Icarus最新文献

{"title":"Seasonal variations of Titan’s haze and mist layers monitored by VIMS-IR onboard Cassini","authors":"Pascal Rannou ,&nbsp;Bruno de Batz de Trenquelléon ,&nbsp;Sébastien Rodriguez ,&nbsp;Benoît Seignovert","doi":"10.1016/j.icarus.2026.116949","DOIUrl":"10.1016/j.icarus.2026.116949","url":null,"abstract":"<div><div>The Cassini orbiter around Saturn monitored Titan with multiple instruments 13 years, between 2004 to 2017. This is about half of a Titan year and this period included a major seasonal change at the North Spring Equinox (NSE) in 2009 that could be observed. The Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini produced a large amount of observations of Titan generally presented under the form of spectro-images. The observations with the IR part of VIMS detector are taken in a spectral range between 0.88 to <span><math><mrow><mn>5</mn><mo>.</mo><mn>12</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> and with a resolving power between R= <span><math><mrow><mi>λ</mi><mo>/</mo><mi>Δ</mi><mi>λ</mi></mrow></math></span> = 120 and 180. The spatial resolution of the images depends on the observation and is few hundreds of meters at the best. In this study, we retrieved the distribution of the photochemical haze (above 80 km) and the condensate mist layer (below 80 km) as a function of latitude, altitude, and tile throughout the Cassini era. We found a haze latitudinal distribution with an extinction increasing from the south to the north at the beginning of the Cassini mission. The distribution evolved around the North Spring Equinox and a turnover was completely achieved at the end of the Cassini mission. This evolution is linked to the stratospheric circulation that blows from the summer hemisphere to the winter polar region. The latitudinal distribution of the mist layer evolves differently than the haze distribution because it depends on both the circulation pattern in the low atmosphere and on the conditions of condensation for several species. The distribution of the mist layer is also modulated with the seasons, but always increases from the equator and inter-tropical latitude band to the poles.</div><div>These results yield a quantitative description of the aerosol layer on Titan and its seasonal evolution. This has been compared with previous works and with the output of the Titan Planetary Climate Model. Producing such results is quite important to constrain climate models. In return, we expect from these climate models to be helpful in fully understanding the meaning of our results and more generally in characterizing Titan’s climate.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"450 ","pages":"Article 116949"},"PeriodicalIF":3.0,"publicationDate":"2026-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146070909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Dynamical evolution of the Uranian satellite system III. The passage through the 7/4 MMR between Miranda and Ariel","authors":"Sérgio R.A. Gomes,&nbsp;Tibi Keizer","doi":"10.1016/j.icarus.2026.116974","DOIUrl":"10.1016/j.icarus.2026.116974","url":null,"abstract":"<div><div>The passage through the <span><math><mrow><mn>5</mn><mo>/</mo><mn>3</mn></mrow></math></span> mean-motion resonance between Ariel and Umbriel, two of Uranus’s largest moons, still raises several open questions. Previous studies suggest that, in order to reproduce the current orbital configuration, Ariel must have had an eccentricity of approximately ∼0.01 before the resonance encounter, which would prevent resonant capture. However, the rapid tidal circularization of Ariel’s orbit implies that some prior mechanism must have excited its eccentricity before the resonance encounter. In this work, we performed a large number of simulations using an <span><math><mi>N</mi></math></span>-body integrator to assess whether the earlier <span><math><mrow><mn>7</mn><mo>/</mo><mn>4</mn></mrow></math></span> mean-motion resonance between Miranda and Ariel could serve as a mechanism to increase Ariel’s eccentricity. Our results show that, due to divergent migration, resonance capture does not occur. As the satellites cross the nominal resonance, Ariel’s eccentricity is only excited to <span><math><mrow><mn>3</mn><mo>.</mo><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>, substantially smaller than the required value. Therefore, the <span><math><mrow><mn>7</mn><mo>/</mo><mn>4</mn></mrow></math></span> mean-motion resonance is not a viable mechanism for increasing Ariel’s eccentricity.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"450 ","pages":"Article 116974"},"PeriodicalIF":3.0,"publicationDate":"2026-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Topological analysis of Europa’s fracture networks","authors":"V.F. Peixoto ,&nbsp;B.E. Morgado ,&nbsp;F.M.W. Tognoli ,&nbsp;C. Haslebacher","doi":"10.1016/j.icarus.2026.116943","DOIUrl":"10.1016/j.icarus.2026.116943","url":null,"abstract":"<div><div>Europa’s surface is dominated by lineaments that record its tectonic evolution and provide key constraints on ice-shell dynamics. While previous studies have primarily relied on descriptive mapping, here we apply a quantitative framework integrating geometric and topological analyses to characterize fracture networks within high-resolution Galileo SSI mosaics. Lineaments were mapped using the deep learning tool <span>LineaMapper</span> followed by manual refinements in QGIS, producing a consistent dataset across two representative areas located in the leading and trailing hemispheres. From these networks, we computed spacing, density (<span><math><msub><mrow><mi>P</mi></mrow><mrow><mn>21</mn></mrow></msub></math></span>), and orientation, and performed a topological analysis with the Python package Fractopo. Within the specific areas investigated, the trailing-hemisphere area exhibits higher lineament density, greater node frequency, and more segmented networks, whereas the leading-hemisphere area contains longer, more continuous lineaments with lower connectivity. Orientation patterns further show that longer fractures preferentially align E–W, consistent with tidal stress predictions. These results indicate that fracture networks in the examined sectors are moderately connected and spatially heterogeneous, reflecting local variations in stress and terrain type. The integrated approach presented here provides a quantitative baseline for future studies and will be particularly valuable for interpreting the unprecedented spatial coverage and resolution expected from ESA’s JUICE and NASA’s Europa Clipper missions.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116943"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145957674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"On the forced orbital plane of the Hilda asteroids","authors":"Ian C. Matheson ,&nbsp;Renu Malhotra","doi":"10.1016/j.icarus.2026.116959","DOIUrl":"10.1016/j.icarus.2026.116959","url":null,"abstract":"<div><div>Hilda-group asteroids librate in Jupiter’s interior 3:2 mean motion resonance. We estimate that the Hilda group is observationally complete up to absolute magnitude <span><math><mrow><mi>H</mi><mo>≤</mo><mn>16</mn><mo>.</mo><mn>3</mn></mrow></math></span>. This provides a statistically useful sample of thousands of resonant objects, all within a narrow range of semi-major axes, to compare with theoretical expectations of their orbital distribution from dynamical theory. We use von Mises–Fisher statistics to calculate the sample mean planes and mean plane uncertainties for the Hilda group and its Hilda, Schubart, and Potomac collisional subfamilies. Although Laplace–Lagrange linear secular theory is considered inapplicable within mean motion resonances, we find that the Laplace plane and the orbital plane of Jupiter are both statistically indistinguishable from the sample mean plane of the Hildas. In future work, we intend to extend this investigation to resonant populations in the Kuiper belt so as to further test the validity of Laplace–Lagrange linear secular theory for the mean planes of resonant populations.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116959"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Terahertz characteristics of regolith simulants: Effects of bulk density and water content on electromagnetic response for planetary remote sensing","authors":"Suyun Wang,&nbsp;Kazuma Hiramatsu","doi":"10.1016/j.icarus.2025.116911","DOIUrl":"10.1016/j.icarus.2025.116911","url":null,"abstract":"<div><div>Electromagnetic properties of regolith are critical for understanding planetary subsurface structure and resource potential. However, their behavior in the terahertz (THz) frequency range remains poorly characterized. THz waves are particularly sensitive to fine-grained structure and hydration state, offering new opportunities for high-resolution planetary subsurface sensing. To investigate these interactions, we performed THz reflection measurements on FJS-1 lunar regolith simulants while varying bulk density (1.44–1.81 g/cm<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>) and volumetric water content (0–46.1%). Measurements were conducted across 220–500 GHz using dual polarizations (HH, VV) and angle-resolved configurations (20–70° incidence angles). Results show clear density and hydration dependence of THz reflection coefficients, with Brewster angle shifts indicating changes in dielectric contrast. VV polarization demonstrated significantly higher sensitivity to both variables than HH polarization, enabling improved discrimination of subsurface properties. Results provide new experimental constraints on THz wave propagation in granular materials under controlled conditions, establishing a measurement framework applicable to future planetary remote sensing strategies for landing site assessment and water detection.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116911"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Mastcam-Z analog spectral imager (MASI): A Mastcam-Z testbed and field instrument","authors":"M.N. Barrington ,&nbsp;C.D. Tate ,&nbsp;A.G. Hayes","doi":"10.1016/j.icarus.2026.116948","DOIUrl":"10.1016/j.icarus.2026.116948","url":null,"abstract":"<div><div>Mastcam-Z is a stereoscopic, zoomable multispectral imaging system located on the Remote Sensing Mast (RSM) of the Perseverance Rover. Mastcam-Z is the first zoomable multispectral imaging system flown on a NASA spacecraft. The Mastcam-Z Analog Spectral Imager is a Mastcam-Z emulator built at Cornell University for three primary purposes: 1) to serve as a testbed for the pre-flight radiometric and geometric calibration of Mastcam-Z, 2) to characterize Mastcam-Z anomalies observed during calibration and operation, and 3) to act as a field instrument for collecting terrestrial analog multispectral data with the same resolution and spectral characteristics as Mastcam-Z images. MASI is engineered using a combination of commercial off-the-shelf (COTS) components and Mastcam-Z flight spare hardware and is calibrated using a similar set of algorithms to Mastcam-Z. Herein, we show that MASI produces reflectance values that are similar to Mastcam-Z laboratory and inflight values, and provide a detailed description of MASI's hardware, software, and spectral data products.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116948"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Alkali recondensation into chondrules","authors":"Emmanuel Jacquet ,&nbsp;Yves Marrocchi ,&nbsp;Sébastien Charnoz","doi":"10.1016/j.icarus.2026.116970","DOIUrl":"10.1016/j.icarus.2026.116970","url":null,"abstract":"<div><div>While sub-mm melt droplets should rapidly lose alkali elements in a vacuum at liquidus temperatures, chondrules are only modestly depleted in them (by less than one order of magnitude). The detection of sodium in olivine cores has previously suggested very high saturating partial pressures of gaseous sodium, but we show that alkalis were lost during heating and recondensed at lower temperatures, essentially in the present-day chondrule mesostases. This recondensation was accompanied by mass-dependent enrichment in light isotopes (for multi-isotope alkalis such as K and Rb), but its limited extent indicates a cooling acceleration (or “quenching”). The isotopic fractionation also constrains the ratio of the chondrule density and the cooling rate prior to the quench around <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> kg.m<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></math></span>.K<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>.h suggesting densities above <span><math><mo>∼</mo></math></span> 10<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>. In a nebular context, this is achievable by radial and vertical concentrations near pressure bumps.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116970"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Inferring meteoroid properties with dynamic nested sampling: A case study of orionid and capricornid shower meteors","authors":"Maximilian Vovk ,&nbsp;Peter G. Brown ,&nbsp;Denis Vida ,&nbsp;Daeyoung Lee ,&nbsp;Emma G. Harmos","doi":"10.1016/j.icarus.2026.116963","DOIUrl":"10.1016/j.icarus.2026.116963","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Importance:&lt;/h3&gt;&lt;div&gt;Accurate estimation of meteoroid bulk density is crucial for assessing spacecraft impact hazards of sub-millimeter to millimeter-sized meteoroids, which represent the bulk of the hazard.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Research Gap:&lt;/h3&gt;&lt;div&gt;Previous studies utilized manual or optimization methods for fitting numerical meteoroid ablation and fragmentation models to optical meteor observations. However, these methods struggled with reliably estimating meteoroid physical properties and the associated uncertainties due to the subjectivity of the modeling approach.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Objective:&lt;/h3&gt;&lt;div&gt;We aim to develop a global and statistically robust optimization method for inferring the physical properties of individual meteors, focusing on bulk density and fragmentation behavior, using multi-instrument optical data.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Methodology:&lt;/h3&gt;&lt;div&gt;We apply Dynamic Nested Sampling to fit an erosion-fragmentation model to measurements of meteor light curve and deceleration. The method was applied to 15 shower meteors observed by the Canadian Automated Meteor Observatory’s (CAMO) mirror tracking and Electron-Multiplied Charge Coupled Device (EMCCD) systems. The method yields posterior distributions and Bayesian evidences for single and double fragmentations.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Key Findings:&lt;/h3&gt;&lt;div&gt;Validation against four synthetic test cases demonstrated accurate recovery of known inputs, with best-guess solutions matching true parameters. We applied this method to 9 Orionids (ORI) and 6 &lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; Capricornids (CAP) ranging in mass from &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;mo&gt;−&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; to &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;mo&gt;−&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; kg. The median bulk density was measured as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;15&lt;/mn&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;9&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;57&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;558&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; kg/m&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; for Orionid meteors and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;33&lt;/mn&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;114&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;1089&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; kg/m&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; for Capricornid meteors. These results are consistent with earlier studies: Orionids exhibit characteristics expected for meteoroids of cometary origin, whereas &lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; Capricornids show systematically higher bulk densities. The CAP results show a second cluster around 1300 kg/m&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, more inline with higher density asteroidal material, but our method achieves this using a more consistent and statistically robust estimation of uncertainties.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Implications:&lt;/h3&gt;&lt;","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116963"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Limit cycles and the climate history of Mars","authors":"Jacob Haqq-Misra","doi":"10.1016/j.icarus.2026.116945","DOIUrl":"10.1016/j.icarus.2026.116945","url":null,"abstract":"<div><div>Evidence for fluvial features and standing liquid water indicate that Mars was a warmer and wetter place in its past; however, climate models have historically been unable to produce conditions to yield a warm early Mars under the faint young sun. Some models invoke thick greenhouse atmospheres to produce continuously warm conditions, but others have argued that available geologic evidence is more consistent with short-duration and transient warming events on an otherwise cold Mars. One possibility of harmonizing these perspectives is that early Mars experienced climate limit cycles that caused the climate to oscillate between short periods of warmth and prolonged periods of glaciation, due to modulation of greenhouse warming by the carbonate-silicate cycle. This study suggests that episodic limit cycling during the Noachian and Hesperian periods provides a hypothetical explanation for the timing and formation of fluvial features on Mars. A schematic time-forward trajectory of the full history of Mars is calculated using an energy balance climate model, which includes an active carbonate-silicate cycle, instellation changes due to the sun’s main sequence evolution, variations in the obliquity of Mars, and supplemental warming from additional greenhouse gases beyond carbon dioxide alone. These calculations demonstrate the viability of a climate history for Mars involving episodic limit cycling to enable the formation of the valley networks at 4.1-3.5<!--> <!-->Ga and delta features at 3.3-3.0<!--> <!-->Ga, interspersed with cold stable climates and ending in the late Amazonian in a carbon dioxide condensation regime. This schematic climate trajectory provides a plausible narrative that remains consistent with available geologic data, and further exploration of warming mechanisms for the climate of Mars should consider the possibility of episodic transient events driven by carbonate-silicate limit cycling.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116945"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Detecting and measuring Transverse Aeolian Ridges on Mars using deep learning","authors":"Alexander M. Barrett ,&nbsp;Matthew R. Balme ,&nbsp;Elena A. Favaro ,&nbsp;Mark J. Woods ,&nbsp;Mateusz Malinowski ,&nbsp;Laila Elsarky ,&nbsp;Kylash Rajendran ,&nbsp;James A. Holmes ,&nbsp;Manish R. Patel","doi":"10.1016/j.icarus.2026.116947","DOIUrl":"10.1016/j.icarus.2026.116947","url":null,"abstract":"<div><div>In this investigation, a Deep Learning (DL) approach was applied to measure the morphometry of Transverse Aeolian Ridges (TARs) on the surface of Mars. A large sample of TARs was segmented from High Resolution Imaging Science Experiment (HiRISE) images, the highest resolution remote sensing dataset presently available for the planet. HiRISE images located between 50°N and 50°S, and from all longitudes were selected. Morphometric parameters such as area, elongation, and orientation were retrieved for this sample using a supervised instance segmentation and geospatial analysis pipeline. The result is the most extensive catalogue of TAR morphometry to date extracted from ∼14 million candidate TARs in ∼7000 HiRISE Images. This was accomplished by training off-the-shelf DL models within a Geographic Information System (GIS) environment. A significant TAR population was found in approximately half of the images surveyed. TAR area, and the lengths of the long and short axes, were found to exhibit a positively skewed log-normal distribution; the median short axis length is 5 m, while the median long axis is 24 m. Median elongation is 0.24. Global TAR orientations are varied, although North-South oriented TARs are the most populous group. This is likely due to the strong east blowing winds predicted by GCM simulations of the modern martian climate. Here we present our latest results and use TAR orientation statistics to describe the emerging picture of global wind patterns on Mars during TAR forming epochs.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116947"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}