Pub Date : 2025-12-01Epub Date: 2025-11-21DOI: 10.1016/j.pss.2025.106218
Sandeepan Dhoundiyal , Moni Shankar Dey , Shashikant Singh , Pattathal V. Arun , Guneshwar Thangjam , Alok Porwal
Accurately identifying minerals from space-borne hyperspectral data is critical in various earth observation tasks as well as in planetary remote sensing; however, it involves unique challenges which limit the applicability of standard algorithms for segmenting hyperspectral images and necessitates the development of specialized approaches tailored to mineral mapping. This paper evaluates the efficacy of various classification algorithms and ensembling strategies for mapping minerals over data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Using insights from this analysis, a novel algorithm that utilizes an ensemble of Support Vector Machines, each trained over a random subset of bands, and Extreme Value Analysis to identify minerals under an open-set regime is proposed. This algorithm returns Kappa over samples from the CRISM machine learning toolkit’s mineral dataset.
{"title":"Open-set mineral identification from CRISM hyperspectral data","authors":"Sandeepan Dhoundiyal , Moni Shankar Dey , Shashikant Singh , Pattathal V. Arun , Guneshwar Thangjam , Alok Porwal","doi":"10.1016/j.pss.2025.106218","DOIUrl":"10.1016/j.pss.2025.106218","url":null,"abstract":"<div><div>Accurately identifying minerals from space-borne hyperspectral data is critical in various earth observation tasks as well as in planetary remote sensing; however, it involves unique challenges which limit the applicability of standard algorithms for segmenting hyperspectral images and necessitates the development of specialized approaches tailored to mineral mapping. This paper evaluates the efficacy of various classification algorithms and ensembling strategies for mapping minerals over data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Using insights from this analysis, a novel algorithm that utilizes an ensemble of Support Vector Machines, each trained over a random subset of bands, and Extreme Value Analysis to identify minerals under an open-set regime is proposed. This algorithm returns Kappa <span><math><mrow><mo>=</mo><mn>0</mn><mo>.</mo><mn>89</mn></mrow></math></span> over <span><math><mrow><mo>∼</mo><mn>470000</mn></mrow></math></span> samples from the CRISM machine learning toolkit’s mineral dataset.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"269 ","pages":"Article 106218"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-21DOI: 10.1016/j.pss.2025.106217
Denis L. Gorshanov, Iraida A. Sokova, Svetlana N. Petrova, Konstantin N. Naumov, Amir Kh. Aliev
A program of observations of asteroids suspected of being binary has been launched at the Pulkovo Observatory in order to search for features inherent in binary asteroids in their lightcurves. The first asteroid observed was asteroid (720) Bohlinia. The following results were obtained from observations performed in September–October 2024. The rotation period of the asteroid (its main component) was confirmed: P = 8.9183 ± 0.0016 h. A decrease in brightness was detected in five segments, which can be interpreted as a result of mutual phenomena (eclipses and occultations) of the primary and secondary components. The recurrence period of the phenomena (the orbital period of the asteroid's satellite) is 17.418 ± 0.006 or 34.836 ± 0.008 h. In the segments of the lightcurve located outside the supposed mutual phenomena, brightness variations were detected, presumably caused by the axial rotation of the satellite with a period of PSat = 1.932 ± 0.003 h. Taking into account the above values obtained from the observations, a numerical model of the binary system was constructed. The selection of its parameters showed that ten variants of the set of parameters are possible, satisfying the observational data: ratio of the sizes of the components, the satellite's orbital period, its orbital inclination (±14°, ±18°, ±21°), the direction of revolution relative to the rotation of the main component and the type of observed mutual phenomena (frontal or back. A forecast was made of the time intervals in which mutual phenomena in the system of components of the asteroid should be expected in the upcoming period of its observability (September–December 2025).
{"title":"Testing the binarity of asteroid (720) Bohlinia using lightcurve analysis","authors":"Denis L. Gorshanov, Iraida A. Sokova, Svetlana N. Petrova, Konstantin N. Naumov, Amir Kh. Aliev","doi":"10.1016/j.pss.2025.106217","DOIUrl":"10.1016/j.pss.2025.106217","url":null,"abstract":"<div><div>A program of observations of asteroids suspected of being binary has been launched at the Pulkovo Observatory in order to search for features inherent in binary asteroids in their lightcurves. The first asteroid observed was asteroid (720) Bohlinia. The following results were obtained from observations performed in September–October 2024. The rotation period of the asteroid (its main component) was confirmed: <em>P =</em> 8.9183 ± 0.0016 h. A decrease in brightness was detected in five segments, which can be interpreted as a result of mutual phenomena (eclipses and occultations) of the primary and secondary components. The recurrence period of the phenomena (the orbital period of the asteroid's satellite) is 17.418 ± 0.006 or 34.836 ± 0.008 h. In the segments of the lightcurve located outside the supposed mutual phenomena, brightness variations were detected, presumably caused by the axial rotation of the satellite with a period of <em>P</em><sub>Sat</sub> = 1.932 ± 0.003 h. Taking into account the above values obtained from the observations, a numerical model of the binary system was constructed. The selection of its parameters showed that ten variants of the set of parameters are possible, satisfying the observational data: ratio of the sizes of the components, the satellite's orbital period, its orbital inclination (±14°, ±18°, ±21°), the direction of revolution relative to the rotation of the main component and the type of observed mutual phenomena (frontal or back. A forecast was made of the time intervals in which mutual phenomena in the system of components of the asteroid should be expected in the upcoming period of its observability (September–December 2025).</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"269 ","pages":"Article 106217"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-24DOI: 10.1016/j.pss.2025.106219
James W. Dottin III
Using in-situ sulfur isotope measurements of glass beads from a Chang'e 5 lunar soil, Wang et al. (2024) argue that volcanism on the moon persisted until 120 Ma. This study critically evaluates their argument using current knowledge of in-situ measurement practices and the existing literature on S-isotope fraction mechanisms. This study argues that the sulfur isotope data used as a mechanism for identifying impact glass beads versus volcanic glass beads was collected and interpreted improperly, while further failing to consider plausible alternative hypotheses. The largest fractionations in the “impact” glass beads could represent mixing with background sulfur in the instrument rather than S loss during impacts. The fractionation among the “volcanic” glass beads may be an issue of instrumental mass fractionation corrections from improper standardization or a previously unidentified lunar sulfur reservoir, rather than S loss during lunar volcanism.
{"title":"“An alternative perspective on the nature of sulfur isotopic variability measured in Chang'e 5 glass beads”","authors":"James W. Dottin III","doi":"10.1016/j.pss.2025.106219","DOIUrl":"10.1016/j.pss.2025.106219","url":null,"abstract":"<div><div>Using in-situ sulfur isotope measurements of glass beads from a Chang'e 5 lunar soil, Wang et al. (2024) argue that volcanism on the moon persisted until 120 Ma. This study critically evaluates their argument using current knowledge of in-situ measurement practices and the existing literature on S-isotope fraction mechanisms. This study argues that the sulfur isotope data used as a mechanism for identifying impact glass beads versus volcanic glass beads was collected and interpreted improperly, while further failing to consider plausible alternative hypotheses. The largest fractionations in the “impact” glass beads could represent mixing with background sulfur in the instrument rather than S loss during impacts. The fractionation among the “volcanic” glass beads may be an issue of instrumental mass fractionation corrections from improper standardization or a previously unidentified lunar sulfur reservoir, rather than S loss during lunar volcanism.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"269 ","pages":"Article 106219"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-27DOI: 10.1016/j.pss.2025.106214
Hadi Madanian , Daniel B. Graham , Ahmad Lalti
In this study we report our analysis of rare observations of Earth’s bow shock motion at sunward geocentric distances as far as 24 Earth radii (RE). We analyze observations from solar wind monitors and two spacecraft constellations on the dayside geospace made during a period of low Mach number and low solar wind conditions associated with a magnetic cloud flux rope of an interplanetary coronal mass ejection (ICME). It is shown that during this period the bow shock standoff distance under these conditions is underestimated by empirical model predictions. The bow shock motion is rather asymmetric, in that the bow shock expansion in the solar wind at 120 km/s is much faster than when it recedes at 14 km/s. It is shown that such an asymmetric motion is driven in part by magnetosheath conditions immediately downstream of the bow shock. As the bow shock expands in the upstream solar wind, heating and deceleration of the solar wind plasma is much more effective due to a higher cross shock electrostatic potential and gyrokinetic effects. These observations are also supported by a numerical model. Further downstream of the bow shock in the magnetosheath, the plasma flow exhibits significant slowdown as a result of the fast outward propagation of the bow shock and further plasma compression.
{"title":"Properties of Earth’s bow shock at large geocentric distances: A case study","authors":"Hadi Madanian , Daniel B. Graham , Ahmad Lalti","doi":"10.1016/j.pss.2025.106214","DOIUrl":"10.1016/j.pss.2025.106214","url":null,"abstract":"<div><div>In this study we report our analysis of rare observations of Earth’s bow shock motion at sunward geocentric distances as far as 24 Earth radii (R<sub>E</sub>). We analyze observations from solar wind monitors and two spacecraft constellations on the dayside geospace made during a period of low Mach number and low <span><math><mi>β</mi></math></span> solar wind conditions associated with a magnetic cloud flux rope of an interplanetary coronal mass ejection (ICME). It is shown that during this period the bow shock standoff distance under these conditions is underestimated by empirical model predictions. The bow shock motion is rather asymmetric, in that the bow shock expansion in the solar wind at <span><math><mo>∼</mo></math></span>120 km/s is much faster than when it recedes at <span><math><mo>∼</mo></math></span>14 km/s. It is shown that such an asymmetric motion is driven in part by magnetosheath conditions immediately downstream of the bow shock. As the bow shock expands in the upstream solar wind, heating and deceleration of the solar wind plasma is much more effective due to a higher cross shock electrostatic potential and gyrokinetic effects. These observations are also supported by a numerical model. Further downstream of the bow shock in the magnetosheath, the plasma flow exhibits significant slowdown as a result of the fast outward propagation of the bow shock and further plasma compression.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"269 ","pages":"Article 106214"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145475485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-09-12DOI: 10.1016/j.pss.2025.106198
Tabaré Gallardo, Rodrigo Cabral
The dynamics of small bodies perturbed by an eccentric planet was done mostly under the assumption of well separated orbits using analytical approximations appropriate for the hierarchical case. In this work we study the dynamics of small bodies in a wide range of eccentricities and inclinations perturbed by a giant planet with , in the non-hierarchical case. We consider small bodies both interior and exterior to the planet. We apply semi-analytical models for the study of resonances and the properties of the secular disturbing function. We perform a frequency analysis of numerical integration of the exact equations of motion to obtain the proper frequencies and corresponding dynamical secular paths. We study the dependence of proper frequencies with the initial mutual inclination and we find a critical inclination around 30 degrees for which the pericenter proper frequency vanishes giving rise to the increase of small bodies eccentricities followed by unstable dynamics. This happens for both interior and exterior small bodies and constitutes a stability barrier in the inclination. For greater inclinations the ZLK mechanism dominates both populations. By means of numerical integration of thousands of small bodies we reproduce the well known pericenter shepherding, but for the exterior populations with low inclinations we also find concentrations of the longitude of the ascending node in the direction of the planetary line of apsides.
{"title":"Dynamical regimes of small bodies perturbed by an eccentric giant planet","authors":"Tabaré Gallardo, Rodrigo Cabral","doi":"10.1016/j.pss.2025.106198","DOIUrl":"10.1016/j.pss.2025.106198","url":null,"abstract":"<div><div>The dynamics of small bodies perturbed by an eccentric planet was done mostly under the assumption of well separated orbits using analytical approximations appropriate for the hierarchical case. In this work we study the dynamics of small bodies in a wide range of eccentricities and inclinations perturbed by a giant planet with <span><math><mrow><msub><mrow><mi>e</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>4</mn></mrow></math></span>, in the non-hierarchical case. We consider small bodies both interior and exterior to the planet. We apply semi-analytical models for the study of resonances and the properties of the secular disturbing function. We perform a frequency analysis of numerical integration of the exact equations of motion to obtain the proper frequencies and corresponding dynamical secular paths. We study the dependence of proper frequencies with the initial mutual inclination and we find a critical inclination around 30 degrees for which the pericenter proper frequency vanishes giving rise to the increase of small bodies eccentricities followed by unstable dynamics. This happens for both interior and exterior small bodies and constitutes a stability barrier in the inclination. For greater inclinations the ZLK mechanism dominates both populations. By means of numerical integration of thousands of small bodies we reproduce the well known pericenter shepherding, but for the exterior populations with low inclinations we also find concentrations of the longitude of the ascending node in the direction of the planetary line of apsides.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106198"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-10-10DOI: 10.1016/j.pss.2025.106204
C.R. Neeraja, S Arivazhagan, P Abishek
The Apollo basin, within the South Pole-Aitken (SPA) basin on the far side of the Moon, is a notable geological feature that offers an understanding of the Moon's history and evolution and showcases a complex geological history influenced by impact processes and volcanic activity. The present study focused on delineating the basaltic flows of the basin along with age determination and lithological discrimination. The current research utilized Chandrayaan-1 Moon Mineralogy Mapper (M3), Chandrayaan-2 Imaging Infra-Red Spectrometer (IIRS), Lunar Reconnaissance Orbiter Camera (LROC) - Wide Angle Camera (WAC), Kaguya Terrain Camera (TC) and Kaguya Multiband Imager (MI) derived maps. The FeO weight percent map, Mg # map generated from Kaguya MI data, and the TiO2 abundance map from LROC WAC data are used for the compositional analysis. The mare is classified into eight distinct units by comparing these parameters with an Integrated Band Depth (IBD) color composite image. Spectral studies are done to identify the pyroxene mineralogy of each unit. By analyzing the pyroxene thermometry plot generated by analyzing the spectral data, two distinct crystallization trends are observed, starting with pigeonite and sub-calcic augite to ferro-augite. The other trend progresses from augite to diopside boundary. The ages of the mare units were estimated using the Crater Size Frequency Distribution (CSFD) method. The study suggests that mare volcanism commenced at approximately 3.5 Ga and progressed to a younger phase between 2.0 and 1.8 Ga. The units A2 and A4 exhibit the highest average model age (AMA) of 3.5 Ga and dominantly exhibit higher calcium content, while unit A8 represents the youngest unit with an age of 1.8 Ga with relatively lower calcium content. Mare volcanism was initiated at the periphery of the basin, particularly in the southern and southeastern regions, and subsequently progressed westward and towards the basin's center. Magmas with diverse chemical compositions derived from varied source regions erupted in the Apollo basin between the Imbrian and Eratosthenian periods.
{"title":"Decoding the Apollo basin: Insights into volcanism, compositional diversity and crustal evolution","authors":"C.R. Neeraja, S Arivazhagan, P Abishek","doi":"10.1016/j.pss.2025.106204","DOIUrl":"10.1016/j.pss.2025.106204","url":null,"abstract":"<div><div>The Apollo basin, within the South Pole-Aitken (SPA) basin on the far side of the Moon, is a notable geological feature that offers an understanding of the Moon's history and evolution and showcases a complex geological history influenced by impact processes and volcanic activity. The present study focused on delineating the basaltic flows of the basin along with age determination and lithological discrimination. The current research utilized Chandrayaan-1 Moon Mineralogy Mapper (M<sup>3</sup>), Chandrayaan-2 Imaging Infra-Red Spectrometer (IIRS), Lunar Reconnaissance Orbiter Camera (LROC) - Wide Angle Camera (WAC), Kaguya Terrain Camera (TC) and Kaguya Multiband Imager (MI) derived maps. The FeO weight percent map, Mg # map generated from Kaguya MI data, and the TiO<sub>2</sub> abundance map from LROC WAC data are used for the compositional analysis. The mare is classified into eight distinct units by comparing these parameters with an Integrated Band Depth (IBD) color composite image. Spectral studies are done to identify the pyroxene mineralogy of each unit. By analyzing the pyroxene thermometry plot generated by analyzing the spectral data, two distinct crystallization trends are observed, starting with pigeonite and sub-calcic augite to ferro-augite. The other trend progresses from augite to diopside boundary. The ages of the mare units were estimated using the Crater Size Frequency Distribution (CSFD) method. The study suggests that mare volcanism commenced at approximately 3.5 Ga and progressed to a younger phase between 2.0 and 1.8 Ga. The units A2 and A4 exhibit the highest average model age (AMA) of 3.5 Ga and dominantly exhibit higher calcium content, while unit A8 represents the youngest unit with an age of 1.8 Ga with relatively lower calcium content. Mare volcanism was initiated at the periphery of the basin, particularly in the southern and southeastern regions, and subsequently progressed westward and towards the basin's center. Magmas with diverse chemical compositions derived from varied source regions erupted in the Apollo basin between the Imbrian and Eratosthenian periods.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106204"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-10-17DOI: 10.1016/j.pss.2025.106205
Adil Murad , Muhammad Adnan , Shahida Parveen , Ikramullah , Fida Younus Khattak
<div><div>The propagation characteristics of low-frequency electrostatic waves are investigated in the magnetized plasma environment of Venus, where both ion cyclotron and ion acoustic modes are examined. The plasma is modeled as a four-component system composed of solar wind electrons, Venus-origin hydrogen (H<span><math><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></math></span>), Venus-origin oxygen (O<span><math><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></math></span>), and solar wind protons (SWP). The electrons are assumed to follow a superthermal <span><math><mi>κ</mi></math></span>-distribution, consistent with spacecraft observations indicating the presence of suprathermal electrons in the Venus ionosheath. Ions are treated as warm fluids, and the analysis includes the effects of an induced magnetic field through the Lorentz force. The low-frequency approximation is justified by the dominance of electrostatic structures and slow wave dynamics near the subsolar region of Venus, as observed in Pioneer Venus Orbiter (PVO) and Venus Express (VEX) missions. This approximation allows neglecting high-frequency electromagnetic components and focusing on the electrostatic behavior critical to understanding plasma transport and wave–particle interactions in the ionosheath.</div><div>A general dispersion relation is derived, solved numerically, and decoupled to reveal three ion cyclotron roots and three ion acoustic roots, each associated with the different ion species. In the nonlinear regime, a Zakharov–Kuznetsov (ZK) equation is derived using reductive perturbation theory to describe the evolution of small but finite-amplitude ion acoustic solitons. The analysis shows that superthermality significantly affects soliton properties: for hydrogen acoustic modes, low <span><math><mi>κ</mi></math></span> values yield rarefactiolitons while higher <span><math><mi>κ</mi></math></span> values support compressive structures, indicating a polarity switch linked to suprathermal electronve s populations. The amplitude and width of the solitons are further influenced by the magnetic field and solar wind proton density—higher field strength reduces width due to enhanced dispersive effects, while increased proton density decreases amplitude in oxygen modes but increases it in hydrogen modes.</div><div>A two-dimensional pulse stability analysis based on the Allen–Rowlands method reveals that both magnetic field and solar wind proton density suppress the first-order instability growth rate. Second-order instability becomes significant beyond the critical propagation angle (<span><math><mrow><mi>θ</mi><mo>></mo><mn>37</mn><mo>.</mo><msup><mrow><mn>8</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span>), particularly for proton modes. These results align with observed electrostatic wave behavior and density fluctuations reported in PVO and VEX datasets, highlighting the role of multi-ion interactions and suprathermal effects in shaping Venus
{"title":"Low frequency electrostatic wave dynamics in the subsolar magnetosheath of Venus: A theoretical framework with multi-ion and suprathermal electrons","authors":"Adil Murad , Muhammad Adnan , Shahida Parveen , Ikramullah , Fida Younus Khattak","doi":"10.1016/j.pss.2025.106205","DOIUrl":"10.1016/j.pss.2025.106205","url":null,"abstract":"<div><div>The propagation characteristics of low-frequency electrostatic waves are investigated in the magnetized plasma environment of Venus, where both ion cyclotron and ion acoustic modes are examined. The plasma is modeled as a four-component system composed of solar wind electrons, Venus-origin hydrogen (H<span><math><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></math></span>), Venus-origin oxygen (O<span><math><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></math></span>), and solar wind protons (SWP). The electrons are assumed to follow a superthermal <span><math><mi>κ</mi></math></span>-distribution, consistent with spacecraft observations indicating the presence of suprathermal electrons in the Venus ionosheath. Ions are treated as warm fluids, and the analysis includes the effects of an induced magnetic field through the Lorentz force. The low-frequency approximation is justified by the dominance of electrostatic structures and slow wave dynamics near the subsolar region of Venus, as observed in Pioneer Venus Orbiter (PVO) and Venus Express (VEX) missions. This approximation allows neglecting high-frequency electromagnetic components and focusing on the electrostatic behavior critical to understanding plasma transport and wave–particle interactions in the ionosheath.</div><div>A general dispersion relation is derived, solved numerically, and decoupled to reveal three ion cyclotron roots and three ion acoustic roots, each associated with the different ion species. In the nonlinear regime, a Zakharov–Kuznetsov (ZK) equation is derived using reductive perturbation theory to describe the evolution of small but finite-amplitude ion acoustic solitons. The analysis shows that superthermality significantly affects soliton properties: for hydrogen acoustic modes, low <span><math><mi>κ</mi></math></span> values yield rarefactiolitons while higher <span><math><mi>κ</mi></math></span> values support compressive structures, indicating a polarity switch linked to suprathermal electronve s populations. The amplitude and width of the solitons are further influenced by the magnetic field and solar wind proton density—higher field strength reduces width due to enhanced dispersive effects, while increased proton density decreases amplitude in oxygen modes but increases it in hydrogen modes.</div><div>A two-dimensional pulse stability analysis based on the Allen–Rowlands method reveals that both magnetic field and solar wind proton density suppress the first-order instability growth rate. Second-order instability becomes significant beyond the critical propagation angle (<span><math><mrow><mi>θ</mi><mo>></mo><mn>37</mn><mo>.</mo><msup><mrow><mn>8</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span>), particularly for proton modes. These results align with observed electrostatic wave behavior and density fluctuations reported in PVO and VEX datasets, highlighting the role of multi-ion interactions and suprathermal effects in shaping Venus","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106205"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-09-18DOI: 10.1016/j.pss.2025.106201
Gurpreet Kaur Bhatia, Sumit Sankhyan
Understanding a planet's early thermal evolution and differentiation is crucial to comprehending the distribution of volatiles in its different reservoirs. Mercury is now known as a volatile rich planet. It has carbon saturated core, deeply buried volatile rich layers, a diamond layer at the core-mantle boundary and graphite floating at the crust. For carbon saturation, Mercury is believed to have accreted from Enstatite/CB chondrite rich building blocks. In the present work, we studied the early thermal evolution and core formation in the interior of Mercury by considering its accretion from water rich Enstatite chondrites prior to the dispersal of solar nebula. The heat sources for the melting and differentiation of Mercury include the decay energy of SLR 26Al and the blanketing effect of the impact generated H2O+CO+H2 along with primordial atmosphere. The results suggest the complete core formation with lowest assumed water content in the building blocks Mercury for accretion timescales ≤1.5 Myr after the formation of CAIs. The longer accretion timescales, it needed higher abundance of water to cause significant blanketing effect at the surface. During differentiation process, the volatiles dissolved in the magma ocean under the pressure of overlying atmosphere, could partition into the core. Hence, the outcomes of present study have implications to explain the distribution of volatile in the interior of Mercury. Conversely, under the strong blanketing effect, the surface silicate could vaporize and dissolve in the steam atmosphere.
{"title":"Mercury's early thermal evolution and core formation in the presence of impact-generated atmosphere during accretion","authors":"Gurpreet Kaur Bhatia, Sumit Sankhyan","doi":"10.1016/j.pss.2025.106201","DOIUrl":"10.1016/j.pss.2025.106201","url":null,"abstract":"<div><div>Understanding a planet's early thermal evolution and differentiation is crucial to comprehending the distribution of volatiles in its different reservoirs. Mercury is now known as a volatile rich planet. It has carbon saturated core, deeply buried volatile rich layers, a diamond layer at the core-mantle boundary and graphite floating at the crust. For carbon saturation, Mercury is believed to have accreted from Enstatite/CB chondrite rich building blocks. In the present work, we studied the early thermal evolution and core formation in the interior of Mercury by considering its accretion from water rich Enstatite chondrites prior to the dispersal of solar nebula. The heat sources for the melting and differentiation of Mercury include the decay energy of SLR <sup>26</sup>Al and the blanketing effect of the impact generated H<sub>2</sub>O+CO+H<sub>2</sub> along with primordial atmosphere. The results suggest the complete core formation with lowest assumed water content in the building blocks Mercury for accretion timescales ≤1.5 Myr after the formation of CAIs. The longer accretion timescales, it needed higher abundance of water to cause significant blanketing effect at the surface. During differentiation process, the volatiles dissolved in the magma ocean under the pressure of overlying atmosphere, could partition into the core. Hence, the outcomes of present study have implications to explain the distribution of volatile in the interior of Mercury. Conversely, under the strong blanketing effect, the surface silicate could vaporize and dissolve in the steam atmosphere.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106201"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-09-24DOI: 10.1016/j.pss.2025.106203
A. Ettehadi , M. Radonjic , M. Mokhtari , R.C. Anderson
Mars sample collection is often hindered by the mechanical fragility of calcium sulfate-filled fractures, which are prone to fragmentation under drilling-induced stress. This study presents a coupled mineralogical and nano-mechanical investigation of such fracture systems in terrestrial Martian analog rocks, aiming to inform Mars Sample Return (MSR) drilling strategies. X-ray diffraction (XRD), scanning electron microscopy in backscattered mode (SEM-BSE), and energy-dispersive spectroscopy (EDS) reveal that gypsum is the dominant fracture-filling phase, exhibiting spatial continuity but considerable heterogeneity at vein–matrix interfaces. The host matrix consists primarily of quartz, albite, and dolomite, creating stark mineralogical contrasts that control fracture evolution and mechanical response. Nano-indentation testing was conducted across gypsum, matrix, and interfacial regions, revealing significant differences in mechanical properties. Gypsum zones show pronounced plasticity and low elastic modulus (E ≈ 10–20 GPa), while matrix minerals such as quartz exhibit higher stiffness (E > 100 GPa) and hardness. Critically, vein–matrix interfaces display intermediate properties and increased indentation depths, indicating weak interfacial bonding and stress localization. These mechanically vulnerable zones are likely to fracture or delaminate during coring operations. By integrating mineralogical heterogeneity with mechanical behavior, this study identifies key failure mechanisms in sulfate-rich terrains and formulates drilling and coring recommendations tailored to mitigate damage. The findings provide essential guidance for tool design, load control strategies, and sample targeting, ultimately improving the reliability of core recovery and scientific return in future Mars exploration missions.
{"title":"Coupled mineralogical and nano-mechanical characterization of calcium sulfate veins in Martian analog rocks: Implications for Mars sample return drilling strategies","authors":"A. Ettehadi , M. Radonjic , M. Mokhtari , R.C. Anderson","doi":"10.1016/j.pss.2025.106203","DOIUrl":"10.1016/j.pss.2025.106203","url":null,"abstract":"<div><div>Mars sample collection is often hindered by the mechanical fragility of calcium sulfate-filled fractures, which are prone to fragmentation under drilling-induced stress. This study presents a coupled mineralogical and nano-mechanical investigation of such fracture systems in terrestrial Martian analog rocks, aiming to inform Mars Sample Return (MSR) drilling strategies. X-ray diffraction (XRD), scanning electron microscopy in backscattered mode (SEM-BSE), and energy-dispersive spectroscopy (EDS) reveal that gypsum is the dominant fracture-filling phase, exhibiting spatial continuity but considerable heterogeneity at vein–matrix interfaces. The host matrix consists primarily of quartz, albite, and dolomite, creating stark mineralogical contrasts that control fracture evolution and mechanical response. Nano-indentation testing was conducted across gypsum, matrix, and interfacial regions, revealing significant differences in mechanical properties. Gypsum zones show pronounced plasticity and low elastic modulus (E ≈ 10–20 GPa), while matrix minerals such as quartz exhibit higher stiffness (E > 100 GPa) and hardness. Critically, vein–matrix interfaces display intermediate properties and increased indentation depths, indicating weak interfacial bonding and stress localization. These mechanically vulnerable zones are likely to fracture or delaminate during coring operations. By integrating mineralogical heterogeneity with mechanical behavior, this study identifies key failure mechanisms in sulfate-rich terrains and formulates drilling and coring recommendations tailored to mitigate damage. The findings provide essential guidance for tool design, load control strategies, and sample targeting, ultimately improving the reliability of core recovery and scientific return in future Mars exploration missions.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106203"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-15Epub Date: 2025-08-16DOI: 10.1016/j.pss.2025.106178
Brian P. Murphy , Cyrielle Opitom , Colin Snodgrass , Sophie E. Deam , Léa Ferellec , Matthew Knight , Vincent Okoth , Bin Yang
We present VLT/MUSE observations of comet 67P/Churyumov-Gerasimenko during its 2021 perihelion passage, from which we generated simultaneous maps of dust, [OI], C, NH, and CN comae across 12 pre- and post-perihelion epochs. These maps reveal the evolutionary and compositional trends of 67P’s coma and further enrich the context and findings of ESA’s Rosetta mission. Dust and gas species displayed distinct structures, where NH and CN signals were uniquely associated with known dust fans, raising the question of possible correlation to the dust and contributions of extended sources. Localised fitted NH scale lengths were 1.5-1.9 larger than those fitted for the rest of the coma, which is consistent with an extended source component for northern pre-perihelion emissions. In the southern hemisphere, CN was correlated with a prominent and sharp dust structure, potentially revealing an extended source origin via larger dust particles that preserve the CN parent species, as evidenced by higher spectral slopes in the region. Gas maps depicted two distinct evolutionary regimes: (1) evolving HO ([OI]1D) and C emissions driven by nucleus sublimation and subsolar insolation, and (2) stable NH and CN emissions associated with seasonal dynamics and possible distributed sources. Dust spectral slope maps revealed spectral slope trends consistent with Rosetta findings, while green/red [OI] ratios generally indicate a coma dominated by HO.
{"title":"Recent Chemo-morphological coma evolution of comet 67P/Churyumov–Gerasimenko","authors":"Brian P. Murphy , Cyrielle Opitom , Colin Snodgrass , Sophie E. Deam , Léa Ferellec , Matthew Knight , Vincent Okoth , Bin Yang","doi":"10.1016/j.pss.2025.106178","DOIUrl":"10.1016/j.pss.2025.106178","url":null,"abstract":"<div><div>We present VLT/MUSE observations of comet 67P/Churyumov-Gerasimenko during its 2021 perihelion passage, from which we generated simultaneous maps of dust, [OI], C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and CN comae across 12 pre- and post-perihelion epochs. These maps reveal the evolutionary and compositional trends of 67P’s coma and further enrich the context and findings of ESA’s Rosetta mission. Dust and gas species displayed distinct structures, where NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and CN signals were uniquely associated with known dust fans, raising the question of possible correlation to the dust and contributions of extended sources. Localised fitted NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> scale lengths were 1.5-1.9<span><math><mo>×</mo></math></span> larger than those fitted for the rest of the coma, which is consistent with an extended source component for northern pre-perihelion emissions. In the southern hemisphere, CN was correlated with a prominent and sharp dust structure, potentially revealing an extended source origin via larger dust particles that preserve the CN parent species, as evidenced by higher spectral slopes in the region. Gas maps depicted two distinct evolutionary regimes: (1) evolving H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O ([OI]<sup>1</sup>D) and C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> emissions driven by nucleus sublimation and subsolar insolation, and (2) stable NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and CN emissions associated with seasonal dynamics and possible distributed sources. Dust spectral slope maps revealed spectral slope trends consistent with Rosetta findings, while green/red [OI] ratios generally indicate a coma dominated by H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"268 ","pages":"Article 106178"},"PeriodicalIF":1.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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