Pub Date : 2026-03-01Epub Date: 2026-02-18DOI: 10.1016/j.pss.2026.106256
R. Tomka , A. Kereszturi , B. Pal
We calculated the ejecta thickness and structural rim uplift at lunar craters larger than 0.45 km at the Artemis Connecting Ridge landing site. This analysis characterises the top few metres of the regolith, a layer that could be drilled by and come into physical contact with landers and rovers. Topographic profiles extracted from fresh craters were used to derive an empirical equation that describes the topography around craters, accounting for the structural rim uplift and back-fallen ejecta. Our results show a maximum cumulative ejecta thickness of 29.9 m at the landing site. This thickness is primarily derived from two craters: most originates from the largest crater (2.78 km in diameter), and a smaller portion comes from the second largest crater (0.86 km in diameter). The ejecta from the largest crater covers 72 km2 with >1 cm thickness. Our models of stratigraphic sections reveal between 1 and 7 superposed ejecta layers across the region. The modelled regolith stratigraphy could be used to better target onsite activity and also interpret the results after measurements and sampling. Future work would incorporate ejecta from craters beyond the target area; here an example was only tested, which showed that the nearby Shackleton could provide up to 180 m thickness, but contributions from other distant craters are expected to be smaller in general.
{"title":"Ejecta thickness and layering estimation for an example Artemis landing site candidate on the Moon","authors":"R. Tomka , A. Kereszturi , B. Pal","doi":"10.1016/j.pss.2026.106256","DOIUrl":"10.1016/j.pss.2026.106256","url":null,"abstract":"<div><div>We calculated the ejecta thickness and structural rim uplift at lunar craters larger than 0.45 km at the Artemis Connecting Ridge landing site. This analysis characterises the top few metres of the regolith, a layer that could be drilled by and come into physical contact with landers and rovers. Topographic profiles extracted from fresh craters were used to derive an empirical equation that describes the topography around craters, accounting for the structural rim uplift and back-fallen ejecta. Our results show a maximum cumulative ejecta thickness of 29.9 m at the landing site. This thickness is primarily derived from two craters: most originates from the largest crater (2.78 km in diameter), and a smaller portion comes from the second largest crater (0.86 km in diameter). The ejecta from the largest crater covers 72 km<sup>2</sup> with >1 cm thickness. Our models of stratigraphic sections reveal between 1 and 7 superposed ejecta layers across the region. The modelled regolith stratigraphy could be used to better target onsite activity and also interpret the results after measurements and sampling. Future work would incorporate ejecta from craters beyond the target area; here an example was only tested, which showed that the nearby Shackleton could provide up to 180 m thickness, but contributions from other distant craters are expected to be smaller in general.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"272 ","pages":"Article 106256"},"PeriodicalIF":1.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147403841","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 : 2026-03-01Epub Date: 2026-02-10DOI: 10.1016/j.pss.2026.106246
J. De Keyser , S. Calders , H. Lamy , F. Verbelen , K. Kolenberg
Meteor count rate time series collected during showers are a prime source of data for characterizing meteor streams. Doing so requires corrections for the sporadic meteor background, for the radiant positions in the sky, and for the specific properties of the observing equipment. This paper presents a suite of methods for analyzing meteor shower count rate time series using variants of the single- and double-exponential shower activity model. The approach relies on a least-squares fitting procedure. It is demonstrated that the basic version of the problem is often ill-posed. Constraining the fitting procedure by making assumptions about the sporadic background offers a partial remedy. To allow for a more robust solution, however, a generalization is developed that includes data from multiple observers. This makes the technique especially powerful when analyzing the data from forward scatter radio meteor networks. A Monte Carlo approach allows to establish confidence intervals on the results obtained. A selection of results illustrates the capabilities and limitations of these methods.
{"title":"Deriving meteor stream properties from meteor count rate time series in a multi-observer network","authors":"J. De Keyser , S. Calders , H. Lamy , F. Verbelen , K. Kolenberg","doi":"10.1016/j.pss.2026.106246","DOIUrl":"10.1016/j.pss.2026.106246","url":null,"abstract":"<div><div>Meteor count rate time series collected during showers are a prime source of data for characterizing meteor streams. Doing so requires corrections for the sporadic meteor background, for the radiant positions in the sky, and for the specific properties of the observing equipment. This paper presents a suite of methods for analyzing meteor shower count rate time series using variants of the single- and double-exponential shower activity model. The approach relies on a least-squares fitting procedure. It is demonstrated that the basic version of the problem is often ill-posed. Constraining the fitting procedure by making assumptions about the sporadic background offers a partial remedy. To allow for a more robust solution, however, a generalization is developed that includes data from multiple observers. This makes the technique especially powerful when analyzing the data from forward scatter radio meteor networks. A Monte Carlo approach allows to establish confidence intervals on the results obtained. A selection of results illustrates the capabilities and limitations of these methods.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"272 ","pages":"Article 106246"},"PeriodicalIF":1.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147403838","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 : 2026-03-01Epub Date: 2026-02-12DOI: 10.1016/j.pss.2026.106254
Christopher P. McKay
Solid organic particles, tholin, produced in Titan's atmosphere come in contact with liquid methane and ethane through rain and in lakes on the surface. Laboratory investigation of the solubility of tholin with the surface hydrocarbons is difficult due to the low solubility in the non-polar, low-temperature liquids. Here we suggest an approach to bypass kinetic limitations by first using high-temperature non-polar hydrocarbons and then replacing the solvent with the cryogenic liquid. To test this, we have measured the solubility of Titan tholin in three solutions: A. isopentane at room temperature, B. liquid ethane at 91 K which was derived from the isopentane solution, and C. liquid ethane at 91 K. Our results suggest that there is considerable solubility of tholin in isopentane at room temperature and that a liquid ethane solution derived from that isopentane mixture retains up to 5% for specific solutes from the isopentane solution. In contrast, a solution from tholin mixed directly with liquid ethane contained much less solute. Further refined and tested, this approach could be of use for laboratory studies of tholin solubility.
{"title":"Titan tholin solubility in liquid ethane enhanced by intermediate isopentane solution","authors":"Christopher P. McKay","doi":"10.1016/j.pss.2026.106254","DOIUrl":"10.1016/j.pss.2026.106254","url":null,"abstract":"<div><div>Solid organic particles, tholin, produced in Titan's atmosphere come in contact with liquid methane and ethane through rain and in lakes on the surface. Laboratory investigation of the solubility of tholin with the surface hydrocarbons is difficult due to the low solubility in the non-polar, low-temperature liquids. Here we suggest an approach to bypass kinetic limitations by first using high-temperature non-polar hydrocarbons and then replacing the solvent with the cryogenic liquid. To test this, we have measured the solubility of Titan tholin in three solutions: A. isopentane at room temperature, B. liquid ethane at 91 K which was derived from the isopentane solution, and C. liquid ethane at 91 K. Our results suggest that there is considerable solubility of tholin in isopentane at room temperature and that a liquid ethane solution derived from that isopentane mixture retains up to 5% for specific solutes from the isopentane solution. In contrast, a solution from tholin mixed directly with liquid ethane contained much less solute. Further refined and tested, this approach could be of use for laboratory studies of tholin solubility.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"272 ","pages":"Article 106254"},"PeriodicalIF":1.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146172897","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 : 2026-03-01Epub Date: 2026-02-05DOI: 10.1016/j.pss.2026.106244
Luca Maggioni , Matteo Teodori , Gianfranco Magni , Michelangelo Formisano , Maria Cristina De Sanctis , Francesca Altieri
This study presents a novel theoretical model based on Smoothed Particle Hydrodynamics (SPH) to simulate volatile emissions triggered by drilling operations on Mars, specifically focusing on the ESA Rosalind Franklin rover’s subsurface exploration of Oxia Planum. The model captures early time interactions between vapor, water ice, dust, and atmospheric carbon dioxide, accounting for thermal and dynamical interactions, and phase transitions dynamics during drilling. The three dimensional borehole and drill geometry are explicitly modeled, along with realistic temperature profiles derived from Martian surface and subsurface conditions. Vapor is assumed to originate from sublimation of water ice due to drill-induced heating. The simulations investigate how different initial volatile compositions, icy grain sizes, and borehole depths influence material redistribution. Results show that the distribution of ice is mainly governed by sublimation and recondensation cycles. When smaller icy grains are considered, water vapor tends to condense efficiently on colder surfaces, forming thin ice layers on the drill rod. Larger icy grains, instead, form more slowly and experience weaker atmospheric drag, occasionally enabling a small fraction to escape the borehole. Moreover, the presence of carbon dioxide alters the vertical motion of dust, constraining it to remain stuck at the bottom of the borehole. The presented model provides a tool to constrain the early-time dynamics of drilling-induced volatile release on Mars and offers a modular framework adaptable to other planetary environments, like the Moon.
{"title":"Smoothed particle hydrodynamics modeling of volatile emissions: Drill-induced releases in the Martian subsurface","authors":"Luca Maggioni , Matteo Teodori , Gianfranco Magni , Michelangelo Formisano , Maria Cristina De Sanctis , Francesca Altieri","doi":"10.1016/j.pss.2026.106244","DOIUrl":"10.1016/j.pss.2026.106244","url":null,"abstract":"<div><div>This study presents a novel theoretical model based on Smoothed Particle Hydrodynamics (SPH) to simulate volatile emissions triggered by drilling operations on Mars, specifically focusing on the ESA Rosalind Franklin rover’s subsurface exploration of Oxia Planum. The model captures early time interactions between vapor, water ice, dust, and atmospheric carbon dioxide, accounting for thermal and dynamical interactions, and phase transitions dynamics during drilling. The three dimensional borehole and drill geometry are explicitly modeled, along with realistic temperature profiles derived from Martian surface and subsurface conditions. Vapor is assumed to originate from sublimation of water ice due to drill-induced heating. The simulations investigate how different initial volatile compositions, icy grain sizes, and borehole depths influence material redistribution. Results show that the distribution of ice is mainly governed by sublimation and recondensation cycles. When smaller icy grains are considered, water vapor tends to condense efficiently on colder surfaces, forming thin ice layers on the drill rod. Larger icy grains, instead, form more slowly and experience weaker atmospheric drag, occasionally enabling a small fraction to escape the borehole. Moreover, the presence of carbon dioxide alters the vertical motion of dust, constraining it to remain stuck at the bottom of the borehole. The presented model provides a tool to constrain the early-time dynamics of drilling-induced volatile release on Mars and offers a modular framework adaptable to other planetary environments, like the Moon.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"272 ","pages":"Article 106244"},"PeriodicalIF":1.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146147483","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 : 2026-03-01Epub Date: 2026-02-20DOI: 10.1016/j.pss.2026.106257
E. Ayari , M. Horányi , N.J. Turner , T. Corbett , J. Fontanese , J. Hillier , S. Kempf , R. Mikula , T. Munsat , J. Schmitt , Z. Sternovsky , J.R. Szalay , M. Trieloff , Z. Ulibarri , A. Westphal
In-situ impact ionization mass spectrometers can reveal the elemental and isotopic compositions of interplanetary and interstellar dust particles throughout the Solar System, thereby enhancing our understanding of their origins and evolution without the associated costs and risks of sample return. We describe laboratory measurements of olivine particles accelerated electrostatically into a prototype impact ionization dust analyzer. Olivine is chosen because it is common in both interplanetary and interstellar dust. The particles were ground from a single olivine crystal chosen to minimize grain-to-grain composition variations, ensuring that the measured spread was the result of the instrument precision. The particles were coated with platinum to allow charging and acceleration. The instrument returns impact-ionization mass spectra whose Fe/Si and Mg/Si ratios agree within the uncertainties with reference measurements of the same sample by energy-dispersive X-ray spectroscopy (EDX). From impacts at 19–25 km s−1, we derive the relative sensitivity factors (RSFs) consistent with previous impact ionization and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) calibrations. The application of these RSFs brings the Mg/Si and Fe/Si ratios into 1 agreement with the independent EDX analysis, allowing for robust identification and discrimination of olivine and pyroxene. The spread of the impact ionization measurements is small enough to distinguish Mg-rich olivine from glassy particles with embedded metals and sulfides (GEMS) at the impact speeds of 19–25 km s−1. The average Mg/Fe and Si/Fe ratios are consistent with those of EDX results over wider velocity ranges of 9–25 and km s−1, respectively. These results demonstrate the power of impact-ionization mass spectrometry in distinguishing common interplanetary materials in dust grains encountered at typical orbital speeds.
原位撞击电离质谱仪可以揭示整个太阳系的行星际和星际尘埃粒子的元素和同位素组成，从而增强我们对它们的起源和演化的理解，而不需要相关的成本和样品返回的风险。我们描述了实验室测量的橄榄石粒子加速到一个原型冲击电离粉尘分析仪静电。之所以选择橄榄石，是因为它在星际和星际尘埃中都很常见。这些颗粒是由单一的橄榄石晶体研磨而成，以尽量减少颗粒之间的成分变化，确保测量的扩散是仪器精度的结果。这些颗粒被镀上了铂，以便充电和加速。该仪器返回的冲击电离质谱，其Fe/Si和Mg/Si比值在不确定度范围内与能量色散x射线光谱（EDX）对同一样品的参考测量值一致。从19-25 km s−1的撞击中，我们得出了与先前撞击电离和飞行时间二次离子质谱（TOF-SIMS）校准一致的相对灵敏度因子（RSFs）。这些RSFs的应用使Mg/Si和Fe/Si比值达到1 σ，与独立的EDX分析一致，允许对橄榄石和辉石进行稳健的识别和区分。撞击电离测量的范围很小，足以在19-25 km s−1的撞击速度下将富镁橄榄石与嵌入金属和硫化物（GEMS）的玻璃状颗粒区分开来。平均Mg/Fe和Si/Fe比值在9 ~ 25 km和≥16 km s−1的较宽速度范围内与EDX结果一致。这些结果证明了碰撞电离质谱法在区分以典型轨道速度遇到的尘埃颗粒中的常见行星际物质方面的能力。
{"title":"Elemental and isotopic analysis of olivine with impact ionization dust instruments","authors":"E. Ayari , M. Horányi , N.J. Turner , T. Corbett , J. Fontanese , J. Hillier , S. Kempf , R. Mikula , T. Munsat , J. Schmitt , Z. Sternovsky , J.R. Szalay , M. Trieloff , Z. Ulibarri , A. Westphal","doi":"10.1016/j.pss.2026.106257","DOIUrl":"10.1016/j.pss.2026.106257","url":null,"abstract":"<div><div>In-situ impact ionization mass spectrometers can reveal the elemental and isotopic compositions of interplanetary and interstellar dust particles throughout the Solar System, thereby enhancing our understanding of their origins and evolution without the associated costs and risks of sample return. We describe laboratory measurements of olivine particles accelerated electrostatically into a prototype impact ionization dust analyzer. Olivine is chosen because it is common in both interplanetary and interstellar dust. The particles were ground from a single olivine crystal chosen to minimize grain-to-grain composition variations, ensuring that the measured spread was the result of the instrument precision. The particles were coated with platinum to allow charging and acceleration. The instrument returns impact-ionization mass spectra whose Fe/Si and Mg/Si ratios agree within the uncertainties with reference measurements of the same sample by energy-dispersive X-ray spectroscopy (EDX). From impacts at 19–25 km s<sup>−1</sup>, we derive the relative sensitivity factors (RSFs) consistent with previous impact ionization and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) calibrations. The application of these RSFs brings the Mg/Si and Fe/Si ratios into 1 <span><math><mi>σ</mi></math></span> agreement with the independent EDX analysis, allowing for robust identification and discrimination of olivine and pyroxene. The spread of the impact ionization measurements is small enough to distinguish Mg-rich olivine from glassy particles with embedded metals and sulfides (GEMS) at the impact speeds of 19–25 km s<sup>−1</sup>. The average Mg/Fe and Si/Fe ratios are consistent with those of EDX results over wider velocity ranges of 9–25 and <span><math><mrow><mo>≥</mo><mn>16</mn></mrow></math></span> km s<sup>−1</sup>, respectively. These results demonstrate the power of impact-ionization mass spectrometry in distinguishing common interplanetary materials in dust grains encountered at typical orbital speeds.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"272 ","pages":"Article 106257"},"PeriodicalIF":1.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147403840","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 : 2026-02-01Epub Date: 2026-02-09DOI: 10.1016/j.pss.2026.106245
G.A. Caritá , M.H.M. Morais , A.F.B.A. Prado , S. Aljbaae
Optimization is a crucial process in astrodynamics, focused on finding the most efficient trajectories with minimum cost, especially in terms of total velocity change (). The inherent complexity of orbital mechanics, particularly in multi-body systems and for long-duration transfers, often limits the effectiveness of traditional gradient-based methods, such as Non-Linear Programming (NLP), which are highly dependent on a high-quality initial guess. To overcome this limitation, meta-heuristic methods, which are robust and gradient-independent, are presented as a viable alternative. The present work evaluates the performance and efficiency of several single-objective meta-heuristic algorithms in the optimization of bi-impulsive transfer trajectories, starting from a Low Earth Orbit (LEO) at 200 km altitude toward retrograde co-orbital resonance using the Planar Restricted Bi-Circular Four-Body Problem (PBCR4BP). A comprehensive comparison was conducted using methods such as variants of Differential Evolution (DE), the Evolutionary Centers Algorithm (ECA), Particle Swarm Optimization (PSO), Simulated Annealing (SA), and Re-sampled Inheritance Search (RIS) and others, comparing them against a Random Search (RAS) baseline. The results demonstrated that Differential Evolution (DE) based methods, notably the DE/rand/1/bin RL and AD-DE/rand/1/bin RL variants, achieved the best overall performance, effectively minimizing both the required and the computational time. Furthermore, the robust optimization strategy successfully identified more efficient solutions than previously reported in the literature, achieving a minimum of 0.1478 km/s. We conclude that meta-heuristic methods, particularly the advanced variants of Differential Evolution, are powerful, reliable, and efficient tools for optimizing transfer trajectories in the complex dynamic environment of the PBCR4BP. However, the sensitivity analysis indicated that long-duration transfers can be highly sensitive to small perturbations, especially for eccentric target orbits near Earth.
{"title":"Comparison of optimization methods for computing bi-impulsive transfer trajectories in the bi-circular restricted four-body problem","authors":"G.A. Caritá , M.H.M. Morais , A.F.B.A. Prado , S. Aljbaae","doi":"10.1016/j.pss.2026.106245","DOIUrl":"10.1016/j.pss.2026.106245","url":null,"abstract":"<div><div>Optimization is a crucial process in astrodynamics, focused on finding the most efficient trajectories with minimum cost, especially in terms of total velocity change (<span><math><mrow><mi>Δ</mi><mi>V</mi></mrow></math></span>). The inherent complexity of orbital mechanics, particularly in multi-body systems and for long-duration transfers, often limits the effectiveness of traditional gradient-based methods, such as Non-Linear Programming (NLP), which are highly dependent on a high-quality initial guess. To overcome this limitation, meta-heuristic methods, which are robust and gradient-independent, are presented as a viable alternative. The present work evaluates the performance and efficiency of several single-objective meta-heuristic algorithms in the optimization of bi-impulsive transfer trajectories, starting from a Low Earth Orbit (LEO) at 200 km altitude toward retrograde co-orbital resonance using the Planar Restricted Bi-Circular Four-Body Problem (PBCR4BP). A comprehensive comparison was conducted using methods such as variants of Differential Evolution (DE), the Evolutionary Centers Algorithm (ECA), Particle Swarm Optimization (PSO), Simulated Annealing (SA), and Re-sampled Inheritance Search (RIS) and others, comparing them against a Random Search (RAS) baseline. The results demonstrated that Differential Evolution (DE) based methods, notably the DE/rand/1/bin RL and AD-DE/rand/1/bin RL variants, achieved the best overall performance, effectively minimizing both the required <span><math><mrow><mi>Δ</mi><mi>V</mi></mrow></math></span> and the computational time. Furthermore, the robust optimization strategy successfully identified more efficient solutions than previously reported in the literature, achieving a minimum <span><math><mrow><mi>Δ</mi><mi>V</mi></mrow></math></span> of 0.1478 km/s. We conclude that meta-heuristic methods, particularly the advanced variants of Differential Evolution, are powerful, reliable, and efficient tools for optimizing transfer trajectories in the complex dynamic environment of the PBCR4BP. However, the sensitivity analysis indicated that long-duration transfers can be highly sensitive to small perturbations, especially for eccentric target orbits near Earth.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"271 ","pages":"Article 106245"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191621","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 : 2026-02-01Epub Date: 2026-01-28DOI: 10.1016/j.pss.2026.106241
Laura Noel García , Juan Agustin Macchi , Pouyan Shen , Ludovic Ferrière , Maria Eugenia Varela
Classical studies have noted the striking interfaces between olivine grains and metal in the Tucson meteorite, often exhibiting well-defined crystal facets. This feature is rare in iron meteorites, particularly for grains smaller than ∼100 μm. Traditionally, these interfaces have been interpreted as a result of recrystallization in the taenite (fcc) stability field, with olivine surfaces reflecting the cubic symmetry of taenite. However, our results suggest that these interfaces are better explained by the idiomorphic growth of olivine, presumably co-crystallizing with metal in a non-epitaxial manner. High-resolution TKD and TEM analyses reveal clean, non-epitaxial olivine/fcc metal interfaces, kamacite (bcc) subgrains, and solute-partitioned epitaxial fcc/bcc interfaces, indicative of solid-state diffusional processes for phase transformation and polygonization following annealing. These findings provide strong evidence that the Tucson meteorite may share a genetic relationship with chondrites, supporting a high-temperature formation scenario where olivine and metal co-condensed from a nebular environment.
{"title":"Evidence of co-temporality between olivine and metal in Tucson","authors":"Laura Noel García , Juan Agustin Macchi , Pouyan Shen , Ludovic Ferrière , Maria Eugenia Varela","doi":"10.1016/j.pss.2026.106241","DOIUrl":"10.1016/j.pss.2026.106241","url":null,"abstract":"<div><div>Classical studies have noted the striking interfaces between olivine grains and metal in the Tucson meteorite, often exhibiting well-defined crystal facets. This feature is rare in iron meteorites, particularly for grains smaller than ∼100 μm. Traditionally, these interfaces have been interpreted as a result of recrystallization in the taenite (fcc) stability field, with olivine surfaces reflecting the cubic symmetry of taenite. However, our results suggest that these interfaces are better explained by the idiomorphic growth of olivine, presumably co-crystallizing with metal in a non-epitaxial manner. High-resolution TKD and TEM analyses reveal clean, non-epitaxial olivine/fcc metal interfaces, kamacite (bcc) subgrains, and solute-partitioned epitaxial fcc/bcc interfaces, indicative of solid-state diffusional processes for phase transformation and polygonization following annealing. These findings provide strong evidence that the Tucson meteorite may share a genetic relationship with chondrites, supporting a high-temperature formation scenario where olivine and metal co-condensed from a nebular environment.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"271 ","pages":"Article 106241"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191622","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 : 2026-02-01Epub Date: 2026-01-29DOI: 10.1016/j.pss.2026.106242
Chinmayee Chaini, Vijay Kumar Jha, Kumar Rajnish
To comprehend the planetary body's evolution, efficient recognition of craters plays a vital role. Initially, crater detection relied on manual observation, which is prone to 40 % disagreement, varying from one researcher to another. Then, various researchers developed techniques for all object detectors based on deep learning (DL) that efficiently detected multi-scale craters. However, researchers have employed hybrid object detectors to perform multi-scale crater identification on the planetary surface by combining the strengths of multiple frameworks, such as a detection head and a feature extractor. As a result, these models suffered from suboptimal hyperparameter settings without optimisation, leading to overfitting, longer training times or reduced detection accuracy. To further refine the hybrid detector's performance, this study applies the Tree-Structured Parzen Estimator (TPE) optimisation technique to automatically tune the critical hyperparameters by identifying the best combinations of learning rate, anchor ratios, batch size, dropout, and other key parameters. On the crater dataset, the suggested model achieves a [email protected] of nearly 92.0 %, a recall of 90.2 %, and a precision of 94.8 %. These findings indicate the effectiveness of the optimisation strategy in accurately detecting craters under diverse terrain conditions, such as occluded, noisy regions with small-scale detections ∼< 0.1 km. The proposed framework of this study demonstrates strong potential for future integration into planetary mapping missions and real-time lunar exploration systems, where both accuracy and computational efficiency are critical.
{"title":"Fully automated crater detection based on the tree-structured parzen estimator sampler technique","authors":"Chinmayee Chaini, Vijay Kumar Jha, Kumar Rajnish","doi":"10.1016/j.pss.2026.106242","DOIUrl":"10.1016/j.pss.2026.106242","url":null,"abstract":"<div><div>To comprehend the planetary body's evolution, efficient recognition of craters plays a vital role. Initially, crater detection relied on manual observation, which is prone to 40 % disagreement, varying from one researcher to another. Then, various researchers developed techniques for all object detectors based on deep learning (DL) that efficiently detected multi-scale craters. However, researchers have employed hybrid object detectors to perform multi-scale crater identification on the planetary surface by combining the strengths of multiple frameworks, such as a detection head and a feature extractor. As a result, these models suffered from suboptimal hyperparameter settings without optimisation, leading to overfitting, longer training times or reduced detection accuracy. To further refine the hybrid detector's performance, this study applies the Tree-Structured Parzen Estimator (TPE) optimisation technique to automatically tune the critical hyperparameters by identifying the best combinations of learning rate, anchor ratios, batch size, dropout, and other key parameters. On the crater dataset, the suggested model achieves a [email protected] of nearly 92.0 %, a recall of 90.2 %, and a precision of 94.8 %. These findings indicate the effectiveness of the optimisation strategy in accurately detecting craters under diverse terrain conditions, such as occluded, noisy regions with small-scale detections ∼< 0.1 km. The proposed framework of this study demonstrates strong potential for future integration into planetary mapping missions and real-time lunar exploration systems, where both accuracy and computational efficiency are critical.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"271 ","pages":"Article 106242"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081419","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 : 2026-02-01Epub Date: 2026-02-03DOI: 10.1016/j.pss.2026.106243
Pryscilla Pires
Earth co-orbitals include quasi-satellites (QS), small bodies in the 1:1 mean-motion resonance that remain gravitationally unbound while tracing long-term loops in a geocentric frame. Their orbital dynamics are well studied, whereas their rotational states remain less explored. In particular, the possibility of synchronous spin–orbit locking (1:1) under solar torque has not yet been tested for real Earth co-orbital objects. Here we investigate the 1:1 resonance for triaxial bodies under realistic orbital constraints. We apply our method to JPL Horizons ephemerides of four near-Earth co-orbitals: 2002 AA, (164207) Cardea (2004 GU), (469219) Kamo‘oalewa (2016 HO), and (706765) (2010 TK) over a 30-year window. Our results show that (the triaxiality parameter in the solar-torque spin model) controls the strength of the spin–orbit coupling, whereas increasing promotes diffusion. Only 2002 AA () retains a compact synchronous island and non-zero capture fractions. For 2004 GU, 2016 HO, and 2010 TK (), coherence is lost and capture becomes indistinguishable from zero. We also perform robustness tests with ephemeris cadence, stroboscopic sampling, and damping, confirming the physical nature of these results. Overall, we show that synchronous locking is detectable only at very low eccentricity and becomes unlikely for , with potential implications for mission targets such as Kamo‘oalewa.
{"title":"Synchronous spin–orbit resonances in earth co-orbital asteroids: A study using parametric and real-ephemeris models","authors":"Pryscilla Pires","doi":"10.1016/j.pss.2026.106243","DOIUrl":"10.1016/j.pss.2026.106243","url":null,"abstract":"<div><div>Earth co-orbitals include quasi-satellites (QS), small bodies in the 1:1 mean-motion resonance that remain gravitationally unbound while tracing long-term loops in a geocentric frame. Their orbital dynamics are well studied, whereas their rotational states remain less explored. In particular, the possibility of synchronous spin–orbit locking (1:1) under solar torque has not yet been tested for real Earth co-orbital objects. Here we investigate the 1:1 resonance for triaxial bodies under realistic orbital constraints. We apply our method to JPL Horizons ephemerides of four near-Earth co-orbitals: 2002 AA<span><math><msub><mrow></mrow><mrow><mn>29</mn></mrow></msub></math></span>, (164207) Cardea (2004 GU<span><math><msub><mrow></mrow><mrow><mn>9</mn></mrow></msub></math></span>), (469219) Kamo‘oalewa (2016 HO<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>), and (706765) (2010 TK<span><math><msub><mrow></mrow><mrow><mn>7</mn></mrow></msub></math></span>) over a 30-year window. Our results show that <span><math><mi>Δ</mi></math></span> (the triaxiality parameter in the solar-torque spin model) controls the strength of the spin–orbit coupling, whereas increasing <span><math><mi>e</mi></math></span> promotes diffusion. Only 2002 AA<span><math><msub><mrow></mrow><mrow><mn>29</mn></mrow></msub></math></span> (<span><math><mrow><mi>e</mi><mo>≈</mo><mn>0</mn><mo>.</mo><mn>013</mn></mrow></math></span>) retains a compact synchronous island and non-zero capture fractions. For 2004 GU<span><math><msub><mrow></mrow><mrow><mn>9</mn></mrow></msub></math></span>, 2016 HO<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and 2010 TK<span><math><msub><mrow></mrow><mrow><mn>7</mn></mrow></msub></math></span> (<span><math><mrow><mi>e</mi><mo>≳</mo><mn>0</mn><mo>.</mo><mn>10</mn></mrow></math></span>), coherence is lost and capture becomes indistinguishable from zero. We also perform robustness tests with ephemeris cadence, stroboscopic sampling, and damping, confirming the physical nature of these results. Overall, we show that synchronous locking is detectable only at very low eccentricity and becomes unlikely for <span><math><mrow><mi>e</mi><mo>≳</mo><mn>0</mn><mo>.</mo><mn>10</mn></mrow></math></span>, with potential implications for mission targets such as Kamo‘oalewa.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"271 ","pages":"Article 106243"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191620","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 : 2026-02-01Epub Date: 2026-01-31DOI: 10.1016/j.pss.2026.106240
N. Wang , Z.Y. Xue , B.B. Zhang , Q.Y. Peng , X.M. Cheng , Y.M. Ye
Phoebe was observed in 2023 and 2024 by Yunnan Observatory 1.0 m telescope. These observations, along with those obtained from 2011–2014 by Yunnan Observatory 2.4 m telescope, were processed using the Gaia DR3 star catalogue. To improve positional measurements, the two-dimensional Gauss fit or the effective point spread function was applied. During the reduction, the geometric distortion of the calibration field was solved, the precision premium was reduced, and the differential colour refraction was accounted for. A total of 368 CCD observations were obtained. The theoretical position of Phoebe was derived from IMCCE ephemeris ph12 and Saturn’s position from JPL ephemeris DE441. The results show that the mean (O-C) is −0.002 and 0.016 arcsec in right ascension and in declination, respectively. The dispersion of our observations is 0.028 and 0.028 arcsec in right ascension and in declination, respectively.
{"title":"The precise CCD positions of Phoebe using Gaia DR3 catalogue","authors":"N. Wang , Z.Y. Xue , B.B. Zhang , Q.Y. Peng , X.M. Cheng , Y.M. Ye","doi":"10.1016/j.pss.2026.106240","DOIUrl":"10.1016/j.pss.2026.106240","url":null,"abstract":"<div><div>Phoebe was observed in 2023 and 2024 by Yunnan Observatory 1.0 m telescope. These observations, along with those obtained from 2011–2014 by Yunnan Observatory 2.4 m telescope, were processed using the Gaia DR3 star catalogue. To improve positional measurements, the two-dimensional Gauss fit or the effective point spread function was applied. During the reduction, the geometric distortion of the calibration field was solved, the precision premium was reduced, and the differential colour refraction was accounted for. A total of 368 CCD observations were obtained. The theoretical position of Phoebe was derived from IMCCE ephemeris ph12 and Saturn’s position from JPL ephemeris DE441. The results show that the mean (O-C) is −0.002 and 0.016 arcsec in right ascension and in declination, respectively. The dispersion of our observations is 0.028 and 0.028 arcsec in right ascension and in declination, respectively.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"271 ","pages":"Article 106240"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191623","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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