Solar System Research最新文献

A new Morphological Catalog of Mercury’s Craters was created at the Sternberg State Astronomical Institute, Moscow State University, together with the Moscow State University of Geodesy and Cartography based on data from the MESSENGER spacecraft. This catalog includes information on the coordinates, diameters, and morphology of 12 365 craters with diameters ≥10 km. The catalog was created using data from the Mercury Crater Catalog, prepared at Brown University (United States), and a global mosaic of Mercury surface images based on data from the MESSENGER spacecraft. Analysis of the new Morphological Catalog has shown that most Mercury craters with a diameter of ≥10 km have a smoothed or partially destroyed rim and a flat floor. The article provides a detailed description of the morphological features of Mercury’s craters. Table 1 shows the percentage of craters with certain features on Mercury and the Moon. It turned out that there are significantly more well-preserved craters on the Moon than on Mercury. Most of Mercury’s craters have terraces and collapses on their inner slopes (65%, compared to 7% of lunar craters). The ratio of craters with different degrees of preservation of the rim, craters with terraces and faults depending on the diameters is presented in detail.

In 2022, the telescope of the Main (Pulkovo) Astronomical Observatory of RAS obtained astrometric and photometric series of observations of a potentially dangerous asteroid (138971) 2001 CB21 during its approach to Earth. Based on the data obtained and data from the MPC website, the asteroid’s orbit was improved and the circumstances of the encounters were investigated with the Earth and Venus and an assessment was made of the influence of nongravitational effects on its motion. Based on photometric observations of the asteroid, a light curve was constructed and its axial rotation period was confirmed: R = 3.305 ± 0.002 h.

Through numerical experiments, the influence of the angular velocity of proper rotation, rotation axis orientation, and asteroid shape parameters on the magnitude of perturbations in its rotational dynamics during close approaches to the Earth has been studied. The dynamics of three asteroids was considered: (99 942) Apophis, (367 943) Duende and 2012 TC4. It was found that asteroids with relatively slow rotation (period P > 5 h) are characterized by significant disturbances: in the case of Apophis (P ≈ 30 h) when approaching the Earth in 2029, changes in the rotation period can reach tens of hours, and deviations in the orientation of the rotation axis of ten degrees. In the case of Duende (P ≈ 8 h) when approaching the Earth in 2013, the change in P did not exceed several hours, deviations in the orientation of the rotation axis could amount to tens of degrees. For asteroids with rapid rotation (P < 1 h) the disturbances are negligible: in the case of asteroid 2012 TC4 (P ≈ 12 min) during its approach to the Earth in 2017, the changes in P did not exceed 10^–5 min, the deviations of the rotation axis were less than 0.01°. It is shown that for asteroids with slow rotation, errors in determining the parameters of the asteroid’s figure can lead to noticeable inaccuracies in estimating the magnitudes of disturbances. In contrast, the uncertainty in knowing the figure of an asteroid with rapid rotation does not affect the assessment of disturbances in its rotational dynamics. In the case of Apophis, disturbances in the rotational motion during the upcoming approach to the Earth in 2029 can lead to a decrease in the value of the A₂ parameter, which characterizes the Yarkovsky effect, to –2.4 × 10^–14 AU/day² or to an increase to –3.2 × 10^–14 AU/day². Perturbations in the rotational dynamics of Duende during its approach to the Earth in 2013 and of asteroid 2012 TC4 during its approach to the Earth in 2017 did not have a noticeable effect on their A₂ values.

The key role of the family of hydromagnetic helicity invariants in connection with the generation and maintenance of magnetic fields in geophysical and astrophysical contexts is discussed. The influence of compressibility and rotation on the turbulent mass transport in helical hydromagnetic flows is investigated using a phenomenological approach at very high Reynolds numbers. The fluctuating effects entering into the averaged MHD equations through their correlation contributions and representing the hydromagnetic turbulent stress, turbulent electromotive force and a number of other correlation functions are modeled using linear closure relations (in the absence of reflective symmetry of small-scale motions) and differential equations for four helical chiral turbulence descriptors, which are: total turbulent plasma energy, turbulent transverse helicity, turbulent residual energy and turbulent residual helicity. It is believed that the model equations for these descriptors, combined with the compressible MHD mean field equations, allow the most complete construction of a self-consistent model of the turbulent dynamo. The ultimate goal of the undertaken research is the development of models of helical hydromagnetic turbulence capable of operating effectively in the hypersonic regime.

The search for new members of young asteroid families is of interest for studying the history of the formation of these families. The paper considers 17 young families. Young families are characterized by strong clustering of both proper and osculating orbital elements. When searching for candidates for new members of young families, the osculating orbital elements were analyzed. Kholshevnikov metrics were estimated, the behavior of nodes and pericenters was analyzed, and a search for low relative-velocity close encounters was performed. For all selected candidates, synthetic proper orbital elements were calculated using the OrbFit software package, based on which a conclusion was made about the belonging of the asteroid to the family. As a result, new members were found for eight young asteroid families.

Using an astronomical model of insolation of the polar day and polar night zones of the Earth, the influence of cosmic factors on the ice conditions in them is estimated. It is shown that the temperature increase in the Northern Hemisphere began about 20 000 years ago due to volcanic events that occurred at that time, as well as in connection with the presence of a surplus of solar energy in this area of the planet, caused by the parameters of the Earth’s orbit: the inclination of the rotation axis, eccentricity, and precession angle. The surplus of thermal energy in the Northern Hemisphere has been preserved since then until the present day and will continue for at least 3000 years, after which the next period of glaciation will begin. Similar data are given for the Southern Hemisphere. It is shown that the melting of northern glaciers has been spread over many millennia due to the high heat of ice fusion and a pronounced phase transition. During melting, thermal energy is spent on the destruction of the ice crystal lattice, and the melt temperature does not increase. During freezing, the reverse process occurs: the energy released during ice crystallization prevents the temperature from decreasing. This process also occurs at a constant temperature. The heat-stabilizing properties of ice have manifested themselves in the form of “temperature shelves” on the graphs of the dependence of the average annual temperature on time, constructed based on the results of the analysis of ice cores obtained in the Southern Hemisphere at the Vostok station and in the Northern Hemisphere in central Greenland. At present, ice reserves in the Northern Hemisphere are coming to an end. Accordingly, the ability of glaciers to stabilize temperature is decreasing. As a result, the frequency and power of natural disasters in the world is growing. The problem of preserving the existing climate is becoming urgent. There is less and less time left for preparing and implementing measures to counteract climate change. Decarbonization cannot resist the ongoing process of destruction of the unique mechanism of natural climate stabilization. It is necessary to look for other ways to solve the problem of preserving the current climate. Among them, on the one hand, various methods of increasing albedo can be considered, and on the other hand, methods of reducing the permeability of the atmosphere by spraying special chemicals with short periods of complete decomposition in the upper layers of the atmosphere over certain areas.

In this paper, a scenario for the formation of the young Emilkowalski asteroid family was constructed based on numerical modeling of the evolution of nominal orbits of the family members. Various variants of the orbital evolution of asteroids were considered depending on the drift velocity of the semimajor axes of the orbits, caused by the influence of the diurnal Yarkovsky effect. Using the method of analyzing the approaches of nodes and pericenters of the orbits, estimates were obtained for the time of possible formation of all possible pairs among the family members. Based on these estimates, a scenario for the formation of the family was constructed, assuming the destruction of the parent body of the asteroid (14 627) Emilkowalski as the main mechanism. It is shown that some of the family members could have formed as a result of the cascading breakup of the parent asteroid’s daughter bodies. The constructed scenario for the formation of the Emilkowalski family can be described as a step-by-step destruction of the parent body of the asteroid (14 627) Emilkowalski with elements of cascading breakup of some fragments.

The data on the distribution of secular resonances in the areas of action of tesseral (orbital) resonances 1 : 5, 1 : 7, 1 : 9, 1 : 10 and 1 : 11 with the speed of rotation of the Earth, as well as an analysis of the dynamics of objects moving in the studied areas are presented. It is shown that secular resonances cover the areas under consideration very densely, which, together with orbital resonances, can lead to chaotization of the motion of objects. Using the example of the orbital evolution of NORAD catalog objects moving in the study area, the issue of the possibility of placing new satellite systems and recycling spent objects in this area is considered.

Tidal dissipation serves as the primary factor influencing the natural satellites’ orbital evolution and provides essential insights into planetary interior properties. The orbital evolution of the Neptune–Triton system due to tidal dissipation can be approximately determined from astrometrically observed positions of Triton over an extended period of time by using an accurate model of the orbital motion. The estimated accuracy of the Triton dynamical model we built and updated fit all the astrometric data. Based on the most complete weighting astrometric observations of Triton, a possible minimum value of the Neptunian tidal dissipation factor Q was estimated to be Q = (10.353 ± 2.517) × 10³ for a conventional value k₂ = 0.127 and a priori constraint of 10 × 10³. When the a priori constraints have a smaller value, the Q-solution also has a smaller value but a weak fit to observations. Therefore, the Q estimated from the existing astrometric data is a plausible minimum value with the current accuracy of astronomical observations. Based on the plausible minimum value of Q and the Love number k₂, it has been analyzed that Triton will reach Neptune’s Roche limit in approximately ~28 Gyr. This indicates a stable orbital evolution of Triton over a long period of time.

The article analyzes and develops new domestic engineering developments of concepts for the creation of lunar bases and vehicles for their construction and operation. The concept of intelligent mobile platforms (IMP) is proposed, which are unified self-propelled chassis with automatic docking and coupling devices (ADCD) and local navigation subsystems. The IMP self-propelled chassis is equipped with various attachments that determine the purpose and technological characteristics of the vehicle. Such vehicles can be used both as independent lunar rovers with hybrid control and as links in a multifunctional lunar train designed for special operations, including long-distance expeditions of hundreds of kilometers. Based on the NASA-published Lunar Reconnaissance Orbiter Camera images, a possible expedition route has been mapped from the International Lunar Research Station (ILRS) location in the Malapert massif region to the far side of the Moon, taking into account illumination levels and terrain elevation angles along the entire route. The expedition’s objective is to conduct scientific research along the route, deliver equipment, and deploy an automated ILRS branch—a lunar observatory on the far side of the Moon in the radio-quiet shadow from Earth. Based on theoretical calculations and design-layout development, a preliminary design has been completed, including the IMP technical configuration and its main performance characteristics.