From 2023 CX1 to Saint-Pierre-le-Viger: A Complete Autopsy of a Small Impacting Asteroid

On February 13, 2023, asteroid 2023 CX1 entered Earth's atmosphere over the English Channel, only seven hours after its discovery. The event produced a bright fireball observed across western Europe and led to the fall of the Saint-Pierre-le-Viger meteorites in Normandy, France. Thanks to rapid international coordination, exceptional public mobilization, and an efficient ground search campaign, the first fragments of the asteroid were recovered within hours. The meteorites, classified as an L5-6 chondrite breccia, were sent for analysis before significant terrestrial contamination. This made 2023 CX1 the first asteroid to be studied in detail in space, in the atmosphere, and in the laboratory.

 

Only eleven asteroids have so far been discovered before impact, and even fewer have been linked to recovered meteorites. Among them, 2023 CX1 stands out as the only ordinary chondrite fall combining pre-impact characterization, detailed instrumental observations of the fireball, and meteorite recovery. By combining telescopic tracking, dynamical modelling, optical and seismo-acoustic analysis of the atmospheric entry, strewn-field reconstruction, and laboratory measurements, we retraced the full history of 2023 CX1, from its origin in the inner main belt to its final fragments on Earth.

 

Our results show that 2023 CX1 was a large, nearly spherical meteoroid, approximately 72 cm in diameter and 650 kg in mass, with an origin consistent with the inner main belt. Cosmogenic nuclide measurements indicate that the meteoroid was liberated from its parent body about 30 million years ago. Despite belonging to one of the most common meteorite groups found on Earth, 2023 CX1 revealed an unusual atmospheric behaviour: instead of fragmenting progressively, it underwent a sudden catastrophic disruption at about 28 km altitude, under a dynamic pressure of ~4 MPa, releasing ~98% of its energy in a single event. This concentrated energy deposition generated a more spherical shock wave than the cylindrical shock waves produced by gradual disintegration, increasing the potential for localized ground-level effects.

 

The multidisciplinary, multi-instrument analysis of the SPLV fall made 2023 CX1 one of the best-characterized small impactors to date. Altogether, this event demonstrates the potential of imminent impactors to open a new path for space-to-lab asteroid studies.