Solar System Research最新文献

Abstract

This paper is devoted to some aspects of the study of relativistic effects (geodetic precession and geodetic nutation, which together constitute geodetic rotation) in the rotation of celestial bodies of the Solar System using the example of Jupiter and its Galilean satellites (Io, Europa, Ganymede, and Callisto). The difference in the angular velocity vectors of geodetic rotation is shown depending on the choice of reference frame. Thus, the absolute value of the angular velocity vector of the geodetic rotation of the satellite under study relative to the barycenter of the Solar System will not coincide with the absolute value of a similar vector of the satellite under study relative to the barycenter of the planet’s satellite system. As a result, the most significant secular and periodic terms of geodetic rotation were determined for the first time: a) of Jupiter and its Galilean satellites in terms of the Euler angles, in the perturbing terms of physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the body under study relative to the barycenter of the Solar System and the plane of the mean orbit of Jupiter of the epoch J2000.0; b) of Galilean satellites of Jupiter in the perturbing terms of physical libration and the absolute value of the angular rotation vector of the geodetic rotation of the studied body relative to the barycenter of the Galilean satellite system of Jupiter and the mean orbit plane of the studied Galilean satellite of the epoch J2000.0. The obtained analytical values of the geodetic rotation of the studied objects can be used for a numerical study of their rotation in the relativistic approximation, and also used to evaluate the influence of relativistic effects on the orbital–rotational dynamics of bodies of exoplanetary systems.

Abstract—

Our study of the spatial and genetic relationship between coronae and lobate plains allows us to draw two important conclusions. (1) About 17% of all volcanic coronae of Venus are sources (coronae–sources) of young lavas that form lobate plains of the Atlian period. A small portion of coronae–sources in the total population of coronae reflects the decrease in the formation rate of mantle diapirs. (2) The area of lobate plains associated with a particular corona and the area of the corona itself are negatively correlated. These relationships allow the existence of only two models for the final stages in the evolution of mantle diapirs. Having analyzed both of these models, we suppose that, during the Atlian period in the geologic history of Venus, either a single zone of neutral buoyancy existed or the lithosphere base was located at approximately the same level.

Abstract—

The work examines the structure of a crater with a diameter of 34 km, located on the mainland in the marginal zone of the south polar region of the Moon within the South Pole–Aitken impact basin. This crater belongs to the Dawes morphological type, which is characterized by a generally flattened, and in detail uneven, hilly-ridge bottom surface. The crater under study has a fractured bottom, which is considered a sign of magma intrusion into the subcrater space. Cracks in the bottom material are represented by hollows from 2 to 10 km long, 0.3–1 km wide and 50–150 m deep. The LROCNAC images show that in the hilly-ridge areas of the bottom the regolith surface has a “wrinkled” texture, and in the subhorizontal areas it is smooth. On one of the sections of the bottom there is a 700-meter crater, the rim of which touches one of the hollows. Judging by the morphology of this crater and the absence of meter-sized stones on its shaft, it was formed in the range of (200–300) million to 1 billion years ago, while the age of the studied 34-kilometer crater is estimated from the density of small craters superimposed on its rim as 3.83 (+0.025; –0.031) billion years. The age of the surface material of the deformed bottom of the crater under study is in the range of (200–300) million to 1 billion years. Probably, the fracturing of the bottom (formation of hollows) was caused by the penetration of an intrusive body or bodies into the subcrater space during the Copernican or early Eratosthenesian periods of the geological history of the Moon. The 34-kilometer crater in question certainly deserves further study.

Abstract

Scientific objectives, instruments, and measurement program of the scientific instrumentation of the Kazachok stationary landing platform of the State Corporation Roscosmos and the European Space Agency (ESA) ExoMars-2022 project are presented. The scientific objectives of research on the landing platform included the long-term climate monitoring, the studies of the atmospheric composition, the mechanisms for dust lifting and related electrical phenomena, atmosphere–surface interactions, the subsurface water abundance, monitoring the radiation situation, and the study of Mars internal structure. To address these problems, 11 Russian and two European instruments with a total mass of 45 kg were built, tested and integrated into the spacecraft. These include a television camera system, meteorological complexes, a suite for studying dust and related electrical phenomena, optical spectrometers and an analytical complex for studying the atmospheric composition, a microwave radiometer, the neutron and gamma spectrometers for surface research, a seismometer, magnetometers and a Mars proper motion experiment to study its internal structure. Although the ExoMars-2022 project has been discontinued, the scientific objectives of the landing platform have not lost their relevance, and the technical solutions and developments implemented in scientific equipment are of interest and promising for further Mars exploration.

Abstract—

A brief history of the creation of star orientation sensors at the Space Research Institute of the Russian Academy of Sciences (IKI RAS) and star catalogs for them is presented. An experiment carried out in the early 1970s on synchronous photography of stars and the Earth’s surface from the manned stations Salyut-2 and -3 is described. The difficulties of entering photographs into electronic computers (computers) of that time are shown. Based on the SAO, Hipparcos and Gaia star catalogs, about 11000 microcatalogs have been compiled around the brightest stars in the celestial sphere. Each of them contains in the center one star with a magnitude of up to 7.8^m and all the surrounding stars up to 13^m within a radius of 15′. The microcatalogs are combined into the “Basic Star Catalog,” which in the near future will be used to compile onboard star catalogs for the orientation sensors of the BOKZ family of spacecraft. To work with the base catalog, two programs have been developed and are used in test mode: Catalog Guide and Star Manager. The first program is designed to view the base catalog, visualize its fragments and compile lists of stars with specified parameters. The second program is of a computational and analytical nature. It contains mathematical models of star orientation sensors of the BOKZ family, as well as a mathematical apparatus that allows for detailed modeling of the most subtle elements of onboard data processing. Both programs can operate in manual and automatic modes. A sequence of actions worked out manually on several stars can then be performed automatically for large lists of stars. The article describes the structure and content of the base directory, and also illustrates working with it using programs specially developed for this purpose.

Abstract

In order to estimate the rate of slope processes on the Moon, we studied the morphology and topographic configuration of 24 craters in the diameter range of 5–15 km. These craters are located in Mare Serenitatis, Mare Crisium, and Mare Fecunditatis, as well as in the continental terrain of Montes Apenninus. The craters were formed in three types of targets: (1) two-layered (continent, overlaid by a mare), (2) single-layered mare, and (3) single-layered continent. The topographic configuration was established for each crater, and the frequency–size distribution of overlapping craters on the walls and in the continuous ejecta zone was determined. The age of the craters was estimated (from 0.31 to 3.83 Gyr) based on the crater density in the ejecta zone. Comparing this density with the density on the walls allowed us to estimate the rate of slope processes. The rate of slope processes (E, mm/Myr) on the Moon is nonlinear and described by a power-law function Е = 4.39А^–1.03, where А is the age (Gyr). The estimated rates of slope processes in our study range from ~17 mm/Myr for the youngest crater to ~0.8 mm/Myr for the oldest crater. The studied craters represent stable landforms, and their configuration remains almost unchanged over billions of years. The target type has no significant influence on either the rate of slope processes or the changes in crater shape over time.

Abstract

Proceeding from the concept of the fractal nature of dust clusters, we develop an evolutionary hydrodynamic model of the formation and growth of loose dust aggregates in an aerodisperse medium of a laminar disk that was originally composed of gas and solid (sub)micron particles. In contrast to a number of classical studies, in which the aggregation process was modeled within an “ordinary” continuous medium and, consequently, the multifractional structure of the dust component of a protoplanetary cloud and the fractal nature of dust clusters being formed during the evolution were often ignored, this paper proposes to consider an ensemble of loose dust aggregates as a special type of a continuous medium, namely, a fractal medium, in which there are points and domains not occupied by dust particles.

Abstract

The aim of this article is to acquaint the reader to the rapidly developing stochastic-thermodynamic theory of irreversible processes using as an example the modeling of structured turbulence. Here, we consider a synergetic approach to the development of a phenomenological model of extremely developed turbulence in a compressible homogeneous fluid, taking into account the nonlinear cooperative processes in it. Inclusion in the model of a set of random variables as internal parameters of the turbulent chaos subsystem, associated with its microstructure, makes it possible in this case to derive, using thermodynamic methods, the Fokker–Planck–Kolmogorov (FPK) kinetic equations in configuration space. Stabilization of the chaos subsystem near the next stationary nonequilibrium state in configuration space corresponds to the transition of the turbulent system to a new state, adequate to the emergence of complex spatiotemporal CSs in a turbulent flow.

Abstract

In this article, the possibility of influence of the hydrodynamic helicity appearing in a rotating disk on synergetic structuring of cosmic substance and on the emergence of the negative turbulent viscosity effect in it is investigated. It is shown that prolonged turbulence damping in a disk can be partly associated with the absence of reflection symmetry of the anisotropic field of turbulent velocities relative to its equatorial plane. It is shown that negative viscosity in the rotating disk system is apparently a manifestation of cascade processes in helical turbulence, when the inverse energy transfer from small to larger vortices occurs.

Abstract—In this article, a closed system of magnetohydrodynamic (MHD) equations on the mean flow scales, which is intended for simulating turbulent flows of electroconductive media in the presence of an electromagnetic field, is derived in the single-fluid MHD approximation.