Icarus最新文献

{"title":"Corrigendum to “Atmospheric response to high-resolution topographical and radiative forcings in a general circulation model of Venus: Time-mean structures of waves and variances” [Icarus 355 (2021) 114154]","authors":"Masaru Yamamoto , Kohei Ikeda , Masaaki Takahashi","doi":"10.1016/j.icarus.2025.116706","DOIUrl":"10.1016/j.icarus.2025.116706","url":null,"abstract":"","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116706"},"PeriodicalIF":2.5,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306289","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":"A novel technique for plasma asymmetry correction in radio occultation profiling","authors":"Keshav R. Tripathi ,&nbsp;T. Imamura ,&nbsp;R.K. Choudhary","doi":"10.1016/j.icarus.2025.116670","DOIUrl":"10.1016/j.icarus.2025.116670","url":null,"abstract":"<div><div>Radio Occultation (RO) experiments often employ the geometrical optics (GO) approximation and the Abel transformation, assuming spherical symmetry of the planetary atmosphere or ionosphere to retrieve electron density profiles. This assumption is also extended to derive temperature, pressure, and neutral density profiles of the lower atmosphere. However, the assumption of spherical symmetry is not always valid and can introduce significant uncertainties in the retrieved electron density profiles. This study proposes a simple retrieval algorithm that accounts for ionospheric asymmetry and demonstrates the effect of solar zenith angle (SZA) variation along the ray path. Unlike traditional methods, it does not rely on the Abel transformation and avoids the assumption of spherical symmetry, making it applicable under diverse geophysical conditions. The method is applied to RO observations around Venus, obtained from the Akatsuki and Venus Express (VEX) radio science experiments. It assumes that plasma is primarily produced by solar radiation and follows the distribution: <span><math><mrow><mi>N</mi><mrow><mo>(</mo><mi>s</mi><mi>z</mi><mi>a</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>×</mo><msup><mrow><mfenced><mrow><mfrac><mrow><mo>cos</mo><mrow><mo>(</mo><mi>s</mi><mi>z</mi><mi>a</mi><mo>)</mo></mrow></mrow><mrow><mo>cos</mo><mrow><mo>(</mo><mi>s</mi><mi>z</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>)</mo></mrow></mrow></mfrac></mrow></mfenced></mrow><mrow><mi>k</mi></mrow></msup></mrow></math></span>, where <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> is plasma density at <span><math><mrow><mi>s</mi><mi>z</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span>, and k = 0.454. Results indicate that using the spherical symmetry assumption overestimates the main peak electron density by 2%–5% and the electron density at lower altitudes by 400%–800%. The proposed method offers a more accurate framework for retrieving electron density profiles, particularly in regions where the spherical symmetry assumption breaks down.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116670"},"PeriodicalIF":2.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306287","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":"New candidate cave entrances on the Moon found using deep learning","authors":"Daniel Le Corre ,&nbsp;Nigel Mason ,&nbsp;Jeronimo Bernard-Salas ,&nbsp;David Mary ,&nbsp;Nick Cox","doi":"10.1016/j.icarus.2025.116675","DOIUrl":"10.1016/j.icarus.2025.116675","url":null,"abstract":"<div><div>Pits and skylights are circular to elliptical, rimless, steep-sided depressions on planetary surfaces formed through gravitational collapse, which are of interest for astrobiological investigation and future space exploration. This is due to their ability to signify the presence of, or allow access to, underground cave systems such as lava tubes. The Lunar Pit Atlas contains 16 such features situated within mare regions that were partly discovered via the automated PitScan tool, which was limited by searchable latitudes and data coverage. In order to search for pits and skylights within these unmapped regions, we have trained a series of Mask R-CNN (Region-based Convolutional Neural Network) models on various combinations of Lunar and Martian remote-sensing imagery to detect Lunar pits and skylights. The best-performing model, named ESSA (Entrances to Sub-Surface Areas), was trained upon all available training data with a ResNet50 backbone. During testing on imagery of the famous Mare Tranquillitatis Pit and self-produced mosaics of proposed lava tube collapses, ESSA achieved average F<span><math><msub><mrow></mrow><mrow><mn>1</mn></mrow></msub></math></span>-scores of 82.4 and 93.7% for the bounding boxes and predicted masks, respectively. Despite only having surveyed <span><math><mo>≈</mo></math></span>1.92% of the Lunar maria, ESSA has detected two previously uncatalogued skylights: the South Marius Hills and Bel’kovich A Pits (SMHP and BAP) - which are possible candidates for cave entrances on the Moon.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116675"},"PeriodicalIF":2.5,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144321154","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":"Exploring the disparate tectonic manifestations of lithospheric shortening on ocean worlds: Enceladus and Europa","authors":"Michael T. Bland","doi":"10.1016/j.icarus.2025.116697","DOIUrl":"10.1016/j.icarus.2025.116697","url":null,"abstract":"<div><div>The moons Europa and Enceladus both have water-ice dominated shells tens of kilometers thick overlying global oceans. Both moons are tidally heated and have high rock mass-fractions relative to other moons in their system, and both have youthful, tectonically deformed surfaces. Despite their many commonalities, the surfaces of the two moons bear little resemblance to one another. Europa's tectonics are dominated by extensional features, including wide bands that imply extremely large surface strains. Features formed by the requisite lithospheric shortening accompanying such extension are largely absent, but long-wavelength folding may have occurred in some locations. Enceladus' tectonics include features formed in both extension and contraction. Unlike Europa, folds, fold and thrust belts, and isolated thrust faults are plentiful there. In this investigation we use numerical simulations of the shortening of ice lithospheres to bring new insight into why two moons with so much in common appear so different from each other. We find that the temperature structure of the lithosphere controls the style of deformation that results from shortening. Warm conditions resulting from higher surface temperatures and heat fluxes produce folding, which is essentially a viscous response to shortening. Cold temperatures resulting from lower surface temperatures and heat fluxes results in faulting, which is a brittle response. Intermediate conditions can lead to complex combinations of folding and faulting. We hypothesize that Europa's surface is generally warm enough for shortening to be accommodated by subtle folds that are difficult to detect in the sparse topography data currently available, whereas Enceladus' colder temperatures favor a combination of folding and faulting. We argue that the dependence of tectonic style on lithospheric temperature self-consistently explains the pattern of tectonics observed across Enceladus, and we emphasize that non-rigid deformation (folding) is not inconsistent with the emerging paradigm of plate tectonics on Europa.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116697"},"PeriodicalIF":2.5,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144321155","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":"Methanol on red TNOs: A link between early composition and irradiation history","authors":"E. Hénault ,&nbsp;D. Baklouti ,&nbsp;R. Brunetto ,&nbsp;Z. Djouadi ,&nbsp;R.G. Urso ,&nbsp;P. Benoit-Lamaitrie ,&nbsp;J. Bourçois ,&nbsp;O. Mivumbi ,&nbsp;C.M. Dalle Ore ,&nbsp;A. Ricca","doi":"10.1016/j.icarus.2025.116669","DOIUrl":"10.1016/j.icarus.2025.116669","url":null,"abstract":"<div><div>Solid methanol is detected on small icy bodies of the outer solar system, namely trans-Neptunian objects (TNOs). Interestingly, all objects with methanol detections also display a strong positive spectral slope in the visible to near-infrared range, commonly attributed to complex organics, that could be formed by space weathering of methanol ice. We question the relationship between this red color and methanol content by performing irradiation experiments on methanol ices, pure and mixed with water, to simulate the ion bombardment of TNO surfaces. To compare the experimental spectral evolution under irradiation to observations, we focused our investigations on the normalized reflectivity gradient between the J and R photometric bands (JR slope) and the methanol to water abundance ratio post-irradiation. We show that ion irradiation triggers the destruction of methanol and the spectral reddening of the ices. Moreover, we find that JR slopes depend on both irradiation dose and initial ice composition. To account for red slopes alongside detectable methanol ice, we conclude that an irradiation gradient needs to be present at the surface of methanol-rich objects. However, methanol needs to be at least as abundant as water in the initial icy mixture, which suggests an early segregation of the icy species. We provide an estimation of the irradiation doses received at different depths of methanol-rich TNO surfaces, consistent with surface exposures of <span><math><mo>∼</mo></math></span>4.5 Gyrs.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116669"},"PeriodicalIF":2.5,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312622","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":"Corrigendum to “The source of hydrogen in earth's building blocks” [Icarus 436 (2025), 116588]","authors":"Thomas J. Barrett ,&nbsp;James F.J. Bryson ,&nbsp;Kalotina Geraki","doi":"10.1016/j.icarus.2025.116694","DOIUrl":"10.1016/j.icarus.2025.116694","url":null,"abstract":"","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116694"},"PeriodicalIF":2.5,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262148","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":"A new MarsRock-FasterRcnn method to extract Mars rocks using HiRISE images at Utopia Plainitia","authors":"Yuhao Wang ,&nbsp;Yongjiu Feng ,&nbsp;Na Sun ,&nbsp;Rong Wang ,&nbsp;Jingbo Sun ,&nbsp;Chao Wang ,&nbsp;Xiong Xu ,&nbsp;Yusheng Xu ,&nbsp;Rong Huang ,&nbsp;Xiaohua Tong","doi":"10.1016/j.icarus.2025.116701","DOIUrl":"10.1016/j.icarus.2025.116701","url":null,"abstract":"<div><div>Rocks on Mars' surface are an important feature of its geomorphology, and rock abundance is a key consideration for the selection of landing sites, as well as the engineering safety of the landing. In this study, we proposed a Faster R-CNN-based intelligent extraction method (i.e., MarsRock-FasterRcnn) for detecting Mars rocks from images (0.25 m/pixel) acquired by the High-Resolution Imaging Camera (HiRISE) onboard the MRO orbiter. MarsRock-FasterRcnn method can extract rocks with diameter of 0.5–2 m on HiRISE images. We built a rock sample set containing 2000 images of size 416 × 416 to train the MarsRock-FasterRcnn model, and finally evaluated the prediction effect of the model using assessment metrics including precision, recall, and F1 score. The results showed that the recall and precision were both about 80 %, and the maximum confidence was above 99 %, indicating excellent model performance. The extraction and validation of rocks in Utopia Plainitia show that the rock abundance is below 7 % in most of the region, and the overall rock abundance in the southern part of the region is below 5 %, indicating weaker effects by the rocky obstacles when landing. We also found a strong relationship between the rock abundance and topography, where a higher rock abundance relates to a greater topographic undulation. This study can provide scientific clues for the investigation of the topography and geology of Mars, as well as engineering constraints for the selection of landing sites for exploration missions.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116701"},"PeriodicalIF":2.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297590","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":"Statistical evaluation of boulder spatial patterns on asteroids and application to Eros, Itokawa and Ryugu","authors":"Tatsuhiro Michikami ,&nbsp;Axel Hagermann","doi":"10.1016/j.icarus.2025.116693","DOIUrl":"10.1016/j.icarus.2025.116693","url":null,"abstract":"<div><div>In planetary science, the statistical properties of spatial distributions are frequently examined to understand the formation and evolution of a body's surface. The surfaces of the asteroids directly explored by spacecraft are covered with numerous boulders and/or regolith particles. However, the spatial distribution of these boulders has not been statistically studied, although much statistical research has been done on the spatial distributions of craters. Thus, it is not known whether the spatial distribution of boulders on asteroids explored by spacecraft is random or not. Squyres et al. (1997) developed a simple model of crater formation and obliteration based on several assumptions, but some of their assumptions do not hold for boulders. In this study, we construct a simple model of the spatial distribution of boulders by verifying some assumptions, and investigate the effect of various assumptions and parameter variations on the model results. From these quantitative calculations, we investigate the spatial distribution of boulders on the asteroids Eros, Ryugu, and Itokawa. Our quantitative results show that boulders on Eros are spatially clustered at the 95 % confidence level. On the other hand, on Ryugu and Itokawa, decameter-sized boulders are spatially less clustered, while meter-sized small boulders are spatially clustered, all at the 95 % confidence level. This suggests that the clustered spatial distribution of small boulders on Ryugu and Itokawa can be explained by their migration.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116693"},"PeriodicalIF":2.5,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298027","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":"How old are hermean smooth plains? A detailed study","authors":"Barbara Giuri ,&nbsp;Carolyn H. van der Bogert ,&nbsp;Harald Hiesinger","doi":"10.1016/j.icarus.2025.116699","DOIUrl":"10.1016/j.icarus.2025.116699","url":null,"abstract":"<div><div>Early surface observations of Mercury by the Mariner 10 spacecraft revealed a heavily cratered surface similar to that of the Moon. Today, the high-resolution images acquired by MESSENGER spacecraft during 2008–2015, greatly enhanced our understanding of the stratigraphy, geology, and volcanic history of the innermost planet. In this study, we investigate the global distribution, origin(s), and age(s) of smooth plains (SPs) deposits on Mercury. Despite numerous studies indicating that SPs were of presumably volcanic origin, the origin of other, smaller-scale deposits remain unclear. This work examines (1) the full extent of smooth materials, regardless of their origin, by generating a new detailed global map of SPs, (2) the absolute model ages (AMAs) of 65 SP units across the mid-latitudes to test their volcanic origin, and (3) the origin(s) and age(s) of other, smaller-scale plains materials. Here, we present the first step of this global study. We find that 33.5 % of the surface of Mercury is covered by smooth plains deposits emplaced within ~100–200 My, between ~3.6 and ~3.8 Ga. This geologically short period of time for the emplacement of all SPs units across the surface of Mercury is best explained by volcanism, thus our work further supports a volcanic origin for most large-scale SPs deposits. The origin of smaller-scale SPs units and of plains materials within crater floors remains uncertain. The model ages for 10 basins and 6 crater fillings show (a) basins dating within the Mansurian-Calorian period, after the emplacement of the extensive SPs, and (b) other units with diverse origins. Three of the six crater fillings have an impact-related origin, one is likely volcanic in origin, and two plains materials are unusually old leaving their origin(s) and age(s) an open question. In the next steps, we aim to evaluate the ages of more of these plains materials distributed across the hermean surface to decipher their potential origin(s) for a complete depiction of SPs on Mercury. To assist in identifying compositionally distinct units, data from BepiColombo mission will prove to be of upmost importance in improving our understanding of the origin of all SPs.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116699"},"PeriodicalIF":2.5,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298019","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":"UPRS-1: A regolith simulant of Utopia Planitia, Mars","authors":"Yiming Diao ,&nbsp;Honglei Lin ,&nbsp;Juan Li ,&nbsp;Shouding Li ,&nbsp;Changyi Xu ,&nbsp;Zhaobin Zhang ,&nbsp;Zongyu Yue ,&nbsp;Bo Zheng ,&nbsp;Xiukuo Sun ,&nbsp;Tao Xu ,&nbsp;Xinshuo Chen ,&nbsp;Yanfang Wu ,&nbsp;Xiao Li","doi":"10.1016/j.icarus.2025.116692","DOIUrl":"10.1016/j.icarus.2025.116692","url":null,"abstract":"<div><div>Understanding the composition and properties of Martian soils is crucial for scientific research and engineering tests for payloads and landers, which is why simulants are utilized in diverse applications in the absence of Martian samples returned to Earth. Existing simulants are predominantly based on the global Martian surface materials and some regions in the southern highlands of Mars, neglecting the northern lowlands such as Utopia Planitia. The Zhurong rover of the Chinese Tianwen-1 mission explored Utopia Planitia, collecting extensive physical and chemical data from surface materials and facilitating the development of a new Mars simulant representing the northern lowlands. Thus, we developed Utopia Planitia Regolith Simulant-1 (UPRS-1) to replicate the soil properties of Utopia Planitia and proposed a quantitative evaluation to assess the high similarity of UPRS-1. The overall similarity parameter of UPRS-1 is 86.1 % via quantitative evaluation. Additionally, its composition is adaptable to specific research requirements, enabling its application in diverse fields, including geotechnical experiments, in-situ resource utilization (ISRU) technology, ground tests for exploration missions, and astrobiology.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116692"},"PeriodicalIF":2.5,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306288","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}