Journal of Geophysical Research: Planets最新文献

{"title":"Asymmetrical Ion Dynamics and Its Impact on Plasma Boundaries in the Martian Magnetosphere","authors":"Yihui Song, Haoyu Lu, Jinbin Cao, Shibang Li, Xiaoshu Wu, Jianxuan Wang, Nihan Chen, Yasong Ge, Yuchen Cao, Jianing Zhao","doi":"10.1029/2025JE009283","DOIUrl":"10.1029/2025JE009283","url":null,"abstract":"<p>The asymmetry in plasma flow governed by the direction of solar wind motional electric field <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mtext>SW</mtext>\u0000 </msub>\u0000 <mo>=</mo>\u0000 <mo>−</mo>\u0000 <msub>\u0000 <mi>V</mi>\u0000 <mtext>SW</mtext>\u0000 </msub>\u0000 <mo>×</mo>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mtext>IMF</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${boldsymbol{E}}_{text{SW}}=-{boldsymbol{V}}_{text{SW}}times {boldsymbol{B}}_{text{IMF}}$</annotation>\u0000 </semantics></math>, which can be referred to as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mtext>SW</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${boldsymbol{E}}_{text{SW}}$</annotation>\u0000 </semantics></math> asymmetry, is one of the most important asymmetries in the Martian plasma environment. In this study, a multifluid magnetohydrodynamic (MHD) model is employed to investigate the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mtext>SW</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${boldsymbol{E}}_{text{SW}}$</annotation>\u0000 </semantics></math> asymmetry of ion motions on the magnetic pileup boundary (MPB) and inside the magnetosphere. The simulation results indicate a more intense solar wind penetration across the bow shock in the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mo>+</mo>\u0000 <mi>Z</mi>\u0000 </mrow>\u0000 <mtext>MSE</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${+Z}_{text{MSE}}$</annotation>\u0000 </semantics></math> hemisphere, which enhances the pileup of magnetic field lines through the mass loading process and compresses the MPB. The electric fields, especially the motional electric field <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mi>M</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${boldsymbol{E}}_{boldsymbol{M}}$</annotation>\u0000 </semantics></math>, exhibit apparent <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mtext>SW</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${boldsymbol{E}}_{text{SW}}$","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The “Analogs for VENus' GEologically Recent Surfaces” (AVENGERS) Initiative: Using Terrestrial Analogs to Study Recent Volcano-Tectonic Activity on Venus and Inform the Characterization of Terrestrial Exoplanets","authors":"P. D’Incecco,&nbsp;J. Filiberto,&nbsp;J. B. Garvin,&nbsp;G. N. Arney,&nbsp;S. A. Getty,&nbsp;E. Kohler,&nbsp;L. M. Zelenyi,&nbsp;L. V. Zasova,&nbsp;O. I. Korablev,&nbsp;M. A. Ivanov,&nbsp;J. W. Head,&nbsp;D. A. Gorinov,&nbsp;S. Bhattacharya,&nbsp;S. S. Bhiravarasu,&nbsp;D. Putrevu,&nbsp;I. López,&nbsp;R. Ghail,&nbsp;P. Mason,&nbsp;J. Brossier,&nbsp;C. Monaco,&nbsp;S. Branca,&nbsp;R. A. Corsaro,&nbsp;D. Trang,&nbsp;J. R. Crandall,&nbsp;N. Mari,&nbsp;M. Blackett,&nbsp;G. Komatsu,&nbsp;A. Kosenkova,&nbsp;I. Flynn,&nbsp;S. Aveni,&nbsp;N. Lang,&nbsp;B. J. Thomson,&nbsp;I. Pagano,&nbsp;S. Cassisi,&nbsp;G. Eggers,&nbsp;R. E. Ernst,&nbsp;H. El Bilali,&nbsp;T. Kremic,&nbsp;J. Lustig-Yaeger,&nbsp;N. Izenberg,&nbsp;L. Bruzzone,&nbsp;M. El Yazidi,&nbsp;E. Ferroni,&nbsp;D. Coero Borga,&nbsp;C. Badia,&nbsp;S. Parisini,&nbsp;G. Fiasconaro,&nbsp;S. Cussini,&nbsp;M. Dolci,&nbsp;E. Brocato,&nbsp;G. Gallardo i Peres,&nbsp;N. Davidova,&nbsp;S. Kane,&nbsp;C. Ostberg,&nbsp;V. Ortega-Ramos,&nbsp;G. Di Achille","doi":"10.1029/2024JE008675","DOIUrl":"10.1029/2024JE008675","url":null,"abstract":"<p>Several missions to Venus have recently been selected for launch, opening a new era for the exploration of the planet. A key question these missions seek to address is whether Venus is geologically active today. Detecting active volcanism on Venus would contribute to a better understanding of volcanic and atmospheric processes on Earth. The <i>Analogs for VENus' GEologically Recent Surfaces</i> (AVENGERS) initiative provides a comparative framework for the identification and analysis of terrestrial analog sites relevant to recent and possibly ongoing volcanic activity on Venus. Although this review focuses on terrestrial analogs for Venus exploration, the AVENGERS initiative also includes investigations that use Venus and Earth as analogs to better understand the evolution of terrestrial exoplanets. In addition, the AVENGERS initiative facilitates international collaboration by connecting Venus mission teams with the broader planetary and exoplanetary science communities. This review describes the scientific context of AVENGERS, details the selection criteria for terrestrial analog sites, and summarizes a set of suitable locations. Methodological approaches in analog studies that support the interpretation of Venus observations are also discussed.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008675","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145058007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origins of the Water Ice Excavated by the Christmas Eve Crater Formation on Mars","authors":"N. Wójcicka,&nbsp;G. S. Collins,&nbsp;V. G. Rangarajan,&nbsp;C. M. Dundas,&nbsp;I. J. Daubar","doi":"10.1029/2024JE008875","DOIUrl":"10.1029/2024JE008875","url":null,"abstract":"<p>On the 24th of December 2021, a meteoroid struck the martian surface, producing a 150-m wide crater and excavating the lowest-latitude water ice observed on Mars to date. Knowledge of the preimpact depth, thickness and lateral continuity of the excavated ice would provide new insight into past environmental changes such as temperature and humidity of the atmosphere. In this work, we use the iSALE3D shock physics code to simulate the crater formation and constrain both the impact parameters and the original location of excavated ice. Analysis of the distal ejecta pattern suggests that the impact angle was 20 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 <mn>2.5</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $pm 2.5{}^{circ}$</annotation>\u0000 </semantics></math> from horizontal. Based on a comparison of the simulated and observed crater morphology, we find the preimpact subsurface likely contained a stronger bedrock layer overlain by 15 m thick regolith layer. Our simulation results show that the ejected ice blocks visible in orbital images originated from shallow depths 3.2–11 m and from radii 30–60 m from the crater center. We conclude that the ice most likely originated from a massive ice layer at 3.2–11 m depth. The ice was likely also laterally discontinuous under the preimpact surface.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008875","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Subsurface Dielectric Permittivity and Structure Along Chang’E-4 Rover's 42-Lunar-Day Traverse Using Diffraction Focusing Methods","authors":"Shaoyue Zhang,&nbsp;Shengbo Chen,&nbsp;Stewart Greenhalgh,&nbsp;Xingguo Huang,&nbsp;Xiaodong Luo,&nbsp;Doyeon Kim","doi":"10.1029/2024JE008903","DOIUrl":"10.1029/2024JE008903","url":null,"abstract":"<p>China's Chang'E-4 probe successfully soft-landed on the lunar far side at Von Kármán crater in January 2019. Onboard, the Lunar Penetrating Radar (LPR) detected subsurface structures and properties such as dielectric permittivity, aiding in our understanding of regolith composition and origin. This study introduces an automatic method for estimating dielectric permittivity using radar diffraction focusing analysis. While developed from traditional seismic analysis, the method is tailored for LPR data by incorporating random noise removal, entropy-based focusing, and lunar-specific parameter optimization to address the challenges of noise interference, complex diffraction overlapping and applicability to LPR data. Applied to Chang'E-4's first 42 lunar-day data, this method revealed subsurface structure and permittivity distributions. Combined with instantaneous amplitudes, centroid frequencies, and geological features, we present a preferred geological interpretation. Our findings suggest that, after experiencing the latest basaltic magma intrusion and subsequent weathering, the region underwent multiple episodes of high ilmenite content ejecta deposition at a depth of 20–33 m. This was followed by several impacts, leaving craters visible today. Subsequently, the area was overlain by at least two ejecta layers with low ilmenite content at a depth of 13–25 m. Later, two meteoroids struck the paleo-surface; the larger one created the most prominent irregular crater on the current surface. Thereafter, ejecta from nearby craters such as Finsen and Von Kármán L covered the area, weathering into the current lunar regolith. Our inversion results demonstrate high reliability, align with previous studies and geological context, and can offer methodological and empirical insights for future planetary missions.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depth to Diameter Relationships for <50 m Diameter Martian Craters","authors":"C. Millot,&nbsp;C. Quantin-Nataf,&nbsp;E. Dehouck,&nbsp;I. Torres,&nbsp;M. Volat","doi":"10.1029/2024JE008844","DOIUrl":"10.1029/2024JE008844","url":null,"abstract":"&lt;p&gt;Impact craters provide key information about the geological history of planetary surfaces. Small craters are particularly useful for determining the target properties and for quantifying erosion rates. On Mars, few studies have been conducted on small craters, especially on their shapes, and little is known about their morphometry. Here, we address this problem using high-resolution orbital data. We mapped &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;80,000 craters with diameters below 50 m over two types of terrains found in Valles Marineris: landslide deposits and Interior Layered Deposits (ILDs). We computed six morphometric relationships from the measurements of the crater depth &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;d&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $d$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and apparent diameter &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mtext&gt;app&lt;/mtext&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${D}_{text{app}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; for each terrain, in the form &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;d&lt;/mi&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mtext&gt;app&lt;/mtext&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $d=c{D}_{text{app}}^{alpha }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. We found a linear relationship &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $(alpha sim 1)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; linking depth and diameter for both terrains, in good agreement with previous results for simple craters over 50 m and below 5 km. We obtained a lower value for &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $c$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; for ILDs, highlighting that freshest craters from our population are shallower than expected for newly formed craters. Hence, we suggest that erosion is the dominant mechanism over the target properties to explain the observed crater ","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008844","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145038318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Statistical Study of Local Dust Storm Occurrences on Mars Using the 2.77 μm CO2 Band Observed by OMEGA/Mars Express","authors":"Akira Kazama,&nbsp;Shohei Aoki,&nbsp;Yann Leseigneur,&nbsp;Mathieu Vincendon,&nbsp;Yasumasa Kasaba,&nbsp;Hiromu Nakagawa,&nbsp;Thomas Gautier,&nbsp;Aymeric Spiga,&nbsp;Tanguy Bertrand,&nbsp;Franck Montmessin,&nbsp;Kazunori Ogohara,&nbsp;Takeshi Imamura,&nbsp;Isao Murata,&nbsp;John Carter","doi":"10.1029/2025JE008987","DOIUrl":"10.1029/2025JE008987","url":null,"abstract":"<p>Local Dust Storms (LDS) are defined as dust storm phenomena that cover an area smaller than 1.6 × 10⁶ km² or persist for less than three sols. The study of LDS is critical for understanding dust transport processes in both horizontal and vertical directions and the evolution of large-scale dust storms on Mars. However, the relatively small scale and short lifetime make it difficult to detect with previous studies. OMEGA onboard Mars Express (MEx) has conducted spectroscopic measurements with high spatial resolution (up to ∼400 m/pixel). Here, we present a method to retrieve dust optical depth and detect LDS using the 2.77 μm CO₂ absorption band. At this wavelength, photons are absorbed before reaching the surface, and the photons collected by OMEGA have been scattered around 20–30 km altitude by dust. We have detected 146 LDS events from the retrieved dust optical depth in MY27-29. The LDS were generally observed in the southern summer season, while frequent occurrences of LDS were observed during the northern summer (Ls = 130°–150°) in MY27. The remarkable increase in LDS is also identified just before the global dust storm in MY28. We found a peak in the probability of LDS around noon in both seasons, Ls = 0°–180° and Ls = 180°–360°. In Ls = 0°–180°, high probability areas are found only in specific regions, such as Chryse Planitia. The probability areas expands over a wide range, except high-latitude north of 40°N in Ls = 180°–360°. These findings highlight the spatiotemporal roles LDS play in dust transport, providing insights into the dust cycle (245/250 words).</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE008987","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145038467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain Localization Along Aphrodite Terra's Chasmata System, Venus: The Role of Frictional Melting and Fault-Melt Interaction","authors":"Thomas Kenkmann,&nbsp;Oguzcan Karagoz,&nbsp;Monika Gurau","doi":"10.1029/2025JE008964","DOIUrl":"10.1029/2025JE008964","url":null,"abstract":"<p>We analyze large-scale shear zones that are exposed along the equatorial chasmata of Eastern Aphrodite Terra to understand the role of strain localization in the deformation of the Venusian crust. These shear zones dip at low angles opposite to the slopes, forming terraces that expose portions of the shear planes. Patchy areas associated with the shear zones form rugged hilly terrains surrounded by radar-smooth plains of presumably low-viscosity material. The hanging wall and footwall of the shear zones and the associated rugged terrain, and smooth surfaces show distinct differences in radar emissivity suggesting lithological contrasts. We propose here that the fault planes are coated with melt films extruding alongside fault breccia. While frictional melting should be enhanced on Venus due to higher ambient temperatures and the presence of water-free mafic rocks, their volumes are likely too small to be detected in synthetic aperture radar data. We suggest that these faults act as conduits transporting magma from shallow subsurface reservoirs to the surface. Melt veneers reduce friction along the fault planes, allowing normal faulting at shallow dips. The trough asymmetries suggest that the faults were initiated as thrust faults and were later reactivated as normal faults, indicating negative inversion tectonics and a change in the geodynamic state from a convergent to an extensional regime. The delicate features associated with the shear zones suggest that fault activation is geologically young. This is supported by small landslide deposits that were likely triggered by seismic activity of the faults.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE008964","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145038178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Venusian Planetary-Scale Waves Observed by Akatsuki Longwave Infrared Camera: Coupled Rossby-Kelvin Waves and Long-Term Variation","authors":"Hiroyuki Koyama,&nbsp;Takeshi Imamura,&nbsp;Takao M. Sato,&nbsp;Toru Kouyama,&nbsp;Makoto Taguchi","doi":"10.1029/2025JE009108","DOIUrl":"10.1029/2025JE009108","url":null,"abstract":"<p>Planetary-scale waves are expected to be crucial in driving the Venusian planetary-scale atmospheric circulation, including the superrotation. To understand the interaction between the waves and the mean flow, we obtained temporal frequency spectra of the cloud-top brightness temperature using thermal infrared images taken by the Longwave Infrared Camera (LIR) onboard Akatsuki over a period of 10 Venus years. Waves in the equatorial region with periods of around 3.5–4.3 days were identified as Kelvin waves, while waves in the mid-latitude region with periods of about 5.0–6.0 days were identified as Rossby waves. The mid-latitude waves with periods 5.0–6.0 days tend to accompany additional local amplitude maxima near the equator, especially when observed at small emission angles. Considering that the contribution function of LIR extends to lower altitudes for smaller emission angles, the result implies that the waves arise from Rossby-Kelvin instability and the associated Kelvin modes reside below the cloud top. Mid-latitude peaks are also sometimes seen around periods of 3.5–4.0 days and are coupled with equatorial modes, indicative of Rossby-Kelvin instability. The coupled Rossby-Kelvin modes are expected to transport angular momentum equatorward to sustain the superrotation. The mid-latitude modes decay with altitude. The periods and amplitudes of the waves change with time, and the variations seem to correlate with the background wind in such a way that waves with small intrinsic frequencies are less prominent.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009108","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Modeling of Tidally Driven Fractures Interacting With Meltwater Lenses on the Surface of Europa","authors":"John C. N. W. Walding,&nbsp;Adriana Paluszny,&nbsp;Robert W. Zimmerman","doi":"10.1029/2024JE008762","DOIUrl":"10.1029/2024JE008762","url":null,"abstract":"<p>Europa, one of Jupiter's Galilean satellites, presents a complex surface characterized by extensive networks of large-scale lineae, along with smaller-scale fracture patterns and regions of chaos terrain. In this study, a three-dimensional finite element model is employed to investigate the processes governing the propagation of fractures within the moon's outer ice shell and their interaction with subsurface meltwater lenses. Fractures are represented as dynamic, growing features, with their evolution controlled by local stress conditions; the driving tidal stresses are determined using a closed-form analytical model of satellite tidal forcing. Particular emphasis is placed on examining how fracture development varies across different longitudes at a latitude of 30<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math> North, where tidal stresses and surface features are especially pronounced. By systematically modeling fracture evolution in the presence of meltwater lenses, the study assesses their potential to catalyze the formation of chaos terrain. The results demonstrate a clear dependence on longitude, with the most significant fracture-lens interactions occurring near the subjovian point (0<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>), 90<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>E, 180<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>E, and 270<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>E−locations associated with a high gradient in the stress field. The presence of a subsurface lens is found to enhance local fracturing in a manner consistent with the proposed hypothesis for chaos terrain generation.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008762","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple Episodes of Fluid Alteration in Jezero Crater Indicated by MIST Mineral Identifications in PIXL XRF Data From the First 1100 Sols of the Mars 2020 Mission","authors":"Eleanor L. Moreland,&nbsp;Kirsten L. Siebach,&nbsp;Gelu Costin,&nbsp;Mike M. Tice,&nbsp;Joel A. Hurowitz,&nbsp;Allan H. Treiman,&nbsp;Justin I. Simon,&nbsp;Yang Liu,&nbsp;Yueyang Jiang,&nbsp;Arya Udry,&nbsp;Erwin Dehouck","doi":"10.1029/2024JE008797","DOIUrl":"10.1029/2024JE008797","url":null,"abstract":"<p>The Mineral Identification by Stoichiometry (MIST) algorithm can identify mineral species in geochemical data sets. MIST is applied to X-ray fluorescence chemical analyses from the Planetary Instrument for X-ray Lithochemistry (PIXL) on the Mars 2020 <i>Perseverance</i> rover to identify mineral phases in abraded rock targets at Jezero crater. We used a Monte Carlo (MC) error propagation technique to assess confidence in the results. Our study reports 24 high-confidence mineral phases from the first 1100 sols of <i>Perseverance's</i> traverse. Primary mineral groups include plagioclase, pyroxene, and olivine, in agreement with previously published results, and support an (ultra)mafic rock source. Additionally, MIST identified a range of phyllosilicate minerals, including nontronite, saponite, hisingerite, greenalite, minnesotaite, and sepiolite; identification of such alteration phases is essential for constraining the aqueous alteration history of Jezero's rocks. An initial survey of the reported phases suggests multiple, distinct stages of fluid alteration in Jezero's history: high temperature and acidic, moderate temperature and circumneutral, and later stage ambient alkaline conditions. MIST results from PIXL data help determine rocks of interest on Mars' surface for investigation by <i>Perseverance</i> and will also be important for informing analysis of samples when returned to Earth.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008797","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}