The Winchcombe fireball—That lucky survivor

1,2,3,4Sarah McMullan et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article []
1Impact and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, SW7 2BP London, UK
2UK Fireball Network (UKFN), UK
3UK Fireball Alliance (UKFAll), UK
4Global Fireball Observatory (GFO), Australia
Published by arrangement with John Wiley & Sons

On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball’s atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s−1). A near-catastrophic fragmentation at ∼0.07 MPa points to the body’s fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.


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