Why the stone exploded

Abstract

Why and how did the Chelyabinsk meteoroid explode at an altitude over 20 km above Earth’s surface? Calculations based on standard approaches used in meteorite research indicate that the abrupt increase in energy release at altitudes between 45–25 km (kinetic explosion) was not the reason, but the consequence of its destruction. The destruction occurred because of mechanical stresses in the meteoroid, created by the air pressure and the reduction of its velocity in the dense layers of the atmosphere. The meteoroid was quite non-uniform in its mechanical properties and contained friable areas of little strength. This resulted in two cascades of destruction, at altitudes between 55–50 and 40–35 km. Intensive ablation of matter from the meteoroid’s surface occurred at altitudes between 50–25 km (ablation is the phenomenon of ‘blowing-off’ matter from the surface of a solid body by high-speed flows of gas. The process of ablation forms the surfaces of meteorites fallen to Earth and makes them smooth, but with specific grooves and notches – regmaglypts). Due to ablation, 99.5 percent of the initial mass of the meteoroid turned into vapor and dust before it fell to the surface of Earth. Only a small fraction of the meteoroid fell to the ground in the form of large and small fragments.