Planetary and Space Science最新文献

{"title":"The thermal impact of the self-heating effect on airless bodies. The case of Mercury’s north polar craters","authors":"Pamela Cambianica ,&nbsp;Emanuele Simioni ,&nbsp;Gabriele Cremonese ,&nbsp;Silvia Bertoli ,&nbsp;Elena Martellato ,&nbsp;Alice Lucchetti ,&nbsp;Maurizio Pajola ,&nbsp;Cristina Re ,&nbsp;Adriano Tullo ,&nbsp;Matteo Massironi","doi":"10.1016/j.pss.2024.105983","DOIUrl":"10.1016/j.pss.2024.105983","url":null,"abstract":"<div><div>Thermal models are essential for studying airless planetary surfaces, as the interaction between topography and thermophysical properties plays a crucial role in determining a surface’s response to localized illumination. Accurate temperature distribution calculations require a comprehensive investigation of sunlight scattering, a process that, despite its computational challenges, cannot be overlooked, especially when high resolution is necessary. Furthermore, thermal analysis is fundamental for assessing the stability of volatiles in polar regions. In this study, we introduce a novel approach by discretizing the Sun into 100 individual elements, allowing for a highly precise simulation of solar flux—an innovation crucial for accurately capturing temperature distributions in Mercury’s polar craters, given the planet’s proximity to the Sun. This level of discretization significantly enhances the accuracy of the thermal model, ensuring a more realistic depiction of how sunlight interacts with crater topography. We developed a dual-model approach that simulates both direct solar illumination and its scattering on two craters, Laxness and Fuller, located at Mercury’s north pole. The illumination and thermal model predict temperature distribution and heat transfer based on the material’s thermal properties and topography. The study examines the interaction between direct sunlight, causing localized heating, and scattered light, which influences the thermal response of surface materials. Detailed illumination maps and temperature profiles were generated over two Hermean years, revealing the significant impact of the self-heating effect on temperature distribution. The results show that specific regions experience indirect solar flux due to the craters’ morphology, particularly in permanently shadowed regions (PSRs) that are heated exclusively by scattered radiation. Maximum temperature profiles for the Laxness and Fuller craters show a substantial temperature increase within PSRs compared to areas exposed to direct illumination. However, while self-heating does not affect the stability of water ice in the Laxness crater, in the Fuller crater, a section within the radar-bright material reaches temperatures of up to 210 K, potentially threatening the stability of water ice. Further investigation with the onboard SIMBIO-SYS instrument on the BepiColombo mission will help to better understand the current state of these craters and their volatile deposits.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"253 ","pages":"Article 105983"},"PeriodicalIF":1.8,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529567","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}

{"title":"Comparison of volatiles evolving from selected highland and mare lunar regolith simulants during vacuum sintering","authors":"Mihail P. Petkov ,&nbsp;Ryan P. Wilkerson ,&nbsp;Gerald E. Voecks ,&nbsp;Douglas L. Rickman ,&nbsp;Jennifer E. Edmunson ,&nbsp;Michael R. Effinger","doi":"10.1016/j.pss.2024.105982","DOIUrl":"10.1016/j.pss.2024.105982","url":null,"abstract":"<div><div>Volatiles evolving from JSC-1A, NU-LHT-4M and CSM-LHT-1G lunar regolith simulants during <em>in vacuo</em> thermal processing were analyzed using mass spectrometry as a function of temperature. Two high-fidelity simulants, JSC-1A (mare) and NU-LHT-4M (highland), were compared to a newly developed CSM-LHT-1G highland simulant, modified to closely match lunar geochemistry. Large autogenous gas loads were observed for all investigated materials. Mineralogical knowledge was used to identify and attribute individual volatile species to reacting, transforming, or decomposing constituents (hydrates, carbonates, sulfates, sulfides, clays, etc.) of the respective regolith simulant in the self-generated gas environment. Cumulative mass losses for individual simulant components as a function of temperature were quantified using mass spectrometry in conjunction with thermogravimetric analysis. Investigation of the four components of CSM-LHT-1G – anorthosite, basalt, augite, and glass – aided the attribution of volatile species to specific compounds and their respective sources. The results showed significant decomposition of non-lunar phases present in the man-made regolith simulants below the typical glass crystallization temperatures, which paves the way to devising methods for enhancing the fidelity of the simulants. High gas loads and corrosive gases (HF and HCl) were recognized as potential hazards, pertaining to the development of large testbed facilities.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"252 ","pages":"Article 105982"},"PeriodicalIF":1.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423961","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}

{"title":"JunoPerijove 34: Update Ganymede 3D-control network and new DEMs study","authors":"I.E. Nadezhdina,&nbsp;A.E. Zubarev,&nbsp;N.A. Kozlova,&nbsp;N.A. Slodarzh,&nbsp;I.P. Karachevtseva","doi":"10.1016/j.pss.2024.105981","DOIUrl":"10.1016/j.pss.2024.105981","url":null,"abstract":"<div><div>During the Juno Perijove 34 the JunoCam acquired four RGB images of Ganymede. These images and updated SPICE kernel for spacecraft's trajectories were used to refine previous 3D-control point network (CPN). As a result, 4954 control points were measured 22,098 times with a minimum of 2 and a maximum of 16 observations per point, based on the 302 best available images from all missions (Voyagers, Galileo and Juno). After adjustment more than 86% of points have accuracy better than 3 km (&gt;97% - better than 5 km). A new libration value for Ganymede 18ʺ is obtained. This updated CPN was used for compiling a new Ganymede global mosaic to support the planning of observations within the JUICE mission. New detailed local DEMs were obtained by stereovectorization for Enki Catena and Tros crater regions. In the Enki chain, the ratio d/D of the depth of craters to their diameter ranges from 0.049 to 0.089 and correlates with the area types (dark or light).</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"252 ","pages":"Article 105981"},"PeriodicalIF":1.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423822","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}

{"title":"Morphological, hydrogeochemical and sedimentological analysis of hypersaline Sambhar Lake, India: An analog to understand evaporitic paleolake basins on Mars","authors":"Deepali Singh ,&nbsp;Priyadarshini Singh ,&nbsp;Nidhi Roy ,&nbsp;Saumitra Mukherjee","doi":"10.1016/j.pss.2024.105974","DOIUrl":"10.1016/j.pss.2024.105974","url":null,"abstract":"<div><div>In the recent decade of astrobiological exploration of the Martian surface, there has been a shift from identifying habitable environments to finding markers indicative of biological activity. It requires a prior understanding of the physical and geochemical environment of the setting to decipher whether the conditions were conducive. Generally, quiescent surroundings of lacustrine basins are considered one of the best targets for the preservation of any biological signatures. However, due to logistical limitations, the geochemical information available is mostly restricted to small areas on the surficial level (or in the subsurface in case of layered deposits or impact craters) where sufficient satellite coverage is available and, in some areas, where rovers/landers have been deployed. In this context, terrestrial lacustrine basins offer valuable insights into the environment required for the formation of the minerals observed on the Martian surface.</div><div>This study was carried out within Sambhar Lake located in the arid/semiarid climatic zone within the Thar desert. It is a hypersaline playa that has undergone several cycles of desiccation and re-filling, sharing its climate-controlled history with that of several paleolakes on Mars. We conducted physicochemical analysis of the samples collected from the lake and its surrounding area and compared our results with samples from the Curiosity rover (at Gale crater) and to those of the studies carried out in basalt-rich parent settings of Iceland. Our results suggest that Sambhar Lake is a Na-Cl type brine with climate-driven hydrology. The shallow cores and rock samples indicated that the area is rich in evaporites. We propose that even the sites with different parent material may be crucial in understanding the geological evolution of paleolakes on Mars and that Sambhar is a great example to study tectono-geomorphic evolution and the climate-induced transition of a lacustrine basin to a playa. Additionally, the lake is also desirable to study extremophiles and their adaptation to changing environmental variables for future planetary missions, including but not limited to, Mars.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"252 ","pages":"Article 105974"},"PeriodicalIF":1.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311089","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}

{"title":"A discussion on estimating small bodies taxonomies using phase curves results","authors":"Alvaro Alvarez-Candal","doi":"10.1016/j.pss.2024.105970","DOIUrl":"10.1016/j.pss.2024.105970","url":null,"abstract":"<div><p>Upcoming large multiwavelength photometric surveys will provide a leap in our understanding of small body populations, among other fields of modern astrophysics. Serendipitous observations of small bodies in different orbital locations allow us to study diverse phenomena related to how their surfaces scatter solar light.</p><p>In particular, multiple observations of the same object in different epochs permit us to construct their phase curves to obtain absolute magnitudes and phase coefficients. In this work, we tackle a series of long-used relationships associating these phase coefficients with the taxa of small bodies and suggest that some may need to be revised in the light of large-number statistics.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"251 ","pages":"Article 105970"},"PeriodicalIF":1.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142242397","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}

{"title":"Thermal extraction of water ice from the lunar surface II - vapor yields for an improved regolith model","authors":"Connor Westcott,&nbsp;Julie Brisset","doi":"10.1016/j.pss.2024.105973","DOIUrl":"10.1016/j.pss.2024.105973","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This work focuses on thermal water extraction on the lunar surface. We previously developed a three-dimensional finite element model (FEM) implementing heat and gas diffusion in the porous granular medium that is icy lunar regolith. Here, we present an improved version of this work in which we implemented a more realistic regolith model. In particular, we addressed previous model simplifications on regolith emissivity and porosity, water sublimation rate, as well as regolith and water ice thermal conductivity and permeability. Incorporating recent modeling and experimental work from the literature, we investigated the effect of these soil properties on the outcome of our simulations, with a particular interest in the yield of the thermal extraction process. Aiming at understanding what thermal water extraction would produce if heating the lunar surface directly, we also studied the effect of open borders on extraction yields.&lt;/div&gt;&lt;div&gt;We find that the crude icy regolith approximation we implemented in Paper I provided a lower estimation of water vapor yields upon heating. Overall and using the same heating methods (surface heating as well as inserted drills), our more accurate regolith model implementation extracted more water from the simulation volume. With this new model, we observed that extraction yields depended mostly on the ice content of the regolith, and to a lesser extent on the heating configuration (number of drills) and power. In two specific configurations, 16 and 25 drills at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; W in 1%vol icy regolith, heating allowed the extraction of nearby ice, efficiently desiccating the entire simulation volume. Apart from these two cases, the highest extraction yields were obtained for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; W surface heating of a volume with closed borders with values over 80%. In open border volumes, highest yields were around 70% achieved for the highest number of drills (16 and 25), at the highest power (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; W) in the regolith with the largest icy fraction. Extraction masses started being noticeable around a few minutes, but reaching most of the maximum possible yields took up to several days in some cases.&lt;/div&gt;&lt;div&gt;Defining an extraction efficiency by combining the yield and extraction times, we found that the best compromise between hardware complexity, time, and yield would be working in open border environments, using dense drill configurations in ice-rich regolith, and loose drill configurations in ice-poor regolith. In both cases, extraction efficiencies were similar at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; W and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"252 ","pages":"Article 105973"},"PeriodicalIF":1.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142318688","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}

{"title":"Isotopic fractionation of methane on Mars via diffusive separation in the subsurface","authors":"John E. Moores,&nbsp;Haley M. Sapers","doi":"10.1016/j.pss.2024.105971","DOIUrl":"10.1016/j.pss.2024.105971","url":null,"abstract":"<div><p>Many processes have been identified in the Martian subsurface which may produce or release methane that eventually can be emitted into the atmosphere. Given the wide range of isotopic values for source carbon reported on Mars and the importance of atmospheric methane isotopologues as a tracer for subsurface processes, it is critical to quantify the level of isotopic fractionation that can occur during subsurface transport. On Earth, isotopic fractionation occurs when methane transport is dominated by Knudsen diffusion through small pores. However, unlike the Earth, on Mars the low atmospheric pressure and commensurate longer mean free path suggest that most subsurface transport of methane occurs in the Knudsen regime, amplifying this effect. Here, we report on simulations of diffusion through the martian subsurface and report on the level of fractionation that would be expected under two end-member scenarios. For Interplanetary Dust Particles (IDPs) incorporated in near-surface sediments in which methane is released quickly upon generation, atmospheric emissions of methane are expected to be representative of the reservoir isotopic ratio. However, for deeper sources in which methane accumulates as trapped gas, subsurface transport will result in depletions of ¹³CH₄ compared to reservoir concentrations by approximately −31‰. Over time, both the reservoir and the emitted gas will evolve to become isotopically enriched in ¹³CH₄ compared to a standard of constant isotopic ratio. This necessitates temporal measurements of emitted methane to understand the <strong><em>δ</em></strong>¹³C of the reservoir and depth of the release, preferably with hourly or better frequency. Finally, a seasonal cycle in <strong><em>δ</em></strong>¹³C with an amplitude of 5.3‰ is expected with adsorption acting to create small temporary reservoirs that are filled and emptied over the year by the subsurface thermal wave. This effect may provide a way to probe near-surface thermophysical properties.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"251 ","pages":"Article 105971"},"PeriodicalIF":1.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324001351/pdfft?md5=8e924cd9a4592418f7b9e727ff8b9bcf&pid=1-s2.0-S0032063324001351-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229930","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}

{"title":"Thermal modeling of the lunar South Pole: Application to the PROSPECT landing site","authors":"Michelangelo Formisano ,&nbsp;Maria Cristina De Sanctis ,&nbsp;Sarah Boazman ,&nbsp;Alessandro Frigeri ,&nbsp;David Heather ,&nbsp;Gianfranco Magni ,&nbsp;Matteo Teodori ,&nbsp;Simone De Angelis ,&nbsp;Marco Ferrari","doi":"10.1016/j.pss.2024.105969","DOIUrl":"10.1016/j.pss.2024.105969","url":null,"abstract":"<div><p>Water ice is distributed on the surface and in the subsurface of the Moon, as confirmed by observational data, and predicted by several numerical models. In this respect, the direct search for lunar water is the main objective of the ESA’s PROSPECT package, that aims to analyze a region of interest at the lunar South Pole. PROSPECT, originally on the Russian Luna 27, is now on the CLPS (Commercial Lunar Provider Service) “CP” 22 mission. In this work, we applied our 3-D FEM thermophysical model to investigate the landing site selected for the CP 22 mission, which is centred at −84.496°S, 31.588°E, and located on the Leibnitz Plateau and within an area of high elevation. The purpose of our model is to investigate regions of interest (ROI) on the lunar surface by working with the real topography at the scale of 5 m, by using the DEM (Digital Elevation Model) of the region. Since the lunar surface is characterized by topographic variations such as craters or boulders, a 3-D model is preferable over a 1-D numerical model. We produced temperature maps of the surface and 1-D temperature vs depth, as well as we produced illumination maps, computing also the indirect contribution. These simulations will provide a complete thermophysical vision of the landing site, offering a theoretical support to the researchers and engineers of the CP 22 mission, and of future lunar missions. In addition, this model can be applied to every site of the Moon surface and subsurface and, in general, to any airless body of the Solar System.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"251 ","pages":"Article 105969"},"PeriodicalIF":1.8,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324001338/pdfft?md5=435c93eae4e4dc3fe608a5718e9afa07&pid=1-s2.0-S0032063324001338-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272635","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}

{"title":"The Visual Monitoring Camera (VMC) on Mars Express: A new science instrument made from an old webcam orbiting Mars","authors":"Jorge Hernández-Bernal ,&nbsp;Alejandro Cardesín-Moinelo ,&nbsp;Ricardo Hueso ,&nbsp;Eleni Ravanis ,&nbsp;Abel Burgos-Sierra ,&nbsp;Simon Wood ,&nbsp;Marc Costa-Sitja ,&nbsp;Alfredo Escalante ,&nbsp;Emmanuel Grotheer ,&nbsp;Julia Marín-Yaseli de la Parra ,&nbsp;Donald Merrit ,&nbsp;Miguel Almeida ,&nbsp;Michel Breitfellner ,&nbsp;Mar Sierra ,&nbsp;Patrick Martin ,&nbsp;Dmitri Titov ,&nbsp;Colin Wilson ,&nbsp;Ethan Larsen ,&nbsp;Teresa del Río-Gaztelurrutia ,&nbsp;Agustín Sánchez-Lavega","doi":"10.1016/j.pss.2024.105972","DOIUrl":"10.1016/j.pss.2024.105972","url":null,"abstract":"<div><p>The Visual Monitoring Camera (VMC) is a small imaging instrument onboard Mars Express with a field of view of ∼40°x30°. The camera was initially intended to provide visual confirmation of the separation of the Beagle 2 lander and has similar technical specifications to a typical webcam of the 2000s. In 2007, a few years after the end of its original mission, VMC was turned on again to obtain full-disk images of Mars to be used for outreach purposes. As VMC obtained more images, the scientific potential of the camera became evident, and in 2018 the camera was given an upgraded status of a new scientific instrument, with science goals in the field of Martian atmosphere meteorology. The wide Field of View of the camera combined with the orbit of Mars Express enable the acquisition of full-disk images of the planet showing different local times, which for a long time has been rare among orbital missions around Mars. The small data volume of images also allows videos that show the atmospheric dynamics of dust and cloud systems to be obtained. This paper is intended to be the new reference paper for VMC as a scientific instrument, and thus provides an overview of the updated procedures to plan, command and execute science observations of the Martian atmosphere. These observations produce valuable science data that is calibrated and distributed to the community for scientific use.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"251 ","pages":"Article 105972"},"PeriodicalIF":1.8,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272634","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}

{"title":"Flow dynamics and thermal effects in the ejecta of the multiple-layered Kotka crater on Mars","authors":"Fabio Vittorio De Blasio ,&nbsp;Fabio Ciceri ,&nbsp;Giovanni Battista Crosta","doi":"10.1016/j.pss.2024.105957","DOIUrl":"10.1016/j.pss.2024.105957","url":null,"abstract":"<div><p>The multiple-layered ejecta surrounding crater Kotka (east of Elysium Mons) are studied using imagery and physical modelling. This particular crater was chosen not only because its ejecta are well preserved, but more importantly because the impact area is surrounded by mounds, which provide a means of determining the velocity of the ejecta based on run-up criteria. If the ejecta passed over a mound of a certain height, the velocity was greater than that necessary to rise up that height, while the presence of a shadow beyond the mound indicates a velocity lower than that limit. Top ejecta flow velocities were found to vary between 25 m/s and 80 m/s. Velocities are also determined based on the length of the jump against craters rims, a criterion that provides an estimate of the velocity, rather than a limit, and are found to be compatible with those estimated with run-up criteria. We find that a first train of ejecta travelling at high velocity was capable of overcoming many mounds. A peculiar rampart often visible at the foot of many of the mounds is interpreted as a frozen hydraulic jump indicating a phase in which the ejecta were about to stop.</p><p>The velocity of the ejecta was found to decrease with distance from the rim but not as fast as a constant friction model would suggest, indicating effective friction that increases with distance, and more complex rheology than pure frictional behavior. The velocities indicate a rheology for the fluidized ejecta in which the debris material was completely fluidized, to the point that the friction coefficient decreased by one to two orders of magnitude compared to the one of fragmented rock. Our conceptual model is that the ejecta material initially contained a large amount of solid ice that was fluidized and vaporized by the impact. The chains of pits visible in the ejecta, interpreted as fossilized bubbles of volatiles released through the hot fluidized material, confirm that high temperatures were reached during impact, as also indicated by analytical estimates. Fluidization altered the rheology of the ejecta in a way that has yet to be understood.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"251 ","pages":"Article 105957"},"PeriodicalIF":1.8,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167373","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}