Speaker
Description
On February 13, 2023, asteroid 2023 CX1 entered Earth's atmosphere over the English Channel, approximately seven hours after its discovery. The event produced a bright fireball observed across western Europe and led to the recovery of the Saint-Pierre-le-Viger meteorites in Normandy, France. This rare combination of pre-impact observations, atmospheric measurements, and laboratory analyses provided an exceptionally well-constrained case study of how a small asteroid deposits its energy in the atmosphere.
By combining telescopic observations, dynamical modelling, optical and seismo-acoustic measurements, strewn-field modelling, and meteorite analyses, we reconstructed the asteroid's likely origin, trajectory, physical properties, and fragmentation behaviour. Comparing results from different instruments and laboratories also revealed discrepancies in some of the measurements and analyses, allowing us to identify limitations and improve existing methods.
2023 CX1, a nearly spherical object approximately 72 cm in diameter and 650 kg in mass, underwent a sudden catastrophic disruption at an altitude of 28 km, under a dynamic pressure of approximately 4 MPa. Rather than depositing its energy progressively along its trajectory, the body released up to 98% of its total energy within a concentrated atmospheric region. Hydrodynamic simulations show that this rapid energy deposition produces a more spherical shock wave than would result from gradual fragmentation, which could increase the ground area exposed to high overpressures for larger impactors.
We will discuss the observational constraints, remaining uncertainties, and implications of these results for modelling atmospheric fragmentation and assessing future impact hazards.
*This presentation is based on the collaborative study published in Egal et al. (2025, Nature Astronomy), co-authored by :
Denis Vida, François Colas, Brigitte Zanda, Sylvain Bouley, Asma Steinhausser, Pierre Vernazza, Ludovic Ferrière, Jérôme Gattacceca, Mirel Birlan, Jérémie Vaubaillon, Karl Antier, Simon Anghel, Josselin Desmars, Kévin Baillié, Lucie Maquet, Sébastien Bouquillon, Adrien Malgoyre, Simon Jeanne, FRIPON International Team, Jiří Borovička, Pavel Spurný, Hadrien A. R. Devillepoix, Marco Micheli, Davide Farnocchia, Shantanu Naidu, Peter Brown, Paul Wiegert, Krisztián Sárneczky, András Pál, Nick Moskovitz, Theodore Kareta, Toni Santana-Ros, Alexis Le Pichon, Gilles Mazet-Roux, Julien Vergoz, Luke McFadden, Jelle Assink, Läslo Evers, Daniela Krietsch, Henner Busemann, Colin Maden, Lisa Maria Eckart, Jean-Alix Barrat, Pavel Povinec, Ivan Sýkora, Ivan Kontul’, Oscar Marchhart, Martin Martschini, Silke Merchel, Alexander Wieser, Matthieu Gounelle, Sylvain Pont, Pierre Sans-Jofre, Sebastiaan de Vet, Ioannis Baziotis, Miroslav Brož, Michaël Marsset, Jérôme Vergne, Josef Hanuš, Maxime Devogèle, Luca Conversi, Francisco Ocaña, Luca Buzzi, Dan Alin Nedelcu, Adrian Sonka, Florent Losse, Philippe Dupouy, Korado Korlević, Dieter Husar, Jost Jahn, Damir Šegon, Mark McIntyre, Ralf Neubert, Pierre Beck, Patrick Shober, Anthony Lagain, Darrel Robertson, Peter Jenniskens, Olivier Hernandez.