The Hoba meteorite smashed into the Earth, but look around it, and you won't see any crater.
When NASA’s OSIRIS-REx spacecraft delivered pristine samples from the asteroid Bennu back to Earth in 2023, scientists knew they were receiving one of the most chemically untouched collections of material ever recovered from the Solar System.
Since then, the returned grains have steadily transformed researchers’ understanding of how asteroids formed, how water altered primitive worlds, and even how the ingredients for life may have spread through the early Solar System.
Now, a new study, published in Nature Communications, has uncovered another surprise hidden inside those microscopic particles. Embedded within Bennu are tiny mineral fragments that formed during the Solar System’s earliest moments—less than 100,000 years after its birth—and they may reveal that the asteroid’s ancient parent body formed much farther from the Sun than scientists once suspected.
The research suggests that Bennu inherited some of the oldest surviving solids ever created, while simultaneously preserving evidence that Jupiter’s formation may have acted as an enormous cosmic filter, separating different populations of dust before planets had even fully formed.
“Our observations of phyllosilicates replacing olivine and interstitial phyllosilicates between olivine grains within AOAs… collectively indicate that these refractory inclusions experienced aqueous alteration on Bennu’s parent planetesimal,” researchers write. “Therefore, they were incorporated into the parent planetesimal before the onset of aqueous alteration, during which phyllosilicates and magnetite formed.”
“These mineralogical, isotopic, and chronological similarities among refractory inclusions in Bennu samples, Ryugu samples, and CI chondrites provide evidence that their parent planetesimal(s) accreted a common suite, and likely similar relative abundances, of high-temperature refractory inclusions and their fragments,” researchers write.
The research concentrates on “refractory inclusions”—tiny mineral-rich objects known as calcium-aluminum-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs). These objects are widely considered the oldest solid materials to condense from the hot gas surrounding the newborn Sun.
Long before planets existed, the infant Solar System consisted of a rotating disk of gas coupled with dust known as the protoplanetary disk. Temperatures near the young Sun exceeded 2,000 degrees Fahrenheit (roughly 1,100 degrees Celsius), allowing only the most heat-resistant minerals to crystallize.
These refractory inclusions were among the very first solids to emerge from that environment before eventually being transported throughout the growing Solar System.
Although scientists have found such inclusions in meteorites for decades, Bennu offered an unprecedented opportunity to examine them in material collected directly from an asteroid rather than from meteorites that survived passage through Earth’s atmosphere.
To investigate, researchers analyzed polished sections prepared from 12 Bennu particles using scanning electron microscopy, transmission electron microscopy, oxygen isotope measurements, and radioactive aluminum-magnesium dating techniques.
The team identified six amoeboid olivine aggregates and three calcium-aluminum-rich inclusions, all remarkably small—none exceeding roughly 100 micrometers across, or about the thickness of a human hair. This turned out to be one of the study’s most important discoveries.
The mineral chemistry and oxygen isotopes showed these inclusions formed in an extremely hot, oxygen-16-rich environment during the Solar System’s earliest stages. Radioactive dating using aluminum-26 indicated at least one inclusion formed essentially at the very beginning of Solar System history, within roughly the first 100,000 years after the earliest known solids condensed.
In other words, Bennu contains fragments that have survived for approximately 4.567 billion years with surprisingly little alteration. Yet, those ancient relics also preserve evidence that they later encountered liquid water.
Several inclusions show minerals partially replaced by phyllosilicates—water-bearing clay minerals—while magnetite and other alteration products reveal that water once circulated through Bennu’s ancient parent body after these primordial objects had already become incorporated into it.
For scientists, that sequence helps establish a timeline. First, the earliest high-temperature solids formed close to the newborn Sun. Later, they were transported outward through the protoplanetary disk. Only after they became part of Bennu’s larger parent asteroid did liquid water alter portions of the rock.
Researchers found distinct similarities between Bennu’s inclusions and those previously identified in samples returned from Japan’s Hayabusa2 mission to asteroid Ryugu, as well as in rare CI carbonaceous chondrite meteorites found on Earth.
The oxygen isotopes, crystal chemistry, and formation ages all closely match, suggesting these seemingly distant objects inherited material from the same population of ancient Solar System building blocks.
That mutual heritage points toward a surprisingly interconnected early Solar System, where material formed close to the Sun was efficiently transported across enormous distances before eventually becoming incorporated into multiple asteroid populations.
However, the absence of something proved just as revealing as what scientists found.
Unlike many carbonaceous meteorites, Bennu contains no large refractory inclusions larger than about one-tenth of a millimeter. Other meteorites frequently preserve inclusions ranging from submillimeter sizes up to several centimeters across.
According to the researchers, the missing population may reflect the increasing influence of the Solar System’s first giant planet.
As proto-Jupiter accumulated mass, its gravity likely created a pressure bump within the gas disk encircling the young Sun. Such pressure bumps act as natural traffic jams for dust, trapping larger particles while allowing much smaller grains to continue drifting through the disk.
Under this scenario, larger refractory inclusions became concentrated closer to Jupiter’s orbit. At the same time, only the smallest particles were able to migrate farther outward into the distant regions where Bennu’s parent body eventually formed.
If correct, Bennu’s microscopic inclusions effectively record the influence of Jupiter before the giant planet had even fully matured.
The hypothesis also helps explain why Bennu, Ryugu, and CI meteorites all possess nearly identical populations of tiny refractory inclusions while lacking the larger varieties commonly found elsewhere.
Rather than showing different source materials, the distinction may instead reflect where—and perhaps when—their parent bodies assembled within the developing protoplanetary disk.
The findings similarly reinforce earlier studies suggesting Bennu is among the Solar System’s most chemically primitive objects. Because large refractory inclusions contain unusually high concentrations of certain elements, their absence helps preserve Bennu’s overall composition close to that of the earliest solar nebula from which the planets formed.
That makes the asteroid an unusually valuable time capsule. Every new microscopic grain examined inside the OSIRIS-REx collection provides another insight into processes that occurred billions of years before Earth existed as a habitable world.
Rather than simply representing rubble from a small asteroid, Bennu appears to preserve a remarkably faithful record of how the Solar System sorted, mixed, transported, and assembled its earliest building materials.
The study also demonstrates why sample-return missions have grown increasingly important to planetary science. Laboratory instruments on Earth can perform measurements impossible for spacecraft operating millions of miles away, letting researchers reconstruct events that occurred within the Solar System’s first fractions of a million years.
“We conclude that Bennu’s parent planetesimal, like those of Ryugu and CI chondrites, accreted small refractory inclusions that persisted in the outer Solar System beyond the influence of the proto-Jupiter-induced pressure bump,” researchers write. “Taken together, these findings highlight the need to integrate Bennu samples into comparative studies of early Solar System solids to better constrain the diversity and possible genetic links among planetesimal formation pathways,” researchers write.
The study, “Refractory inclusions in Bennu samples indicative of outer Solar System accretion,” appeared in Nature Communications.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com
When a meteorite tore through a New Jersey home, the homeowner quickly preserved the fragments. Now, they're giving scientists a look at Earth's early history.
The post New Jersey Meteorite Offers Early Solar System Clues appeared first on Sky & Telescope.
A ring in Quebec’s wilderness turned out to be a rare cosmic scar.
Researchers from the University of British Columbia studying material from the mysterious dinosaur-killer meteorite that wiped out 75% of Earth’s species, including non-avian dinosaurs, have determined the doomsday space rock was likely a rare type of carbonaceous chondrite.
Although the international team behind the discovery, which includes researchers from Paris, Brussels, and Vienna, said the evidence for this category of “oddball” meteorite offers a viable solution to its mysterious composition, they note that the rarity of chondrite meteorites makes its origin a new mystery that needs to be solved by future research.
They also note that a chondrite meteorite impact would have much less effect on atmospheric sulfur, which is critical to most extinction models, potentially casting doubt on its central role in dinosaur extinction.
According to a statement, the Cretaceous-Paleogene impactor resulted in one of the largest extinction events in the planet’s history. While most scientists agree that the event played a significant role in ending the dinosaurs’ reign, the study’s authors note that “the exact mechanism and the extent of the impact-extinction link are debated.” They also note that the origin and composition of the dinosaur killer have remained a mystery.
An analysis of the Chicxulub impact structure reveals that the doomsday dinosaur-killer meteorite was between 10 and 15 kilometers (approximately 6 to 9 miles) wide. Estimates also suggest it impacted Earth at 64,000 km/m (40,000 mph) beneath the modern-day Yucatán Peninsula in Mexico.
Although previous studies identified the meteorite as similar to carbonaceous chondrites, the researchers said that carbonaceous chondrites are a diverse class of space rock, “leaving the exact nature of the impactor unclear.”
“Carbonaceous chondrites of the Ornans class (CO) are definitely not like the typical meteors you find in museum collections,” explained study co-author and visiting professor Dr. Philippe Claeys.
For example, the professor explained, a CO contains fewer volatile elements, such as zinc, carbon, Sulphur, and H20 “than other classes of meteorites we’ve discovered so far on Earth.”
To try to unravel the mystery of the dinosaur-killer meteorite, the researchers teamed up with scientists from the Institut de Physique du Globe and the Université de Paris to conduct high-precision nickel isotope measurements of meteor samples from the event that have been collected over the years from the thin, worldwide layer of clay created by the explosive impact.
Dr. Claeys, a professor at Vrije Universiteit Brussel, currently visiting the Pacific Center for Isotopic and Geochemical Research in Earth, Ocean and Atmospheric Sciences at UBC, noted the challenging nature of the isotopic analysis, primarily due to the limited number of samples.
“Only a minute fraction of the projectile is preserved in the planet’s KT clay layer because the entire meteorite vaporized upon impact,” the researcher explained.
Still, the study authors explain, evaluating Nickel isotopes offers several advantages over other testing methods. For example, Nickel has five isotopes that the researchers note “allow for up to three separate internally normalized signatures.” They also highlight the availability of Nickel in “virtually all types of available early Solar System solids,” including iron meteorites, which allows for comparison with a wide variety of potential impactors.
Finally, they write, CI chondrites have a distinct Ni isotope signature from the rest of the class, therefore “making it possible to distinguish a CI-like impactor clearly” from other meteorite types.
After completing an isotopic analysis of samples of marine clays containing microscopic pieces of the ejecta, the team said their results “constrain the impactor to one group of carbonaceous chondrites, CO chondrites, “ as well as some evidence for “ungrouped chondrites.”
“By combining our new Ni isotope data with the existing evidence, we demonstrate that the composition of the Chicxulub impactor was most likely CO chondrite-like,” the researchers write, adding that this identification is possible “given nickel’s high abundance in primitive meteorites compared to the Earth’s crust and the distinct isotope compositions they record.”
While the isotopic analysis offers a compelling solution to the composition of the famed dinosaur-killer that slammed into Earth millions of years ago, the team said the identification casts doubt on the extent of its role in the dinosaurs’ extinction. Specifically, they note that CO chondrites are “dry” compared to others in their class, meaning they contain much less of the volatiles that most extinction theories cite as a significant mechanism.
“As highly volatile elements, such as C, N, and S, in CO chondrites are less abundant than in the typical CCs, questions arise whether the impactor was an essential contributor to the volatiles released during the impact,” they explained.
The most important volatile in most extinction theories is Sulfur (S). However, the authors note, CO chondrites would deliver “approximately half as much S” as more common types.
If the new analysis is correct, it also puts the dinosaur-killer’s origin in question. The authors note that possible sources include distant, debris-rich regions of the outer Solar System or even the outer area of the asteroid belt near Jupiter.
Combined with the compositional analysis lacking volatiles, the team notes that their findings allow “further studies of the mechanism behind the extinction.”
When discussing the potential implications of their findings, the researchers said their study “highlights the extraterrestrial origin of the K-Pg mass extinction and the isotopes of Ni as a well-suited tool to characterize the nature of extraterrestrial material on Earth.” They also note that the composition of the dinosaur-killer “opens the door for further research into the connection between the impact and the mass extinction.”
From a scientific perspective, the research said their work “highlights the use of Ni isotopes in fingerprinting extraterrestrial materials on Earth,” and helps evaluate the risks associated with “potential future impact events and their consequences.” The study also shows how even an uncommon type of space rock can permanently alter the planet’s history.
“Being impacted by such a rare, distant projectile really underscores how unlucky the dinosaurs were,” Dr. Claeys said.
The researcher also noted that the lack of volatiles in this category of meteorite “doesn’t alter our theory of what caused the extinction event.” However, he notes, if correct, the result “makes it less likely that Sulphur contained in the impactor was the smoking gun.” Instead, the fine debris “thrown into the atmosphere” by the forceful impact would have been the primary factor in the end of the dinosaurs.
The study “The origin of Cretaceous-Palaeogene impactor revealed by nickel isotopes” was published in Science Advances.
Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org
Login