Upcoming missions to the Moon represent new science opportunities and challenges. The electrostatic nature of the regolith combined with the solar wind makes it loft and adhere to almost any surface, which represents a threat for future manned and robotic missions. Understanding the charge state of the lunar soil under a representative environment is a key step towards ensuring safe lunar missions. While the global first order effect of exposure to the Sun's UV is to charge the soil positively, past experiments suggested that the transported dusts could be charged negatively. This counter-intuitive behavior was then supported by modeling, which explained the existence of negative charges but also predicted that of positively charged ones. To investigate the charging behavior of dust under a representative environment, we developed an experimental protocol based on a polarized sensitive sensor dedicated to the charge measurement of single dust grains with an accuracy of about 1 fC. The first set of measurements obtained with JSC-1A lunar dust simulants in high vacuum reveals the bipolar nature of lunar dust net charge in the regolith when exposed to UVs. Indeed, both positive and negative dusts were detected, supporting the complexity of the regolith charging processes suggested by the models.
{"title":"Measurement of bipolar charge distribution of lunar dust simulant under VUV irradiation","authors":"Rémi Pacaud , Jean-Charles Matéo-Vélez , Sébastien Hess , Sylvain Ranvier","doi":"10.1016/j.pss.2025.106120","DOIUrl":"10.1016/j.pss.2025.106120","url":null,"abstract":"<div><div>Upcoming missions to the Moon represent new science opportunities and challenges. The electrostatic nature of the regolith combined with the solar wind makes it loft and adhere to almost any surface, which represents a threat for future manned and robotic missions. Understanding the charge state of the lunar soil under a representative environment is a key step towards ensuring safe lunar missions. While the global first order effect of exposure to the Sun's UV is to charge the soil positively, past experiments suggested that the transported dusts could be charged negatively. This counter-intuitive behavior was then supported by modeling, which explained the existence of negative charges but also predicted that of positively charged ones. To investigate the charging behavior of dust under a representative environment, we developed an experimental protocol based on a polarized sensitive sensor dedicated to the charge measurement of single dust grains with an accuracy of about 1 fC. The first set of measurements obtained with JSC-1A lunar dust simulants in high vacuum reveals the bipolar nature of lunar dust net charge in the regolith when exposed to UVs. Indeed, both positive and negative dusts were detected, supporting the complexity of the regolith charging processes suggested by the models.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"263 ","pages":"Article 106120"},"PeriodicalIF":1.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943182","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 : 2025-05-02DOI: 10.1016/j.pss.2025.106119
C.L. Campbell , J.E. Moores
Since landing in 2012, the Mars Science Laboratory (MSL, Curiosity) has been investigating local aerosols through atmospheric imagery taken by its onboard Navigation Cameras (NCAMs). In particular, a Zenith Movie (ZM), is a vertically pointed 8-frame movie that is used to classify meteorological wind direction based on aerosol movement within the frames. Several Mars Year (MY) worth of data have been analysed and found repeatable wind directions year-to-year. Water-ice clouds in the Aphelion season had strong Easterly winds, which agrees with modelling that shows a strong cross-equatorial Hadley cell in this season. The Perihelion season did not show any strong directions, which was attributed to the chaotic motion seen in dust clouds expected during this season. When compared to the Rover Environmental Monitoring Station (REMS) onboard MSL, wind directions from the ZMs did not agree with REMS results. This mismatch between REMS and ZM wind results indicates that aerosols observed in imagery are most likely well above the crater rather than at the surface where REMS is located.
自2012年登陆火星以来，火星科学实验室（MSL，好奇号）一直在通过其机载导航相机（NCAMs）拍摄的大气图像调查当地的气溶胶。特别是，Zenith Movie （ZM）是一个垂直指向的8帧Movie，用于根据帧内的气溶胶运动来分类气象风向。对几个火星年（MY）的数据进行了分析，发现每年都有可重复的风向。远日点季节的水冰云有很强的东风，这与模型显示的这个季节有很强的横跨赤道的哈德利环流相一致。近日点季节没有显示出任何强烈的方向，这归因于在这个季节预计会出现的尘埃云的混乱运动。当与MSL上的漫游者环境监测站（REMS）进行比较时，来自ZMs的风向与REMS的结果不一致。REMS和ZM风结果之间的不匹配表明，在图像中观察到的气溶胶很可能在陨石坑上方，而不是在REMS所在的表面。
{"title":"Using imagery from the Mars Science Laboratory mission to understand wind properties of aerosols aloft","authors":"C.L. Campbell , J.E. Moores","doi":"10.1016/j.pss.2025.106119","DOIUrl":"10.1016/j.pss.2025.106119","url":null,"abstract":"<div><div>Since landing in 2012, the Mars Science Laboratory (MSL, Curiosity) has been investigating local aerosols through atmospheric imagery taken by its onboard Navigation Cameras (NCAMs). In particular, a Zenith Movie (ZM), is a vertically pointed 8-frame movie that is used to classify meteorological wind direction based on aerosol movement within the frames. Several Mars Year (MY) worth of data have been analysed and found repeatable wind directions year-to-year. Water-ice clouds in the Aphelion season had strong Easterly winds, which agrees with modelling that shows a strong cross-equatorial Hadley cell in this season. The Perihelion season did not show any strong directions, which was attributed to the chaotic motion seen in dust clouds expected during this season. When compared to the Rover Environmental Monitoring Station (REMS) onboard MSL, wind directions from the ZMs did not agree with REMS results. This mismatch between REMS and ZM wind results indicates that aerosols observed in imagery are most likely well above the crater rather than at the surface where REMS is located.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"263 ","pages":"Article 106119"},"PeriodicalIF":1.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947816","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 : 2025-04-25DOI: 10.1016/j.pss.2025.106128
A. Szilágyi-Sándor, B. Székely
One of the unique valleys in the southern hemisphere of Mars is the 700 km long Nirgal Vallis. The catchment area of the river-like valley, presumably formed in the Hesperian period (3000–3700 Ma ago), has been shaped over time by many influences. The goal of this study is to explore and separate these potential influences including changes in the water level of the Uzboi Vallis, its erosion base. The other aim is to detect and describe the effects of tectonic processes for we have found potential evidence. Our working hypothesis is that Nirgal Vallis was once a river valley: our study analyses this possibility. The climate of Mars has undergone drastic changes in the past, and liquid water is currently not stable on the surface. The formation of former river valleys after the active wet period continued, including Nirgal Vallis. Morphometric techniques were applied based on MOLA, THEMIS, and HiRISE data. The topography of the Nirgal Vallis have been analyzed by swath analysis, calculation of various geomorphometric parameters, and runoff model. HiRISE digital terrain models having decimeter-scale resolution derived from the HiRISE stereopairs have been used for the detailed analysis.
A subdivision of the Nirgal Vallis according to its tectonic geomorphological structures was established. The swath analysis and the runoff model calculation show that, although the valley does not have a strict thalweg today, i.e., water currently cannot flow down it, the valley does have a trend of slope along the whole length and even intermittent slope changes can be observed along the whole valley. Several small-scale morphological features were also identified using MOLA data.
We conclude that the tectonic processes have transformed the morphology of the riverbed: it is divided into small sections (closed basins) so that currently water would not be able to flow down in it. Extraterrestrial (i.e. effects from outside Mars) causes on Mars also influence this, i.e. the formation of larger and smaller craters has also left its mark on the topography. We interpret the subperpendicular elongated morphological features on the plateau surrounding Nirgal Vallis as wrinkle ridges: their size, shape and spacing is similar to those identified by previous authors elsewhere. We also found evidence that the valley bottom has also been modified by the processes that formed the wrinkle ridges. Our observations imply younger tectonic influence of the area, presumably, postdating the fluvial erosional regime.
The Luki Crater, located near the confluence of Nirgal Vallis and Uzboi Vallis, has also been analyzed, and evidence has been found to be tectonically modified. This modification is in congruence with the results of other analyses indicating tectonic influence of Nirgal Vallis. Our results may also have implications for formation of the Uzboi Vallis, though this will require further studies.
{"title":"The evolution of Nirgal Vallis (Mars) based on morphometric results: does tectonics play a role?","authors":"A. Szilágyi-Sándor, B. Székely","doi":"10.1016/j.pss.2025.106128","DOIUrl":"10.1016/j.pss.2025.106128","url":null,"abstract":"<div><div>One of the unique valleys in the southern hemisphere of Mars is the 700 km long Nirgal Vallis. The catchment area of the river-like valley, presumably formed in the Hesperian period (3000–3700 Ma ago), has been shaped over time by many influences. The goal of this study is to explore and separate these potential influences including changes in the water level of the Uzboi Vallis, its erosion base. The other aim is to detect and describe the effects of tectonic processes for we have found potential evidence. Our working hypothesis is that Nirgal Vallis was once a river valley: our study analyses this possibility. The climate of Mars has undergone drastic changes in the past, and liquid water is currently not stable on the surface. The formation of former river valleys after the active wet period continued, including Nirgal Vallis. Morphometric techniques were applied based on MOLA, THEMIS, and HiRISE data. The topography of the Nirgal Vallis have been analyzed by swath analysis, calculation of various geomorphometric parameters, and runoff model. HiRISE digital terrain models having decimeter-scale resolution derived from the HiRISE stereopairs have been used for the detailed analysis.</div><div>A subdivision of the Nirgal Vallis according to its tectonic geomorphological structures was established. The swath analysis and the runoff model calculation show that, although the valley does not have a strict thalweg today, i.e., water currently cannot flow down it, the valley does have a trend of slope along the whole length and even intermittent slope changes can be observed along the whole valley. Several small-scale morphological features were also identified using MOLA data.</div><div>We conclude that the tectonic processes have transformed the morphology of the riverbed: it is divided into small sections (closed basins) so that currently water would not be able to flow down in it. Extraterrestrial (i.e. effects from outside Mars) causes on Mars also influence this, i.e. the formation of larger and smaller craters has also left its mark on the topography. We interpret the subperpendicular elongated morphological features on the plateau surrounding Nirgal Vallis as wrinkle ridges: their size, shape and spacing is similar to those identified by previous authors elsewhere. We also found evidence that the valley bottom has also been modified by the processes that formed the wrinkle ridges. Our observations imply younger tectonic influence of the area, presumably, postdating the fluvial erosional regime.</div><div>The Luki Crater, located near the confluence of Nirgal Vallis and Uzboi Vallis, has also been analyzed, and evidence has been found to be tectonically modified. This modification is in congruence with the results of other analyses indicating tectonic influence of Nirgal Vallis. Our results may also have implications for formation of the Uzboi Vallis, though this will require further studies.</div><div>These results suggest that the a","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"262 ","pages":"Article 106128"},"PeriodicalIF":1.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878449","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 : 2025-04-17DOI: 10.1016/j.pss.2025.106118
Vasilij G. Chiorny , Yurij N. Krugly , Vasilij G. Shevchenko , Ivan G. Slyusarev , Olga I. Mikhalchenko
Here we present the physical characteristics of 24 discovered and 2 probable small binary asteroids at the inner main belt based on photometric lightcurves of the primary components of these systems obtained in the standard VR spectral bands, as well as the determination of the V–R color indices and the absolute magnitudes HV of the studied objects. We also make estimates of the effective diameters of six asteroids which radiometric data are not available.
Analysis of the V–R color indices, revised albedo, color indices obtained from the SDSS and Sky-Mapper surveys, as well as recently published spectral characteristics in the visible and infrared wavelength ranges, allows us to effectively make a taxonomy of the observed asteroids. We have determined that the most of these primary components of the main-belt small binary asteroids belong to the moderate-albedo S-type with the mean albedo 0.24 ± 0.08. Also, there are moderate-albedo asteroids of the A, M, Q, and V-types as well as high-albedo E-type in our sample. It should be noted that asteroids with low albedo are absent in our set of binary asteroids.
{"title":"Absolute photometry of small main-belt binary asteroids. Physical properties","authors":"Vasilij G. Chiorny , Yurij N. Krugly , Vasilij G. Shevchenko , Ivan G. Slyusarev , Olga I. Mikhalchenko","doi":"10.1016/j.pss.2025.106118","DOIUrl":"10.1016/j.pss.2025.106118","url":null,"abstract":"<div><div>Here we present the physical characteristics of 24 discovered and 2 probable small binary asteroids at the inner main belt based on photometric lightcurves of the primary components of these systems obtained in the standard <em>VR</em> spectral bands, as well as the determination of the <em>V–R</em> color indices and the absolute magnitudes <em>H</em><sub>V</sub> of the studied objects. We also make estimates of the effective diameters of six asteroids which radiometric data are not available.</div><div>Analysis of the <em>V–R</em> color indices, revised albedo, color indices obtained from the SDSS and Sky-Mapper surveys, as well as recently published spectral characteristics in the visible and infrared wavelength ranges, allows us to effectively make a taxonomy of the observed asteroids. We have determined that the most of these primary components of the main-belt small binary asteroids belong to the moderate-albedo S-type with the mean albedo 0.24 ± 0.08. Also, there are moderate-albedo asteroids of the A, M, Q, and V-types as well as high-albedo E-type in our sample. It should be noted that asteroids with low albedo are absent in our set of binary asteroids.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"262 ","pages":"Article 106118"},"PeriodicalIF":1.8,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143903466","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 : 2025-04-09DOI: 10.1016/j.pss.2025.106117
B. Dotson, A. St John, R. Hall, D. Sapkota, D. Britt, P. Metzger
With humans returning to the Moon under the Artemis program, understanding and mitigating effects from Plume Surface Interactions (PSI) will be essential for the protection of personnel and equipment on the Moon. To help characterize the underlying mechanics associated with viscous erosion and crater formation, experimental measurements using regolith simulants and subsonic, non-reacting flows were completed using compressed air in a splitter plate, plume cratering setup. More specifically, these investigations examined the underlying effects of bulk density, cohesion, and exhaust flow characteristics on viscous erosion rates and crater formation using Lunar highlands simulant (LHS-1), Lunar mare simulant (LMS-1), LHS-1D (Dust) simulants, and 40–80 μm glass beads in atmosphere. Results show that particle size distribution can ultimately influence crater shapes and erosion rates, likely owing to internal angle of friction. Measurements show that increasing bulk density, especially from an uncompacted to a slightly compacted state, decreases erosion rate by as much as 50 %. While cohesion of granular material can mitigate erosion rates to some extent, higher levels of cohesion above 1000 Pa may actually increase viscous erosion rates due to particle clumping. A modified version of Metzger's (2024a)equation for volumetric erosion rate is presented, with limitations discussed. These modified equations for viscous erosion, with limitations noted, show that geotechnical properties play an important role in viscous erosion and should be considered in PSI computer models for future mission planning.
{"title":"Understanding the effects of geotechnical properties on viscous erosion rate from plume surface interactions","authors":"B. Dotson, A. St John, R. Hall, D. Sapkota, D. Britt, P. Metzger","doi":"10.1016/j.pss.2025.106117","DOIUrl":"10.1016/j.pss.2025.106117","url":null,"abstract":"<div><div>With humans returning to the Moon under the Artemis program, understanding and mitigating effects from Plume Surface Interactions (PSI) will be essential for the protection of personnel and equipment on the Moon. To help characterize the underlying mechanics associated with viscous erosion and crater formation, experimental measurements using regolith simulants and subsonic, non-reacting flows were completed using compressed air in a splitter plate, plume cratering setup. More specifically, these investigations examined the underlying effects of bulk density, cohesion, and exhaust flow characteristics on viscous erosion rates and crater formation using Lunar highlands simulant (LHS-1), Lunar mare simulant (LMS-1), LHS-1D (Dust) simulants, and 40–80 μm glass beads in atmosphere. Results show that particle size distribution can ultimately influence crater shapes and erosion rates, likely owing to internal angle of friction. Measurements show that increasing bulk density, especially from an uncompacted to a slightly compacted state, decreases erosion rate by as much as 50 %. While cohesion of granular material can mitigate erosion rates to some extent, higher levels of cohesion above 1000 Pa may actually increase viscous erosion rates due to particle clumping. A modified version of Metzger's (2024a)equation for volumetric erosion rate is presented, with limitations discussed. These modified equations for viscous erosion, with limitations noted, show that geotechnical properties play an important role in viscous erosion and should be considered in PSI computer models for future mission planning.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"261 ","pages":"Article 106117"},"PeriodicalIF":1.8,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822359","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 : 2025-04-09DOI: 10.1016/j.pss.2025.106104
Qifang Zheng , Rong Huang , Yusheng Xu , Fangzhao Zhang , Changjiang Xiao , Luning Li , Xiaohua Tong
Martian impact craters contain prolific geomorphic information; their types provide vital indicators reflecting the geological evolution and chronology of celestial bodies. Currently, visual inspection is the most commonly used and widely accepted approach for identifying the crater types and their morphological features. However, it is a subjective task and requires professional knowledge. In this work, we present a method for the automatic morphologic classification of Martian craters using imbalanced Mars image datasets. Specifically, we classified and cropped Tianwen-1’s MoRIC images according to the morphological features of craters based on Robbins’ impact crater catalog; a dataset of six different types of Mars impact craters was established using the images. Based on this dataset, we classified the Mars impact craters using three popular neural network models with CNN and Transformer architectures. Meanwhile, to address the imbalanced samples in the network training process, a common problem in planetary remote sensing datasets, we introduce two methods (i.e., label smoothing strategy and weighted loss function) to suppress its influence on classification accuracy. Experimental results show that the Vision Transformer (ViT) model has the highest classification accuracy, reaching 90.3%. The label smoothing strategy performs well in CNN approaches, among which VGGNet11 improves the accuracy by 2.2%. By contrast, the weighted loss function performs well in ViT, and the classification accuracy of ViT improves by 1.3%. These results demonstrate a promising future for applying deep neural networks to identify and morphologically analyze Martian craters automatically.
{"title":"Automatic morphologic classification of Martian craters using imbalanced datasets of Tianwen-1’s MoRIC images with deep neural networks","authors":"Qifang Zheng , Rong Huang , Yusheng Xu , Fangzhao Zhang , Changjiang Xiao , Luning Li , Xiaohua Tong","doi":"10.1016/j.pss.2025.106104","DOIUrl":"10.1016/j.pss.2025.106104","url":null,"abstract":"<div><div>Martian impact craters contain prolific geomorphic information; their types provide vital indicators reflecting the geological evolution and chronology of celestial bodies. Currently, visual inspection is the most commonly used and widely accepted approach for identifying the crater types and their morphological features. However, it is a subjective task and requires professional knowledge. In this work, we present a method for the automatic morphologic classification of Martian craters using imbalanced Mars image datasets. Specifically, we classified and cropped Tianwen-1’s MoRIC images according to the morphological features of craters based on Robbins’ impact crater catalog; a dataset of six different types of Mars impact craters was established using the images. Based on this dataset, we classified the Mars impact craters using three popular neural network models with CNN and Transformer architectures. Meanwhile, to address the imbalanced samples in the network training process, a common problem in planetary remote sensing datasets, we introduce two methods (i.e., label smoothing strategy and weighted loss function) to suppress its influence on classification accuracy. Experimental results show that the Vision Transformer (ViT) model has the highest classification accuracy, reaching 90.3%. The label smoothing strategy performs well in CNN approaches, among which VGGNet11 improves the accuracy by 2.2%. By contrast, the weighted loss function performs well in ViT, and the classification accuracy of ViT improves by 1.3%. These results demonstrate a promising future for applying deep neural networks to identify and morphologically analyze Martian craters automatically.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"262 ","pages":"Article 106104"},"PeriodicalIF":1.8,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833259","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 : 2025-04-08DOI: 10.1016/j.pss.2025.106112
Kai Zenk , Dominic Dirkx , Sam Fayolle
Being among the most promising candidates for potential extraterrestrial habitats within our Solar System, the Galilean satellites are going to be extensively studied by the upcoming JUICE and Europa Clipper missions. Both spacecraft will provide radio science tracking data, which will allow the satellites ephemerides to be determined to much greater accuracy than is currently the case. Yet, with no flybys of Io, these data sets will be skewed towards the three outer satellites. To mitigate this imbalance, optical space-based astrometry from JUICE will provide a valuable contribution.
To quantify the contribution of JUICE astrometry, we have performed the inversion of simulated optical astrometric observations by JUICE, using suitable a priori covariance to represent the radio science-only solution. Incorporating the astrometry into the ephemeris solution requires the consideration of the offset between Io’s centre-of-figure (COF, which astrometry measures) and the centre-of-mass (COM, which the ephemeris solution requires). We explicitly account for the offset between COF and COM as an estimated parameter in our model.
We assess the contribution of the optical observations to the ephemeris solution as a function of the radio science true-to-formal-error ratio (describing the statistical realism of the simulated radio science solution), as well as optical data quantity and planning. From this, we discuss to which extent space-based astrometry could help to validate the radio science solution, and under which conditions the data could improve the orbital solution of Io.
Significant contributions of astrometry to Io’s orbital solution occur for radio science true-to-formal-error ratios of 4 and higher (for the along-track and normal direction). This shows that optical space-based astrometry can improve and/or validate the radio science solution. Reductions in the obtainable uncertainties for the COF-COM-offset range from about 20 to 50 per cent – depending on the number of observations – using suitable algorithms to select the epochs at which observations are to be simulated. In particular, observations during the high-inclination phase have proven especially beneficial.
Our results show that constraints on the COM-COF offset of Io could be obtained from astrometry at the level 100 m – 1 km, depending on the quantity and planning of the observations. This could provide a novel data point to constrain Io’s interior. Moreover, the astrometric data will provide independent validation – and possibly improvement – of the orbital solution of Io.
伽利略卫星是太阳系内最有希望成为潜在地外栖息地的候选卫星之一，即将进行的 JUICE 和 Europa Clipper 任务将对其进行广泛研究。这两个航天器都将提供无线电科学跟踪数据，这将使卫星星历的确定比目前更加精确。然而，由于没有飞越木卫二，这些数据集将偏向于三颗外围卫星。为了量化 JUICE 天体测量的贡献，我们对 JUICE 的模拟光学天体测量观测数据进行了反演，使用适当的先验协方差来代表仅用于无线电科学的解决方案。将天体测量纳入星历表求解需要考虑木卫二的图形中心（COF，天体测量测量）和质量中心（COM，星历表求解需要）之间的偏移。我们将 COF 和 COM 之间的偏移量作为模型中的一个估计参数明确考虑在内。我们评估了光学观测对星历解的贡献，将其作为无线电科学真实与形式误差比（描述模拟无线电科学解的统计真实性）以及光学数据数量和规划的函数。由此，我们讨论了天基天体测量在多大程度上可以帮助验证无线电科学解决方案，以及在哪些条件下这些数据可以改进木卫二的轨道解决方案。这表明天基光学天体测量法可以改进和/或验证无线电科学解决方案。根据观测数据的数量，使用合适的算法来选择模拟观测的时间，COF-COM 偏移的不确定性可降低约 20%到 50%。我们的结果表明，根据观测的数量和规划，可以从 100 米到 1 公里的天体测量中获得木卫二 COM-COF 偏移的约束条件。这可以提供一个新的数据点来约束木卫二的内部。此外，天体测量数据将对木卫一的轨道解决方案进行独立验证，并可能加以改进。
{"title":"Constraining the ephemeris and interior structure of Io using space-based astrometry by JUICE","authors":"Kai Zenk , Dominic Dirkx , Sam Fayolle","doi":"10.1016/j.pss.2025.106112","DOIUrl":"10.1016/j.pss.2025.106112","url":null,"abstract":"<div><div>Being among the most promising candidates for potential extraterrestrial habitats within our Solar System, the Galilean satellites are going to be extensively studied by the upcoming JUICE and Europa Clipper missions. Both spacecraft will provide radio science tracking data, which will allow the satellites ephemerides to be determined to much greater accuracy than is currently the case. Yet, with no flybys of Io, these data sets will be skewed towards the three outer satellites. To mitigate this imbalance, optical space-based astrometry from JUICE will provide a valuable contribution.</div><div>To quantify the contribution of JUICE astrometry, we have performed the inversion of simulated optical astrometric observations by JUICE, using suitable <em>a priori</em> covariance to represent the radio science-only solution. Incorporating the astrometry into the ephemeris solution requires the consideration of the offset between Io’s centre-of-figure (COF, which astrometry measures) and the centre-of-mass (COM, which the ephemeris solution requires). We explicitly account for the offset between COF and COM as an estimated parameter in our model.</div><div>We assess the contribution of the optical observations to the ephemeris solution as a function of the radio science true-to-formal-error ratio (describing the statistical realism of the simulated radio science solution), as well as optical data quantity and planning. From this, we discuss to which extent space-based astrometry could help to validate the radio science solution, and under which conditions the data could improve the orbital solution of Io.</div><div>Significant contributions of astrometry to Io’s orbital solution occur for radio science true-to-formal-error ratios of 4 and higher (for the along-track and normal direction). This shows that optical space-based astrometry can improve and/or validate the radio science solution. Reductions in the obtainable uncertainties for the COF-COM-offset range from about 20 to 50 per cent – depending on the number of observations – using suitable algorithms to select the epochs at which observations are to be simulated. In particular, observations during the high-inclination phase have proven especially beneficial.</div><div>Our results show that constraints on the COM-COF offset of Io could be obtained from astrometry at the level 100 m – 1 km, depending on the quantity and planning of the observations. This could provide a novel data point to constrain Io’s interior. Moreover, the astrometric data will provide independent validation – and possibly improvement – of the orbital solution of Io.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"261 ","pages":"Article 106112"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829564","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 : 2025-04-08DOI: 10.1016/j.pss.2025.106116
Sylvain Blunier , Dimitrios Athanasopoulos , Clemens Dittmar , Freja Thoresen , Aidan Cowley , Anna Fogtman
Protecting astronauts from radiation is a critical challenge for extended missions on the lunar surface. To mitigate the risks from Galactic Cosmic Rays (GCR) and solar flares, future habitats must be designed with robust shielding against these hazards. Utilizing lunar regolith presents a promising solution, offering effective radiation protection to avoid transporting heavy, prefabricated materials. In this work, we simulated a two-layer lunar dome made of a thin aluminum-based alloy as an inner layer and an outer layer made of lunar regolith. Combined with an advanced mesh-type computerized human phantom, these simulations give a detailed insight into the radiation exposure of astronauts in such habitats. Using the ICRU (International Commission on Radiation Units) sphere as a simplified human phantom we computed the dose equivalent (DE) as a function of the thickness of the outer layer using the BON2020 GCR model. The simulation was repeated at different thicknesses using the ICRP 145 computerized female human phantom to characterize the impact on individual organs. Our study introduces a novel model giving the DE and effective dose equivalent (EDE) exposure experienced by astronauts within a regolith-made lunar dome under GCR during solar minimum conditions, contingent upon the dome's wall thickness. Our comprehensive analysis reveals a decrease in EDE when stacking regolith until 45 g·cm-2. Until 105 g·cm-2, the production of secondary particles would potentially induce more dose than it would protect. We observe rapid attenuation of heavy ions within 45 g·cm-2 of regolith thickness, while the presence of secondary neutrons produced by the interaction of primary protons and alphas with the regolith increases the impact on radiation exposure. Notably, the EDE behind a shield comprised of only 1.136 g·cm-2 of aluminum measures 291 mSv·y-1 with a body-averaged mean quality factor of 3.3, whereas adding 45 g·cm-2 of regolith reduces this exposure to 213 mSv·y-1 and the quality factor to 2.2. Our investigation identifies the skin, breasts, brain, and surface bones as the organs most affected by radiation exposure, with comparable magnitudes of impact across all organs. These findings also underscore the importance of considering organ-specific effects when assessing radiation hazards in space environments.
{"title":"Regolith-Based Lunar Habitat for Astronaut Radiation Protection and Organ Dose Assessment.","authors":"Sylvain Blunier , Dimitrios Athanasopoulos , Clemens Dittmar , Freja Thoresen , Aidan Cowley , Anna Fogtman","doi":"10.1016/j.pss.2025.106116","DOIUrl":"10.1016/j.pss.2025.106116","url":null,"abstract":"<div><div>Protecting astronauts from radiation is a critical challenge for extended missions on the lunar surface. To mitigate the risks from Galactic Cosmic Rays (GCR) and solar flares, future habitats must be designed with robust shielding against these hazards. Utilizing lunar regolith presents a promising solution, offering effective radiation protection to avoid transporting heavy, prefabricated materials. In this work, we simulated a two-layer lunar dome made of a thin aluminum-based alloy as an inner layer and an outer layer made of lunar regolith. Combined with an advanced mesh-type computerized human phantom, these simulations give a detailed insight into the radiation exposure of astronauts in such habitats. Using the ICRU (International Commission on Radiation Units) sphere as a simplified human phantom we computed the dose equivalent (DE) as a function of the thickness of the outer layer using the BON2020 GCR model. The simulation was repeated at different thicknesses using the ICRP 145 computerized female human phantom to characterize the impact on individual organs. Our study introduces a novel model giving the DE and effective dose equivalent (EDE) exposure experienced by astronauts within a regolith-made lunar dome under GCR during solar minimum conditions, contingent upon the dome's wall thickness. Our comprehensive analysis reveals a decrease in EDE when stacking regolith until 45 g·cm<sup>-2</sup>. Until 105 g·cm-2, the production of secondary particles would potentially induce more dose than it would protect. We observe rapid attenuation of heavy ions within 45 g·cm<sup>-2</sup> of regolith thickness, while the presence of secondary neutrons produced by the interaction of primary protons and alphas with the regolith increases the impact on radiation exposure. Notably, the EDE behind a shield comprised of only 1.136 g·cm<sup>-2</sup> of aluminum measures 291 mSv·y<sup>-1</sup> with a body-averaged mean quality factor of 3.3, whereas adding 45 g·cm<sup>-2</sup> of regolith reduces this exposure to 213 mSv·y<sup>-1</sup> and the quality factor to 2.2. Our investigation identifies the skin, breasts, brain, and surface bones as the organs most affected by radiation exposure, with comparable magnitudes of impact across all organs. These findings also underscore the importance of considering organ-specific effects when assessing radiation hazards in space environments.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"261 ","pages":"Article 106116"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820286","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 : 2025-04-08DOI: 10.1016/j.pss.2025.106115
Xiaosi Zhou
Venus and Titan, two very different terrestrial bodies in the solar system possessing extremely hot and extremely cold near-surface dense atmospheres, respectively, have been identified as having surface dune distributions associated with aeolian sand transport. Previous studies on planetary dunes have rarely involved a detailed investigation of flow behavior over dunes under such extreme environmental conditions. This study takes the highly migratory elementary barchan dune as the research object, and aiming at the realistic thermophysical environment of the wind field near the surfaces of Venus and Titan, a computational fluid dynamics model of the turbulent boundary layer on the surface that considers the real gas effect and planetary gravity constraints was constructed to carry out numerical experiments and comparative analysis of the hydrodynamic behavior of sand dunes induced by different planetary atmospheric environments. The predicted results show that there are notable differences in the leeward secondary flow structures of the barchan dunes induced by the real gas flows of Venus and Titan. Under the conditions of a 0-km elevation and the same incident flow speed, the flow reattachment length of the Venusian dune is slightly smaller than that of Titan's dune. This may be caused by differences in the thermo-hydrodynamics of planetary atmospheric fluids and differences in the turbulent flow represented by the flow Reynolds number. In essence, for Venusian dunes with high Reynolds number turbulence, the kinematic viscosity, as the only variable parameter, has no significant impact on the flow reattachment length. At the same wind intensity conforming to the in-situ data, for both Venus and Titan, the dune areas where the wind can cause fine sand of the same size to take off and subsequently be eroded tend to be located on the crest of the dune. The maximum dimensionless friction velocity, which is used to characterize the erosion intensity, decreases linearly with increasing elevation on Venus. This indirectly clarifies the previous argument about the relationship between planetary atmospheric density and aeolian geomorphology scales in a new light. The quantitative comparisons of the eroded extent and intensity on dune surfaces suggest that the induced effect of the atmospheric environment on Titan at 0 km is the closest to that on Venus at 11 km. This research can provide inspiration and a theoretical reference for the study of comparative planetology in the field of aeolian geomorphology.
{"title":"Numerical experiments on the hydrodynamic structure of a barchan dune constrained by dense atmospheres: Comparative applications to Venus and Titan","authors":"Xiaosi Zhou","doi":"10.1016/j.pss.2025.106115","DOIUrl":"10.1016/j.pss.2025.106115","url":null,"abstract":"<div><div>Venus and Titan, two very different terrestrial bodies in the solar system possessing extremely hot and extremely cold near-surface dense atmospheres, respectively, have been identified as having surface dune distributions associated with aeolian sand transport. Previous studies on planetary dunes have rarely involved a detailed investigation of flow behavior over dunes under such extreme environmental conditions. This study takes the highly migratory elementary barchan dune as the research object, and aiming at the realistic thermophysical environment of the wind field near the surfaces of Venus and Titan, a computational fluid dynamics model of the turbulent boundary layer on the surface that considers the real gas effect and planetary gravity constraints was constructed to carry out numerical experiments and comparative analysis of the hydrodynamic behavior of sand dunes induced by different planetary atmospheric environments. The predicted results show that there are notable differences in the leeward secondary flow structures of the barchan dunes induced by the real gas flows of Venus and Titan. Under the conditions of a 0-km elevation and the same incident flow speed, the flow reattachment length of the Venusian dune is slightly smaller than that of Titan's dune. This may be caused by differences in the thermo-hydrodynamics of planetary atmospheric fluids and differences in the turbulent flow represented by the flow Reynolds number. In essence, for Venusian dunes with high Reynolds number turbulence, the kinematic viscosity, as the only variable parameter, has no significant impact on the flow reattachment length. At the same wind intensity conforming to the in-situ data, for both Venus and Titan, the dune areas where the wind can cause fine sand of the same size to take off and subsequently be eroded tend to be located on the crest of the dune. The maximum dimensionless friction velocity, which is used to characterize the erosion intensity, decreases linearly with increasing elevation on Venus. This indirectly clarifies the previous argument about the relationship between planetary atmospheric density and aeolian geomorphology scales in a new light. The quantitative comparisons of the eroded extent and intensity on dune surfaces suggest that the induced effect of the atmospheric environment on Titan at 0 km is the closest to that on Venus at 11 km. This research can provide inspiration and a theoretical reference for the study of comparative planetology in the field of aeolian geomorphology.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"261 ","pages":"Article 106115"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816979","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}
<div><div>The study of cometary molecular emissions provides crucial insights into the primordial composition of the Solar System and the physical and chemical processes shaping these icy bodies. Comets, as remnants of the early Solar System, serve as natural archives of volatile compounds that offer a glimpse into the conditions of the protoplanetary disk. In this work, we analyze an optical pre-perihelion spectrum of comet C/2023 A3 (Tsuchinshan-ATLAS), obtained using the DOLORES spectrograph at the Telescopio Nazionale Galileo (TNG) on May 1, 2024. The cometary spectrum was reduced using standard procedures implemented in the IRAF software package. To characterize the volatile inventory of comet C/2023 A3, we derived the production rate of CN, the only detectable molecular emission, and calculated upper limits for undetected species, including C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, C<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>. These constraints were obtained by analyzing the noise level in continuum regions and integrating theoretical line profiles, accounting for instrumental resolution and observational conditions. We calculated a CN production rate of (3.89<span><math><mrow><mo>±</mo><mn>0</mn><mo>.</mo><mn>21</mn></mrow></math></span>)<span><math><mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s. Despite significant dust contamination, which likely obscures weaker molecular emission lines typically associated with cometary activity, we derived upper limits for the production rates of key volatile species: Q<span><math><mrow><msub><mrow></mrow><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></msub><mo><</mo><mn>3</mn><mo>.</mo><mn>12</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>24</mn></mrow></msup></mrow></math></span> molec/s, Q<span><math><mrow><msub><mrow></mrow><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub><mo><</mo><mn>1</mn><mo>.</mo><mn>30</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s, and Q<span><math><mrow><msub><mrow></mrow><mrow><mi>N</mi><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub><mo><</mo><mn>2</mn><mo>.</mo><mn>79</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s, respectively. We also determined the <span><math><mrow><mi>A</mi><mi>f</mi><mi>ρ</mi></mrow></math></span> parameter, obtaining a value of <span><math><mrow><mn>4329</mn><mo>±</mo><mn>56</mn></mrow></math></span> cm, which confirms the high dust production rate previously reported for this comet. The logarithmic ratio of production rates, <span><math><mrow><mo>log</mo><mfenced><mrow><mi>Q</mi><mrow><mo>(</mo>
{"title":"Pre-perihelion observations of the carbon-depleted comet C/2023 A3 (Tsuchinshan-ATLAS). Insights into CN production and molecular upper limits","authors":"Pamela Cambianica , Giovanni Munaretto , Gabriele Cremonese , Alessandra Mura , Fiorangela La Forgia , Luca Bizzocchi , Monica Lazzarin , Cristina Puzzarini , Mattia Melosso , Vania Lorenzi , Walter Boschin","doi":"10.1016/j.pss.2025.106102","DOIUrl":"10.1016/j.pss.2025.106102","url":null,"abstract":"<div><div>The study of cometary molecular emissions provides crucial insights into the primordial composition of the Solar System and the physical and chemical processes shaping these icy bodies. Comets, as remnants of the early Solar System, serve as natural archives of volatile compounds that offer a glimpse into the conditions of the protoplanetary disk. In this work, we analyze an optical pre-perihelion spectrum of comet C/2023 A3 (Tsuchinshan-ATLAS), obtained using the DOLORES spectrograph at the Telescopio Nazionale Galileo (TNG) on May 1, 2024. The cometary spectrum was reduced using standard procedures implemented in the IRAF software package. To characterize the volatile inventory of comet C/2023 A3, we derived the production rate of CN, the only detectable molecular emission, and calculated upper limits for undetected species, including C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, C<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>. These constraints were obtained by analyzing the noise level in continuum regions and integrating theoretical line profiles, accounting for instrumental resolution and observational conditions. We calculated a CN production rate of (3.89<span><math><mrow><mo>±</mo><mn>0</mn><mo>.</mo><mn>21</mn></mrow></math></span>)<span><math><mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s. Despite significant dust contamination, which likely obscures weaker molecular emission lines typically associated with cometary activity, we derived upper limits for the production rates of key volatile species: Q<span><math><mrow><msub><mrow></mrow><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></msub><mo><</mo><mn>3</mn><mo>.</mo><mn>12</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>24</mn></mrow></msup></mrow></math></span> molec/s, Q<span><math><mrow><msub><mrow></mrow><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub><mo><</mo><mn>1</mn><mo>.</mo><mn>30</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s, and Q<span><math><mrow><msub><mrow></mrow><mrow><mi>N</mi><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub><mo><</mo><mn>2</mn><mo>.</mo><mn>79</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></mrow></math></span> molec/s, respectively. We also determined the <span><math><mrow><mi>A</mi><mi>f</mi><mi>ρ</mi></mrow></math></span> parameter, obtaining a value of <span><math><mrow><mn>4329</mn><mo>±</mo><mn>56</mn></mrow></math></span> cm, which confirms the high dust production rate previously reported for this comet. The logarithmic ratio of production rates, <span><math><mrow><mo>log</mo><mfenced><mrow><mi>Q</mi><mrow><mo>(</mo>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"261 ","pages":"Article 106102"},"PeriodicalIF":1.8,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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