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A meteorite recovered immediately upon its fall to Earth on July 16, 2024, is helping NASA scientists uncover new clues about ancient water, the chemical evolution of primitive asteroids, and the ingredients that may have helped make life possible throughout the early solar system.
This rapid recovery began when an amateur astronomer in New Jersey quickly recognized that a newly fallen meteorite had landed on his property. Recognizing its scientific value and wearing protective gloves, he collected the fragments and stored them in aluminum foil and glass containers, which preserved delicate minerals and organic compounds that are often altered by moisture, weather, and contamination.
As the meteorite fell to Earth, cameras across New Jersey captured its fiery passage through the atmosphere. Scientists used these observations to reconstruct the fireball's trajectory and, after recovering the meteorite, combined this data with laboratory analyses to determine where in the solar system the rock most likely originated. In a study published Wednesday in the journal Science Advances, researchers found evidence that ancient salty water altered minerals within the meteorite's parent asteroid, preserving unique minerals and a rich inventory of organic compounds.
"When we have both a documented fireball and a quick recovery of its meteorite, we can learn not only what the rock is made of, but where it came from in the asteroid belt," said Peter Jenniskens, meteor astronomer at both NASA's Ames Research Center in California's Silicon Valley and the SETI Institute, and lead author of the study.
Named for the township where it was recovered, the Hillsborough meteorite belongs to a class of carbon-rich meteorites known as CM carbonaceous chondrites. These primitive rocks preserve some of the oldest materials in the solar system, recording the chemical processes that shaped asteroids more than 4.5 billion years ago.
While examining the unusually pristine meteorite, researchers found a mosaic of tiny broken-up rocks and noticed that some contained unusually high concentrations of sodium - an unexpected finding for this type of meteorite. The surprising signal prompted a closer investigation using powerful electron microscopes that allowed scientists to examine the meteorite from the millimeter scale down to individual atoms. By combining observations across multiple scales, researchers reconstructed the history of the minerals and the fluids that once flowed through them.
These analyses revealed microscopic fractures filled with sodium-rich material left behind by ancient brines. Unlike pure water, brines contain dissolved salts that allow them to transport elements and chemically alter the rocks they move through. In the case of the Hillsborough sample, those ancient fluids altered the asteroid's minerals and left behind chemical evidence that remained preserved for billions of years.
Scientists were also able to detect fragile sodium-carbonate salts that normally react with moisture in Earth's atmosphere before they can be studied. Jangmi Han, a paper co-author and mineralogist at NASA's Johnson Space Center in Houston, identified evidence of ancient brines preserved within microscopic fractures. Similar salts were identified in samples returned from the asteroids Bennu and Ryugu by NASA's OSIRIS-REx mission and JAXA's (Japan Aerospace Exploration Agency) Hayabusa2 mission. However,Hillsborough marks the first time the salts have been identified in a CM carbonaceous chondrite meteorite, offering a new glimpse into the surfaces of the primitive asteroids that produced these meteorites.
Together, these findings suggest that ancient, salt-rich brines were more widespread among primitive asteroids than previously recognized, and provide scientists with new opportunities to compare how water altered different asteroid bodies across the early solar system.
"The chips of the most salt-rich bits of this meteorite are quite comparable to the samples returned by the Hayabusa2 and OSIRIS-REx missions," said Mike Zolensky, a meteorite researcher at NASA Johnson and co-author of the study. "They're not identical. They're different in some very interesting ways, but they've seen very similar processes."
