Bennu asteroid reveals its contents to scientists − and clues to how the building blocks of life on Earth may have been seeded
NASA’s OSIRIS-REx mission returned samples from asteroid Bennu, revealing insights into life’s ingredients on Earth, paralleling those found in the Revelstoke meteorite’s analysis.
A bright fireball streaked across the sky above mountains, glaciers and spruce forest near the town of Revelstoke in British Columbia, Canada, on the evening of March 31, 1965. Fragments of this meteorite, discovered by beaver trappers, fell over a lake. A layer of ice saved them from the depths and allowed scientists a peek into the birth of the solar system.
Nearly 60 years later, NASA’s OSIRIS-REx mission returned from space with a sample of an asteroid named Bennu, similar to the one that rained rocks over Revelstoke. Our research team has published a chemical analysis of those samples, providing insight into how some of the ingredients for life may have first arrived on Earth.
Born in the years bracketing the Revelstoke meteorite’s fall, the two of us have spent our careers in the meteorite collections of the Smithsonian Institution in Washington, D.C., and the Natural History Museum in London. We’ve dreamed of studying samples from a Revelstoke-like asteroid collected by a spacecraft.
Then, nearly two decades ago, we began turning those dreams into reality. We joined NASA’s OSIRIS-REx mission team, which aimed to send a spacecraft to collect and return an asteroid sample to Earth. After those samples arrived on Sept. 24, 2023, we got to dive into a tale of rock, ice and water that hints at how life could have formed on Earth.
In this illustration, NASA’s OSIRIS-REx spacecraft collects a sample from the asteroid Bennu. NASA/Goddard/University of Arizona
The CI chondrites and asteroid Bennu
To learn about an asteroid – a rocky or metallic object in orbit around the Sun – we started with a study of meteorites.
Asteroids like Bennu are rocky or metallic objects in orbit around the Sun. Meteorites are the pieces of asteroids and other natural extraterrestrial objects that survive the fiery plunge to the Earth’s surface.
We really wanted to study an asteroid similar to a set of meteorites called chondrites, whose components formed in a cloud of gas and dust at the dawn of the solar system billions of years ago.
The Revelstoke meteorite is in a group called CI chondrites. Laboratory-measured compositions of CI chondrites are essentially identical, minus hydrogen and helium, to the composition of elements carried by convection from the interior of the Sun and measured in the outermost layer of the Sun. Since their components formed billions of years ago, they’re like chemically unchanged time capsules for the early solar system.
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So, geologists use the chemical compositions of CI chondrites as the ultimate reference standard for geochemistry. They can compare the compositions of everything from other chondrites to Earth rocks. Any differences from the CI chondrite composition would have happened through the same processes that formed asteroids and planets.
CI chondrites are rich in clay and formed when ice melted in an ancient asteroid, altering the rock. They are also rich in prebiotic organic molecules. Some of these types of molecules are the building blocks for life.
This combination of rock, water and organics is one reason OSIRIS-REx chose to sample the organic-rich asteroid Bennu, where water and organic compounds essential to the origin of life could be found.
Evaporites − the legacy of an ancient brine
Ever since the Bennu samples returned to Earth on Sept. 24, 2023, we and our colleagues on four continents have spent hundreds of hours studying them.
The instruments on the OSIRIS-REx spacecraft made observations of reflected light that revealed the most abundant minerals and organics when it was near asteroid Bennu. Our analyses in the laboratory found that the compositions of these samples lined up with those observations.
The samples are mostly water-rich clay, with sulfide, carbonate and iron oxide minerals. These are the same minerals found in CI chondrites like Revelstoke. The discovery of rare minerals within the Bennu samples, however, surprised both of us. Despite our decades of experience studying meteorites, we have never seen many of these minerals.
We found minerals dominated by sodium, including carbonates, sulfates, chlorides and fluorides, as well as potassium chloride and magnesium phosphate. These minerals don’t form just when water and rock react. They form when water evaporates.
Bennu’s rocks formed 4.5 billion years ago on a larger parent asteroid. That asteroid was wet and muddy. Under the surface, pockets of water perhaps only a few feet across were evaporating, leaving the evaporite minerals we found in the sample. That same evaporation process also formed the ancient lake beds we’ve seen these minerals in on Earth.
Bennu’s parent asteroid likely broke apart 1 to 2 billion years ago, and some of the fragments came together to form the rubble pile we know as Bennu.
These minerals are also found on icy bodies in the outer solar system. Bright deposits on the dwarf planet Ceres, the largest body in the asteroid belt, contain sodium carbonate. The Cassini mission measured the same mineral in plumes on Saturn’s moon Enceladus.
We also learned that these minerals, formed when water evaporates, disappear when exposed to water once again – even with the tiny amount of water found in air. After studying some of the Bennu samples and their minerals, researchers stored the samples in air. That’s what we do with meteorites.
Unfortunately, we lost these minerals as moisture in the air on Earth caused them to dissolve. But that explains why we can’t find these minerals in meteorites that have been on Earth for decades to centuries.
Until scientists were able to conduct a controlled sample return with a spacecraft and carefully curate and store the samples in nitrogen, we had never seen this set of minerals in a meteorite.
An unexpected discovery
Before returning the samples, the OSIRIS-REx spacecraft spent over two years making observations around Bennu. From that two years of work, researchers learned that the surface of the asteroid is covered in rocky boulders.
We could see that the asteroid is rich in carbon and water-bearing clays, and we saw veins of white carbonate a few feet long deposited by ancient liquid water. But what we couldn’t see from these observations were the rarer minerals.
We used an array of techniques to go through the returned sample one tiny grain at a time. These included CT scanning, electron microscopy and X-ray diffraction, each of which allowed us to look at the rock at a scale not possible on the asteroid.
Cooking up the ingredients for life
From the salts we identified, we could infer the composition of the briny water from which they formed and see how it changed over time, becoming more sodium-rich.
This briny water would have been an ideal place for new chemical reactions to take place and for organic molecules to form.
While our team characterized salts, our organic chemist colleagues were busy identifying the carbon-based molecules present in Bennu. They found unexpectedly high levels of ammonia, an essential building block of the amino acids that form proteins in living matter. They also found all five of the nucleobases that make up part of DNA and RNA.
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Based on these results, we’d venture to guess that these briny pods of fluid would have been the perfect environments for increasingly complicated organic molecules to form, such as the kinds that make up life on Earth.
When asteroids like Bennu hit the young Earth, they could have provided a complete package of complex molecules and the ingredients essential to life, such as water, phosphate and ammonia. Together, these components could have seeded Earth’s initially barren landscape to produce a habitable world.
Without this early bombardment, perhaps when the pieces of the Revelstoke meteorite landed several billion years later, these fragments from outer space would not have arrived into a landscape punctuated with glaciers and trees.
In an exciting development for astronomers and space enthusiasts alike, scientists have confirmed the discovery of a new interstellar object—officially named 3I/ATLAS—currently passing through our solar system. This marks only the third known object from another star system to visit us, following the mysterious ‘Oumuamua in 2017 and the icy 2I/Borisov in 2019.
The object was first detected on July 1, 2025, by the ATLAS telescope in Chile. Initially cataloged as A11pl3Z, further analysis confirmed that its speed and orbital trajectory are hyperbolic—meaning it’s not bound by the Sun’s gravity and is merely passing through, just like its rare predecessors.
What Do We Know About 3I/ATLAS?
Origin: The object’s interstellar origin is confirmed by its high velocity—traveling at around 60 km/s (37 miles per second)—and its hyperbolic orbit. Composition: Unlike ‘Oumuamua, which sparked debate due to its lack of a visible tail, 3I/ATLAS appears to be a comet, exhibiting a faint coma and short dust tail. Size: The comet’s nucleus could be as large as 10 kilometers (6 miles) across, though dust and debris around it may be inflating those estimates. Distance from Earth: It will come no closer than 150 to 240 million miles, posing no threat to our planet. Visibility: It’s currently about 420 million miles from the Sun and will reach its closest approach (perihelion) around October 29–30, 2025. After briefly disappearing behind the Sun, it may reappear for additional observation in December.
🚨 A comet from another star system is flying through our solar system right now! 🌠 Meet 3I/ATLAS — only the 3rd interstellar object ever seen! 👽✨ SpaceTok 3IATLAS Oumuamua Interstellar ScienceTok AstronomyFacts DidYouKnow CosmicVisitor #STMDailyNews https://stmdailynews.com/a-new-interstell…our-solar-system/ ♬ original sound – STMDailyNews – STMDailyNews
Why Interstellar Objects Matter
Interstellar objects are not just celestial curiosities—they are time capsules carrying information about the environments where they formed, likely in entirely different star systems. Their compositions, movements, and structures give scientists rare glimpses into the diversity of planetary building blocks in our galaxy.
‘Oumuamua puzzled scientists with its unusual shape and lack of comet-like activity, while 2I/Borisov looked more like a traditional comet. Now, 3I/ATLAS gives us another chance to compare and contrast these space travelers and deepen our understanding of how solar systems form and evolve.
Eyes on the Sky
Though faint and fast-moving, 3I/ATLAS is already being tracked by observatories around the world. With modern telescopes and tools that weren’t available even a decade ago, astronomers are optimistic about gathering unprecedented data on this rare visitor.
Whether you’re a seasoned stargazer or a casual cosmic tourist, it’s thrilling to know that something from another solar system is soaring through our cosmic backyard—reminding us of the vastness and wonder of the universe.
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
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From life-saving inventions and cultural breakthroughs to game-changing ideas buried by bias, our series digs up the truth behind the minds that mattered.
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Every year, on July 2nd, enthusiasts, skeptics, and the curious alike come together to observe World UFO Day. This unique celebration is an invitation to lift our eyes to the skies and ponder the vastness of the universe and the mysteries it holds. While Hollywood has given us thrilling depictions of UFO encounters, World UFO Day encourages us to delve into the real questions: Are we alone in the cosmos? What secrets lie beyond our planetary boundaries?
The Origins of World UFO Day
July 2nd was chosen to commemorate the infamous 1947 Roswell incident, where an unidentified flying object reportedly crashed in Roswell, New Mexico. Though officially explained as a weather balloon, the event sparked countless theories and remains a cornerstone of UFO lore. This day aims to raise public awareness about UFOs and advocate for the disclosure of government files to better understand these phenomena.
Why Celebrate UFO Day?
Awareness and Education: UFO Day encourages public interest in a topic that spans history and science. It’s a chance to learn about the different types of UFO sightings and their historical significance.
Promoting Scientific Inquiry: Encouraging scientific exploration is crucial. Discussions around UFOs can inspire interest in astronomy, astrophysics, and other scientific fields.
Fostering Community: People from diverse backgrounds join discussions, share experiences, and even hold sky-watching events. It’s a day to connect with others who are intrigued by the mysteries of the universe.
How to Get Involved
Host a Sky-Watching Event: Gather friends and family and spend the night sky-watching. You might be surprised at what you can see!
Educate Yourself: Dive into documentaries, books, and articles about UFOs. Understanding the science and history can offer new perspectives.
Join Online Communities: Participate in forums or online groups dedicated to UFO discussions. Sharing experiences and theories can lead to fascinating conversations.
World UFO Day, observed on July 2nd, invites us to explore UFO sightings, encouraging curiosity and scientific inquiry into the universe’s mysteries. https://stmdailynews.com worldufoday UFOsightings #CosmicCuriosity♬ original sound – STMDailyNews – STMDailyNews
A Day of Curiosity and Exploration
World UFO Day is more than just pondering the existence of extraterrestrial life; it’s a celebration of curiosity and the never-ending quest for knowledge. So, whether you’re a believer or a skeptic, take a moment on July 2nd to look up and consider the endless possibilities of our universe. Who knows what you might discover?
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‘Extraordinary claims require extraordinary evidence’ − an astronomer explains how much evidence scientists need to claim discoveries like extraterrestrial life
The universe is filled with countless galaxies, stars and planets. Astronomers may find life one day, but they will need extraordinary proof.
ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi Chris Impey, University of Arizona
The detection of life beyond Earth would be one of the most profound discoveries in the history of science. The Milky Way galaxy alone hosts hundreds of millions of potentially habitable planets. Astronomers are using powerful space telescopes to look for molecular indicators of biology in the atmospheres of the most Earth-like of these planets.
But so far, no solid evidence of life has ever been found beyond the Earth. A paper published in April 2025 claimed to detect a signature of life in the atmosphere of the planet K2-18b. And while this discovery is intriguing, most astronomers – including the paper’s authors – aren’t ready to claim that it means extraterrestrial life exists. A detection of life would be a remarkable development.
The astronomer Carl Sagan used the phrase, “Extraordinary claims require extraordinary evidence,” in regard to searching for alien life. It conveys the idea that there should be a high bar for evidence to support a remarkable claim.
I’m an astronomer who has written a book about astrobiology. Over my career, I’ve seen some compelling scientific discoveries. But to reach this threshold of finding life beyond Earth, a result needs to fit several important criteria.
When is a result important and reliable?
There are three criteria for a scientific result to represent a true discovery and not be subject to uncertainty and doubt. How does the claim of life on K2-18b measure up?
First, the experiment needs to measure a meaningful and important quantity. Researchers observed K2-18b’s atmosphere with the James Webb Space Telescope and saw a spectral feature that they identified as dimethyl sulfide.
On Earth, dimethyl sulfide is associated with biology, in particular bacteria and plankton in the oceans. However, it can also arise by other means, so this single molecule is not conclusive proof of life.
Second, the detection needs to be strong. Every detector has some noise from the random motion of electrons. The signal should be strong enough to have a low probability of arising by chance from this noise.
The K2-18b detection has a significance of 3-sigma, which means it has a 0.3% probability of arising by chance.
That sounds low, but most scientists would consider that a weak detection. There are many molecules that could create a feature in the same spectral range.
The “gold standard” for scientific detection is 5-sigma, which means the probability of the finding happening by chance is less than 0.00006%. For example, physicists at CERN gathered data patiently for two years until they had a 5-sigma detection of the Higgs boson particle, leading to a Nobel Prize one year later in 2013.
The announcement of the discovery of the Higgs boson took decades from the time Peter Higgs first predicted the existence of the particle. Scientists, such as Joe Incandela shown here, waited until they’d reached that 5-sigma level to say, ‘I think we have it.’
Third, a result needs to be repeatable. Results are considered reliable when they’ve been repeated – ideally corroborated by other investigators or confirmed using a different instrument. For K2-18b, this might mean detecting other molecules that indicate biology, such as oxygen in the planet’s atmosphere. Without more and better data, most researchers are viewing the claim of life on K2-18b with skepticism.
Claims of life on Mars
In the past, some scientists have claimed to have found life much closer to home, on the planet Mars.
Over a century ago, retired Boston merchant turned astronomer Percival Lowell claimed that linear features he saw on the surface of Mars were canals, constructed by a dying civilization to transport water from the poles to the equator. Artificial waterways on Mars would certainly have been a major discovery, but this example failed the other two criteria: strong evidence and repeatability.
Lowell was misled by his visual observations, and he was engaging in wishful thinking. No other astronomers could confirm his findings.
Mars, as taken by the OSIRIS instrument on the ESA Rosetta spacecraft during its February 2007 flyby of the planet and adjusted to show color.ESA & MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA, CC BY-SA
In 1996, NASA held a press conference where a team of scientists presented evidence for biology in the Martian meteorite ALH 84001. Their evidence included an evocative image that seemed to show microfossils in the meteorite.
However, scientists have come up with explanations for the meteorite’s unusual features that do not involve biology. That extraordinary claim has dissipated.
More recently, astronomers detected low levels of methane in the atmosphere of Mars. Like dimethyl sulfide and oxygen, methane on Earth is made primarily – but not exclusively – by life. Different spacecraft and rovers on the Martian surface have returned conflicting results, where a detection with one spacecraft was not confirmed by another.
The low level and variability of methane on Mars is still a mystery. And in the absence of definitive evidence that this very low level of methane has a biological origin, nobody is claiming definitive evidence of life on Mars.
Claims of advanced civilizations
Detecting microbial life on Mars or an exoplanet would be dramatic, but the discovery of extraterrestrial civilizations would be truly spectacular.
The search for extraterrestrial intelligence, or SETI, has been underway for 75 years. No messages have ever been received, but in 1977 a radio telescope in Ohio detected a strong signal that lasted only for a minute.
This signal was so unusual that an astronomer working at the telescope wrote “Wow!” on the printout, giving the signal its name. Unfortunately, nothing like it has since been detected from that region of the sky, so the Wow! Signal fails the test of repeatability.
‘Oumuamua is the first object passing through the solar system that astronomers have identified as having interstellar origins.European Southern Observatory/M. Kornmesser
In 2017, a rocky, cigar-shaped object called ‘Oumuamua was the first known interstellar object to visit the solar system. ‘Oumuamua’s strange shape and trajectory led Harvard astronomer Avi Loeb to argue that it was an alien artifact. However, the object has already left the solar system, so there’s no chance for astronomers to observe it again. And some researchers have gathered evidence suggesting that it’s just a comet.
While many scientists think we aren’t alone, given the enormous amount of habitable real estate beyond Earth, no detection has cleared the threshold enunciated by Carl Sagan.
Claims about the universe
These same criteria apply to research about the entire universe. One particular concern in cosmology is the fact that, unlike the case of planets, there is only one universe to study.
A cautionary tale comes from attempts to show that the universe went through a period of extremely rapid expansion a fraction of a second after the Big Bang. Cosmologists call this event inflation, and it is invoked to explain why the universe is now smooth and flat.
In 2014, astronomers claimed to have found evidence for inflation in a subtle signal from microwaves left over after the Big Bang. Within a year, however, the team retracted the result because the signal had a mundane explanation: They had confused dust in our galaxy with a signature of inflation.
On the other hand, the discovery of the universe’s acceleration shows the success of the scientific method. In 1929, astronomer Edwin Hubble found that the universe was expanding. Then, in 1998, evidence emerged that this cosmic expansion is accelerating. Physicists were startled by this result.
Two research groups used supernovae to separately trace the expansion. In a friendly rivalry, they used different sets of supernovae but got the same result. Independent corroboration increased their confidence that the universe was accelerating. They called the force behind this accelerating expansion dark energy and received a Nobel Prize in 2011 for its discovery.
On scales large and small, astronomers try to set a high bar of evidence before claiming a discovery.Chris Impey, University Distinguished Professor of Astronomy, University of Arizona
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Chris Impey, University Distinguished Professor of Astronomy, University of Arizona
This article is republished from The Conversation under a Creative Commons license. Read the original article.
