A large international collaboration, involving nearly one hundred researchers worldwide and led by Auriane Egal (FRIPON / Montreal Planetarium / University of Western Ontario) publishes today in Nature Astronomy (see also ArXiv) the first comprehensive study of an asteroid tracked from space through to its impact on Earth. The analysis of asteroid 2023 CX1 represents a unique opportunity for both science and planetary defense.
Discovered on February 12, 2023, barely seven hours before entering Earth’s atmosphere, 2023 CX1 struck over Normandy on February 13 at 02:59 UTC. Nearly spherical, it measured just under one meter in diameter with an estimated mass of about 650 kg. It catastrophically disrupted at an altitude of about 28 km, releasing 98% of its kinetic energy in a fraction of a second — an exceptional behavior for an object of this size. The explosion scattered more than a hundred fragments across Normandy. The recovered meteorite, named Saint-Pierre-Le-Viger (SPLV), is the only ordinary chondrite ever studied from space to laboratory.
An unprecedented scientific mobilization
More than 100 scientists and citizen observers across Europe, America, Africa, and Australia joined forces to investigate every aspect of this exceptional fall: telescopic discovery, orbital tracking, atmospheric observations through optical, infrasound and seismic data, and geochemical laboratory analyses. This unique alliance between professional and citizen science demonstrates the power of international cooperation when facing rare and critical celestial events.
Key scientific findings
- A record prediction — 2023 CX1 is only the 7th asteroid ever detected prior to impact. Thanks to a novel observational strategy, ESA and NASA predicted the time and location of the fall with unprecedented accuracy.
- A world first — Space agencies and the FRIPON/Vigie-Ciel network mobilized the public to record the asteroid’s atmospheric entry, resulting in the first large-scale “targeted” observation of a meteor. It also enabled the rapid recovery of meteorites on the ground, thanks to an exceptional citizen mobilization.
- An “ordinary” asteroid… but unique — 2023 CX1 is the only imminent impactor identified as an ordinary L-type chondrite, the most common class among meteorites on Earth.
- An orbit with unmatched precision — The difference between the predicted and observed atmospheric trajectory was less than 20 meters, making SPLV the meteorite with one of the most precisely measured orbits to date.
- A traced origin — Analyses show that 2023 CX1 separated from its parent body in the inner main belt about 30 million years ago.
- An atypical fragmentation — Withstanding high dynamic pressures (4 MPa), the asteroid disintegrated abruptly around 28 km altitude, generating a concentrated spherical shock wave.
- An increased risk — Hydrodynamic simulations reveal that this type of fragmentation could cause greater ground damage than progressive fragmentations, as observed for the 2013 Chelyabinsk event.
Implications for planetary defense
This study highlights the need to integrate spectral, structural, and dynamical characterization of pre-impact asteroids into planetary defense protocols. L-type chondrite-related asteroids, originating from the inner main belt, may require reinforced alert systems and adapted evacuation plans in the event of a threat.
“We confirmed the existence of a new population of asteroids linked to L-type chondrites, capable of fragmenting abruptly in the atmosphere and releasing almost all their energy at once. Such asteroids must be accounted for in planetary defense strategies, as they pose an increased risk to populated areas,” explains Auriane Egal, astrophysicist at the Montreal Planetarium and member of the FRIPON/Vigie-Ciel network.
Further reading:
- “Catastrophic disruption of asteroid 2023 CX1 and implication for planetary defence”, Egal et al., Nature Astronomy (2025), 10.1038/s41550-025-02659-8
- “Recovery and planned study of the Saint-Pierre-Le-Viger meteorite: an achievement of the FRIPON/Vigie-Ciel citizen science program”, Zanda et al., 86th Annual Meeting of the Meteoritical Society (2023)
- https://espacepourlavie.ca/en/fall-and-recovery-asteroid-2023-cx1
- https://www.fripon.org/meteorites-found-after-observation-of-asteroid-2023cx1-fireball-abovenormandy-france/
- “Fall and recovery of Asteroid 2023 CX1”: https://youtu.be/7kjliXyLiJ8?si=aJErRoGWROFfCEpH