New insights into shatter cones formation from MEMIN experiments

We recovered shatter cone fragments from the ejecta of hypervelocity impact experiments, performed in the framework of MEMIN. The fragments geometries were characterized by WLI, and the fractures surfaces themselves by SEM. We estimated low bulk shock pressures of 2 to 5 GPa for the material in which the shatter cones have formed. The microstructural investigation revealed intricate melt films and shear deformation along the shatter cone surface, indicating increasing strain towards the same. Combining our observations with a possible formation model, we interpret shatter cones as the result of symmetric crack branching of rapidly propagating fractures with a resulting mixed mode I/II fracture surface.