Solar System Research最新文献

Compositional and structural understanding of asteroids, especially the moderately small (and frequent) Near Earth Asteroids is important not only for science but also for possible mitigation against their any future impact. However, space weathering substantially modifies the surface infrared spectra, making it difficult to identify their composition. Laboratory tests of artificial weathering by simulated solar wind on meteorites were conducted and reviewed in this study. During the simulations, an increase in the iron content, amorphization, water loss and other structural changes were observed, which usually decreases the mechanical hardness of the very thin surface layer. Using these results, the question was formulated and evaluated here: could such surface changes influence the joint behavior of grain groups when effects driven by YORP forces modify the global shape of asteroids. Based on the evaluation, 10–100 million years of time scale changes are expected to occur both mineral structure and global asteroid shape. The related theoretical consequences and research questions are summarized here.

The EXO-UV program is an international, interdisciplinary collaboration between astrophysicists and biologists aimed at expanding the characterization of ultraviolet radiation (UVR) environments on exoplanets. UVR is particularly relevant because it reaches the surface of planets and can influence their habitability. High UVR fluxes emitted during flares and superflares are of particular interest due to the limited information available regarding their biological impact and the lack of experimental studies to evaluate their influence. Our first initial study in the EXO-UV program focused on experimentally studying the potential biological impact of a flare and a superflare on Proxima b, and the second considered a superflare on the TRAPPIST-1 system planets e, f, g. The survival of microorganisms belonging to both the Bacteria and Archaea domains (Deinococcus radiodurans, Pseudomonas aeruginosa, Escherichia coli, Haloferax volcanii) was evaluated. Microorganisms were exposed to UVR (UVC = 254 nm) at fluence rates and fluences equivalent to those they would receive from flares and superflares on the unshielded surfaces of these planets. Our results show the existence of a small fraction of the cell population that can tolerate these high fluences, suggesting that previous research underestimated the ability of “life as we know it” to withstand these high UVR fluxes. These results also document the tolerance of well-known microorganisms to high fluences of UVR related to flares and superflares in quantities and at wavelengths that these microorganisms do not experience on the present Earth.

The aim of this paper is to investigate the motion properties of the infinitesimal variable mass body under the effects of gravitational forces of the primaries and the Poynting–Robertson drag. The equations of motion are determined for the above said perturbations along with those caused by the second primary having modified Newtonian potential. Utilizing these equations of motion, we analytically evaluate the equilibrium points and their stability as well as reveal the numerical study for potential surfaces, equilibrium points, basins of attractions and the stability of equilibrium points. This study presents useful insights for understanding the impact of various perturbations on the motion of small particles in a system and provides the impetus for innovative research in the field of dynamical astronomy and celestial mechanics.

To achieve a detailed picture of the isolated potential primary xenon components during stepwise oxidation of nanodiamond-enriched fractions (NDEF) of meteorites, a new isotopically anomalous component Xe-pr3 has been introduced. The peculiarity of this component is a lower value of the ratio ¹³⁴Xe/¹³⁶Xe compared to that component used in (Fisenko et al., 2024b) Xe-pr2n (0.529 versus 0.591, respectively). As a result, the modeling interval of possible values of the ratio ¹³⁴Xe/¹³⁶Xe has increased in anomalous isotopic compositions of isolated xenon. This has led to the possibility of obtaining a complete and detailed picture of the isolated putative xenon components based on the analysis of high-precision data for xenon isolated during stepwise oxidation of LD1 NDEF of the Murchison meteorite (CM2) (Lewis, 1994). Comparative analysis of isolated xenon components using calculated cosmogenic neon contents (²¹Ne_c) showed the following. The relatively low-temperature, nearly isotopically normal Xe-P3 component in NDEF meteorites, identified in (Huss, Lewis, 1994), is contained in an individual carrier phase with low thermal-oxidative stability. This component, according to the authors’ concept, represents a mixture of Xe-P3n with Xe-S in a ratio of 1 : 0.013. The carrier phase of this component is likely to be diamond-like rims. Their surface localization is indicated by the simultaneous release of radiogenic ¹²⁹Xe. The release of isotopically anomalous Xe-pr1n corresponds to the layer-by-layer oxidation of diamond grains. When using SiC-X grains as the carrier phase, the components Xe-pr3 (Fisenko et al., 2024a) its unusual (“explosive”) release (about 70% at one oxidation stage) is explained by us by the formation of surface amorphous films of silicon dioxide on these grains. The assumption about SiC-X grains as a carrier phase of the isotopically anomalous component Xe-pr3 is confirmed by the revealed connection between this component and cosmogenic neon ²¹Ne_c. It is also shown that the “normal” primary component of neon in terms of isotopic composition (designated by us as Ne-P3n) corresponds to the isotopic composition of neon isolated at the high-temperature oxidation stage of LD1 NDEF. Therefore, the isotopic composition of the Ne-P3 component is the result of mixing the primary composition with an additional portion of the isotope ²²Ne (Ne-E) in a ratio of 1 : 0.05. This mixing probably occurred early in the evolution of the protoplanetary cloud of the Solar system. Successful modeling of the isotopic compositions of xenon isolated at almost all stages of the temperature range of oxidation of LD1 NDEF of the Murchison meteorite using a new(?) potentially primary component of xenon in combination with the rest allows us to consider them real and possible when analyzing xenon in NDEF of other meteorites.

Lunar regolith is considered as a primary raw material for potential infrastructure construction on the Moon. To test additive manufacturing methods, it is necessary to create lunar regolith simulants that replicate its chemical and mineralogical composition. Among terrestrial materials, volcanic ash shows the closest resemblance to regolith. The ash from the Tolbachik volcano possesses chemical and mineral composition similar to lunar regolith. A soil simulant has been developed, featuring a chemical and mineralogical composition that combines both mare and highland characteristics of lunar regolith. Testing of this simulant was performed using laser sintering technology. Successful sintering experiments with Tolbachik volcano tephra enabled production of a component with an average microhardness value of 630 HV.

The processes of dispersion and absorption accompanying the propagation of an electromagnetic wave lead to the fact that the radio signal slows down and weakens when passing through electron plasma in the ionosphere as well as through dusty plasma. The article solves the problem of restoring both the electron concentration in the ionosphere and dusty plasma particle concentration based on radio signals from satellite systems. The derivation of analytical relations for determining the total electron content (TEC) in the ionosphere (as well as the total particle content (TPC) in the dusty plasma) is considered based on the retranslation of radio signals of the global navigation satellite system (GNSS) on two frequencies using a small-sized CubeSat retransmission satellite. Methods for calculating TEC both from direct satellite signals and based on cross-retransmission using a small-sized retransmission satellite are considered. In spite of the investigations of electron plasma in ionosphere and dusty plasma are based on different principles, this paper shows that mathematical basis of the radio tomography and the restoration algorithms for its implementation occur the same for these cases under consideration. Analytical relations are given and calculation algorithms are described. As a result, two computational radiotomography algorithms and respective software have been built using various tomography restoration methods, namely, the slice theorem and the method of back projection.

The study presents modeling results of the primary atmosphere loss for the young mini-Neptune HD 207496b under the influence of thermal flux from its core, with a significant mass fraction of water in its composition. For exoplanet HD 207496b, (Barros et al., 2023) considered two internal structure scenarios: (1) a rocky (iron–silicate) core surrounded by a hydrogen–helium envelope, and (2) an ocean world with an iron core, silicate mantle, and extended water mantle. Both scenarios demonstrate potentially high efficiency of hydrogen–helium atmosphere loss through photoevaporation. Evdokimov and Shematovich (2025) evaluated the escape of the primary hydrogen–helium envelope via an alternative mechanism—thermal flux from the core. Their results showed that for a rocky core with a primordial hydrogen–helium atmosphere under the adopted model parameters, this mechanism proves insufficiently effective and should not significantly impact the gaseous envelope’s evolution. This work demonstrates that if HD 207496b currently represents a rocky core covered by a water mantle with a steam atmosphere (ocean world), the thermal flux from the planetary interior could have driven substantial loss of its primary hydrogen–helium atmosphere within the first few to tens of millions of years of evolution. The remaining primary gaseous envelope would subsequently undergo erosion via photoevaporation. Thus, HD 207496b’s evolutionary history may have included distinct phases dominated by different atmospheric loss mechanisms. The study reveals that atmospheric loss efficiency strongly depends on both the core radius and its internal energy. These parameters require refinement and are linked to interior structure models (including subsurface temperature profiles) as well as potential additional energy sources—core compression, radiogenic heating, and tidal heating.

The meteorites of the SNC group are presumed to be of Martian origin. The meteorites of the HED group (Howardites, Eucrites, Diogenites) are believed to come to Earth from the asteroid Vesta and asteroids of its family (Vestoids). The flux of differentiated SNC and HED meteorites to the Earth was estimated based on an analysis of distribution of meteorite falls and finds by mass. The fluxes of the SNC (50 pc/yr, 70 kg/yr) and HED (800 pc/yr, 260 kg/yr) meteorites are comparable in mass to the lunar meteorite flux (90 pc/yr, 110 kg/yr) despite very favorable conditions for transporting ejecta from lunar craters to the Earth compared to Mars and the asteroid belt. The amount of ejecta from Mars craters potentially capable of reaching the Earth is about two orders of magnitude greater than the corresponding amount of the Moon ejecta generated over the same time period. But the transport velocity of matter from the Moon to the Earth is also higher by about two orders of magnitude. It may be the main factor that levels the fluxes of matter from these bodies. The similarity of fluxes from the Moon and from an even more distant body, Vesta, is most likely due to the formation on Vesta and Vestoids at low gravity of a larger mass of crater ejecta moving to heliocentric orbits intersecting with the Earth’s orbit. The relative content of HED meteorites of different types in the flux to the Earth corresponds to the data of spectral mapping of Vesta’s surface by the Dawn spacecraft. The flux of SNC meteorites does not match the composition of the Mars surface as studied by Mars rovers and orbiting spacecraft. In general, the fluxes of matter from Mars and Vesta as well as from the Moon did not affect the composition of the Earth’s crust during its formation.

The surface morphology of the permanently shadowed floors of near-polar craters Faustini, Shoemaker, and Haworth and the regularly illuminated floors of craters Macrobius and Boss was studied on the basis of the photogeologic analysis of images acquired with the ShadowCam onboard the Korea Pathfinder Lunar Orbiter and the Narrow Angle Cameras of the Lunar Reconnaissance Orbiter (LROC NAC), as well as with the use of the Lunar Orbiter Laser Altimeter (LOLA) measurement data. It has been shown that craters with diameters from tens to hundreds of meters dominate the surface morphology of the floors of all five craters studied. On the inner slopes of the craters, both shadowed in near-polar craters and regularly illuminated in nonpolar craters, an undulating surface texture resembling an elephant hide is observed. On the floors of craters Macrobius and Boss, there are gently sloping hills, while such hills are absent on the floors of craters Faustini, Shoemaker, and Haworth; i.e., the floors of the studied near-polar craters are flatter on the scale of a few kilometers. On the floors of near-polar craters, craters with lobate rims are observed. Formation of these rims are apparently connected with the presence of H₂O ice in the target material. Craters of this kind represent only a few percent of the total number of craters considered. They are located in different places of the studied areas and differ in size, which apparently suggests that water ice in the target material is unevenly distributed over the area and depth of occurrence. On the floors of craters Macrobius and Boss, there are rare craters, which somewhat resemble the lobate morphology. This observation requires further study.