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Predominance of porphyritic textures in chondrules due to density sorting of precursor materials? Constraints from melting experiments
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-16 DOI: 10.1016/j.icarus.2025.116510
Scott A. Whattam
Although chondrule textures are diverse, the absolute number of texture types is relatively small essentially encompassing cryptocrystalline (glassy) to microcrystalline (radial pyroxene), barred, granular, metallic and porphyritic/micro-porphyritic varieties; and the vast majority (∼70–90 %) of all textures are a variety of porphyritic (e.g., porphyritic olivine,). Textural diversity has been attributed to the influence of many variables, e.g., bulk composition, duration of heating, cooling rate and size of precursor phases. Here, I show experimentally that when charges are heated initially at 1550 °C that differences in the bulk compositions have an enormous effect on ultimate texture. I construct several bulk compositions by mixing varied quantities of olivine with plagioclase and pyroxene. When synthetic chondrule materials are heated below their liquidus (maximum 1718 °C), the predominant texture is porphyritic if olivine (liquidus of ∼1844 °C) is abundant. If more easily fusible dust (En + An liquidus of 1429 °C) is abundant, barred and glassy chondrule textures result. Assuming amoeboid olivine aggregates (AOA) are possible precursors, I also replaced olivine by synthetic (pre-sintered) granoblastic olivine aggregates (GOA) and isothermally produced PO chondrule analogs when ‘AOA’ (with En + An) mixtures have Ol: En + An ratios of 99:01 to 30:70, but glass-rich analogs at mixtures with ratios of 20:80 and 10:90. If charges are subsequently cooled at 1000 °C/h to 100 °C/h after an isothermal dwell of 1 h at 1550 °C, PO analogs prevail at ratios of Ol:En + An of 30:70 and (presumably, based on isothermal experiments) higher, barred olivine (BO)-like analogs occur at ratios of 20:80; elongated skeletal hopper olivine (EHO) ensues at ratios of 10:90. Models of chondrule formation have not explained the propensity of PO textures but these experiments suggest simply that the predominance of PO chondrules is largely a function of the abundance of Mg in the chondrule precursors and that the ratio of olivine to dust was high in chondrule precursors. Stratification of chondrule precursors may have occurred before chondrule formation, resulting in a greater volume of denser olivine in the central region and greater volume of less dense, fusible An+En in the periphery. Results are compatible with large chondrule-forming regions with a great variety of chondrules being formed in the same event(s) at the same temperature.
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引用次数: 0
The phase- and color-ratio techniques as applied to Dawn images of the dwarf planet Ceres and asteroid (4) Vesta
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-15 DOI: 10.1016/j.icarus.2025.116507
Ivan G. Slyusarev , Valeria V. Rychahova , Vadym G. Kaydash , Irina N. Belskaya , Yuriy G. Shkuratov , Vasilij G. Shevchenko
Identification of regolith structure anomalies on atmosphereless Solar System bodies is important as an indicator of the surface changes. With the phase ratio method, we are able to map phase curve slopes and distinguish the areas with different regolith optical roughness. These areas are caused by topographic slope processes, formation of new craters and the possible effects of endogenous processes. Global mapping of asteroid (4) Vesta and the dwarf planet Ceres from two orbits High Altitude Mapping Orbit (HAMO) and Low Altitude Mapping Orbit (LAMO) provide the necessary data for applying the phase-ratio technique to these bodies. Using multispectral images from the Dawn Framing Camera (FC) for the dwarf planet Ceres and the asteroid (4) Vesta, phase-ratio and color-ratio methods were applied for selected areas on surfaces of Vesta (Laelia, Laeta, Aricia, Vibidia) and Ceres (Ahuna Mons, craters Occator, Oxo, Xevioso). The phase-ratio method gives us a good tool for both bodies, Ceres and Vesta, to detect changes in regolith structure associated with mass movement due to slope processes on crater walls and hillsides, as well as with ejecta from the youngest craters.
{"title":"The phase- and color-ratio techniques as applied to Dawn images of the dwarf planet Ceres and asteroid (4) Vesta","authors":"Ivan G. Slyusarev ,&nbsp;Valeria V. Rychahova ,&nbsp;Vadym G. Kaydash ,&nbsp;Irina N. Belskaya ,&nbsp;Yuriy G. Shkuratov ,&nbsp;Vasilij G. Shevchenko","doi":"10.1016/j.icarus.2025.116507","DOIUrl":"10.1016/j.icarus.2025.116507","url":null,"abstract":"<div><div>Identification of regolith structure anomalies on atmosphereless Solar System bodies is important as an indicator of the surface changes. With the phase ratio method, we are able to map phase curve slopes and distinguish the areas with different regolith optical roughness. These areas are caused by topographic slope processes, formation of new craters and the possible effects of endogenous processes. Global mapping of asteroid (4) Vesta and the dwarf planet Ceres from two orbits High Altitude Mapping Orbit (HAMO) and Low Altitude Mapping Orbit (LAMO) provide the necessary data for applying the phase-ratio technique to these bodies. Using multispectral images from the Dawn Framing Camera (FC) for the dwarf planet Ceres and the asteroid (4) Vesta, phase-ratio and color-ratio methods were applied for selected areas on surfaces of Vesta (Laelia, Laeta, Aricia, Vibidia) and Ceres (Ahuna Mons, craters Occator, Oxo, Xevioso). The phase-ratio method gives us a good tool for both bodies, Ceres and Vesta, to detect changes in regolith structure associated with mass movement due to slope processes on crater walls and hillsides, as well as with ejecta from the youngest craters.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116507"},"PeriodicalIF":2.5,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445720","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}
引用次数: 0
A case for young igneous volcanism in the Terra Sirenum region, Mars
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-14 DOI: 10.1016/j.icarus.2025.116512
Shreekumari Patel , Harish , S. Vijayan , M.R. El-Maarry
In this study, we concentrate on an large field of 73 cones situated on the floor of an unnamed crater centered at 27.6°S, 156.9°W. This crater has been subjected to detailed investigations by at least three different scientific teams, each supporting various hypotheses like sedimentary and igneous volcanism regarding the cones origins. The cone field is circumferentially distributed around a triad of primary fractures, which have instigated the formation of the graben structure within the crater. The crater floor exhibits a variety of geomorphological and stratigraphic units, suggesting that the crater has undergone a complex history of different episodes of geological events, including volcanism, tectonic activity and potential fluvial processes. Cones display one of two broad morphologies: domical cones and pitted cones. The morphometric analysis of the WCR/WCO in relation to the Cone width of pitted cones aligns with the trends observed in both terrestrial and Martian scoria cones. However, the morphometric measurements of domical cones deviate from the discernible trends typically seen in igneous volcanic structures, sedimentary formations on Earth, and Martian edifices. The cumulative Size-Frequency Distribution (CSFD) analysis indicates the formation of the cone field in the crater occurred between ∼1.26 Ga and ∼1 Ga, corresponding to the Mid-Amazonian epoch. Spectral analysis of the crater floor units indicates the presence of kaolinite, along with low-calcium and high-calcium pyroxene minerals, which could potentially be a marker of volcanic as well as aqueous activities. However, the spectral signature of high-calcium pyroxene in the cone-field bearing crater unit suggests a recent igneous volcanic origin. This study highlights the complex geological history of the unnamed crater, with spectral and morphometric analyses suggesting a likely igneous volcanic origin for the cones amidst evidence of tectonic and aqueous activity.
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引用次数: 0
The mystery of the missing mantle problem and insights from spectroscopy 地幔失踪问题之谜和光谱学的启示
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-11 DOI: 10.1016/j.icarus.2025.116506
B.G. Rider-Stokes , S.L. Jackson , T.H. Burbine , R.C. Greenwood , E.M. MacLennan , L.F. White , S.S. Russell , M. Anand , M.M. Grady
Differentiation of planetesimals results in the segregation of materials, with the densest materials sinking, producing a metallic core, while the lighter fraction, rises, fabricating a crust. While there are multiple examples of planetary crusts (e.g., V-type asteroids) and metallic cores (e.g., M-type asteroids), there appears to be a scarcity of mantle-like materials in both the asteroid (e.g., A-type asteroids) and meteorite record. This lack of olivine-dominated material has been dubbed ‘The Missing Mantle Problem’. Here we measure the reflectance spectra of four olivine-rich meteorites expected to originate from the mantle of differing planetesimals. Following the Bus-DeMeo taxonomy, NWA 12264 and Chassigny can be classified as Sa-types, while NWA 8535 and NWA 15717 are classified as Q-types. This result implies that mantle-like materials are not restricted to A-type asteroids as previously expected. This study provides a significant step toward the resolution of the apparent shortage of olivine-rich material in the early Solar System.
{"title":"The mystery of the missing mantle problem and insights from spectroscopy","authors":"B.G. Rider-Stokes ,&nbsp;S.L. Jackson ,&nbsp;T.H. Burbine ,&nbsp;R.C. Greenwood ,&nbsp;E.M. MacLennan ,&nbsp;L.F. White ,&nbsp;S.S. Russell ,&nbsp;M. Anand ,&nbsp;M.M. Grady","doi":"10.1016/j.icarus.2025.116506","DOIUrl":"10.1016/j.icarus.2025.116506","url":null,"abstract":"<div><div>Differentiation of planetesimals results in the segregation of materials, with the densest materials sinking, producing a metallic core, while the lighter fraction, rises, fabricating a crust. While there are multiple examples of planetary crusts (e.g., V-type asteroids) and metallic cores (e.g., M-type asteroids), there appears to be a scarcity of mantle-like materials in both the asteroid (e.g., A-type asteroids) and meteorite record. This lack of olivine-dominated material has been dubbed ‘The Missing Mantle Problem’. Here we measure the reflectance spectra of four olivine-rich meteorites expected to originate from the mantle of differing planetesimals. Following the Bus-DeMeo taxonomy, NWA 12264 and Chassigny can be classified as Sa-types, while NWA 8535 and NWA 15717 are classified as Q-types. This result implies that mantle-like materials are not restricted to A-type asteroids as previously expected. This study provides a significant step toward the resolution of the apparent shortage of olivine-rich material in the early Solar System.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116506"},"PeriodicalIF":2.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
引用次数: 0
Multi-instrument sounding of a Jovian thunderstorm from Juno
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-10 DOI: 10.1016/j.icarus.2025.116465
Shawn R. Brueshaber , Zhimeng Zhang , John H. Rogers , Gerald Eichstädt , Glenn S. Orton , Davide Grassi , Leigh N. Fletcher , Cheng Li , Shinji Mizumoto , Alessandro Mura , Fabiano Oyafuso , Ramanakumar Sankar , Michael H. Wong , Candice J. Hansen , Steven Levin , Scott Bolton
Thunderstorms play a significant role in transporting heat from the deep interior to space on giant planets. We present observations of a 3,400-km wide thunderstorm complex in Jupiter’s North Equatorial Belt (NEB) during the 38th periapse of the Juno spacecraft on 29 Nov. 2021. Data were acquired by the Microwave Radiometer (MWR), the visible light JunoCam instrument, the Jovian InfraRed Auroral Mapper (JIRAM), and from supporting Earth-based imaging. This was the first time Juno was able to observe a thunderstorm at suitably low emission angles with multiple instruments at close range (5,690 km), making it the most comprehensive close-up assessment of a Jovian thunderstorm to date. Lightning detection confirmed the Storm’s vigorous convective nature. MWR brightness temperatures indicate this Storm appears to be wholly contained within the weather layer, i.e., no deeper than the expected base of the H2O cloud, and not as a result of any detected deep-seated upwelling beneath the H2O cloud base. Earth-based observations tracked it over its 2-week lifespan, providing evidence that mesoscale-to-synoptic-scale forcing mechanisms were involved in sustaining it, including the intriguing possibility of a humidity front (‘dryline’), a sharp gradient in the vapor abundance, promoting lift along a concentrated region.
{"title":"Multi-instrument sounding of a Jovian thunderstorm from Juno","authors":"Shawn R. Brueshaber ,&nbsp;Zhimeng Zhang ,&nbsp;John H. Rogers ,&nbsp;Gerald Eichstädt ,&nbsp;Glenn S. Orton ,&nbsp;Davide Grassi ,&nbsp;Leigh N. Fletcher ,&nbsp;Cheng Li ,&nbsp;Shinji Mizumoto ,&nbsp;Alessandro Mura ,&nbsp;Fabiano Oyafuso ,&nbsp;Ramanakumar Sankar ,&nbsp;Michael H. Wong ,&nbsp;Candice J. Hansen ,&nbsp;Steven Levin ,&nbsp;Scott Bolton","doi":"10.1016/j.icarus.2025.116465","DOIUrl":"10.1016/j.icarus.2025.116465","url":null,"abstract":"<div><div>Thunderstorms play a significant role in transporting heat from the deep interior to space on giant planets. We present observations of a 3,400-km wide thunderstorm complex in Jupiter’s North Equatorial Belt (NEB) during the 38th periapse of the Juno spacecraft on 29 Nov. 2021. Data were acquired by the Microwave Radiometer (MWR), the visible light JunoCam instrument, the Jovian InfraRed Auroral Mapper (JIRAM), and from supporting Earth-based imaging. This was the first time Juno was able to observe a thunderstorm at suitably low emission angles with multiple instruments at close range (<span><math><mo>∼</mo></math></span>5,690 km), making it the most comprehensive close-up assessment of a Jovian thunderstorm to date. Lightning detection confirmed the Storm’s vigorous convective nature. MWR brightness temperatures indicate this Storm appears to be wholly contained within the weather layer, i.e., no deeper than the expected base of the H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O cloud, and not as a result of any detected deep-seated upwelling beneath the H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O cloud base. Earth-based observations tracked it over its <span><math><mo>∼</mo></math></span> 2-week lifespan, providing evidence that mesoscale-to-synoptic-scale forcing mechanisms were involved in sustaining it, including the intriguing possibility of a humidity front (‘dryline’), a sharp gradient in the vapor abundance, promoting lift along a concentrated region.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116465"},"PeriodicalIF":2.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420863","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}
引用次数: 0
Synthesized microstructures and reflectance spectra of solids in the ice Ih–MgCl2•12H2O system: Implications for Europa
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-10 DOI: 10.1016/j.icarus.2025.116481
Thomas B. Czernik , Kevin Robertson , Cameron Meyers , Christine McCarthy , Greg Hirth , Reid F. Cooper
The existence of hydrated MgCl2 on Europa's surface has been suggested by remote sensing spectrometry, but this interpretation is limited by the low signal-to-noise ratio of the data and a lack of relevant laboratory-derived spectra within spectral libraries. Furthermore, the compaction state of Europa's surface remains poorly constrained, yet there is a lack of laboratory-measured spectra for dense specimens that are necessary to understand endmember behavior of a dense surface. We acquired vis-near-infrared reflectance spectra at wavelengths from 0.35 to 2.5 μm for synthetic specimens in the ice Ih–MgCl2•12H2O system. Reflectance spectra were measured for dense water-ice aggregates with different grain sizes and were used to assess the influence of density on spectral signature. In general, large-grained aggregates exhibited decreased albedo, broadening of absorption bands, and decreased absorption band depth. Additionally, reflectance spectra of powdered MgCl2•12H2O were measured as a function of particle size and were observed to contain spectral features distinct from other hydration states (MgCl2•nH2O, n = 1,2,4,6,8). Particle size dependency observed in the spectra of powdered MgCl2•12H2O mirrored grain size dependent trends observed in the spectra of dense water-ice aggregates. We also measured the spectra of eutectic (20.6 wt% MgCl2) and porphyritic hypoeutectic (7.7 and 16.4 wt% MgCl2) dense ice Ih–MgCl2•12H2O aggregates. We argue that the microstructures of synthesized eutectic and hypoeutectic aggregates are suitable to represent texture likely existent in Europa's shell and are appropriate for use in mechanical testing where texture needs to be carefully considered.
{"title":"Synthesized microstructures and reflectance spectra of solids in the ice Ih–MgCl2•12H2O system: Implications for Europa","authors":"Thomas B. Czernik ,&nbsp;Kevin Robertson ,&nbsp;Cameron Meyers ,&nbsp;Christine McCarthy ,&nbsp;Greg Hirth ,&nbsp;Reid F. Cooper","doi":"10.1016/j.icarus.2025.116481","DOIUrl":"10.1016/j.icarus.2025.116481","url":null,"abstract":"<div><div>The existence of hydrated MgCl<sub>2</sub> on Europa's surface has been suggested by remote sensing spectrometry, but this interpretation is limited by the low signal-to-noise ratio of the data and a lack of relevant laboratory-derived spectra within spectral libraries. Furthermore, the compaction state of Europa's surface remains poorly constrained, yet there is a lack of laboratory-measured spectra for dense specimens that are necessary to understand endmember behavior of a dense surface. We acquired vis-near-infrared reflectance spectra at wavelengths from 0.35 to 2.5 μm for synthetic specimens in the ice Ih–MgCl<sub>2</sub>•12H<sub>2</sub>O system. Reflectance spectra were measured for dense water-ice aggregates with different grain sizes and were used to assess the influence of density on spectral signature. In general, large-grained aggregates exhibited decreased albedo, broadening of absorption bands, and decreased absorption band depth. Additionally, reflectance spectra of powdered MgCl<sub>2</sub>•12H<sub>2</sub>O were measured as a function of particle size and were observed to contain spectral features distinct from other hydration states (MgCl<sub>2</sub>•nH<sub>2</sub>O, <em>n</em> = 1,2,4,6,8). Particle size dependency observed in the spectra of powdered MgCl<sub>2</sub>•12H<sub>2</sub>O mirrored grain size dependent trends observed in the spectra of dense water-ice aggregates. We also measured the spectra of eutectic (20.6 wt% MgCl<sub>2</sub>) and porphyritic hypoeutectic (7.7 and 16.4 wt% MgCl<sub>2</sub>) dense ice Ih–MgCl<sub>2</sub>•12H<sub>2</sub>O aggregates. We argue that the microstructures of synthesized eutectic and hypoeutectic aggregates are suitable to represent texture likely existent in Europa's shell and are appropriate for use in mechanical testing where texture needs to be carefully considered.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116481"},"PeriodicalIF":2.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
引用次数: 0
Boulder-induced spin variability in the YORP effect
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-10 DOI: 10.1016/j.icarus.2025.116487
Dahlia A. Baker, Jay W. McMahon
Boulders have been observed as a dominant feature on all rubble-pile asteroids, as seen by recent survey missions to small bodies. Thermal re-radiation induced torque, known as the YORP effect, is a dominant influence on the rotational dynamics of a body in the rubble-pile size regime below 1 km in diameter. YORP is also extremely sensitive to small-scale topography such as regolith, boulders, and craters. We analyze the effects of boulders on the YORP spin torque of an asteroid, where simulated populations are based on the observed size and placement distributions on real bodies, to show how influential these features are when making YORP estimates. Models are produced by adding many geometric boulder shapes to an existing asteroid shape model. This analysis applies previous polyhedral YORP approximations which calculate the spin and obliquity coefficients through summation over faceted shapes. YORP is seen to be highly variable with boulder size, placement, and dominant orientation on both Bennu and Itokawa shape models. We find that the maximum influence due to a boulder can be up to 135% of the total YORP when large boulders affect the dynamics or several small ones have a combined effect. For a single feature, this is a large and highly sensitive and variable global influence and represents the maximum of the observed size range. These results also pertain to a static case, while there is expected material redistribution and breakup through the experience of YORP spin changes which may be a factor in limiting unbounded YORP spin-up or spin-down over time. We compare the magnitude and uncertainty of boulder-induced YORP torque to other analytical models.
{"title":"Boulder-induced spin variability in the YORP effect","authors":"Dahlia A. Baker,&nbsp;Jay W. McMahon","doi":"10.1016/j.icarus.2025.116487","DOIUrl":"10.1016/j.icarus.2025.116487","url":null,"abstract":"<div><div>Boulders have been observed as a dominant feature on all rubble-pile asteroids, as seen by recent survey missions to small bodies. Thermal re-radiation induced torque, known as the YORP effect, is a dominant influence on the rotational dynamics of a body in the rubble-pile size regime below 1 km in diameter. YORP is also extremely sensitive to small-scale topography such as regolith, boulders, and craters. We analyze the effects of boulders on the YORP spin torque of an asteroid, where simulated populations are based on the observed size and placement distributions on real bodies, to show how influential these features are when making YORP estimates. Models are produced by adding many geometric boulder shapes to an existing asteroid shape model. This analysis applies previous polyhedral YORP approximations which calculate the spin and obliquity coefficients through summation over faceted shapes. YORP is seen to be highly variable with boulder size, placement, and dominant orientation on both Bennu and Itokawa shape models. We find that the maximum influence due to a boulder can be up to 135% of the total YORP when large boulders affect the dynamics or several small ones have a combined effect. For a single feature, this is a large and highly sensitive and variable global influence and represents the maximum of the observed size range. These results also pertain to a static case, while there is expected material redistribution and breakup through the experience of YORP spin changes which may be a factor in limiting unbounded YORP spin-up or spin-down over time. We compare the magnitude and uncertainty of boulder-induced YORP torque to other analytical models.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"431 ","pages":"Article 116487"},"PeriodicalIF":2.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386432","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}
引用次数: 0
New observations of topographic slumps in Valles Marineris, Mars: Investigating the role of recurring slope lineae
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-10 DOI: 10.1016/j.icarus.2025.116503
Amelia Ascione , Lujendra Ojha , Matthew Chojnacki , Vidushi Dhaka
Small-scale landslides, termed topographic slumps, are commonly co-located with seasonally active recurring slope lineae (RSL) on Mars. Previously identified topographic slumps initiated beneath or around the terminal points of RSL, suggesting that RSL activity may trigger slump formation. In this study, we conducted a comprehensive survey of HiRISE images spanning Mars years (MY) 29 to 37 in the southern mid-latitudes, northern mid-latitudes, and equatorial latitudes. We report eight newly identified topographic slumps that formed over the past 4 Mars years. Despite a comprehensive survey, these slumps were exclusively observed on slopes within Valles Marineris. While most of these slumps were co-located with RSL, two occurred on slopes lacking any detectable RSL activity. All slumps, however, formed on steep slopes (>27°) with inferred high sediment supply. We analyzed slump morphologies, seasonalities, and slope parameters to discuss potential topographic slump formation mechanisms. We suggest that if RSL are dry granular flows, gradual oversteepening due to debris accumulation beneath their termini could promote slumping. However, the limited number of topographic slumps relative to the widespread occurrence of RSL suggests that these features may be unrelated, or that unknown alternative conditions are necessary to initiate slump formation.
{"title":"New observations of topographic slumps in Valles Marineris, Mars: Investigating the role of recurring slope lineae","authors":"Amelia Ascione ,&nbsp;Lujendra Ojha ,&nbsp;Matthew Chojnacki ,&nbsp;Vidushi Dhaka","doi":"10.1016/j.icarus.2025.116503","DOIUrl":"10.1016/j.icarus.2025.116503","url":null,"abstract":"<div><div>Small-scale landslides, termed topographic slumps, are commonly co-located with seasonally active recurring slope lineae (RSL) on Mars. Previously identified topographic slumps initiated beneath or around the terminal points of RSL, suggesting that RSL activity may trigger slump formation. In this study, we conducted a comprehensive survey of HiRISE images spanning Mars years (MY) 29 to 37 in the southern mid-latitudes, northern mid-latitudes, and equatorial latitudes. We report eight newly identified topographic slumps that formed over the past 4 Mars years. Despite a comprehensive survey, these slumps were exclusively observed on slopes within Valles Marineris. While most of these slumps were co-located with RSL, two occurred on slopes lacking any detectable RSL activity. All slumps, however, formed on steep slopes (&gt;27°) with inferred high sediment supply. We analyzed slump morphologies, seasonalities, and slope parameters to discuss potential topographic slump formation mechanisms. We suggest that if RSL are dry granular flows, gradual oversteepening due to debris accumulation beneath their termini could promote slumping. However, the limited number of topographic slumps relative to the widespread occurrence of RSL suggests that these features may be unrelated, or that unknown alternative conditions are necessary to initiate slump formation.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116503"},"PeriodicalIF":2.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429605","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}
引用次数: 0
Extensional structures at lunar lobate scarps
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-10 DOI: 10.1016/j.icarus.2025.116493
Thomas Frueh , Ralf Hetzel , Thomas R. Watters , Carolyn H. van der Bogert , Jaclyn D. Clark , Cole Nypaver , Harald Hiesinger
The Moon's lithosphere has been in a net compressional stress regime for the past 3.6 billion years, leading to the formation of globally distributed kilometer-scale thrust faults that form lobate scarps at the surface. Lobate scarps are among the youngest features on the lunar surface. A sign of their recent activity is the presence of meter-scale extensional structures in their hanging walls, which are generally either parallel or perpendicular to the scarp-forming thrust fault. However, the origin of these structures and their orientation relative to the primary fault is not well understood. Here, we present detailed tectonic maps of three lobate scarps (Lee-Lincoln, Lilius C-1, and Morozov-1), which reveal sets of fault-perpendicular to fault-parallel extensional structures at all scarps. Using high-resolution digital elevation models, we measure along-strike variations in fault throw and document maximum throws of ∼216 m for Lee-Lincoln, ∼98 m for Lilius C-1, and ∼140 m for Morozov-1. By comparison with terrestrial analogs, we show that fault-parallel extensional structures are mainly formed by flexural bending of the hanging wall, whereas fault-perpendicular features are potentially formed by along-strike variations in thrust orientation, and potential strike-slip components on the thrust fault. We hypothesize that small extensional structures preferably either form near the main displacement, at the most recently active regions of a scarp, or at segment boundaries. Based on degradation-rate estimates, we propose that small graben provide the best evidence for very recent activity of lobate scarp faults, because the graben form during coseismic slip events on the thrust faults.
{"title":"Extensional structures at lunar lobate scarps","authors":"Thomas Frueh ,&nbsp;Ralf Hetzel ,&nbsp;Thomas R. Watters ,&nbsp;Carolyn H. van der Bogert ,&nbsp;Jaclyn D. Clark ,&nbsp;Cole Nypaver ,&nbsp;Harald Hiesinger","doi":"10.1016/j.icarus.2025.116493","DOIUrl":"10.1016/j.icarus.2025.116493","url":null,"abstract":"<div><div>The Moon's lithosphere has been in a net compressional stress regime for the past 3.6 billion years, leading to the formation of globally distributed kilometer-scale thrust faults that form lobate scarps at the surface. Lobate scarps are among the youngest features on the lunar surface. A sign of their recent activity is the presence of meter-scale extensional structures in their hanging walls, which are generally either parallel or perpendicular to the scarp-forming thrust fault. However, the origin of these structures and their orientation relative to the primary fault is not well understood. Here, we present detailed tectonic maps of three lobate scarps (Lee-Lincoln, Lilius C-1, and Morozov-1), which reveal sets of fault-perpendicular to fault-parallel extensional structures at all scarps. Using high-resolution digital elevation models, we measure along-strike variations in fault throw and document maximum throws of ∼216 m for Lee-Lincoln, ∼98 m for Lilius C-1, and ∼140 m for Morozov-1. By comparison with terrestrial analogs, we show that fault-parallel extensional structures are mainly formed by flexural bending of the hanging wall, whereas fault-perpendicular features are potentially formed by along-strike variations in thrust orientation, and potential strike-slip components on the thrust fault. We hypothesize that small extensional structures preferably either form near the main displacement, at the most recently active regions of a scarp, or at segment boundaries. Based on degradation-rate estimates, we propose that small graben provide the best evidence for very recent activity of lobate scarp faults, because the graben form during coseismic slip events on the thrust faults.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116493"},"PeriodicalIF":2.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
引用次数: 0
Exploring water-ice deposits in lunar polar craters with Chandrayaan-2 DFSAR data 利用 Chandrayaan-2 DFSAR 数据探索月球极地陨石坑中的水冰沉积物
IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-02-06 DOI: 10.1016/j.icarus.2025.116492
Nidhi Verma , Megha Bhatt , Mayand Dangi , Shashi Kumar , Anil Bhardwaj
Detection of water-ice deposits using synthetic aperture radar (SAR) is a cost-effective, and efficient approach to understand lunar water resources. As water is crucial to supporting human-based space exploration, current and near upcoming lunar missions are primary concentrated on mapping and quantification of water ice exposures on surface and subsurface levels. The circular polarization ratio greater than one (CPR >1) derived using the orbital radar observations is considered as an important SAR derived parameter for water-ice detection. This study aims to investigate 14 craters near the lunar poles with high CPR (CPR >1), as identified in previous studies, using the L-band (24 cm) dual frequency synthetic aperture radar (DFSAR) onboard Chandrayaan-2. In addition to CPR, we computed the degree of polarization (DOP) after applying parallax error correction that helps in reducing misinterpretation. Our findings are based on orthorectified DFSAR calibrated data analysis. We found that the CPR of crater interiors is not significantly different from that of their surroundings, and this pattern is consistent throughout all the 14 craters selected. Further, we also found a linear inverse relationship between CPR and DOP for the interior and exteriors of the craters, with R2 ∼ 0.99, indicating a strong correlation between these two parameters. We found only ∼2 % of total pixels are above CPR > 1, which indicates that there is less possibility of homogeneous water-ice but the possibility of water-ice mixed with the subsurface regolith cannot be ruled out.
{"title":"Exploring water-ice deposits in lunar polar craters with Chandrayaan-2 DFSAR data","authors":"Nidhi Verma ,&nbsp;Megha Bhatt ,&nbsp;Mayand Dangi ,&nbsp;Shashi Kumar ,&nbsp;Anil Bhardwaj","doi":"10.1016/j.icarus.2025.116492","DOIUrl":"10.1016/j.icarus.2025.116492","url":null,"abstract":"<div><div>Detection of water-ice deposits using synthetic aperture radar (SAR) is a cost-effective, and efficient approach to understand lunar water resources. As water is crucial to supporting human-based space exploration, current and near upcoming lunar missions are primary concentrated on mapping and quantification of water ice exposures on surface and subsurface levels. The circular polarization ratio greater than one (CPR &gt;1) derived using the orbital radar observations is considered as an important SAR derived parameter for water-ice detection. This study aims to investigate 14 craters near the lunar poles with high CPR (CPR &gt;1), as identified in previous studies, using the L-band (24 cm) dual frequency synthetic aperture radar (DFSAR) onboard Chandrayaan-2. In addition to CPR, we computed the degree of polarization (DOP) after applying parallax error correction that helps in reducing misinterpretation. Our findings are based on orthorectified DFSAR calibrated data analysis. We found that the CPR of crater interiors is not significantly different from that of their surroundings, and this pattern is consistent throughout all the 14 craters selected. Further, we also found a linear inverse relationship between CPR and DOP for the interior and exteriors of the craters, with R<sup>2</sup> ∼ 0.99, indicating a strong correlation between these two parameters. We found only ∼2 % of total pixels are above CPR &gt; 1, which indicates that there is less possibility of homogeneous water-ice but the possibility of water-ice mixed with the subsurface regolith cannot be ruled out.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"432 ","pages":"Article 116492"},"PeriodicalIF":2.5,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420862","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}
引用次数: 0
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