Solar System Research最新文献

The paper develops a weakly nonlinear theory of Poincaré waves. The nondegeneracy of the Poincaré wave dispersion law leads to the presence of resonant interactions in perturbation theory. A study of the dispersion relation of Poincaré waves showed that three-wave interactions are absent in the quadratic nonlinear approximation. In this paper, a linear equation of the envelope is derived. A qualitative study of the dispersion law showed the existence of four-wave interactions of Poincaré waves. Equations of nonlinear interactions of four waves for the amplitudes of Poincaré waves are derived. The Manley–Rowe equations are obtained, which determine the distribution of energy and its transfer between interacting waves. The nonlinear dynamics of interacting waves is investigated. The saturation effect of Poincaré waves, which is important for geophysical hydrodynamics, has been predicted. An analytical solution is obtained that describes the saturation effect of Poincaré waves in time.

We analyze photometric observations of stars, which experienced microlensing events at the considered time, in order to compare the efficiency of detecting exoplanets in observations performed at thirteen different telescopes and with several approaches to the selection of observable events. In constructing an algorithm of the optimal selection of targets for these observations and in comparing the detection efficiencies for several telescopes, we considered models of the night-sky brightness that satisfy the data of infrared observations carried out in 2011 with the Optical Gravitational Lensing Experiment (OGLE) telescope and the RoboNet telescopes (FTS, FTN, and LT) used to search for planets with the microlensing method. The considered models of the night-sky brightness can be used for various observations (not only microlensing events). The time intervals, during which microlensing events can be observed, were determined with accounting for the positions of the Sun and the Moon and the other constraints on the telescope pointing. Our algorithm allows us to determine the already known microlensing events that are accessible for observation with a particular telescope and to select targets, for which the probability of detecting an exoplanet is maximal. The events, which would maximize the probability of detecting exoplanets, were selected for observations. The probability of detecting an exoplanet is usually proportional to the mirror diameter of a telescope. Telescopes with a wider field of view, such as the OGLE, are more effective in finding new microlensing events. To observe different microlensing events, it is usually better to use different nearby telescopes. However, all such telescopes are often better to use for observing the same event in those relatively short time intervals that correspond to the peak brightness of the event.

A method for reducing nonlinearity in the problem of asteroid orbit determination is considered. The method is based on the use of variables that take into account the stretching of the initial confidence region mainly along the trajectory when the initial epoch is located far from the observational arc. It is shown that in this case, the nonlinearity of the inverse problem is revealed only along the largest axis of the confidence ellipsoid, which is directed almost along the trajectory of the object, while the other axes are not deformed. This allows us to introduce new variables in which one (largest) axis is curved and approximated using polynomials, while the remaining axes remain the same as in the confidence ellipsoid. The confidence region in the new variables is an ellipsoid, which makes it possible to fill it with a cloud of random points according to the law of multidimensional normal distribution and, thus, significantly increase their number. In addition, it is shown that with a significant distance of the initial epoch from the observational arc, the coordinates and velocities noticeably correlate, which simplifies the approximation of the point cloud using an ellipsoid. The method was used to estimate the probability of a collision with the Earth (and the Moon) of potentially dangerous asteroids 2024 YR4, 2023 DO and 2018 CB in their upcoming closest approach.

Cislunar space, as a strategically significant domain for humanity’s future survival and development, has become a new battleground for deep space exploration activities among leading spacefaring nations. Driven by the growing demands for deep space exploration missions, the monitoring and early warning of cislunar space debris have increasingly become a priority. Precise orbit determination (POD) of cislunar space targets provides essential support for debris surveillance. Against this backdrop, this study proposes a ground/space/lunar integrated optical observation model, implemented through SPOT (Small Body and Planets Precise Orbit Determination Toolkit)—a software platform independently developed by Wuhan University’s Planetary Geodesy Team. We conducted numerical simulations for POD of targets at Earth–Moon libration points L1, L4, and L5. The results demonstrate that the orbit determination accuracy using only ground-based observations is on the order of several hundred meters. Space-based observations can serve as a valuable supplement to ground-based data, providing a modest improvement in accuracy. However, the addition of lunar-based observations significantly enhances the orbit determination accuracy, reducing position errors and uncertainties to the order of tens of meters. Furthermore, variations in the noise level of lunar-based observations have a stronger impact on orbit determination accuracy than space-based observations. Finally, comparative experiments verify the necessity of solving the solar radiation pressure coefficient Cr for improving orbit determination accuracy. These findings highlight the tremendous potential of lunar-based optical observations in achieving high-precision orbit determination for cislunar space targets and provide valuable insights for future advancements in deep-space situational awareness and autonomous navigation.

We analyzed regions with concentrations of coronae that are sources of young lava fields and large volcanoes on Venus and established the following: (1) such coronae and volcanoes represent genetically unrelated structures that are spatially separated in many regions of the planet, while in some regions they occur together or only coronae or only volcanoes are present; (2) coronae that are sources of lava fields are associated with regional zones of extension—belts of grooves and/or rift zones—whereas volcanoes show a weaker association with these zones; (3) dome-shaped coronae are concentrated on the surface of Venus in zones of rift fracturing, primarily in the Ulfrun and Parga regions. This association of volcanic coronae with rifts is likely explained by the reactivation of coronae during the late Atlian period of the planet’s geological history; (4) large volcanoes are more widely distributed across the surface of Venus than dome-shaped coronae. Approximately half of the volcanoes are concentrated in the Ulfrun, Parga, and Eistla regions. Their localization is not linked to regional zones of extension; (5) the identified regions of concentration of large volcanoes and dome-shaped coronae, which are sources of lava fields, mark the areas of young volcanic activity on Venus (Ulfrun, Parga, and Eistla).

To increase the efficiency of interplanetary flights, it is advisable to use low-energy trajectories with a small change energy on transfer between massive bodies. The paper considers an approach to designing transit trajectories based on the flyby of libration points L1 and L2 with near-zero velocity, which corresponds to the minimum possible energy change on the trajectory. In the model of a circular restricted three-body problem, these trajectories correspond to motion over invariant manifolds of libration points. Transit trajectories are modeled, and their parameters (capture duration and orbital parameters) are estimated within the framework of the circular and elliptical three-body problem. The influence of the ratio of the masses of massive bodies and the eccentricity of the orbit of a smaller body on the parameters of low-energy transit trajectories in a elliptic restricted three-body problem is analyzed. Examples of trajectories suitable for practical use in interplanetary missions, in the Earth–Moon system, in the Jupiter and Saturn systems are considered.

This study examines Korean historical records of daylight sightings of Jupiter to estimate the empirical limiting magnitude for observing celestial bodies without optical aid during daylight. Using sources such as Joseonwangjo-Sillok (The Veritable Records of the Joseon Dynasty), Seungjeongwon-Ilgi (The Daily Records of the Royal Secretariat of the Joseon Dynasty), and Donggung-Ilgi (The Daily Records of the Royal Education Bureau for the Crown Prince of the Joseon Dynasty), we identified 40 instances of daylight observations of Jupiter during the Joseon dynasty (1392–1910). Employing astronomical algorithms and modern ephemeris, we calculated sunrise, solar transit, and sunset times to identify the observation hour, confirming whether the events occurred during daytime or twilight. Additionally, we determined the azimuth and magnitude of Jupiter during each recorded event to verify the direction and brightness of the observed phenomenon. Our analysis yielded the following key findings: (1) The records of daylight sightings of Jupiter are concentrated in the 16th and 17th centuries, corresponding to prolonged periods of solar activity minima. (2) These observations occurred during broad daylight rather than twilight. (3) The limiting magnitude for unaided daylight observations of a celestial body is at least –2.1.

In addition to craters, the surface of Venus contains radiatively bright and dark patches, the formation of which is believed to be caused by the impact of a shock wave. Estimates based on approximate models of asteroid deceleration in the atmosphere and point explosions substantiate the assumption that dark spots arise as a result of strong destruction (vaporization) of stones by a shock wave near the epicenter of the explosion at pressures of about 1–10 GPa, and the light outer part of the splotches is explained by the blowing away of small particles by an air flow at velocities of about 100 m/s at greater distances. Direct calculations of the fragmentation and braking of asteroids with sizes of 0.6–1 km carried out in this work showed that the maximum pressure values are significantly lower than those required to destroy the rocks, and it is concluded that a more probable mechanism for the formation of dark spots is the melting of the surface layer by thermal radiation from the bolide.

Titan, Saturn’s largest moon, is unique in its composition, structure, and formation history. Titan stands out among other bodies in the Solar System due to its dense nitrogen-methane atmosphere with a variety of organic compounds and a surface covered with liquid hydrocarbons. Based on cosmochemical and geophysical data, equations of state of meteoritic matter and H₂O (water, water ice) models of the internal structure of Titan, composed of carbonaceous (CI/CM) and ordinary (L/LL) chondrites, with different contents of organic material (OM) of low (ρ_OM ~ 1.3−1.4 g/cm³) and high (1.4 < ρ_OM < 2.2 g/cm³) density have been constructed. In the absence of OM, three-layer models of a partially differentiated satellite with an outer water-ice shell, an intermediate rock-ice mantle, and an inner CI/CM or L/LL core may be implemented. The presence of an impurity OM with a density 1.3–1.8 g/cm³ in Titan’s chondrite material provides the possibility of transition from three-layer partially differentiated models of the satellite to two-layer models of full differentiation (without rock-ice mantle)—structures free from restrictions on the melting of mantle ice. The structure of a fully differentiated Titan generally includes: a water-ice shell with a mandatory internal ocean and a layer of partially melted high-pressure V-VI ices and a central CI/CM or L/LL chondrite core with a radius of ~2100 km. Such models without OM admixture do not satisfy the conditions of conservation of mass and moment of inertia of the satellite; their consistency with geophysical constraints is due to the presence of OM in amounts of 10−22 wt % and 20−28 wt % in the CI/CM and L/LL cores, respectively. Models of Titan with high density OM (ρ_OM > 1.8 g/cm³) do not suggest separation of the ice and rock components, the satellite remaining partially differentiated. The estimates of the organic material content of Titan are consistent with those for a number of other icy moons of the giant planets and most Kuiper belt objects that formed beyond the snow line. This may indicate a common reservoir of precursor material in the outer Solar System and also suggests a potential genetic link between celestial bodies in this region, which requires further study.

The paper considers the phenomenon of electromagnetic (EM) noise during the dynamics of dust particles in a fairly dense plasma-dust environment. The study combines theoretical and experimental concepts of dust charging mechanisms, observation methods, including laboratory modeling, and measurements of noise signals in terrestrial arid regions. A key objective is to characterize the frequency spectra of electromagnetic radiation generated during these processes, particularly in the low and medium frequency ranges (kHz to MHz), which are relevant for understanding dust storms and their role in Mars’ atmospheric electricity. The findings provide insights into Martian dust charging, radio emission properties, and potential implications for planetary exploration. By comparing terrestrial and Martian discharge phenomena, this work contributes to a more comprehensive understanding of dust-driven electrostatic and electromagnetic interactions, which are crucial for future mission planning and atmospheric modeling.