Abstract: The article considers the current problems of predicting the Earth's collision with asteroids and comets. Mathematical modeling of analyzed process of asteroids falling into oceans and seas is especially complex. Such models are based on solving the classical Euler-Navier-Stokes equations. The relevance of abovementioned problem is also justified by a number of features of the Black Sea basin, including the presence of a large amount of hydrogen sulfide and methane. An estimate of the concentration of hydrogen sulfide in the air during an asteroid fall into the Black Sea was obtained. It is shown that the main emission is associated with expected release of deep waters to the surface in the area of the fall, due to which the concentration of hydrogen sulfide in the surface layer of the atmosphere can reach one gram / cubic meter. In the cloud formed by the steam emission, the concentration of hydrogen sulfide does not exceed 0.04 gram/cubic meter. Based on obtained results of their study, authors come to conclusion that the content of hydrogen sulfide in the steam, and then in resulting cloud, is half the dangerous values at which the evacuation of the population is necessary. The principal difference between an asteroid hitting water and hitting a solid surface is that it does not immediately explode or melt but goes under water. In certain areas of the sea, the fall of an asteroid to the bottom can cause methane emissions, including due to the melting of gas hydrates. In this case, an explosive concentration of the gas-air mixture can be achieved. Perhaps the greatest danger is associated with the impact of the asteroid on the bottom and the subsequent exit of deep waters to the surface.

Keywords: model calculations, safety, methane, comet, hydrogen sulfide, release of hydrogen sulphide, water wapor, crater, Black Sea, asteroid