A rarity on Earth: The Hillsborough meteorite is only the 22nd observed CM-type fall in history, and only the second witnessed fall of a CM1/2 classification (following the Kolang fall in Indonesia in 2020).
The chemical profile of the Hillsborough meteorite supports this prebiotic potential:Organic ingredients: The rock is composed of 1.8% carbon and 0.07% nitrogen by weight, featuring isotope ratios typical of primitive space matter.
Astrobiologists at NASA’s Goddard Space Flight Centre concluded that the complex distribution of amino acids inside the rock was actively formed inside the parent asteroid, assisted by this liquid-brine chemistry.
When these types of asteroid fragments bombarded the early Earth billions of years ago, they effectively delivered a ready-made organic inventory that helped spark terrestrial life.
To preserve the rare specimen for future generations, fragments of the Hillsborough meteorite will be curated and displayed at the American Museum of Natural History in New York City.
An international team of researchers has discovered highly unusual, salt-rich chemistry preserved inside a meteorite that crashed through the roof of a New Jersey home
Published in the journal Science Advances, the study reveals that the rock contains pristine evidence of concentrated, briny fluids from the near-surface of a primitive asteroid, a process never before seen in this class of space rock, which may explain how the building blocks of life were delivered to Earth.
The Hillsborough strike and pristine recovery
On July 16, 2024, a meteor the size of a heavy suitcase entered Earth’s atmosphere at 32,000 mph (14.4 km/s), generating a sonic boom over New York City. While Doppler weather radar detected a falling cloud of pebbles, only one large fragment, weighing over two pounds, was recovered because it crashed directly through a bedroom ceiling in Hillsborough, New Jersey.
Recognising the find, the homeowner immediately used disposable gloves and aluminium foil to seal the fragments in glass jars.
“Thanks to the homeowner’s quick reaction, these are the most pristine CM1/2 meteorites we know of,” said lead author and meteor astronomer Peter Jenniskens of the SETI Institute and NASA’s Ames Research Center.
A rare intermediate class: CM1/2 Carbonaceous Chondrite
When scientists analysed the Hillsborough specimen, they identified it as a CM-type carbonaceous chondrite (a class of primitive, carbon-rich meteorites).
However, its internal makeup was highly unusual:
Water alteration: The mineral structures were far more extensively altered by liquid water than is typically observed in standard CM2 meteorites.
Intermediate classification: Researchers classified the rock as a CM1/2 carbonaceous chondrite, an intermediate stage between highly altered (CM1) and moderately altered (CM2) states.
A rarity on Earth: The Hillsborough meteorite is only the 22nd observed CM-type fall in history, and only the second witnessed fall of a CM1/2 classification (following the Kolang fall in Indonesia in 2020).
Clues of near-surface asteroid brines
The most significant finding came from inside the meteorite’s matrix. Scientists found tiny, salt-rich CM1 fragments embedded within the rock, suggesting they originated from a region near the parent asteroid’s surface where liquid water evaporated, leaving behind highly concentrated pockets of salt.
Similar briny fluid signatures have recently been returned to Earth by spacecraft missions—namely JAXA’s Hayabusa 2 from asteroid Ryugu and NASA’s OSIRIS-REx from asteroid Bennu—but those belonged to a different family of meteorites (CI-type). Finding these briny signatures in a CM-type meteorite shows that liquid salt-water processes were far more common on primitive asteroids than previously assumed.
Catalysing the Chemistry of Life
The presence of highly concentrated salt brines is a major finding for astrobiologists. Liquid brines prevent essential nutrients like phosphate from solidifying, allowing them to remain dissolved in water where they can react. Brines also act as a catalyst, driving chemical reactions between organic carbon molecules and surrounding minerals.
The chemical profile of the Hillsborough meteorite supports this prebiotic potential:
Organic ingredients: The rock is composed of 1.8% carbon and 0.07% nitrogen by weight, featuring isotope ratios typical of primitive space matter.
Organo-metallic compounds: Mass spectrometry revealed a high fraction of magnesium-organic compounds, which are the product of organic molecules binding directly to minerals. In living organisms, similar organo-metallic compounds are vital for oxygen transport (blood) and photosynthesis.
Prebiotic inventory: The rock also contained a rich suite of soluble organics, including amino acids and carboxylic acids.
Astrobiologists at NASA’s Goddard Space Flight Centre concluded that the complex distribution of amino acids inside the rock was actively formed inside the parent asteroid, assisted by this liquid-brine chemistry. When these types of asteroid fragments bombarded the early Earth billions of years ago, they effectively delivered a ready-made organic inventory that helped spark terrestrial life.
To preserve the rare specimen for future generations, fragments of the Hillsborough meteorite will be curated and displayed at the American Museum of Natural History in New York City.
