Journal of Geophysical Research: Planets最新文献

{"title":"Iron Isotope Fractionation on Vesta Driven by Magma Ocean Process","authors":"Jinting Kang,&nbsp;Zhengyu Hou,&nbsp;Haochen Yang,&nbsp;Xue Tang,&nbsp;Weibiao Hsu,&nbsp;Fang Huang","doi":"10.1029/2026JE009894","DOIUrl":"https://doi.org/10.1029/2026JE009894","url":null,"abstract":"<p>Magma oceans represent a pivotal stage in the early evolution of terrestrial planets. Early-formed asteroids, driven by the decay of ²⁶Al, may have also experienced such magma ocean processes. To investigate potential magma ocean differentiation on asteroid 4 asteroids, we reported high-precision iron isotope data for 25 eucrites and 13 diogenites. Eucrites exhibit a δ⁵⁶Fe range of approximately 0.1‰, varying from −0.044 to 0.073‰, with a mean value of 0.020 ± 0.013‰ (2SE, <i>N</i> = 25). Diogenites display δ⁵⁶Fe ranging from −0.051 to 0.018‰, yielding an average of −0.004 ± 0.011‰ (2SE, <i>N</i> = 13). The observed Fe isotope variation and offset between eucrites and diogenites cannot be produced by terrestrial weathering, impacts, and core formation. Combined with MELTS modeling using two different initial compositions for Vesta, the isotope variation can be explained by magma ocean differentiation. A cross-planetary comparison is made with the Moon, where magma ocean differentiation and associated Fe isotope variations have been extensively studied. Vestan samples exhibit remarkably limited δ⁵⁶Fe variation (∼0.1‰) compared to lunar basalts (∼0.3‰). This dichotomy may reflect distinct magma ocean evolution pathways across planetary bodies: later pyroxene crystallization, the absence of ilmenite-driven mantle overturn, and rapid cooling in the case of Vesta. Thus, planetary geochemical diversity is fundamentally shaped by magma ocean dynamics modulated by body size, composition, and thermal history.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145493","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":"High-Fidelity Lunar Mare Agglutinates and Their Mechanical Effects on Lunar Regolith Simulants","authors":"Shun Wang,&nbsp;Yue Teng,&nbsp;Yifei Cui,&nbsp;Ao Luo,&nbsp;Dianqing Li","doi":"10.1029/2026JE009810","DOIUrl":"https://doi.org/10.1029/2026JE009810","url":null,"abstract":"<p>Lunar agglutinates, which are glass-rich aggregates formed through space weathering, are a key constituent of lunar regolith and strongly influence its engineering properties. This study develops a high-fidelity agglutinate simulant via high-temperature vacuum sintering, yielding particle morphology and chemical composition similar to those of Chang'e-5 samples. The effects of key sintering parameters, including temperature, binder fraction, structural support agent content, and dwell time, on the microstructure and single-particle compression strength are investigated. Furthermore, a new lunar regolith simulant (WHU-1A) is produced by incorporating different agglutinates, and its mechanical response is assessed through angle-of-repose and small-scale triaxial tests. The results demonstrate that, under controlled density conditions, agglutinate characteristics significantly influence regolith mechanical behavior. Weakly bonded agglutinates induce a limited increase in shear strength, whereas extensively melted agglutinates markedly enhance shear strength but also promote strain softening. This coupled strengthening–softening effect is most pronounced in specimens with high glass content.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145512","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":"3D Architecture of Kodiak Butte as Evidence of Fluvial or Shoal-Water Environments in Jezero Crater, Mars","authors":"O. A. Kanine,&nbsp;M. P. Lamb,&nbsp;B. L. Ehlmann,&nbsp;J. P. Grotzinger,&nbsp;C. D. Tate","doi":"10.1029/2026JE009882","DOIUrl":"https://doi.org/10.1029/2026JE009882","url":null,"abstract":"<p>The Mars 2020 mission has explored depositional environments recorded in a fan-shaped deposit on the western side of Jezero crater. Kodiak butte is an isolated outcrop of sedimentary rock ∼1 km south of the western fan scarp and may be an erosional remnant of said fan. Sedimentary strata of Kodiak butte were first interpreted to represent Gilbert delta foresets and a lake depth of at least 10 m. Subsequent closer-range images of the northern face of Kodiak have resolved additional details of stratal geometries, permitting alternative interpretations of depositional environments. Rover visible-wavelength images, a three-dimensional digital outcrop model, and principal component analysis-based plane-fitting allow detailed facies mapping and measurements of stratal geometries in Kodiak. We observed three sets of gravel-bearing, steeply inclined beds ∼3, ∼7, and ∼10 m thick with local accretion directions ranging from ∼NW clockwise to ∼SW (covering ∼230° azimuth). These sets are interpreted as deposits from downstream-migrating bars with lobate geometries, consistent with mid-channel bars in a braided river or mouth bars in a shoal-water delta. The geometry of the inclined beds indicate channelized bankfull flow ∼4.2 m deep under persistent currents flowing south-southeast to south-southwest. The proposed hydrodynamic conditions, potentially continuous with the rest of the western fan succession, are high energy with limited settling of fine-grained sediment from suspension in a quiescent setting, indicating a lower biosignature preservation potential than previously hypothesized.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009882","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149072686","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":"Coupled Effects of Grain Size and Metallic Iron on Spectral and Polarimetric Properties of Lunar Simulants","authors":"Eunjin Cho,&nbsp;Seungju Han,&nbsp;Young-Jae Kim,&nbsp;Serin Kim,&nbsp;Keewook Yi,&nbsp;Eunji Yi,&nbsp;Dongha Shin,&nbsp;Enxi Jin,&nbsp;Mingyeong Lee,&nbsp;Chae Kyung Sim,&nbsp;Minsup Jeong","doi":"10.1029/2026JE009905","DOIUrl":"https://doi.org/10.1029/2026JE009905","url":null,"abstract":"<p>The lunar surface is heterogeneous in grain size and metallic iron abundance due to diverse histories of space weathering. The spectral and polarimetric properties of the lunar regolith are strongly affected by both grain size and metallic iron particles. However, because physical and chemical alteration processes are closely coupled in their effects on optical properties, their combined influence remains poorly constrained. In this study, lunar simulants (JSC-1A and KLS-1) were sieved into two bulk-type and three size-separated fractions, and hydrogen reduction was conducted to produce metallic iron particles on grain surfaces. The spectral and polarimetric properties of these samples were then systematically measured. After reduction, reflectance decreases while the degree of positive polarization increases, consistent with Umov's law. In addition, reflectance contrasts among grain sizes are reduced because fine grains preferentially darken, whereas the polarization–albedo relation remains sensitive to grain size. The reflectance of bulk-type fractions is intermediate, unlike that of natural bulk lunar soils, which resembles the finest fractions. In contrast, the polarization–albedo behavior of bulk-type fractions is close to that of the finest fraction. These differences from natural lunar soils suggest that agglutinates, which are absent in our reduced samples, may be important for the optical properties of natural bulk lunar soils. Further comparisons using natural lunar soils will help clarify the relative roles of agglutinates and grain-surface weathering products in controlling the optical properties of lunar regolith.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009905","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149072685","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":"Stratigraphic Partitioning of Evaporites Through the Clay-Sulfate Transition in Gale Crater, Mars","authors":"W. Rapin,&nbsp;G. Dromart,&nbsp;G. Caravaca,&nbsp;J. Schieber,&nbsp;D. Rubin,&nbsp;L. Edgar,&nbsp;S. Gupta,&nbsp;A. Roberts,&nbsp;T. Magnin,&nbsp;B. Clark,&nbsp;L. Kah,&nbsp;R. Sheppard,&nbsp;M. Loche,&nbsp;O. Gasnault,&nbsp;D. Burtt,&nbsp;E. Dehouck,&nbsp;S. Le Mouélic,&nbsp;A. R. Vasavada","doi":"10.1029/2026JE009783","DOIUrl":"https://doi.org/10.1029/2026JE009783","url":null,"abstract":"<p>Changing surface conditions on Mars during the Hesperian eon (∼3.6–3.0 billion years ago) produced widespread stratal sequences transitioning from clay to sulfate-bearing according to orbital data. Using data collected in situ at Gale crater by the Curiosity rover, we examined both the sedimentology and geochemistry of a 210-m-thick succession across a reference clay-sulfate transition. Four intervals (A–D) are defined based on both sedimentary structures and nodule distribution and composition, reflecting changes in depositional setting and diagenetic parameters. Large trough cross-beds, which become prevalent within interval A and dominate intervals B and C, are interpreted to indicate eolian processes, whereas dark-toned lens-shaped sandstone bodies in interval C point to recurring fluvial incursions. Planar bedding in uppermost interval D suggests damp or wet interdune conditions. ChemCam analyses show nodules are enriched in calcium and magnesium sulfates. The highest observed nodule densities coincides with strata interpreted to reflect damp or wet depositional environments (A, C, D), whereas their near-absence corresponds to the interval interpreted as the driest (B). We propose that this stratigraphic partitioning of the type, density, and sulfate-content of nodules indicates that they mostly formed during early diagenesis via capillary evaporation in the shallow subsurface, with only subordinate late-stage remobilization. The preserved strata record fluctuations in water availability and sediment supply, driven by repeated changes in climate, rather than by a single drying trend. These observations suggest new constraints on the fate of sulfur on early Mars and sulfate evaporite formation within sedimentary basins.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009783","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146771","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":"Phase Stability of Fe–Si Alloy at Super-Earth Core Conditions","authors":"Vinay Rastogi,&nbsp;Raymond F. Smith,&nbsp;Melissa Sims,&nbsp;Martin G. Gorman,&nbsp;Marius Millot,&nbsp;Todd C. Hufnagel,&nbsp;June K. Wicks","doi":"10.1029/2026JE009891","DOIUrl":"https://doi.org/10.1029/2026JE009891","url":null,"abstract":"<p>Silicon is proposed to be a major impurity in the Fe-rich cores of the Earth and large rocky exoplanets, where it may influence the density, phase equilibrium, and thermal evolution of planetary interiors. Here, we constrain the composition-dependent phase boundary between hcp and B2 stability in Fe–Si alloys at terapascal (TPa) pressures (1 TPa = 1,000 GPa = 10 million atmospheres), using Fe–11 wt.%Si as an intermediate composition. By employing laser-driven ramp compression combined with nanosecond in situ X-ray diffraction, we determined that Fe–11 wt.%Si retains a hexagonal-closed-packed (hcp) structure up to pressures of 1.15 TPa. This data set, compared to previous studies, shows that at these extreme pressure states there is a transition from hcp <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>→</mo>\u0000 </mrow>\u0000 <annotation> $to $</annotation>\u0000 </semantics></math> B2 stability for Si wt.% impurities in the 11%–15% range. These results provide new constraints on Fe–Si phase boundaries and improve the understanding of equations of state and compositions relevant to the core of super-Earth planets. We used our experimental results to calculate the mass–radius relationships for planets composed of a Fe–Si core and a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>M</mi>\u0000 <mi>g</mi>\u0000 <mi>S</mi>\u0000 <mi>i</mi>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>3</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> $MgSi{O}_{3}$</annotation>\u0000 </semantics></math> mantle. The results suggest that some exoplanets previously modeled with a pure Fe core may have larger cores when silicon impurities are considered.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048478","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":"Investigating Galactic Cosmic Ray Ionization’s Contribution to Aerosol Formation on Neptune and a Potential Link to the Relationship Between Brightness and Solar Activity","authors":"Martin B. B. Enghoff,&nbsp;Paul N. Romani,&nbsp;John E. P. Connerney,&nbsp;John L. Jørgensen","doi":"10.1029/2025JE009520","DOIUrl":"https://doi.org/10.1029/2025JE009520","url":null,"abstract":"<p>In this work we investigate how ionization from Galactic Cosmic Rays (GCRs) can affect aerosol nucleation on Neptune and discuss potential implications for the observed brightness variations that appear to follow the solar cycle. We calculate the planetary vertical cutoff rigidity for Neptune based on the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>8</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}_{8}$</annotation>\u0000 </semantics></math> magnetic field model and a modified version of the particle trajectory code the Geomagnetic Cutoff Rigidity Computer Program. By combining the cutoff rigidity with the known GCR spectrum we calculate the proton flux into the atmosphere of Neptune at the 49 km level above 1 bar (0.082 bar, 53 K) at both solar minimum and maximum and find it to vary between a factor 1.2 and 2.2 in the areas of high proton flux, depending on the cosmic ray spectrum used. Using the Infrared Space Observatory nominal atmospheric profile and methane supersaturation scenarios based upon observations of the methane fraction, we then calculate vertical profiles of neutral homogeneous and ion-induced nucleation rates to identify potential altitudes sensitive to ion-induced nucleation induced by GCRs. We construct a planetary map of potential ion-induced nucleation hotspots. Using this map and the variation of sub-Earth latitude of Neptune, we then investigate a potential bias in brightness observations of Neptune. We find that it could potentially help explain the shift between anti-correlation and direct correlation of solar activity and the brightness of Neptune, but note that there are currently too many variables to conclude with confidence to what degree our explanation contributes.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009520","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048440","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":"Visible to Near-Infrared Properties of Felsic Rocks: Plagioclase Detection Limits and Applications to Mars Orbital Spectra","authors":"Hunter Vannier,&nbsp;Briony H. N. Horgan,&nbsp;Michael Phillips,&nbsp;Michael Eddy,&nbsp;Rebecca Greenberger,&nbsp;Arya Udry","doi":"10.1029/2026JE009705","DOIUrl":"https://doi.org/10.1029/2026JE009705","url":null,"abstract":"<p>Widespread plagioclase detections on Mars using orbital visible to near infrared (VNIR) reflectance spectra have led to multiple interpretations of “feldspathic” terrain, ranging from ancient crustal material and evolved plutons to volcanic lava flows. A systematic, laboratory-based study of plagioclase detectability in whole igneous rocks is needed to contextualize these detections. We analyzed 42 feldspar-bearing igneous rocks (∼50–77 wt.% SiO₂; ∼25–60 vol.% plagioclase) using VNIR and mid-infrared (MIR) laboratory spectra, bulk chemistry/mineralogy, microscopic analyses of rock texture, and plagioclase chemistry to assess the characteristics influencing plagioclase signatures in whole-rock spectra. We find that 1.25 μm absorption bands are common in intrusive samples, and that plagioclase can be spectrally detected at abundances &lt;40 vol.%, even in the presence of ∼20 vol.% mafic hydrous minerals. We find that large (mm-scale) grain size is a driver of plagioclase detection, and that oxides are highly effective at subduing absorption bands. Plagioclase with a wide range of compositions (An_25–47,90) can produce a 1.25 μm absorption, unless iron-depleted (&lt;0.13 wt.% FeO). Alteration can obscure the 1.25 μm absorption, causing rocks with similar plagioclase abundances and chemistries to exhibit different bulk VNIR spectra. Unambiguous detection of feldspathic rocks on Mars is only likely for: (a) plagioclase-rich crust (e.g., anorthosites or other plagioclase cumulates), (b) intrusive felsic rocks with limited alteration and plagioclase with iron &gt;0.13 wt.%, and (c) plagioclase-phyric effusive rocks with little or no mafic phenocrysts. MIR spectra can distinguish felsic (granite, granodiorite, monzonite) and mafic (anorthosite, basalts) rocks with similar 1.25 μm absorptions.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009705","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146656","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":"Crustal Magnetic Control of the Martian Oxygen Corona","authors":"Wenlong Li,&nbsp;Hao Gu,&nbsp;Jun Cui,&nbsp;Xu Huang,&nbsp;Shiqi Wu,&nbsp;Wenjun Liang,&nbsp;Jiang Yu,&nbsp;Lei Li","doi":"10.1029/2025JE009573","DOIUrl":"https://doi.org/10.1029/2025JE009573","url":null,"abstract":"<p>Crustal magnetic fields on Mars play a crucial role in regulating interactions between the solar wind and the upper atmosphere. While previous studies have mainly examined their effects on ionospheric plasma, their potential influence on the neutral atmosphere has remained largely unexplored. Here we present the first comprehensive assessment of how crustal magnetism affects the Martian oxygen corona. By combining Mars Atmosphere and Volatile EvolutioN (MAVEN) Neutral Gas and Ion Mass Spectrometer and Langmuir Probe and Waves observations with numerical modeling, we show that in regions of strong crustal magnetization, enhanced <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>O</mi>\u0000 <mn>2</mn>\u0000 <mo>+</mo>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}_{mathrm{2}}^{+}$</annotation>\u0000 </semantics></math> and electron densities, together with reduced electron temperature, create favorable conditions for the production of hot O through dissociative recombination. Model results indicate that the oxygen corona in strong-field regions is about 36% denser than in weak-field regions. By integrating the modeled upward hot O flux above the local escape energy at the exobase, we further find that the escape rate of neutral hot O is enhanced in strong-field regions by about 38%. In addition, the elevated exospheric O density in strong-field regions increases <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>O</mi>\u0000 <mo>+</mo>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}^{+}$</annotation>\u0000 </semantics></math> production, potentially facilitating solar wind pickup and enhancing <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>O</mi>\u0000 <mo>+</mo>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}^{+}$</annotation>\u0000 </semantics></math> escape above the exobase. These findings reveal that crustal magnetic fields indirectly modulate the Martian oxygen corona and can enhance both the escape of neutral hot O and the production of exospheric <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>O</mi>\u0000 <mo>+</mo>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}^{+}$</annotation>\u0000 </semantics></math> available for pickup escape through their effects on the upper atmospheric plasma environment.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048518","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":"Martian Sand Dunes as Natural Ice Sensors: How to Identify Ice Composition From Dune-Ice Morphology","authors":"Jacob M. Widmer,&nbsp;Mackenzie Day,&nbsp;Serina Diniega","doi":"10.1029/2026JE009760","DOIUrl":"https://doi.org/10.1029/2026JE009760","url":null,"abstract":"<p>The seasonal exchange of martian volatiles between the atmosphere and surface drives the formation and modification of gullies, spiders, and other surface features on Mars. Studies of such seasonal ice-driven activity rely on correct interpretations of ice composition and coverage. However, data sets that discriminate ice composition often have coarse resolution or limited spatial coverage. In this work, we investigate whether the surface morphological patterns of seasonal ice on sand dunes reflect different ice compositions and thus could be used to interpret the meter-scale ice environment over the dunes. Using HiRISE images collected over sand dunes in the northern mid-latitudes (30–65°N), we grouped observations by patterns in dune-ice morphology and interpreted the ice composition of each group. Interpretations of ice composition were then compared to the ice compositions derived from coincident thermal and spectral observations. We found that dune ice with both a high surface brightness and sublimation spots or cracks corresponded to CO₂ ice, whereas dunes that exhibited increased surface brightness without sublimation spots or cracks corresponded to H₂O ice. These interpretations are corroborated by prior seasonal ice cap mapping results, surface temperature observations, and the position of spectrally derived seasonal ice cap edges, despite orders-of-magnitude differences in data set resolution. This work provides a new opportunity to probe the martian seasonal H₂O cycle while also improving landform-scale ice composition interpretations for studies of surface features thought to form from ice-regolith interactions.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009760","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146750","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}