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1.
Numerical simulation of atmospheric disturbances during the first hours after the Chelyabinsk and Tunguska space body impacts has been carried out. The results of detailed calculations, including the stages of destruction, evaporation and deceleration of the cosmic body, the generation of atmospheric disturbances and their propagation over distances of thousands of kilometers, have been compared with the results of spherical explosions with energy equal to the kinetic energy of meteoroids. It has been shown that in the case of the Chelyabinsk meteorite, an explosive analogy provides acceptable dimensions of the perturbed region and the perturbation amplitude. With a more powerful Tunguska fall, the resulting atmospheric flow is very different from the explosive one; an atmospheric plume emerges that releases matter from the meteoric trace to an altitude of the order of a thousand kilometers. 相似文献
2.
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. 相似文献
3.
Kosarev I. B. Loseva T. V. Nemtchinov I. V. Shuvalov V. V. Greely R. 《Solar System Research》2002,36(4):278-292
This paper presents the results of the calculation of spectral and angular characteristics of radiation emitted by the disturbed region after the vertical impacts on the Martian surface of stony meteoroids with radii R
0 from 1 to 100 m at speeds of 11–20 km/s. The time dependences are given for the density of the radiation flux incident on horizontal surface areas located at different distances from the impact point. For small impactors (R
0= 1 m), the heating of the surface and surrounding gas by the radiation impulse from the hot region formed after the impact is insignificant even at the crater edge. However, the radiation impulse that heats up the surface is also emitted during the meteoroid flight through the atmosphere. Although this heating is insufficient to initiate evaporation, heat transfer by turbulent diffusion leads to the formation of a layer with temperatures that substantially exceed the initial temperature of the atmosphere. For large impactors (R
0 = 100 m), the total specific impulse of the plume radiation gives rise to the emergence of the heated layer with a thickness on the order of several meters within several kilometers of the impact point. The formation of this warm layer may lead to the formation of a high-speed jet moving along the Martian surface as well as eddies at the front of the precursor with a subsequent intense rise of dust. 相似文献
4.
It is shown that the inclusion of the effect of internal friction on the deformation of a damaged meteoroid leads to a marked
(by 10–20 km) decrease in the height of the meteoroid deceleration and, hence, the height of the energy release. The possible
decrease of the role of internal friction due to “acoustic fluidization” and the penetration of impact-compressed gas through
the cracks in the interior of the damaged meteoroid are discussed. 相似文献
5.
E. E. Grigorenko S. D. Shuvalov H. V. Malova V. Yu. Popov V. N. Ermakov E. Dubinin L. M. Zelenyi 《Solar System Research》2017,51(5):347-361
During the last 15 years, the Current Sheets (CSs) have been intensively studied in the tail of the terrestrial magnetosphere, where protons are the dominated ion component. On the contrary, in the Martian magnetotail heavy ions (O+ and+ 0) usually dominate while the abundance of protons can be negligible. Hence it is interesting to study the spatial structure and plasma characteristics of such “oxygen” CSs. MAVEN spacecraft (s/c) currently operating on the Martian orbit with a unique set of scientific instruments allows observation of the magnetic field and three-dimensional distribution functions of various ion components and electrons with a high time resolution. In this paper, we analyse nine intervals of the CSs observed by MAVEN in the near-Mars tail at the distances from the planet ~1.5–1R M , where R M is the radius of Mars. We analyse the spatial structure of the CSs and estimate their thickness for different magnetic configurations and relative abundance of the heavy and light ions in the sheets. It is shown that, similarly to the CSs in the Earth’s magnetotail, the thickness and complexity of the spatial structure of the Maritan CSs (i.e. the presence of embedded and / or peripheral current structures) depend on the magnetic configuration of the sheets, which, in turn, affects the fraction of the quasi-adiabatic particles in the CSs. 相似文献
6.
Artem'eva N. A. Kosarev I. B. Nemtchinov I. V. Trubetskaya I. A. Shuvalov V. V. 《Solar System Research》2001,35(3):177-180
In November 1999, light flashes were recorded on the Moon at the peak of the Leonid stream activity. It is likely that they were produced by the impacts of the stream particles on the lunar surface. In the present work the impacts of cometary particles are studied by solving a two-dimensional radiative-gasdynamic problem for particles of different sizes and densities; the flux of radiation of postimpact hot gas and plasma is calculated, and the luminous efficiencies are estimated, as are the sizes of the particles which could produce the observed flashes. 相似文献
7.
Valery Shuvalov Henning Dypvik Elin Kalleson Ronny Sets? Fridtjof Riis 《Earth, Moon, and Planets》2012,108(3-4):175-188
The newly discovered Ritland impact structure (2.7?km in diameter) has been modeled by numerical simulation, based on detailed field information input. The numerical model applies the SOVA multi-material hydrocode, which uses the ANEOS equation of state for granite, describing thermodynamical properties of target and projectile material. The model displays crater formation and possible ejecta distribution that strongly supports a 100?m or less water depth at the time of impact. According to the simulations resurge processes and basinal syn- and postimpact sedimentation are highly dependent on water depth; in more than 100?m of water depth, much more powerful resurge processes are generated than at water depths shallower than 100?m (the Ritland case). In Ritland the 100?m high (modeled) crater rim formed a barrier and severely reduced the resurge processes. In the case of deeper water, powerful resurge processes, tsunami wave generations and related currents could have triggered even more violent crater fill sedimentation. The presented model demonstrates the importance of understanding the interactions between water layer and both syn-impact crater fill and ejecta distribution. According to the presented simulations ejecta blocks up to 10?m in diameter could be transported up to about 5?km outside the crater rim. 相似文献
8.
Glazachev D. O. Popova O. P. Podobnaya E. D. Artemieva N. A. Shuvalov V. V. Svetsov V. V. 《Izvestiya Physics of the Solid Earth》2021,57(5):698-709
Izvestiya, Physics of the Solid Earth - 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... 相似文献
9.
This study presents the results of the numerical modeling of the Lunar Crater Observation and Sensing Satellite (LCROSS) space experiment, which is scheduled for 2009 by NASA. It is demonstrated that a spacecraft with a mass of 2 tons impacting the Moon at a velocity of 2.5 km/s creates an ejecta plume with a size of more than 100 km and a mass exceeding 100 tons. The detailed characteristics of the ejecta are given and their relation to the impactor structure is investigated. 相似文献
10.
Assessment of Kinetic Energy of Meteoroids Detected by Satellite-Based Light Sensors 总被引：1，自引：0，他引：1
I.V. Nemtchinov V.V. Svetsov I.B. Kosarev A.P. Golub' O.P. Popova V.V. Shuvalov R.E. Spalding C. Jacobs E. Tagliaferri 《Icarus》1997,130(2):259-274
Radiation energies of bright flashes caused by disintegration of large meteoroids in the atmosphere have been measured using optical sensors on board geostationary satellites. Light curves versus time are available for some of the events. We have worked out several numerical techniques to derive the kinetic energy of the meteoroids that produced the flashes. Spectral opacities of vapor of various types of meteoroids were calculated for a wide range of possible temperatures and densities. Coefficients of conversion of kinetic energy to radiation energy were computed for chondritic and iron meteoroids 10 cm to 10 m in size using radiation–hydrodynamics numerical simulations. Luminous efficiency increases with body size and initial velocity. Some analytical approximations are presented for average conversion coefficients for irons and H-chondrites. A mean value of this coefficient for large meteoroids (1–10 m in size) is about 5–10%. The theory was tested by analyzing the light curves of several events in detail.Kinetic energies of impactors and energy–frequency distribution of 51 bolides, detected during 22 months of systematic observations in 1994–1996, are determined using theoretical values of luminous efficiencies and heat-transfer coefficients. The number of impacts in the energy range from 0.25 to 4 kt TNT is 25 per year and per total surface of the Earth.The energy–frequency distribution is in a rather good agreement with that derived from acoustic observations and the lunar crater record. Acoustic systems have registered one 1 Mt event in 12 years of observation. Optical systems have not detected such an event as yet due to a shorter time of observation. The probability of a 1 Mt impact was estimated by extrapolation of the observational data. 相似文献