Модель абляции используется для оценки физических параметров метеороидов миллиметрового размера. В используемой модели абляции энергия набегающего потока расходуется только на потерю массы метеороида. Подбор параметров (размер и плотность) метеороидов для воспроизведения кривых блеска осуществляется с помощью автоматизированного подхода. Исследовано влияние теплоты абляции на массу, плотность и размер метеороидов. Оценки параметров метеороидов, полученные в рамках данной модели, сравниваются с оценками по эмпирическим соотношениям и с оценками по другой модели абляции. The ablation model is used to estimate the physical parameters of millimeter-sized meteoroids. In the ablation model used, the energy of the incident flow is spent only on the loss of mass of the meteoroid. The selection of parameters (size and density) of meteoroids for the reproduction of light curves is carried out using an automated approach. The influence of ablation heat on the mass, density and size of meteoroids was investigated. The estimates of meteoroid parameters obtained within the framework of this model are compared with estimates based on empirical relationships and with estimates based on another ablation model.

Возможны два предельных сценария ударов крупных космических тел: кратерообразующий удар, когда почти вся начальная кинетическая энергия тела идет на образование кратера, и так называемый«метеорный взрыв», при котором энергия выделяется в атмосфере. В переходных сценариях потеря энергии в атмосфере является существенной, но поверхности Земли тело достигает с энергией, достаточной для кратерообразования. Опасные последствия таких ударов должны оцениваться с учетом этого разделения энергии. На основе проведенных расчетов и простой квазиэмпирической модели взаимодействия космических тел с атмосферой предложены аппроксимационные формулы для определения доли энергии, потерянной космическим телом при пролете в атмосфере в переходных режимах. Результаты дают возможность описать появление и рост размера кратера с ростом размера ударника, который сейчас некорректно описывается используемыми в онлайн калькуляторах соотношениями, и скорректировать оценки опасных последствий для переходных сценариев. There are two ultimate impact scenarios for large space bodies: a crater-forming impact, when almost all of the initial kinetic energy of the body goes to the formation of a crater, and the “meteor explosion”, in which the energy is released in the atmosphere. In transient scenarios, the loss of energy in the atmosphere is significant, but the body reaches the Earth’s surface with enough energy to form a crater. The hazardous consequences of such impacts must be assessed with this energy separation in mind. On the basis of the performed calculations and a simple quasi-empirical model of the interaction of space bodies with the atmosphere, scaling relations for determining the fraction of energy lost by a space body during a passage in the atmosphere in transient modes are proposed. The results provide an opportunity to properly describe the appearance and growth of a crater as the impactor size increases, which is currently described incorrectly in online calculators of asteroid-comet hazard, and to adjust the estimates of other dangerous consequences for transient variants.

We completed numerical simulations of a number of asteroid and comet impacts on Earth to predict related shock wave and thermal radiation effects and to estimate seismic effects, as well as ionospheric disturbances. Using interpolation of the results, we were able to estimate these effects for arbitrary impact parameters. In addition, we used previously developed models to estimate the size of the impact crater and ejecta thickness. Finally, we developed a user-friendly web-based calculator () that quickly estimates shock wave pressure and radiation exposure at a given location, as well as crater size and average ejecta layer thickness, if any, seismic magnitude, change in ionospheric density, and some other values. The input parameters of the calculator are the impactor diameter and density, its speed and inclination angle of the trajectory above the atmosphere, and the coordinates of the observer (the point on the ground where it is necessary to determine the impact consequences). This paper describes the methods of numerical simulations and techniques for approximating the results. We present a few examples of how to assess the impact hazard, in particular, overpressure and wind speed on the surface, thermal radiation, and seismic shaking after a crater-forming impact or an airburst in the atmosphere.

В последние десятилетия на Марсе были обнаружены свежие места падения космических тел метровых размеров. Примерно половина этих космических объектов разрушается в разреженной атмосфере Марса и приводит к образованию кратерных полей рассеяния (кластеров). Расширенный каталог мест падения космических тел включает данные о 1438 недавних датированных местах падения, образованных между 2007 и 2021 гг. В работе рассматривается большая часть расширенного каталога недавних датированных мест падения космических тел, для которой доступны данные о размере и расположении кратеров в кластерах. Данные расширенного каталога дали возможность оценить показатель степени в дифференциальном и кумулятивном инкрементальном распределении как 2.7 и 2.2. Полученная оценка степени в кумулятивном распределении ниже, чем предполагается в большинстве работ, но близка к оценкам, полученным по нерасширенному каталогу. Было предложено разделить места падения метеороидов на Марсе на 3 типа: первый - доминирующий главный кратер, второй - 2 наибольших кратера сравнимы и третий - 3 или более сравнимых наибольших кратера, все дополнены (или нет) значительно более мелкими кратерами. Мы предполагаем, что выделенные группы могут соответствовать различным типам ударников и (или) различным типам разрушения метеороида в атмосфере. In recent decades, fresh impacts of meter-scaled cosmic bodies were discovered on Mars. Approximately half of these objects are destroyed in the rarefied atmosphere of Mars and their impacts lead to the formation of crater clusters (crater scattering fields). The expanded impact site catalog includes data on 1438 recent dated impact sites formed between 2007 and 2021. This paper considers a large part of the expanded catalog, for which data on the size and location of craters in clusters are available. Expanded catalog data provided an opportunity to estimate the exponent in the differential and cumulative incremental distribution as 2.7 and 2.2. The obtained estimate of the cumulative distribution exponent is lower than suggested in most studies, but it is close to the estimates obtained from the non-expanded catalog. In order to classify crater clusters, it was proposed to group them into 3 types: the first has a dominant main crater, the second collects 2 largest comparable craters, and the third has 3 or more comparable largest craters, in all cases largest craters may be supplemented (or not) by significantly smaller craters. We are assuming that the identified groups may correspond to different types of impactors and (or) different types of meteoroiddestruction in the atmosphere.

An ablation model is used to describe the interaction of small meteoroids with the Earth’s atmosphere. In this model, the mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid substance. The meteoroid is considered in two modifications as a solid and a porous object. An automated method for estimating the parameters of meteoroids (mass, size, and density) from light curves is developed based on the model of small meteor body ablation, which has been used to estimate the parameters of the Perseid meteors with a brightness of -2m to +2m. The effect of the dependence for saturated vapor pressure and the residual on the parameters of the meteoric body is analyzed. It is shown that for the same meteor, the use of different dependences for pressure or different residuals leads to the dispersion of the meteor mass estimate of not more than 10-15% of the average value, and for the meteor size not more than 35-40%. The difference between the maximum and minimum density estimates can be up to five times. The selected dependence for the saturation vapor pressure strongly affects the shape of the light curve, the quality of its approximation, and the density estimate. The average porosity for all meteoroids is 86±5%, which is close to the values for IDP. The density of meteoroids is determined with a large error. The selected model better describes meteoroids with the degree of skewness of the light curve in the range of 0.4 - 0.5. The use of the porous body model has little effect on the mass estimate, while the density estimates increase by up to 2 times.

An ablation model is used to describe the interaction of small meteoroids with the Earth's atmosphere. In this model, the mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid substance. The meteoroid is considered in two modifications as a solid and a porous object. An automated method for estimating the parameters of meteoroids (mass, size, and density) from light curves is developed based on the model of small meteor body ablation, which has been used to estimate the parameters of the Perseid meteors with a brightness of -2m to +2m. The influence of the dependence of the structure (solid/porous) on the parameters of the meteoric body is considered. The estimates of the mass of meteoroids using different model modifications are close to each other (the deviation is no more than 25%) and they coincide with the photometric mass of the meteoroid. The average porosity for all meteoroids is 72% and 84% depending on the model, which is close to the values for IDP. The density of meteoroids is determined with a large error.

Recently, about 1200 fresh meteoroid impact sites were discovered on Mars, they are single craters and crater fields with crater sizes up to 50 m. Atmosphere density on the surface of Mars corresponds to about 30 km height of the Earth's atmosphere. Thus, scattering fields of craters on Mars allow one to study fragmentation details, which are hidden in terrestrial conditions. Previously, data on 77 Martian clusters were analyzed. To estimate the trajectory of meteoroids, the scattering ellipses were constructed. The ellipse size determines the angle of the meteoroid entry into the atmosphere and provides information about the height of destruction and the density of a space object. For more than 70% of clusters, the obtained azimuth estimations are within 20° of those determined by independent evaluations. For some clusters, the flight direction can be specified from crater ejecta on Martian HiRISE images. Estimations of azimuth angles for 42 clusters coincide with previous results obtained for 70% of clusters, while the data on the flight direction fit only for 30%. The discrepancy between different estimations of azimuth angles requires the use of other approaches. Continuing on the topic, this work presents numerical modeling of the flight and fragmentation of a meteoroid in the atmospheres of two planets, Mars and Earth. It is assumed that the simulation results will allow one to determine meteoroid parameters, in particular, the trajectory parameters. The main purpose of the presented work is to demonstrate the efficiency of the fragmentation model, its applicability to Martian clusters, and the difference in the scattering fields on the Earth and Mars: the atmospheric sorting effect is weak on Mars, and the scattering field is mainly dependent on fragmentation and the lateral spreading of fragments. The area of the simulated cluster is described with an accuracy of about 10%; the size of the maximum crater, with an accuracy of about 35%. The ratios of crater diameters to the maximum crater diameter for the model and real cluster are close to each other. In the future, it is planned to implement a series of numerical simulations with different initial data and to compare the results with real clusters on Mars, which have already been analyzed in previous works. The aim is to propose the advanced methods for determining the direction of the flight of meteoroids and the properties of impactors such as density and strength.

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.

We study the process of meteoroid interaction with the Earth's atmosphere, in particular, the effect of ablation.An ablation model is used, where mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid's substance.An automated method is suggested, where we estimate the physical parameters of a meteoroid by comparing data from observations and models of known parameters.Model constraints and features of the models are discussed.

Exploration of small craters and craters clusters on Mars allows one to study meteoroid fragmentation details that cannot be detected in terrestrial conditions.It was suggested earlier that the description of a cluster with a scattering ellipse allows one to estimate the meteoroids' trajectory, which is connected with orbital parameters of the impactor.Independent construction of scattering ellipses and comparison with crater ejecta demonstrate the accuracy and find out some problems of this approach.

In the morning of June 21, 2018 (1:16 Universal Time (UTC)) the space body entered the Earth atmosphere in the Lipetsk region, Russia. This event was detected by a number of registration systems in cars, satellite observations of bolide light curve and subsequent dust trail. The videos, photos, satellite data allow us to calculate the trajectory and the orbit of the Ozerki bolide. The atmospheric entry velocity is 14. 9 +/- 1 km/s. The height of the depression point is 32.8 +/- 0.9 km and that of the maximum brightness is 27.2 +/- 0.9 km. The pre-atmospheric orbit of the Ozerki meteoroid was also calculated: q = 0.67 +/- 0.04 AU, a = 0.84 +/- 0.02 AU, e = 0.199 +/- 0.030, i = 18.44 degrees +/- 3.05 degrees, Omega = 89.6561 degrees and omega = 335.29 degrees +/- 5.15 degrees. The geocentric radiant position is RA = 307.51 degrees +/- 3 degrees and DEC = 43.11 degrees +/- 3.degrees The found material was called Ozerki meteorite and it is classified as an ordinary chondrite (L6). The estimated: mass of the meteoroid is 94 +/- 20 tons, the energy is 2.5 +/- 0.5 kt TNT, diameter is 3.7 +/- 0.5 m.

Asteroids risk models require understanding how an asteroid (or a comet) entering into the atmosphere can harm people and infrastructure. Radiation produced due to the flight of a cosmic object in the atmosphere and due to an emission of a plume is one of the main dangerous consequences of a crater-forming impact. This thermal radiation can be strong enough to be dangerous to people, to ignite fires and even to melt rocks. The effects of the radiation may be estimated based on the data on nuclear explosions or based on the especially elaborated model. Numerical simulation of the impacts of large cosmic objects provides a basis for construction of scaling relations, which allow estimating easily the thermal exposure distribution on the surface and some other important parameters. These scaling relations are useful tool for rapid assessments of hazardous effects of thermal radiation. All scaling relations described in this article are implemented in the developed web-based Calculator for fast assessment of dangerous consequences from the impact of cosmic objects on the Earth.

The airburst events at Chelyabinsk and Tunguska in Russia are the best-documented asteroid impacts of recent times. Models that assess the potential danger from such events rely on an accurate picture of their aftermath. Here, we re-examine the most critical eyewitness accounts of the Tunguska airburst, namely those that describe injuries and casualties, and those that paint a picture of what events were responsible. Not all relevant information has survived in the written record and there are contradictions that create some ambiguity. We find that inside and near the tree-fall area were at least 30 people. Many lost consciousness and at least 3 passed away (immediately or later) as a direct consequence of the Tunguska event. The airburst created a butterfly-shaped pattern of glass damage extending 4–5 times wider than that seen at Chelyabinsk. At these larger distances, any injuries from falls, shattering glass cuts, or from UV radiation exposure were not reported.

Asteroids risk models require understanding how an asteroid (or a comet) entering into the atmosphere can harm people and infrastructure. A shock wave is one of the main dangerous effects of the cosmic object impact. Serial numerical simulations of high-velocity impacts of cosmic objects from 10 m to 3 km in diameter are used to build scaling relations of shock wave properties (overpressure and wind speed) near the surface. Obtained scaling relations, which are dependent only on parameters of impactor, are used for the Tunguska and Chelyabinsk events and show satisfactory agreement with observations and numerical models. A separate class of scaling laws presents crater-forming impacts and shows much better correlation with models than previously used estimates. All scaling relations described in this paper are implemented into the web-based Calculator for fast assessment of hazardous consequences from the impact of cosmic objects on the Earth. The Calculator is available at the link: http://AsteroidHazard.pro.

Quick assessment of hazardous effects from impacts of large celestial bodies is achieved through the development of a new consequence calculator. A distinctive feature of this calculator is a new block, the Hazardous-Orbit Constructor, which simulates the conditions of entry of a celestial body into the Earth’s atmosphere and determines the orbital parameters of the body based on given atmospheric entry conditions. This block is used to simulate the atmospheric entry conditions of known asteroids and meteoroids and to determine the orbital parameters of known bolides leading to meteorite fall events. For the case of asteroid 2008 TC3 and the Přibram meteorite, it is shown that within the potential impact area of the celestial body, the atmospheric entry angle may vary considerably.