Physical Phenomena at the Fall of the Small Space Bodies on the Ground and their Modelling
The paper describes physical processes such as deceleration, ablation, and fragmentation that accompany the entry of cosmic bodies into the Earth’s atmosphere. Applicable mathematical methods are also presented. The entry of an 80-m-diameter asteroid allows to explain all observed enigmatic effects of the Tunguska event - butterfly-shaped forest fallout, white nights in Europe, and absence of extraterrestrial materials at the impact site. The Chelyabinsk meteoroid is 4-5 times smaller in size. However, bow shock waves are strong enough to destroy windows within an area of 2000 km<sup>2</sup>. Intermediate-sized bodies (10-100 m in diameter) are the most dangerous cosmic objects for modern civilization. Their impacts occur every 100-1000 years and cannot be predicted in advance; although they cannot reach the surface, damaged area may exceed 1000 sq.km.