Meteorites help scientists understand the early Solar System, but some are more “shocked” by impacts than others. Carbonaceous chondrites, despite water-related changes, experience less shock than ordinary chondrites.
A Kobe University study has finally solved this decades-old puzzle. Researchers found that when meteorites are hit, organic materials in carbonaceous chondrites undergo oxidation, reducing shock effects—something ordinary chondrites lack.
This discovery could help guide future missions, including potential sample collection from Ceres, a dwarf planet rich in carbonaceous material.
Kobe University astrophysicist Kurosawa Kosuke was intrigued by a 20-year-old theory suggesting that meteorite impacts release water vapor, which ejects materials into space. While promising, the theory had gaps—it lacked calculations to confirm if enough water vapor would be produced, and it didn’t explain why some carbon-rich meteorites without water-containing minerals were also less shocked.
Small fragments of carbon-containing asteroids are too fragile to survive atmospheric entry
Kurosawa set out to investigate, believing that carbon-containing materials might react differently under impact. He used a two-stage light gas gun, a device he had developed, connected to a sample chamber. This allowed his team to fire high-speed pellets at meteorite-like samples. This setup enabled them to analyze impact-generated gases while preventing contamination from the gunshot itself.
The experiments demonstrated that intense chemical reactions produce superheated carbon monoxide and carbon dioxide gases when carbon-containing meteorites are impacted. The force of the following explosion is strong enough to eject the highly shocked rock material into space.
Interestingly, this phenomenon only occurs in carbon-rich meteorites, while carbon-poor ones remain intact. This led researchers to conclude that carbon-containing meteorites experience shock like others, but the evidence is violently expelled, making them seem less affected. Essentially, their shocking history is erased by the explosion itself.
Not all is lost despite the violent ejection of shocked material from carbon-rich meteorites. The research team calculated that gravity might be strong enough to pull the expelled debris back to the surface on larger celestial bodies, such as Ceres.
This means that over time, Ceres could have built up a layer of highly shocked material from past impacts. These findings offer a valuable guideline for future planetary exploration, suggesting that missions to Ceres could uncover preserved records of impact history, potentially unlocking new insights into the early Solar System’s dynamics.
Journal Reference:
- Kurosawa, K., Collins, G.S., Davison, T.M. et al. Impact-driven oxidation of organics explains chondrite shock metamorphism dichotomy. Nat Commun 16, 3608 (2025). DOI: 10.1038/s41467-025-58474-2
