Venus’ thick atmosphere is capable of destroying kilometer-sized bodies such as asteroids, creating various types of traces on the surface. While larger cosmic bodies are able to reach the surface, creating impact craters or crater dispersion fields, smaller bodies effectively transfer the initial kinetic energy into the atmosphere, resulting in an “atmospheric explosion” at some altitude. In these cases, the most visible marks on the surface of Venus are created by atmospheric shock waves and the flow of gas behind the shock fronts reflected from the solid surface. The transitional sizes of impactors that break up in the atmosphere but reach the surface give rise to clusters of craters. The paper presents the first results of three-dimensional calculations of the destruction of rocky asteroids in the atmosphere of Venus, indicating significant differences from simple two-dimensional axisymmetric calculations.

Приведены результаты трехмерных расчетов деформации, фрагментации и торможения астероида размером 1.5 км в атмосфере Венеры. Сравнение с результатами проведенных ранее двумерных расчетов показало, что используемая в двумерных расчетах осевая симметрия приводит к более сильному торможению фрагментов разрушенного астероида, чем в трехмерной геометрии, более соответствующей реальности. Полученная в трехмерных расчетах структура разрушенного астероида, состоящего из нескольких крупных и множества мелких фрагментов, по-видимому, может объяснить причину образования кратерных кластеров и темных и ярких пятен (splotches), наблюдаемых на поверхности Венеры. The results of calculations of deformation, fragmentation and deceleration of asteroids 1.5–5 km in size in the atmosphere of Venus are presented. The fraction of energy lost by asteroids during their passage through the atmosphere and the effective dimensions of an asteroid (or a cloud of its fragments) at the moment of impact on a solid surface are determined. It is shown that asteroids 1–2 km in size reach the surface of Venus in the form of a cloud of fragments with a diameter of 5–20 km, the kinetic energy of which is 10– 1000 times less than the initial energy of the asteroid. Such impacts do not appear to result in the formation of classical single craters or crater fields, but may be responsible for the formation of dark and bright spots (splotches) observed on the surface of Venus.

A quantitative comparison of sea level differences calculated from sea surface current velocities and satellite altimetry measurements was carried out. The velocities were calculated by the automatic method for tracing thermal inhomogeneities based оn a sequence of infrared images with a priori estimation of the calculation accuracy. Comparisons were carried out along the tracks of an altimetry satellite and at the points of the regular grid, to which the values from the tracks are interpolated. Ageostrophic components were estimated for the calculated velocities. At the distances of about 100 km, their contribution did not exceed the accuracy of altimetry measurements (2-4 cm). Along the tracks, the estimates of sea level differences calculated from the velocities were close to those computed from satellite altimetry. At the regular grid points, the estimates of sea level differences by velocities were significantly higher than the estimates of sea level differences by satellite altimetry, which is explained by the drawbacks of the optimal interpolation scheme used. It was concluded that the joint use of two types of measurements to retrieve the World Ocean circulation is reasonable.

Приведены результаты трехмерного численного моделирования падения десятикилометровых ядер комет со скоростями от 20 до 50 км/с под углом 45 градусов на твердую поверхность и в океан глубиной до 6 км. В расчетах получены максимальные массы, выброшенных в атмосферу океанской воды, вещества кометы и грунта, а также массы океанской воды, вещества кометы и грунта, оставшиеся в атмосфере через 10 минут после удара. Определена масса паров в выбросах. The results of three-dimensional numerical modeling of the oblique impacts of ten-kilometer water comets with velocities of 20 to 50 km/s at an angle of 45° onto a solid surface and into an ocean up to 6 km deep are presented. The maximum masses of ocean water, comet and soil matter ejected into the atmosphere, as well as the masses of water, impactor and soil matter remaining in the atmosphere 10 minutes after the impact are calculated. The mass of vaporized ejecta is determined.

— The results of numerical simulation of the generation and the initial stage of tsunami wave propagation during the impacts of asteroids with sizes of about 10 km into an ocean with a depth of 1 to 6 km are presented. The calculations obtained the amplitudes and wavelengths at a distance of 2000 km from the impact point. Approximate formulas are given that make it possible to estimate the amplitudes and wavelengths with an accuracy of 10–20%. The conclusion is confirmed that when an asteroid with a size of about ten kilometers falls into the ocean, long tsunami waves are generated, similar to those that occur during earthquakes.

Gas and dust clouding after large-scale blasting at Sitovo Quarry in the Lipetsk Region and the resultant pollution of the neighborhoods of the nearest towns is studied. The concentrations of solid particles less than 2.5  $$\mu$$ m in size are determined in real time using modern equipment. The electronic filming of a large-scale blast and the dust cloud transfer with the wind within the limits of the quarry allowed considering a theoretical partial problem on propagation of fine-dispersion dust from the upper portion of the cloud from a height of 50–100 m to the recording points on ground surface beyond the quarry limits. The methods of computational fluid dynamics are used to model flow at the bottom of the atmospheric boundary layer disturbed by the wind interaction with the quarry topography. It is shown that turbulent diffusion ensures vertical dispersion of micro particles down to the recording points. An explanation is proposed for the revealed non-monotonic maximal concentration of dust over ground surface with an increasing distance from the quarry.

Abstract—Destruction on the Earth’s surface caused by a shock wave is one of the most important and dangerous effects from asteroid and comet impacts. The overpressure and wind speed behind the shock wave front, leading to various dangerous effects, can be estimated on the basis of specially developed models of the interaction of cosmic objects with the atmosphere and the Earth’s surface. The shock wave is also the cause of seismic effects, but this work only considers the direct effect of the shock wave. A serial numerical modeling of the interaction of cosmic objects with the atmosphere has previously been performed for a large number of different scenarios under the hydrodynamic model. Analysis of the modeling results provides scaling relations that allow you to estimate the overpressure, wind speed behind the shock wave and their distribution on the surface, if you know the impactor’s parameters, its velocity and trajectory inclination angle. These relations take into account the spatial inhomogeneity of the overpressure distribution on the Earth’s surface. The suggested scaling relations were tested on the data of the Chelyabinsk and Tunguska events, which showed a good correspondence with the observed destruction data. The obtained scaling relations are used in the online calculator ( http://www.AsteroidHazard.pro ), which allows you to quickly and quite accurately estimate the various effects of impacts.

Abstract—Mass industrial explosions on extended benches of open pits are the most effective way to crush rock. Such explosions are accompanied by the rise of a gas and dust cloud. Three-dimensional numerical experiments are used to study the interaction of ascending gas and dust clouds generated by three, five, and multiple linearly arranged explosions in open pit mines. We examine both the initial stage of formation of a hot rarefied dust and gas cloud after the scattering of detonation products and the subsequent rise of thermals caused by buoyancy forces. We have obtained the dependences of the rise altitude and the size of the gas and dust clouds on the distance between adjacent explosions.

The results of numerical modeling of the vertical fall of ten-kilometer asteroids onto a solid surface and into an ocean with a depth of 1 to 7 km are presented. The calculations obtained the maximum masses of water and soil emitted into the atmosphere, as well as the masses of water and soil remaining in the atmosphere 30 minutes after the impact. It is concluded that that when asteroids about ten kilometers in size fall into the ocean, the impact on the Earth's atmosphere will, apparently, be no less strong than when asteroids fall on land.

Cometary impacts on Earth, as comets themselves, especially aperiodic ones, have been much less studied compared to asteroids. Nevertheless, despite the rarity of such impacts, they occurred in the past and cannot be ruled out in the near future. Moreover, the impacts of interstellar and, in principle, even intergalactic objects with hyperbolic orbits are possible. One such comet 2I/Borisov has been discovered quite recently. To assess the influence of such objects on Earth, we carried out numerical simulations of the impacts of cometary nuclei with diameters of 1 and 3 km on solid Earth at speeds of 70 and 170 km/s at an angle of 45° to the surface. Modeling was carried out using a hydrodynamic computer code with allowance for thermodynamic properties of a dusty core and shell of a comet and Earth’s crust in solid and molten state. Fluxes of thermal radiation on Earth’s surface were determined based on an approximate solution of the radiation transfer equation, taking into account optical properties of vapors and air. We estimated areas affected by air shock waves, masses of material ejected into the atmosphere and atmospheric pollution, magnitudes of earthquakes, areas of potential fires. The most dangerous direct effect is associated with the possibility of fires in areas that are much larger than both the size of an impact crater and the area of low-velocity ejecta from a crater, ranging in diameter from 3000 km with the minimum of considered impact energies up to 14 000 km with the maximum impact energy. Long-term effects of the impacts are associated with air pollution by fine dispersed ejecta, chemical components, darkening of the atmosphere.

The results of numerical simulation of kilometer-sized asteroid impacts on different types of terrain (a flat surface, a mountain, and a depression) are presented. The results show that terrain features significantly affect the amplitude of the shock wave propagating along the surface, the fireball size, the radiation fluxes on the surface, and the distribution of ejecta around the crater. This effect is significant if terrain inhomogeneities are equal to or larger than the impactor in size.

In this paper we present the results of numerical modeling of the Chelyabinsk dust train during the first 3 min after the meteoroid entry which are in qualitative agreement with observations. Then we analyze the possibility of plume formation after impacts of small cosmic bodies and make some calculations for the Tunguska event which, unfortunately, cannot be compared directly with observations. We also estimate long-lasting disturbances in the upper atmosphere caused by the plume formation.

Numerical simulation of the destruction, evaporation, deceleration, and emission of the Chelyabinsk superbolide has been carried out. The model assumes that the main energy is radiated in the stage when the asteroid is already completely destroyed and does not have solidity (quasi-liquid approximation). The radiation transfer during the motion is taken into account in the approximation of radiative heat conductivity and volumetric emission. The distributions of temperatures and densities are obtained at the moments when the bolide is at different altitudes. The intensity of radiation at the Earth’s surface is calculated at certain times by solving the radiative transfer equation along the rays passing through the luminous region using the air and LL-chondrite vapor absorption coefficients. The features of superbolide radiation, the contribution of air and vapor to radiation, the size of the luminous region, and the radiation spectrum have been considered. The calculated efficiency of radiation—17% of the kinetic energy of a cosmic body—agrees with the results of observations. It is shown that due to anisotropy of the superbolide radiation, the determination of luminous efficiency from measurements can depend on the observation point. For estimations, the pointsource approximation can be used, but in general, the source luminous efficiency is unknown, and its location is determined with some error; therefore, numerical simulation is required to reliably estimate the consequences of space body falls.