Solar System Research最新文献

Throughout the exploration of the Solar System using spacecraft, Mercury has received less attention compared to Venus and Mars as the inner planet due to the inherent challenges of designing efficient trajectories in terms of both time and energy. A mission to Mercury requires a substantial reduction in the spacecraft’s heliocentric velocity, enabling its transfer into the inner Solar System. This trajectory optimization problem remains complex due to the interplay between gravitational influences, spacecraft constraints, and mission objectives. This study focuses on the development and optimization of interplanetary trajectories that minimize the total characteristic velocity (Δv) while meeting constraints on flight duration and flyby altitudes during gravity assist maneuvers. The proposed methodology incorporates gravity assist maneuvers near Earth, Venus, and Mercury, combined with deep space maneuvers (DSMs) for phasing and energy optimization. Two new trajectory designs are presented as examples, demonstrating improvements over traditional approaches by reducing mission duration by one year without exceeding the characteristic velocity budget of NASA’s MESSENGER mission. These results underscore the potential for further improvements in trajectory optimization through refined algorithms and expanded mission constraints. This work highlights the importance of integrating advanced computational techniques with modern propulsion technologies to enhance the feasibility of Mercury exploration. By addressing key challenges in mission design, it contributes to a growing framework for more efficient and scientifically productive missions to the innermost planet of the Solar System.

The effects of temperature, impacts, and irradiation on Chelyabinsk LL5 chondrite light-colored lithology matter were simulated in the laboratory conditions. Various changings of the texture and structure registered by different methods and techniques. As similarity as differences between the experimental results and the natural dark-colored lithology samples of Chelyabinsk LL5 were detected. Irradiation with Ar ions cause darkening, but this effect touches a surface only. While the shock experiment with the spherically-converted shock waves produced all types of lithologies that were found among the Chelyabinsk LL5 chondrite collection. Impact melt zone was formed under maximum pressure at the center of the sample. Next—zone with extensive silicate melting, then zone of dark lithology or black-ring zone, and zone of additionally shock-loaded original light-colored lithology situated in the shocked ball sample. Heating to 1100°C led to the dark-colored lithology structure formation with troilite melting, metal recrystallization, and optical darkening. Heating for a lower temperature produced effects in morphology of the metal and troilite inclusions. While heating for higher temperature induce melting of the host silicates and new crystals grows. It was assumed that dark-colored lithology was formed as a result of heating of the material of light-colored lithology. This assumption was verified by experimental studies of the meteorite substance after thermal, shock and radiation effects in laboratory experiments.

A description of plasma–dust processes in the vicinity of comets is given. It has been shown that they can manifest themselves in situations where the comet is quite far from the Sun. In addition, plasma–dust processes can have a significant impact on the formation of the bow shock wave as a result of the interaction of the comet’s coma with the solar wind. It has been demonstrated that for a comet with nucleus parameters close to those of Halley’s comet, dusty plasma in the vicinity of the nucleus is formed due to electrostatic interactions, i.e., similar to the formation of dusty plasma near other atmosphereless cosmic bodies such as Mercury, the Moon, the satellites of Mars, etc., provided that the distance from the comet to the Sun is at least ~2.5–3.5 AU. On the contrary, if the comet is closer to the Sun, the dynamics of dust particles is determined by the intensity of the gas flow from the comet’s nucleus. The role of plasma–dust processes in the formation of the bow shock wave is considered. It turns out that for a comet with a nucleus of about 1-km radius and a relatively dense dust coma, an important role in the formation of the bow shock wave can be played by anomalous dissipation associated with the process of dust particle charging. Apparently, the nature of such a bow shock wave is similar to the nature of dust ion–acoustic shock waves.

It is shown that the features of the formation of a dusty plasma system above the surface of an asteroid, compared to typical airless celestial bodies such as the Moon, Mercury, the moons of Mars, and others, are primarily associated with two factors: the influence of water on asteroids and the influence of processes involving the interaction of dust with gas flow (for active asteroids). The possibility of water formation in the near-surface regolith of an asteroid is noted, within the framework of a mechanism involving the interaction of solar wind protons with the asteroid’s regolith in the presence of silver sulfide. It is demonstrated that in the formation of a dusty plasma system near an active asteroid, not only are electrostatic interactions important but also processes related to gas flow from areas of the asteroid’s surface containing water. In this case, it becomes possible to interpret relatively large dust particles as levitating above the asteroid’s surface, while smaller particles do not levitate and are carried away by the gas flow from the asteroid’s surface.

Recently, fresh impacts of meter-scaled cosmic objects were discovered on Mars. About half of the projectiles, which formed these impact sites, are destroyed in rarefied atmosphere of Mars and form crater clusters, unfragmented meteoroids result in single craters. Atmospheric density near the Martian surface correspond to about 30 km altitude in the terrestrial atmosphere, thus the study of clusters provides a unique opportunity to estimate meteoroid parameters independently, to investigate various fragmentation types for objects of different composition and origin. This paper considers a processed part of an expanded catalog of impact sites. Data about craters and clusters provide an opportunity to estimate the exponent in the differential and cumulative incremental size-frequency distribution of projectiles as 2.7 and 2.2. Fragmented and not fragmented meteoroids are described by the same distribution. It was suggested to classify clusters into 3 types; the first one refers to one major crater supplemented by some much smaller ones; densely populated clusters (with more than 20 craters) correspond to the second type and the final group relates to sparsely populated clusters (less than 20 craters), which have 2 or more comparable largest craters. The various proposed groups may correspond to different fragmentation scenarios and/or meteoroid properties.

The paper suggests a possible scenario of a flight to Neptune’s moons Triton and Nereid. At the moment, Triton and Nereid remain among the least studied moons in Solar system. A detailed study of Triton can confirm a number of theories about its origin. The study of Nereid, the third largest satellite of Neptune with the greatest eccentricity among all known moons, will help to better understand the evolution of the Neptune moon system and confirm or refute the hypothesis that Triton was captured by Neptune’s gravity and seriously destroyed the original system of its moons. A significant problem in the study of giant planets and their satellites is the lack of effective space transport systems that allow delivering a large payload over such long distances. One of the most promising solutions to this problem is the use of propulsion systems with low thrust, ensuring the implementation of the flight with minimal expenditure of the working fluid. The scenario allows a spacecraft with low-thrust engines to reach Neptune by performing two gravity assist maneuvers near Earth and one gravity assist maneuver near Jupiter. The flyby of Triton and Nereid is carried out within the framework of one mission and make possible to explore the surface of both moons from a distance of 10 thousand km. The achievement of this task is carried out by using a modern ion propulsion system with a specific impulse of 3500 s and a thrust of 0.15 N. It is shown that with an initial mass of 850 kg and a mission duration of 29 years, the total cost of the propellant will not exceed 350 kg.

In this paper, a method for selecting potential rubble pile near-Earth asteroids (NEAs) is proposed. The method is based on statistical analysis of the number of asteroid associations with sporadic meteors from the Global Meteor Network (GMN) database, as well as the value of the of the minimum orbital distance between the Earth and the asteroid (MOID), its magnitude, and the rotation period. The number of associations was calculated for each asteroid i.e., the number of meteors with relatively close meteoroids’ orbits. To determine associations between NEAs and meteors, well known orbital dissimalrity criteria (D-criteria) were used: Southworth and Hawkins, Drummond criteria and Kholshevnikov metric. A meteor was associated with an asteroid if the D-criteria values between their orbits did not exceed selected thresholds. The method is based on the assumption that the proportion of associations in which meteors are genetically related to the asteroid in qestion is significant relative to the total number of associations. With that in mind, we impose a number of constraints regarding the orbits and the rotation periods of the NEAs. A table of asteroids with the largest number of associations which satisfy the imposed restrictions is provided. These asteroids are recommended for further study using polarimetric, photometric and other types of observations to verify whether they belong to the rubble pile type or not. We stress the importance of considering the distribution of the number of associations by dates, depending on the Earth’s orbital position, when moving on to the consideration of individual asteroids.

The paper presents new radar maps of the south polar region of the Moon at 4.2 cm wavelength with an average spatial resolution of 90 m. The maps are based on radar images obtained in 2023 using the 64-m TNA-1500 antenna of the Bear Lakes Satellite Communications Center of the Special Design Bureau of the Moscow Power Engineering Institute and the 13.2-m RT-13 radio telescopes at the Svetloe and Zelenchukskaya observatories of the Institute of Applied Astronomy of the Russian Academy of Sciences. Radar images are formed in a specific coordinate system relating the Doppler frequency shift with the propagation time delay of the echo components, which makes it difficult to tie them to selenographic coordinates. In this paper, an original method for converting echo Doppler frequency and time delay to selenographic latitude and longitude is proposed, using bilinear interpolation by ephemeris nodal values, taking into account long integration times. The accuracy of the reference of the maps constructed in this way was assessed and compared with the LROC WAC global optical map of the Moon and mosaics of permanently shadowed regions from LROC NAC. It is shown that radar maps at 4.2 cm wavelength contain features of the lunar surface that are hidden in optical images and are located in the regolith at depths of up to 1 m or in permanently shadowed regions of the south polar region of the Moon. The maps of the lunar echoes specular and diffuse polarization components, as well as a map of the distribution of circular polarization ratios, are available on the Internet at http://luna.iaaras.ru/ and can be useful for studying the geological history of the Moon, searching for ice deposits, and selecting safe landing sites when planning future lunar missions.

This study is focused on the problem of determining the position of a satellite at entry to and exit from the planet’s penumbra with the use of an analytical equation in the closed form. The approach taken is based on the geometric representation of the second-order curve that appeared when the plane of the satellite orbit cuts the conical surface formed by the intersection of sunlight rays and the boundaries of a central body. The time moments of the satellite’s entry to the penumbra and umbra of the planet are determined from the intersection of this curve with the satellite orbit. Based on these ideas, an analytical method for determining the duration of eclipses of a satellite by a planet has been developed. Its application to the analysis of the orbits of an artificial satellite of Venus has been demonstrated. It is ascertained that the method simplifies the search for orbits, the parameters of which satisfy the requirements for the duration of the shadow segment. It is shown that the method can be extended to the solution of the problem of determining the moments of time, at which the satellite passes the region obscured by the planetary atmosphere. It is illustrated on provided examples that the proposed approach can be applied to solving practically important problems in the study of Venus and its atmosphere.

The paper considers the issues of designing transfer trajectories of spacecraft moving along bounded orbits in vicinities of Sun–Earth libration points to the Near-Earth asteroids Apophis and 2001 WN₅. The study was conducted for the James Webb Space Telescope and the Spectrum–Roentgen–Gamma spacecraft operating near the L₂ Sun–Earth libration point. It is shown that these spacecraft can be transferred to trajectories of a close approach to the target celestial bodies at low fuel costs. The results of numerical calculations of the values of the characteristic velocity required for such flights with the subsequent return of the spacecraft to the vicinity of the initial libration point in order to continue the main mission are presented. The advantage of the proposed concept for the design of flight schemes to Near-Earth asteroids is that all sections of the spacecraft trajectories are located in a vicinity of the Earth.