In 2024, a small meteorite fell in a suburb of New York City. The event itself caused quite a stir at the time. Now, a chemical analysis of the rock has shown that it was once part of a world where aqueous salt solutions existed.
How the Meteorite Fell to Earth
On July 16, 2024, a daytime meteor passing slightly south of the Statue of Liberty shook New York with a sonic boom. An international team of scientists now reports in the journal Science Advances that shortly afterward, a meteorite weighing more than 2 pounds crashed through the roof of a house in Hillsborough, New Jersey. A forensic examination of the fragments showed that they contained preserved pieces from the near-surface layer of a primitive asteroid, where the material had been exposed to concentrated saline fluids—a process previously unknown for this type of protoplanetary world. This was reported by phys.org.
That day, a rock the size of a heavy airline suitcase entered Earth’s atmosphere at a speed of 14.4 kilometers per second. Sixty observers from New York, New Jersey, Connecticut, Rhode Island, and Pennsylvania reported to the American Meteor Society that they had seen the meteor, while 16 people in New York and New Jersey felt the shock wave.
The rock was fragile and quickly broke into pieces. The meteor disappeared from view at an altitude of 35 kilometers. After it vanished, weather Doppler radar at Newark Airport briefly detected a long cloud of falling stones stretching from Staten Island to New Jersey. Hillsborough was located at the far end of this cloud, where the largest stones fell. Only one was recovered because it struck a house.
The homeowner described what happened as follows:
“I was at home at the time, heard a loud crash, and discovered a hole in the ceiling of the primary bedroom. I noticed a strong odor resembling sulfur and saw numerous black fragments, as well as debris and black dust covering my bed, carpet, and the surrounding areas.”
He then immediately preserved and documented the entire scene, using disposable gloves and aluminum foil to place the meteorite fragments in glass jars.
A Rare CM1/2 Carbonaceous Chondrite
After examining the rocks, scientists determined that they belonged to one of two known types of primitive meteorites called CM carbonaceous chondrites, in which the letter “M” comes from the Mighei meteorite, which fell in Ukraine in 1889.
According to study co-author Mike Zolensky, a meteoriticist at NASA’s Johnson Space Center in Houston, analysis of the Hillsborough meteorite revealed fragments that had experienced more extensive exposure to water on the parent asteroid than is usually observed in CM2 carbonaceous chondrites. Based on the analysis, the sample was classified as a CM1/2 carbonaceous chondrite—an intermediate classification between the CM1 and CM2 petrographic types.
Hillsborough is the 22nd recorded fall of a CM-type meteorite, but only the second recorded fall of a CM1/2 carbonaceous chondrite, after the Kolang meteorite, which fell in North Sumatra, Indonesia, in 2020. All the others are CM2 meteorites. No falls of CM1 meteorites have been recorded.
Clues from Ancient Saline Deposits
Another known primitive type of carbonaceous chondrite is called CI, in which the letter “I” comes from the Ivuna meteorite, which fell in Tanzania in 1938. Pristine samples of this type were returned from the asteroid Ryugu by the Japanese space agency JAXA’s Hayabusa2 mission and from the asteroid Bennu by the U.S. space agency NASA’s OSIRIS-REx mission. Numerous signs of exposure to saline fluids located directly beneath the surface of their parent asteroids were found in them.
Zolensky and his colleague Chang-Mi Han identified small, salt-rich CM1 fragments in the Hillsborough meteorite, indicating that they originated from a near-surface region of the parent asteroid where liquid water evaporated and concentrated the salts. They are now working to identify the salt minerals and compare them with similar phases found in samples returned to Earth from the asteroids Ryugu and Bennu.
A high concentration of salt in saline fluids could potentially promote the formation of molecules that are crucial to life on Earth. Saline solutions allow phosphates to remain in solution and may catalyze chemical reactions between organic compounds and precipitated minerals.
“Carbon and nitrogen isotope studies indicate that primitive carbonaceous chondrites, particularly CM types, delivered organic matter to the early Earth,” noted cosmochemist Queenie Chan of Royal Holloway, University of London, England, and biogeochemist Nana Ogawa of the Biogeochemistry Research Center at the Japan Agency for Marine-Earth Science and Technology. “The Hillsborough meteorite contained 1.8% carbon and 0.07% nitrogen by mass and also had carbon and nitrogen isotopes characteristic of CM meteorites.”
Organic Molecules That Formed Inside the Meteorite
The meteorite contained a wide variety of soluble organic compounds, and the range of its composition confirms that the Hillsborough meteorite experienced greater exposure to water than most other CM meteorites.
“A significant proportion of the compounds formed as a result of interactions between organic matter and minerals,” noted organic mass-spectrometry specialist Philippe Schmitt-Kopplin of the Technical University of Munich. “We do not know whether these organic magnesium compounds formed as a result of chemical reactions with brine or were simply left behind by earlier impact processes associated with the meteorite’s fall.”
In living organisms, organometallic compounds are found in blood and participate in photosynthesis. Among the soluble organic compounds, researchers identified many amino acids similar to those found in CM2 chondrites that experienced a more moderate degree of alteration.
Astrobiologist Danny Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and his team at Goddard’s Astrobiology Analytical Laboratory concluded that the delivery of amino acids, carboxylic acids, and other soluble organic molecules by CM-type bodies may have contributed to the formation of the prebiotic organic inventory that preceded the emergence of life on Earth. Their analysis indicates that the complex distribution of amino acids observed in the Hillsborough meteorite formed inside the parent body, probably under the influence of chemical processes in brine.
