Impact Disruption of Bjurböle Porous Chondritic Projectile

Abstract

The ∼200 m s ^−1 impact of a single 400 kg Bjurböle L/LL ordinary chondrite meteorite onto sea ice resulted in the catastrophic disruption of the projectile. This resulted in a significant fraction of decimeter-sized fragments that exhibit power-law cumulative size and mass distributions. This size range is underrepresented in impact experiments and asteroid boulder studies. The Bjurböle projectile fragments share similarities in shape (sphericity and roughness at small and large scales) with asteroid boulders. However, the mean aspect ratio (3D measurement) and apparent aspect ratio (2D measurement) of the Bjurböle fragments is 0.83 and 0.77, respectively, indicating that Bjurböle fragments are more equidimensional compared to both fragments produced in smaller-scale impact experiments and asteroid boulders. These differences may be attributed either to the fragment source (projectile versus target), to the high porosity and low strength of Bjurböle, to the lower impact velocity compared with typical asteroid collision velocities, or potentially to fragment erosion during sea sediment penetration or cleaning.

Keywords

• Planetary geology
• Meteorites
• Chondrites
• Impact phenomena
• Asteroids