a less extraterrestrial explanation. On-going assessments, led by Abel Méndez, are being pursued under the "Arecibo Wow!" Project, an initiative established to analyze unexplained radio signals from space in the search for extraterrestrial intelligence.

"We look at old archives with modern science methodologies. It's a bit like space archaeology," said Wow! Signal researcher Hector Socas Navarro, director of the European Solar Telescope Foundation and a staff scientist at the Instituto de Astrofísica de Canarias.

New clues

Researchers from that project have re-analyzed decades of previously unpublished observations and archival data from the Ohio State University SETI program. The result is the most precise characterization yet of the perplexing signal from afar and revealing new clues to its origin.

"Our newly derived properties may help finally pinpoint the source of the Wow! Signal," Méndez told Space.com. While the group's just-published paper focused on revising the known properties of the Wow! Signal, "we also discovered new properties that we look forward to sharing in an upcoming paper," he advised.

"We aim to archive and share all data from the Big Ear telescope by 2027, marking the 50th anniversary of the Wow! Signal," Méndez added.

Natural astrophysical origin?

In a recent posting on the Arecibo Wow! Project's website, Méndez underscored the team's output to date.

The research findings spotlight the prospect that the Wow! Signal was created by a natural astrophysical origin, Méndez and colleagues report. Also the work does make radio interference "an increasingly unlikely explanation," they add.

"This study doesn't close the case," Méndez points out. "It reopens it, but now with a much sharper map in hand."

Méndez and fellow researchers hypothesize that the Wow! Signal was caused by a sudden brightening of the hydrogen line in interstellar clouds, triggered by a powerful transient radiation source such as a magnetar flare or soft gamma repeater (SGR).

"Our results don't solve the mystery of the Wow! Signal," Méndez states. "But they give us the clearest picture yet of what it was and where it came from. This new precision allows us to target future observations more effectively than ever before."

Citizen science — join the search

The continuing research into the Wow! Signal has spurred the creation of the Wow@Home project. This initiative is a low-cost way that others can now actively search for similar signals and other rare cosmic events, including potential technosignatures of other star folk — in real time.

Wow@Home project officials found that the Wow! Signal was strong enough that even small telescopes could potentially detect similar signals.

Indeed, a network of small radio telescopes offers several distinct advantages compared to large professional observatories.

Low-cost systems can operate autonomously around the clock, "making them ideal for continuous monitoring of transient events or long-duration signals that professional telescopes cannot commit to observing full-time," Méndez and colleagues suggest.

Wow-like signal strength

Wow@Home is a cost-effective, engaging, and accessible, ideal for education, citizen science, and expanding participation in radio astronomy.

"A complete setup costs around $500, including a dedicated computer, but we are not selling these systems. Instead, we will provide recommendations for the necessary parts and offer free software to power the telescope and connect it to the Wow@Home network to search for transient events," a Wow@Home posting explains.

The software is built on analysis methods the project's developing to detect Wow-like signals in the archive data of professional observatories, as part of their Arecibo Wow! undertaking.

For more information on Wow@Home, visit the project's website. The group's recent research report is available on arXiv.org and will be submitted to the Astrophysical Journal.

"We consider water to be required for life because that is what's needed for Earth life. But if we look at a more general definition, we see that what we need is a liquid in which metabolism for life can take place," study leader Rachana Agrawal, a postdoctoral student at the Massachusetts Institute of Technology (MIT), said in a statement.

Agrawal and her team studied ionic liquids — salts that are liquid at sub-boiling temperatures (below 212 degrees Fahrenheit, or 100 degrees Celsius) — as a potential hospitable environment for life. Per the researchers' laboratory experiments, ionic liquids can likely form from ingredients found on rocky planets and moons.

Most importantly, the team determined that ionic liquids could form where liquid water can't, thanks to its ability to remain liquid at a wide range of temperatures and pressures. And ultimately, these ionic liquids might be able to support biomolecules like proteins.

"[T]his can dramatically increase the habitability zone for all rocky worlds," said Agrawal.

As things go in science, this discovery was something of a happy accident. Initially, the team set out to investigate signs of life on Venus, looking to find a way to collect and evaporate sulfuric acid from Venus' clouds. But when the researchers ran their evaporation experiments, they found that a liquid layer always remained. That layer, they determined, was an ionic liquid, formed when sulfuric acid reacted with glycine.

"From there, we took the leap of imagination of what this could mean," said Agrawal. "Sulfuric acid is found on Earth from volcanoes, and organic compounds have been found on asteroids and other planetary bodies. So, this led us to wonder if ionic liquids could potentially form and exist naturally on exoplanets."

More study is necessary, of course. "We just opened up a Pandora's box of new research," said MIT professor Sara Seager, a co-author of the study. "It's been a real journey."

The team's paper was published Monday (Aug. 11) in the journal Proceedings of the National Academy of Sciences.

Using the Atacama Large Millimeter/ submillimeter Array (ALMA), a system of radio telescopes in Chile, the team detected traces of 17 complex organic molecules in the protoplanetary disc of V883 Orionis, a young star located around 1,305 light-years away in the constellation of Orion.

V883 Orionis is an infant star, or protostar, that is estimated to be just 500,000 years old, and it's in the active phase of gathering mass and forming planets. If 0.5 million years old seems ancient, consider that our middle-aged sun is about 4.6 billion years old.

Complex organic molecules are molecules that have more than five atoms, at least one of which is carbon. They have been seen around sites of star and planet formation previously.

However, the compounds discovered around V883 Orionis include the first tentative detections of ethylene glycol and glycolonitrile, compounds that are considered precursors to the building blocks of life. For instance, glycolonitrile is a precursor of the amino acids glycine and alanine, as well as the nucleobase adenine, one of the building blocks of DNA and RNA.

The find could therefore provide a missing link in the story of the evolution of molecules around young stars, accounting for the period between the initial formation of stars and the growth of planets in their surrounding protoplanetary disks.

"Our finding points to a straight line of chemical enrichment and increasing complexity between interstellar clouds and fully evolved planetary systems," team leader Abubakar Fadul, a scientists at the Max Planck Institute for Astronomy (MPIA) in Germany, said in a statement.

A cosmic chemical assembly line

Stars start life when overdense clumps in vast clouds of interstellar gas and dust collapse under their own gravity. This creates a protostar that continues to gather matter from its natal envelope until it has sufficient mass to trigger the fusion of hydrogen to helium in its core. That's the nuclear process that defines what a main-sequence star is.

As this proceeds, material around the budding star flattens out into a swirling donut of gas and dust called a protoplanetary disk, from which planets will eventually emerge.

The transition from protostar to a young main-sequence star is a violent one, replete with intense radiation, shocked gas, and gas being ejected from the protoplanetary disk. This is thought to be deleterious to the continued existence of complex chemicals built during earlier stages of the protostar's existence.

This has led to the development of a so-called "reset scenario" that sees the chemicals needed for life forming at later stages in the existence of the protoplanetary disk, as planets, asteroids, and comets are formed.

However, the new discovery suggests that this reset scenario is unnecessary.

"Now it appears the opposite is true," said team member and MPIA scientist Kamber Schwarz. "Our results suggest that protoplanetary disks inherit complex molecules from earlier stages, and the formation of complex molecules can continue during the protoplanetary disk stage."

The team theorizes that the period between the energetic protostellar phase and the establishment of a protoplanetary disk would be too brief for complex organic molecules to form in detectable amounts. The upshot of this is that the conditions that predefine biological processes may not be restricted to individual planetary systems, but may be more widespread.

Because the chemical reactions that create complex organic molecules proceed better in colder conditions, they could occur in icy dust that later gathers to form large bodies.

That means these molecules could remain hidden in dust, rock and ice in young planetary systems, only accessible when heating by the central star warms those materials.

This is something seen in our own solar system when comets from the outer region of our planetary system pass close to the sun, creating cometary tails and halos called comas.

Though V883 Orionis hasn't yet reached the mass needed to achieve nuclear fusion, there is a heating mechanism available in this young system for a similar thawing to occur: When material falls to the star, facilitating its growth, bursts of intense radiation are triggered.

"These outbursts are strong enough to heat the surrounding disk as far as otherwise icy environments, releasing the chemicals we have detected," said Fadul.

It's fitting that ALMA, an array of 66 radio telescopes located in the Atacama Desert region of northern Chile, has been integral to probing deeper into the disk around V883 Orionis. It was this array, after all, that first discovered the water snow line in the disk of V883 Orionis back in 2016.

"While this result is exciting, we still haven't disentangled all the signatures we found in our spectra," Schwarz said. "Higher resolution data will confirm the detections of ethylene glycol and glycolonitril and maybe even reveal more complex chemicals we simply haven't identified yet."

Fadul suggested that astronomers need to look at light from stars like V883 Orionis and its protoplanetary disk in other wavelengths of the electromagnetic spectrum to find even more evolved molecules.

"Who knows what else we might discover?" Fadul concluded.

The team's research is available as a preprint on the paper repository arXiv.

While signs of life on the world have failed to conclusively present themselves to the James Webb Space Telescope (JWST), the powerful space telescope has discovered that this planet is so rich in liquid water that it could be an ocean, or "Hycean" world.

"This has certainly increased the chances of habitability on K2-18 b" Nikku Madhusudhan, the University of Cambridge scientist behind the original K2-18b discovery as well as the new study, told Space.com. "This is a very important development and further increases the chance of a Hycean environment in K2-18 b. It confirms K2-18 b to be our best chance to study a potential habitable environment beyond the solar system at the present time."

The story regarding the habitability of K2-18 b began back in April 2025, when Madhusudhan and fellow researchers from the University of Cambridge announced they had found what they called the "strongest evidence yet" of life beyond the solar system around this distant super-Earth (it's around nine times as massive as our planet).

The evidence came from the tentative detection of molecules that, when found in the atmosphere of Earth, are typically the result of biological processes of living things. The pressure was then on to confirm these potential biosignatures: dimethyl sulfide and dimethyl disulfide.

The team set about this by observing four separate instances of K2-18 b crossing, or "transiting," the face of its parent red dwarf star, located about 124 light-years away, during its roughly 33-Earth-day orbit. Because chemicals absorb and emit light at characteristic wavelengths, when light from a parent star passes through a planet's atmosphere, the molecules in that atmosphere leave their telltale fingerprints in the spectrum of starlight.

"With four additional transit observations using JWST, we have measured the spectrum of K2-18 b’s atmosphere with unprecedented precision," Renyu Hu, the new study's team leader and a NASA Jet Propulsion Lab scientist, told Space.com. "The spectrum allowed us to conclusively detect both methane and carbon dioxide in the planet's atmosphere and to constrain their abundances. This information points to a planet with a water-rich interior."

Hu explained that the team searched for signals of dimethyl sulfide and other organic sulfur molecules in the spectrum using several independent models, but did not find conclusive evidence for their presence.

"This was not necessarily disappointing," Hu continued. "We're excited about establishing the planet’s water-rich nature."

Is K2-18 b a ocean world?

Saying it's now confirmed that K2-18 b is water-rich, Hu explained that the next step is to discover if the planet possesses a global liquid water ocean.

Ironically, one of the most positive signs of such an ocean is the fact that the atmosphere of this super-Earth appears to lack water vapor.

"The spectrum we obtained does not show signs of water vapor. If the atmosphere truly lacks water, this suggests that water has been depleted — most likely through condensation," Hu said. "On Earth, this process is known as the 'cold trap,' and geoscientists consider it essential for retaining water over billions of years by preventing it from escaping to space.

"Observing a similar process on an exoplanet would be very exciting. Rigorously confirming the absence of water can by itself be a scientifically important goal for future observations," Hu said.

However, Hu cautioned that the spectrum detected by the JWST could also be explained by an alternative model in which the atmosphere actually contains abundant water vapor.

Establishing whether K2-18 b and other similar temperate, sub-Neptune-sized planets possess liquid water oceans, Hu says, will also require detecting the presence of a broader set of atmospheric gases beyond methane and carbon dioxide. It would also require an absence of molecules like ammonia, carbon monoxide and sulfur dioxide, which, as of yet, have indeed not been detected in the atmosphere of K2-18 b

"This conclusion is based on theoretical work by my group and several others," Hu added. "With the new observations providing valuable context, we've summarized these insights into a roadmap to help guide future observations and studies."

Meanwhile, the search for the biosignatures, dimethyl sulfide and dimethyl disulfide, is far from done; while not hitting the significance level required for a confirmation, this research did provide a stronger signal from these molecules than were provided by previous examinations.

"The evidence for dimethyl sulfide in the present work is significantly higher than what we had with our previous observations in the same near-infrared wavelength range," Madhusudhan said. "However, this evidence is still not high enough to claim a conclusive detection.

"We also need to be able to distinguish dimethyl sulfide from other possible contributors, such as methyl mercaptan, which is also a biosignature on Earth."

It looks certain that K2-18 b will continue to hold the interest of astronomers for some time.

"It is great that we are able to infer tentative signs of potential biosignatures with current JWST observations, but significantly more time is needed for conclusive detections. A key question is whether the atmosphere contains one or more biosignatures," Madhusudhan said. "At the same time, extensive theoretical and experimental efforts are needed to robustly identify biological and non-biological pathways for candidate biosignature molecules."

One thing the team is sure of, though, is the progress made thus far in the study of K2-18 b wouldn't have been possible without the JWST. And, the $10 billion space telescope is set to play a key role in the future investigation of this super-Earth.

"Our observations and analyses add to the growing list of exciting discoveries that highlight the truly transformative science enabled by JWST," Hu concluded. "While we found its Near-Infrared Spectrograph [NIRSpec] particularly well suited to address the goals of our study, other JWST instruments or observational modes could provide complementary and highly valuable information to further enhance our understanding of this planet."

The team's research is available as a preprint on the paper repository arXiv.

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

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

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

Life's chemical details

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

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

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

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

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

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

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

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

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

The other side of the story

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

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

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

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

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

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

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

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

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

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

That's the theory of a team of researchers who looked at hundreds of extrasolar planets, or exoplanets, observed by NASA's Transiting Exoplanet Survey Satellite (TESS).

TESS hunts exoplanets by catching them as they cross the face of, or "transit," their parent star, which causes a tiny drop in light from that star. The study team discovered that light from stars neighboring the one being transited could "contaminate" TESS' data, making it look like the transiting planet is blocking less light than it actually is. And that would make the planet look smaller than it is.

"We found that hundreds of exoplanets are larger than they appear, and that shifts our understanding of exoplanets on a large scale," University of California, Irvine researcher and team leader Te Han said in a statement. "This means we may have actually found fewer Earth-like planets so far than we thought."

Exoplanets throw shade

Exoplanets are so distant and faint that it is only on rare occasions that astronomers can image them directly.

That means the transit method has become the most successful way of detecting worlds beyond the solar system. It requires the planet and its star to be at the right angle in relation to Earth, and for astronomers to wait for the planet to make two transits to confirm its existence.

The transit method is best at spotting short-period planets orbiting close to their host stars, because they make more frequent transits. The method also favors larger planets, which block more light.

"We’re basically measuring the shadow of the planet," said team member and UC Irvine astronomer Paul Robertson.

The team gathered hundreds of TESS observations of exoplanets, sorting them by the width of the exoplanets in question.

They then used computer modeling and data from the European Space Agency's (ESA) star-tracking mission Gaia to estimate how much light contamination TESS is experiencing during its observations.

"TESS data are contaminated, which Te's custom model corrects better than anyone else in the field," said Robertson. "What we find in this study is that these planets may systematically be larger than we initially thought. It raises the question: Just how common are Earth-sized planets?"

Move over Earth-like worlds: ocean planets could be more common

Because of the biases of the transit method mentioned above, the number of exoplanets detected with TESS having sizes and compositions similar to those of Earth was already low.

"Of the single-planet systems discovered by TESS so far, only three were thought to be similar to Earth in their composition," Han explained. "With this new finding, all of them are actually bigger than we thought."

The likely outcome of this is that those exoplanets are larger ocean planets or "hycean worlds" covered by a large single ocean. Those worlds could also be gas giants smaller than Jupiter, like Neptune and Uranus.

That impacts the search for life because, though hycean worlds are packed with water, they could be lacking other ingredients needed for life to arise.

"This has important implications for our understanding of exoplanets, including, among other things, prioritization for follow-up observations with the James Webb Space Telescope, and the controversial existence of a galactic population of water worlds," Roberston added.

The next step for Han, Roberston, and colleagues is to re-examine planets previously deemed uninhabitable due to their size, to see if they are larger than previously thought.

In the meantime, the research is a reminder to astronomers to be cautious when assessing TESS data.

The team's research was published on Monday (July 14) in the Astrophysical Journal Letters.

These lakes and Titan's seas are filled with liquid hydrocarbons like ethane and methane rather than water. And though we know water is a key ingredient of life on Earth, astrobiologists have theorized that Titan's liquid hydrocarbons could allow the molecules needed for life to form, whether that life is similar to what we see on Earth or a very different form of life.

This new research suggests a way vesicles could form on Titan based on what we know about its atmosphere and chemistry. The formation of such compartments is a key step on the road to the development of "protocells."

"The existence of any vesicles on Titan would demonstrate an increase in order and complexity, which are conditions necessary for the origin of life," Conor Nixon of NASA's Goddard Space Flight Center said in a statement.

"We're excited about these new ideas because they can open up new directions in Titan research and may change how we search for life on Titan in the future."

The path to life starts with pockets

The process of creating vesicles begins with molecules called amphiphiles, dual-nature molecules with both water-loving (hydrophilic) and water-repellent (hydrophobic) ends. Under certain conditions, these molecules can self-organize to create vesicles.

On Earth, when amphiphiles meet water, they group together to form spheres similar to soap bubbles with the water-loving end facing outwards, protecting the hydrophobic end.

If two layers of amphiphiles are together, they can form a bilayer "ball" with a shell of water sandwiched between the two layers of molecules. A structure that resembles a living cell.

This process would be very different on Titan due to its environment, one that is radically different than Earth's.

Titan isn't just the largest moon in the solar system; it is also the moon with the densest atmosphere. This is primarily because of Titan's cool temperature and its distance from the sun, which prevents its atmosphere from being stripped by the solar wind.

From 2004 to 2017, the Cassini spacecraft was able to stare through this substantial atmosphere to discover how the meteorological cycle of Titan has influenced its surface.

Though the majority of Titan's atmosphere is composed of nitrogen, its clouds are composed of methane that erodes the surface and river channels as it falls as rain and fills its lakes and seas. When exposed to sunlight, the methane evaporates and rises to the atmosphere again, regenerating Titan's clouds.

The activity of methane through Titan's atmosphere allows complex chemistry to happen, particularly when sunlight splits methane molecules, creating fragments that recombine as complex organic molecules.

This team theorizes that vesicles might form on Titan when sea-spray droplets are thrown into the atmosphere by methane raindrops landing on the surface of lakes and seas.

If the surfaces of Titan's seas are coated with layers of amphiphiles, the sea-spray droplets will be too. That means when those launched droplets fall back to the methane seas, they meet the amphiphile sea-layer and form a bilayer vesicle, enclosing the original droplet.

Over time, these vesicles could be dispersed through the lakes and seas, interacting and potentially leading to the creation of protocells.

The discovery is sure to generate excitement for NASA's forthcoming Dragonfly mission, which will set off for Titan in 2028. Arriving in 2034, the nuclear-powered rotocopter craft aims to explore prebiotic chemistry and habitability on the Saturnian moon.

Understanding this process as it occurs on Titan, if it is occurring, could shed light on the mystery of how life emerged on Earth.

The team's research was published on July 10 in the journal International Journal of Astrobiology.

"It's harder, but certainly not impossible, to live in these conditions," Christopher Glein, an ocean worlds scientist at the Southwest Research Institute (SwRI) in San Antonio told Space.com.

Cassini discovered Enceladus' plumes of water vapor, which jet out from large cracks in the icy surface called "tiger stripes" at the moon's southern polar region, in 2005. Although the Cassini mission, which ended in a blaze of glory in September 2017 when the orbiter plunged into Saturn, was not designed to sample material from such plumes, two of its instruments, the Cosmic Dust Analyzer and the Ion and Neutral Mass Spectrometer, were able to at least get a taste of them during close flybys of the icy moon. What they found offered clues as to the contents of the ocean deep within Enceladus that feeds the plumes.

"The payoff from Cassini far exceeded what it was designed to accomplish," said Glein. "We discovered a habitable ocean at Enceladus."

Those measurements remain our best study so far of any of the ocean moons of the outer solar system, and through geochemical modeling scientists are able to draw some conclusions. New research — by Glein and his SwRI colleague, planetary archaeologist Ngoc Truong — has determined that the pH of the ocean beneath Enceladus' ice is moderately high, between 10.1 and 11.6

The pH scale is a measure of how acidic or alkaline something is, 1 being highly acidic, 14 being highly alkaline, and 7 being neutral. Hence Enceladus' ocean is quite alkaline. For comparison, Earth's ocean has a pH of about 8.

The researchers arrived at this conclusion by studying the abundance and distribution of phosphate minerals in the ice grains within the plumes, in particular the ratio of mono-hydrogen phosphate (HPO4) to regular phosphate (PO4), which is a direct indicator of the pH level of the water. The range of possible pH that Glein and Truong found is higher than the previous estimates of 8 to 9. However, those estimates were made before 2023, when further detailed analysis of Cassini's data revealed high concentrations of phosphates in the plumes.

The alkalinity is a signature of interactions between water and iron-, magnesium- and sodium-bearing silicate rock on the ocean floor. These water-rock interactions release sodium hydroxide (NaOH) into the ocean that subsequently reacts with carbon dioxide and produces the high alkalinity.

"One consequence of these conditions is a high carbonate alkalinity, which supercharges the solubility of calcium phosphate minerals — like apatite. Your teeth might dissolve in Enceladus' ocean," said Glein.

Such high alkalinity would be somewhat challenging for life. "High pH tends to break apart biological polymers," said Glein when asked by Space.com. "However, we know that some microbes on Earth can tolerate the range of pH found on Enceladus."

These terrestrial, alkaline-loving microbes are extremophiles called alkaliphiles. And there's another boost for the possibility of life in Enceladus' ocean, since the water-rock interactions produce minerals and ions that can be used by microbial life for energy and sustenance. The conditions even provide clues as to where in the ocean we might find such life, should it exist there.

"Metals become less soluble at higher pH, so iron may be scarce in Enceladus' ocean," said Glein. "I think the best place to live would be at the seafloor. If you're a microbe, you could directly 'mine' iron and other metals from minerals without relying on solubility. We might want to think about biofilms on Enceladus."

Based on the alkalinity, the chemical composition of the plumes as measured by Cassini and the expected minimal outgassing of carbon dioxide from the ocean, Glein and Truong have assembled a list of minerals and molecules that we could expect to find in Enceladus' ocean. The most abundant compounds on the list are sodium, chlorine, sodium carbonate, carbonate ions, ammonia and potassium ions.

"The composition does make sense for deep circulation of ocean water through the rocky core of Enceladus," said Glein.

One surprise was the inferred high abundance of molecular hydrogen (H2). However, its concentration is similar to some deep-sea environments on Earth, such as the vast field of hydrothermal vents in iron-rich rocks called the "Lost City" deep in the Atlantic Ocean.

"There, H2 supports life by supplying a source of chemical energy," said Glein.

Although the list of mineral constituents in the ocean is not confirmed — we'd have to return to Enceladus to do that — it just shows that we don't need to venture into the depths of the dark water to learn the ocean's secrets. Just flying through the plumes is enough to give us a good indication. Cassini did so without specialized equipment for analyzing molecules and compounds within the plumes, since when it was launched (October 1997) the plumes had not even been discovered. Glein thirsts to return with a dedicated mission carrying state-of-the-art instruments specifically designed for the job.

"Imagine what we could find," he mused. "The picture for Enceladus is of an ocean that is intensely affected by water-rock interactions. Enceladus is a geochemical paradise!"

Glein and Truong's findings were published online June 20 in the journal Icarus.

Grandiose headlines often promise proof that we are not alone, but scientists remain cautious. Is this caution unique to the field of astrobiology? In truth, major scientific breakthroughs are rarely accepted quickly.

Newton’s laws of motion and gravity, Wegener’s theory of plate tectonics, and human-made climate change all faced prolonged scrutiny before achieving consensus.

But does the nature of the search for extraterrestrial life mean that extraordinary claims require even more extraordinary evidence? We’ve seen groundbreaking evidence in this search beforehand, from claims of biosignatures (potential signs of life) in Venus’s atmosphere to NASA rovers finding “leopard spots” – a potential sign of past microbial activity – in a Martian rock.

Both stories generated a public buzz around the idea that we might be one step closer to finding alien life. But on further inspection, abiotic (non-biological) processes or false detection became more likely explanations.

In the case of the exoplanet, K2-18 b, scientists working with data from the James Webb Space Telescope (JWST) announced the detection of gases in the planet’s atmosphere – methane, carbon dioxide, and more importantly, two compounds called dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). As far as we know, on Earth, DMS/DMDS are produced exclusively by living organisms.

Their presence, if accurately confirmed in abundance, would suggest microbial life. The researchers even suggest there’s a 99.4% probability that the detection of these compounds wasn’t a fluke – a figure that, with repeat observations, could reach the gold standard for statistical certainty in the sciences. This is a figure known as five sigma, which equates to about a one in a million chance that the findings are a fluke.

So why hasn’t the scientific community declared this the discovery of alien life? The answer lies in the difference between detection and attribution, and in the nature of evidence itself.

JWST doesn’t directly “see” molecules. Instead, it measures the way that light passes through or bounces off a planet’s atmosphere. Different molecules absorb light in different ways, and by analysing these absorption patterns – called spectra – scientists infer what chemicals are likely to be present. This is an impressive and sophisticated method – but also an imperfect one.

It relies on complex models that assume we understand the biological reactions and atmospheric conditions of a planet 120 light years away. The spectra suggesting the existence of DMS/DMDS may be detected because you cannot explain the spectrum without the molecule you’ve predicted, but it could also result from an undiscovered or misunderstood molecule instead.

Climate comparison

Given how momentous the conclusive discovery of extraterrestrial life would be, these assumptions mean that many scientists err on the side of caution. But is this the same for other kinds of science? Let’s compare with another scientific breakthrough: the detection and attribution of human-made climate change.

The relationship between temperature and increases in CO₂ was first observed by the Swedish scientist Svante Arrhenius in 1927. It was only taken seriously once we began to routinely measure temperature increases. But our atmosphere has many processes that feed CO₂ in and out, many of which are natural.

So the relationship between atmospheric CO₂ and temperature may have been validated, but the attribution still needed to follow.

Carbon has three so-called flavors, known as isotopes. One of these isotopes, carbon-14, is radioactive and decays slowly. When scientists observed an increase in atmospheric carbon dioxide but a low volume of carbon-14, they could deduce that the carbon was very old – too old to have any carbon-14. Fossil fuels – coal, oil and natural gas – are composed of ancient carbon and thus are devoid of carbon-14.

So the attribution of anthropogenic climate change was proven beyond reasonable doubt, with 97% acceptance among scientists. In the search for extraterrestrial life, much like climate change, there is a detection and attribution phase, which requires the robust testing of hypotheses and also rigorous scrutiny.

In the case of climate change, we had in situ observations from many sources. This means roughly that we could observe these sources close up. The search for extraterrestrial life relies on repeated observations from the same sensors that are far away. In such situations, systematic errors are more costly.

Further to this, both the chemistry of atmospheric climate change and fossil fuel emissions were validated with atmospheric tests under lab conditions from 1927 onwards. Much of the data we see touted as evidence for extraterrestrial life comes from light years away, via one instrument, and without any in situ samples.

The search for extraterrestrial life is not held to a higher standard of scientific rigor but it is constrained by an inability to independently detect and attribute multiple lines of evidence.

For now, the claims about K2-18 b remain compelling but inconclusive.

That doesn’t mean we aren’t making progress. Each new observation adds to a growing body of knowledge about the universe and our place in it. The search continues – not because we’re too cautious, but because we are rightly so.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

That's according to scientists who have found that lichen in the Mojave Desert managed to survive for 3 months under levels of intense radiation from the sun that had previously been considered lethal to this organism.

While the lichen was badly damaged, it was able to recover and eventually replicate. That indicates to scientists that other extraterrestrial life that requires photosynthesis could prosper on terrestrial or rocky extrasolar planets, or "exoplanets," even if they are exposed to radiation from their own star that had previously been considered deadly.

"The study was motivated by a curious observation," team member and Desert Research Institute scientist Henry Sun said in a statement. "I was just walking in the desert, and I noticed that the lichens growing there aren't green, they're black. They are photosynthetic and contain chlorophyll, so you would think they'd be green.

"So I wondered, 'What is the pigment they're wearing?' And that pigment turned out to be the world's best sunscreen."

Lichen is composed of algae or cyanobacteria that exist symbiotically with fungi. The lichen that formed the basis of this research is Clavascidium lacinulatum, or the "common lichen," found in arid regions across the globe, including Europe, Asia, North Africa, and, of course, the U.S.

Common lichen. Not so common sunscreen

Life on Earth thrives on light from the sun, which plants and other life forms use to create sugars via photosynthesis. But sunlight is a mix of electromagnetic radiation of different wavelengths, and some of this radiation is not so useful to life; in particular, ultraviolet light.

Terrestrial organisms have evolved to cope with Ultraviolet A (UVA) radiation and less common UVB radiation. In humans, UVA is associated with skin aging and wrinkle formation, while UVB causes skin damage like tanning, sunburn, and can even lead to skin cancer.

However, light that leaves our star also contains UVC radiation, which has a shorter wavelength than UVA or UVB light and carries more energy, making it much more harmful to life, damaging DNA, and preventing reproduction. In fact, UVC is so lethal that it can be used to sterilize air and water, wiping out microorganisms like bacteria and viruses.

Fortunately, our atmosphere filters out much of the ultraviolet light blasted at us from the sun, protecting life from its harshest effects. UVC radiation is completely absorbed, meaning it doesn't reach the surface of our planet. But terrestrial worlds in other star systems may not be so lucky.

This could be especially detrimental to life around so-called M-class and F-class stars, which are hotter and brighter than the sun and are known to belt out intense UVC radiation, especially during stellar flares.

"After the launch of the James Webb Space Telescope (JWST), which can see extremely far into space, the excitement shifted from finding life on Mars to these exoplanets," Sun said. "We're talking about planets that have liquid water and an atmosphere."

Sun and colleagues wanted to see how lichen coped with bombardment by UVC radiation, so they placed a sample next to a UVC lamp for 3 months in a controlled setting.

"In order for a microorganism to persist on a planet, it has to last longer than a day," Sun explained. "So, our experiment had to be long enough to be ecologically significant. We also wanted to go beyond just activity and demonstrate viability."

To their surprise, half the cells comprising the lichen regained the ability to replicate after water was reintroduced to them.

After further investigation with chemists from the University of Nevada, Sun and colleagues found that this is because the acids of the lichen are akin to nature's version of the additives used to make plastics UV-resistant.

Diving deeper, the team cut through the lichen, finding that the top layer was darker, almost like a suntan in humans. Furthermore, they found that when the fungi and the algae that make up lichen were separated, the algae died within minutes of UVC exposure.

The team surmised that because lichen isn't regularly exposed to UVC thanks to Earth's atmosphere, its protective layer evolved as a bonus of its UVA and UVB shielding rather than as an aid to survival.

"We came to the conclusion that the lichen's top layer—a less than millimeter thick skin, if you will—assures that all the cells below are protected from radiation," Sun continued. "This layer acts as a photostabilizer and even protects the cells from harmful chemical reactions caused by the radiation, including reactive oxygen."

As for this discovery's implications for life on other worlds, the team posits that some exoplanets may "be teeming with colonial microorganisms that, like the lichens in the Mojave Desert, are 'tanned' and virtually immune to UVC stress."

"This work reveals the extraordinary tenacity of life even under the harshest conditions, a reminder that life, once sparked, strives to endure," team leader and NASA Goddard Space Flight Center researcher Tejinder Singh said. "In exploring these limits, we inch closer to understanding where life might be possible beyond this planet we call home."

The team's research was published on June 12 in Astrobiology

The signs were rooted in a tentative detection of dimethyl sulfide (DMS) — a molecule produced on Earth solely by marine life — and/or its close chemical relative DMDS, which is also a potential biosignature, in the atmosphere of the exoplanet. This finding, along with the possibility that K2-18b is a "Hycean world" with a liquid water ocean, sparked significant interest about its potential to support life.

However, these results have sparked intense debate among astronomers. While recognizing this finding would be a groundbreaking achievement and a major testament to the James Webb Space Telescope's (JWST) capabilities if true, many scientists remain skeptical, questioning both the reliability of the detected DMS signature as well as whether DMS itself is a dependable sign of life in the first place. As such, many independent teams have been conducting follow-up studies about the original claims — and a newly published one only adds to the debate, suggesting the Cambridge scientists' DMS detection wasn't significant enough to warrant the publicity it received.

"Among the physical sciences, astronomy enjoys a privileged position," Rafael Luque, a post doctoral researcher at the University of Chicago, told Space.com. "It is more frequently covered in the media thanks to its visual appeal and the big philosophical and universal questions it addresses. It was therefore expected that — even if tentative — the detection of a potential biomarker in the atmosphere of an exoplanet would have extensive coverage."

The significance of significance

Luque and his colleagues, including fellow postdoctoral researchers Caroline Piaulet-Ghorayeb and Michael Zhang, remain unconvinced that what astronomers observed on K2-18b was in fact a credible signature indicating life. In a recent arxiv preprint — which is yet to be peer-reviewed — their team re-examined the validity of the original evidence. "This is how science works: evidence and counterevidence go hand in hand,” he stated.

When scientists study data from different instruments separately, they might end up with conflicting results — it's like finding two different "stories" about a subject that don't match. "This is, in fact, what happened in the original team's papers," Zhang told Space.com. "They inferred a much higher temperature from their MIRI (mid-infrared) data than from their NIRISS and NIRSpec (near-infrared) data. Fitting all the data with the same model ensures that we're not telling contradictory stories about the same planet."

Thus, the team conducted a joint analysis of K2-18b using data from all three of the JWST's key instruments — the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph (NIRSpec), which capture near-infrared light, and the Mid-Infrared Instrument (MIRI), which detects longer mid-infrared wavelengths. The goal was to ensure a consistent, planet-wide interpretation of K2-18b's spectrum that the team felt the original studies both lacked.

"We reanalyzed the same JWST data used in the study published earlier this year, but in combination with other JWST observations of the same planet published […] two years ago," Piaulet-Ghorayeb told Space.com. "We found that the stronger signal claimed in the 2025 observations is much weaker when all the data are combined."

These signals may appear weaker when all data is combined because the initial "strong" detection may have been overestimated, the team says, due to being based on a limited initial data set. Combining data from multiple sources lets scientists cross-check and verify the strength — and validity — of a particular signal.

"Different data reduction methods and retrieval codes always give slightly different results, so it is important to try multiple methods to see how robust the results are," explained Piaulet-Ghorayeb. "We never saw more than insignificant hints of either DMS or DMDS, and even these hints were not present in all data reductions."

"Importantly, we showed that when testing a wider range of molecules that we expect to be produced abiotically in the atmosphere, the same observed spectral features can be reproduced without the need for DMS or DMDS," she continued.

More than one path to a result

Molecules in an exoplanet's atmosphere are typically detected through spectral analysis, which identifies unique "chemical fingerprints" based on how the planet's atmosphere absorbs specific wavelengths of starlight as it passes — or transits — in front of its host star. This absorption leaves distinct patterns in the light spectrum that reveal the presence of different molecules.

"Each molecule’s signature is unique, but different molecules can have some features that fall in similar places because of their close molecular structures," explained Piaulet-Ghorayeb.

The difference between DMS and ethane — a common molecule in exoplanet atmospheres — is just one sulfur atom, and current spectrometers, including those on the JWST, have impressive sensitivity, but still face limits. The distance to exoplanets, the faintness of signals, and the complexity of atmospheres mean distinguishing between molecules that differ by just one atom is extremely challenging.

"It is widely recognized as a huge problem for biomarker detection, though not an insurmountable one, because different molecules do have subtly different absorption features," said Piaulet-Ghorayeb. "Until we can separate these signals more clearly, we have to be especially careful not to misinterpret them as signs of life."

Beyond technical limitations, another source of skepticism is how the data has been interpreted statistically. Luque points out that the 2023 study described the detection of DMS as "tentative," reflecting the preliminary nature of the finding. However, the most recent 2025 paper reported that the detection of DMS and/or DMDS reached 3-sigma significance — a level that, while below the 5-sigma threshold required for a confirmed discovery, is generally considered moderate statistical evidence.

"Surprisingly, this latest work was used to double down on the claim for DMS and even more complex molecules to be present. The detection, however, is not statistically significant nor robust, as we show in our work.

Despite these uncertainties, the team is worried that media coverage has continued to spotlight bold claims about DMS and other molecules. "The [JWST] telescope is incredibly powerful, but the signals we're detecting are very small. As a community, we have to make sure that any claims we make about a planet’s composition are robust to the choices made when processing the data from the telescope," said Piaulet-Ghorayeb.

"Researchers have the responsibility to double-check and verify, but the media is also responsible for duly reporting these follow-up works to the general public," added Luque. "Even if they have less catchy titles."

"As Carl Sagan once said, 'extraordinary claims require extraordinary evidence,'" said Luque. "That threshold was not met by how the results were disseminated to the general public."

Whether we'll ever get a clear answer about life on K2-18 b is uncertain — not just because of technological limits, but because the case for follow-ups with the JWST may simply not be strong enough. "JWST is continuing to observe K2-18b, and even though the new observations won't have the ability to detect life, we will soon find out more about the planet's atmosphere and interior," Zhang said.

Recently, the Coller Dolittle Challenge awarded the winner of its first $100,000 annual prize to accelerate progress toward interspecies two-way communication. A prize of equal value will be awarded every year until a team deciphers the secret to interspecies communication.

This year's winning team of researchers has discovered that dolphin whistles could function like words — with mutually understood, context-specific meaning.

Crack the code

The winning team was led by Laela Sayigh from the Woods Hole Oceanographic Institution. The researchers are studying the resident bottlenose dolphin community offshore of Sarasota, Florida.

They were on the lookout for "non-signature" whistles, which comprise approximately 50% of the whistles produced by Sarasota dolphins. Non-signature whistles differ from the more widely studied "signature" whistles, which are referential, name-like vocalizations.

Sayigh's team used non-invasive suction-cup hydrophones, which they placed on the dolphins during unique catch-and-release health assessments, as well as digital acoustic tags.

"Bottlenose dolphins have long fascinated animal communication researchers," Sayigh said in a statement. "Our work shows that these whistles could potentially function like words, shared by multiple dolphins."

Sayigh and her team can now use deep learning in an attempt to "crack the code" and analyze those whistles.

Zoologist's guide to the galaxy

But what does all this have to do with E.T.?

"My interests are very firmly here on Earth, in learning about how dolphins communicate with each other," Sayigh told Space.com "I do know that there are others in the animal communication world that are interested in this, however."

One of those researchers is Arik Kershenbaum, an associate professor and director of studies at Girton College, part of the University of Cambridge in England. He's the author of "The Zoologist's Guide to the Galaxy: What Animals on Earth Reveal About Aliens — and Ourselves" (Viking, 2020).

Kershenbaum explained that the book is about life on Earth, because "that's all we have to look at." He also contributed a white paper for a workshop at the Search for Extraterrestrial Intelligence (SETI) Institute in California, titled "What Animal Studies Can Tell Us about Detecting Intelligent Messages from Outside Earth."

Cross-species database

In that paper for the SETI Institute, Kershenbaum and colleagues concluded that animal communication research is the closest we are likely to get to studying extraterrestrial signals, until such signals are actually received.

"Many of the challenges facing SETI research are similar to those already addressed in the investigation of animal behavior, and the evolutionary origins of human language," they wrote. "Indeed, the evolution of language on Earth may in fact have been driven and constrained by similar principles to those operating on life on other planets."

The researchers have proposed the establishment of a large cross-species database of communicative signals, made available to all SETI and animal behavior researchers.

In addition, they also proposed that tools, algorithms and software used to analyze these signals should be made publicly available for application to these data sets, "so that comparative studies can take full advantage of the expertise from the biological, mathematical, linguistic and astronomical communities."

Complex vocalizations

The topic of dolphin language interpretation, as well as the vocalizations of humpback whales and the field of non-human communications more broadly, is increasingly drawing the interest of SETI researchers and astrobiologists, explained Bill Diamond, president of the SETI Institute.

Humpback whales have very complex vocalizations, Diamond told Space.com, "where it seems clear that they are transmitting information and not simply making sounds associated with mating, feeding or dealing with threats. They plan ahead and communicate complex instructions to one another."

Leading that look is SETI researcher Laurance Doyle, who's working on a project in partnership with the Alaska Whale Foundation to study the vocalizations of humpback whales.

Fundamental rules

For Diamond, the relevant research question is whether or not there are some fundamental mathematical rules associated with the transmission of information that would be universal — like the laws of physics and chemistry — within our known universe.

"If there's an underlying rule structure to the transmission of information, and we can decipher it," Diamond said, "we would firstly be able to recognize a detected SETI signal as containing information, and therefore intelligence. And, possibly, we might even ultimately be able to translate it!"

According to Diamond, "there's definitely a connection between SETI/astrobiology and the study of non-human communication and non-human intelligence."

Scientists from NASA's Jet Propulsion Laboratory (JPL) in Southern California, along with researchers in India and Saudi Arabia, have discovered 26 previously unknown bacterial species in the clean rooms that were used to prep NASA's Phoenix Mars lander for its August 2007 launch.

Clean rooms are decontaminated and intensely controlled environments specifically designed to prevent microbial life from hitching a ride into space. But some microorganisms, known as extremophiles, show impressive resilience in inhospitable environments, whether that's the vacuum of space, hydrothermal vents on the slopes of undersea volcanoes, or even NASA clean rooms.

"Our study aimed to understand the risk of extremophiles being transferred in space missions and to identify which microorganisms might survive the harsh conditions of space," study team member Alexandre Rosado, a researcher at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, said in a statement.

"This effort is pivotal for monitoring the risk of microbial contamination and safeguarding against unintentional colonization of exploring planets," Rosado added.

These hardy microbes may also offer insights that could benefit life on Earth. The scientists performed genetic research on samples gathered from the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, one of the last stops for Phoenix before its launch from neighboring Cape Canaveral Space Force Station (then known as Cape Canaveral Air Force Station).

They found 53 strains that they determined belonged to 26 novel species. And they dug into the genomes of these newfound extremophiles, looking for clues that could help explain their extraordinary survivability. The keys might be in genes linked to DNA repair, detoxification of harmful substances and boosted metabolism, according to the team.

"The genes identified in these newly discovered bacterial species could be engineered for applications in medicine, food preservation and other industries," said Junia Schultz, a postdoctoral fellow at KAUST.

And, of course, the research will help NASA improve its clean room protocols to minimize the risk of biological contamination on future missions.

"Together, we are unraveling the mysteries of microbes that withstand the extreme conditions of space — organisms with the potential to revolutionize the life sciences, bioengineering and interplanetary exploration," said Kasthuri Venkateswaran, a retired JPL scientist and a lead author of the study on the research, which was published May 12 in the journal Microbiome.

The image, a blurry composite of more than a thousand grayscale snapshots later colorized by scientists, was taken during a precision flyby of Mars on March 1, 2025. At its closest point, the spacecraft skimmed just 550 miles (884 kilometers) above the Martian surface, in a maneuver known as a gravity assist, which used the Red Planet's gravitational pull to slow the spacecraft and adjust its orbit around the sun ahead of a crucial leg of its nearly 2-billion-mile (3.2 billion km) journey to Jupiter.

The brief encounter also served a scientific purpose: It gave the mission team a chance to test the spacecraft's instruments in deep space, including the thermal imager E-THEMIS (short for Europa Thermal Imaging System), which will eventually scan Europa's surface for signs of recent or ongoing geologic activity. Over an 18-minute span on March 1, the instrument took over 1,000 grayscale images — one per second — which began arriving on Earth on May 5, according to a NASA statement.

To confirm the instrument's accuracy, the mission team compared the new infrared imagery with long-term thermal maps of Mars gathered by NASA's Mars Odyssey orbiter, which has been observing the Red Planet since 2001. The Odyssey team even coordinated observations before, during, and after the Europa Clipper flyby to allow for a direct side-by-side comparison, according to the statement.

"We wanted no surprises in these new images," Phil Christensen, a professor of earth and space exploration at Arizona State University who serves as the principal investigator of the E-THEMIS instrument, said in the statement. "The goal was to capture imagery of a planetary body we know extraordinarily well and make sure the dataset looks exactly the way it should, based on 20 years of instruments documenting Mars."

E-THEMIS detects infrared light — essentially heat — allowing scientists to map temperatures across a planetary surface. After the spacecraft reaches the Jupiter system in 2030, these thermal scans will help identify hotspots that could point to recent geologic activity beneath Europa's icy shell, according to the statement.

Infrared imaging will also help pinpoint where Europa's vast subsurface ocean might lie closest to the surface, scientists say. The moon is etched with ridges and fractures, features that scientists suspect result from oceanic forces — like rising water or convection currents — pulling apart the ice from below.

"We want to measure the temperature of those features," Christensen said. If Europa is active, its fractures could be warmer than surrounding ice — especially where the ocean lies near the surface or past eruptions left lingering heat, he added.

The Mars flyby also marked the first full in-flight test of Clipper's radar instrument, which couldn't be tested in its entirety on Earth due to the size of its antennas. Preliminary telemetry suggests the test was successful, with detailed analysis of the data still to come, the statement read.

With the Mars flyby complete, Clipper's next gravity assist will come from Earth in 2026. The spacecraft is expected to enter Jupiter orbit in April 2030, after which it will begin a series of 49 close encounters with Europa that will allow scientists to investigate the moon's life-hosting potential.

While it's not exactly a social science, it turns out bacteria have their own versions of these social structures, too — and because the earliest fossil evidence for life on our planet was indeed bacterial, studying how bacteria live together may help microbiologists piece together how life began on Earth long ago. One day, it may help us discover life on other planets.

Along these lines, in research published last year, scientists took a closer look at the behavior of a type of bacteria called multicellular magnetotactic bacteria (MMB). What they found was fascinating: MMB has a peculiar way of grouping. Despite each member of this bacterial clan existing as a single-celled organism, none of them can survive that way. Instead, they combine together and act as one giant, multicellular organism that scientists call "consortia."

Another special element of MMB is the "magnetotactic" in its name, which means it orients itself based on Earth's magnetic field. If you compare MMB to a social cell of people, which shifts toward a social ideal, MMB orients itself and knows where to be based on the Earth's magnetic poles.

MMB lands "somewhere in-between a single-celled organism and much more complex life" Roland Hatzenpichler, a microbiologist and associate professor in the Department of Chemistry and Biochemistry at Montana State University, Bozeman and author of the new research, told Space.com. He described the consortia as "anywhere from 30 to 100 cells" living together. The sheer existence of MMB also suggests they may be caught in one of the "bottlenecks" of life formation on Earth, according to Hatzenpichler.

In other words, perhaps MMB is caught in a stage of evolution between a single-celled organism and a more complex, multicellular form of life, like an insect or a fish..

In other words, perhaps MMB was not meant to be a single-celled organism, but just couldn't transition to its multicellular future.

MMB doesn't just want to stay connected — it needs to for survival.

Where is MMB found?

The study researchers got their MMB samples from a tidal pool in Massachusetts, which Hatzenpichler is a known site for purple sulfur bacteria. He described the sediment containing the MMB as brown with purple dots.

"The pond itself is basically just this brownish, gooey sediment," Hatzenpichler said. "Sprinkled in are these purple bacteria."

In terms of all known life on Earth, there's really no other organism that compares to MMB, Hatzenpichler said.

There are different species of MMB, Hatzenpichler said, "but they are all pretty related to each other."

Working together; dying together

Compared to single-celled organisms, which can swim freely using their whip-like tails known as "flagella," MMB have some communicating to do in order to move. Otherwise, there would be a conflict of interest, so to speak.

"If the whole thing moves right, it means that the bacterial cells on one side need to stop spinning, or spin the other direction than the ones on the opposing side," Hatzenpichler said.

He explained that in order to pull this off, there "must be some quick social interaction at the very least to communicate, 'okay, who is swimming forward now and who is not doing that.'"

This type of social cuing between bacteria isn't completely unique, though. Hatzenpichler said a bacterial social cueing phenomenon called "quorum sensing" has been studied for a while, and usually dictates movement or helps bacteria discern how many of their own kind are around them. Disease-causing bacteria, for example, may benefit from sticking together as it makes it harder for the immune system to attack, Hatzenpichler explained.

But what is the purpose of MMB — or of multicellular structures that aren’t exactly multicellular? According to Hatzenpichler, scientists don't exactly know. An obvious con is that if a cell ever wants to live individually again, for whatever reason, they can't.

"It's good to work together, right?" Hatzenpichler said. However: "At some point it might not be beneficial anymore to stick around with your buddies. But if you don't, you die."

But cooperating together may also be advantageous if you're able to split up the work. And, on a much smaller scale, scientists may eventually find that what happens in MMB consortia could mirror the different jobs cells have in the human body.

"Your heart cells do something completely different than your brain cells, which are completely different than the lung and so on," Hatzenpichler said. More studies are needed to see if there is such a "mutually exclusive" relationship with MMB, as has been seen among other organisms that don't have an obligate multicellular lifestyle. (Obligate is the scientific term that means the MMB can’t survive if separated as a single cell.)

"We're not there yet, but I think this is basically where the research is going now," he said.

Life formation and being 'more than the sum of parts'

Perhaps the most beautiful thing about MMB is that it poses philosophical questions as well as scientific ones: Is it multicellular or not, and what does MMB say about life that's more complicated than bacteria?

"You could see this entirety of 50 cells as one organism, so to speak, because individually, they die if they separate — they show unified behavior towards a common goal," Hatzenpichler said.

"I think the same argument can be made for an animal," he said. "Sometimes our cells fight for our overall health, and other times, they don’t."

Another takeaway from the latest research on MMB is what it suggests about life formation in general, and how life can build very complex structures out of something comparatively simple, Hatzenpichler said. In the future, it's possible more research on unique organisms like MMB may even aid discovery of life outside Earth.

"You have this emergent phenomena that comes out of that, where the system is more than the sum of its parts."

The team's research was published on July 11, 2024 in the journal PLOS Biology.