AN ANALYTICAL MODEL OF THE ATMOSPHERIC ENTRY OF LARGE METEORS AND ITSAPPLICATION TO THE TUNGUSKA EVENT

The atmospheric entry of a meteor is quite complex, with the body losi ng kinetic energy both from atmospheric drag and from mass loss due to aerodynamic heating. Moreover, high pressures on the windward side of the body result in enormous compressive stresses which may exceed the yield strength of the material and cause rapid fragmentation of the m eteor. While ablative mass loss is not important for extremely large o bjects, it must be accurately estimated to correctly predict the traje ctories of objects that are several tens of meters in diameter. The cu rrent paper describes a computer model which performs calculations of shock layer conditions, accounting for the time varying temperature di stribution, radiative cooling of the shocked gases, and blockage of su rface heating by ablation products. Application of the model to the we ll-known Tunguska Event indicates that the responsible bolide was prob ably a carbonaceous chondrite, although a stony asteroid or a cometary body cannot be conclusively ruled out.