Icarus最新文献

{"title":"Exobase and homopause altitudes in the Martian upper atmosphere: Solar cycle variability and response to the 2018 global dust storm","authors":"N.V. Rao ,&nbsp;V. Leelavathi ,&nbsp;Neha Gupta","doi":"10.1016/j.icarus.2025.116565","DOIUrl":"10.1016/j.icarus.2025.116565","url":null,"abstract":"<div><div>Understanding the composition of volatile gases in the Martian upper atmosphere and the mechanisms governing their escape into outer space is crucial for unraveling planetary evolution. Two critical neutral atmospheric boundaries, the exobase and the homopause, play key roles in this context. In this study, we conducted a detailed analysis of the exobase and homopause altitudes derived from measurements by the Neutral Gas and Ion Mass Spectrometer (NGIMS) aboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. The exobase and homopause altitudes observed in this study range from 140 to 200 km and 90–135 km, respectively, broadly agreeing with values reported in previous studies. Using extended observations, this study reveals significant interannual variability in these altitudes. Both the exobase and homopause were found to be higher during moderate solar activity compared to solar minimum. During moderate solar activity, these two altitudes rise and fall nearly synchronously, while this coupling weakens during solar minimum. Seasonal trends are also pronounced, with elevated altitudes observed during perihelion and in the summer hemisphere, particularly during the southern summer. These findings suggest that enhanced solar activity during moderate solar periods increases atmospheric heating, elevating atmospheric scale heights and causing the exobase and homopause to rise and fall in-phase. In contrast, during solar minimum, weaker thermal forcing reduces the influence of atmospheric expansion, allowing gravity wave activity to dominate the variability of the homopause. During the 2018 global dust storm (GDS), exobase altitudes were elevated with reduced sinusoidal amplitude, while homopause altitudes exhibited significant fluctuations. These results indicate that thermospheric expansion raises the altitudes of both boundaries during the GDS, but enhanced gravity wave activity introduces substantial fluctuations in the homopause altitude, disrupting its coupling with the exobase and resulting in a phase shift between the variations of these two critical altitudes.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"435 ","pages":"Article 116565"},"PeriodicalIF":2.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697852","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":"Masses of binary asteroid systems with strong solar perturbations","authors":"M.I. Varfolomeev ,&nbsp;N.V. Emelyanov","doi":"10.1016/j.icarus.2025.116546","DOIUrl":"10.1016/j.icarus.2025.116546","url":null,"abstract":"<div><div>We give refined values for the masses for the following binary asteroid systems with strong solar perturbations: (379) Huenna, (3548) Eurybates-Queta, (3749) Balam, (88611) Teharonhiawako-Sawiskera, (160256) 2002 PD₁₄₉, (341520) Mors-Somnus, (364171) 2006 JZ₈₁, (524531) 2002 XH₉₁, 1998 WW₃₁, and 2003 QY₉₀. The masses were refined by numeric integration of the equations of motion where perturbations from the Sun’s gravity were taken into account. Assuming the satellite orbits to be close to Keplerian, the initial integration parameters and the masses of the systems can be refined by the least-squares method in which the coefficients of the conditional equations are calculated using the Keplerian motion formulae. For some systems with strong solar perturbations (2001 QW₃₂₂, 2006 BR₂₈₄, 2006 CH₆₉, (525462) 2005 EO₃₀₄, (612147) 2000 CF₁₀₅, (612687) 2003 UN₂₈₄) the masses could not be refined since the rms residuals increase when solar perturbations are taken into account, which can be caused by insufficient interval or amount of observations. For most systems, the obtained values for masses are within the error limits of the values obtained using only Keplerian model. However, for a number of satellites, the Keplerian model of motion, which does not take into account solar perturbations, gives significant deviations in the apparent positions exceeding the accuracy of modern observations. These systems are (379) Huenna, (3548) Eurybates-Queta, (3749) Balam, (160256) 2002 PD₁₄₉, and (364171) 2006 JZ₈₁. For the systems for which it was possible to refine the masses, we give elements of their satellites’ osculating orbits for the epoch close to the date of their first observation.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116546"},"PeriodicalIF":2.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644815","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":"Mars ionosphere TEC estimation from MARSIS data: A new approach","authors":"M. Cartacci ,&nbsp;B. Sánchez-Cano ,&nbsp;A. Cicchetti ,&nbsp;R. Noschese ,&nbsp;B. Langlais ,&nbsp;R. Orosei","doi":"10.1016/j.icarus.2025.116545","DOIUrl":"10.1016/j.icarus.2025.116545","url":null,"abstract":"<div><div>We describe a new implementation of the Contrast Method (CM) algorithm (<span><span>Picardi and Sorge, 2000</span></span>; <span><span>Ilyushin Ya and Kunitsyn, 2004</span></span>; <span><span>Cartacci et al., 2013</span></span>) used to correct the phase distortion of the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (<span><span>Picardi et al., 2005</span></span>; <span><span>Jordan et al., 2009</span></span>) in its subsurface mode.</div><div>The New CM is designed following an improved approach which allows not only to perform its original task but also to estimate the Total Electron Content (TEC) of the Mars ionosphere with a better accuracy respect to the past (<span><span>Cartacci et al., 2013</span></span>; <span><span>Cartacci et al., 2017</span></span>), in the nightside when the transmitted frequency is close to the ionosphere plasma frequency as well as in the dayside, thanks to a lesser use of theoretical approximations in the method development.</div><div>Moreover, taking advantage of almost 16 years of MARSIS operations, corresponding to about 8700 orbits, we present an improved global map of the night side TEC variations due to the interaction with the Mars crustal magnetic field (<span><span>Safaeinili et al., 2007</span></span>; <span><span>Cartacci et al., 2013</span></span>).</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116545"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636296","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":"The impact of cometary outbursts on the orbits of comets in the Oort cloud","authors":"A.Y. Merkulova,&nbsp;A.K. Pavlov,&nbsp;D.V. Belousov","doi":"10.1016/j.icarus.2025.116547","DOIUrl":"10.1016/j.icarus.2025.116547","url":null,"abstract":"<div><div>The surface layers of cometary nuclei are intensively irradiated by high energy protons, α-particles and heavy ions of galactic cosmic ray (GCR), leading to the formation of ions and radicals in the comet's matter. At low temperatures, high concentrations of radicals accumulated in the ice can be followed by a rapid release of energy during spontaneous or induced recombination. This process can provoke a gas release from the comet's surface layers. The resulting gas flux leads to a change in the velocity of comets, which affects the stability of their orbits. Repeated outbursts can occur over the comet's lifetime in the Oort cloud. This mechanism depends on the comet's size, the initial eccentricity, and the ejected mass during the outburst. We modeled the impact of repeated cometary outbursts on the orbits of comets in the Oort cloud. The results indicate that 49.5 % of comets with radii R_c = 0.4 km and 72.4 % of comets with R_c = 0.3 km and initial eccentricities e_c ≥ 0.9 could leave the Oort cloud due to repeated outbursts. This fraction leaving comets for the initial eccentricities e_c &gt; 0 is 19.3 % for R_c = 0.4 km and 54.1 % for R_c = 0.3 km, respectively. The mechanism has the most effect on highly elongated orbits of comets.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116547"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620612","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":"Visible spectroscopy of 3 KBOs and 1 Centaur","authors":"R.K. Williams,&nbsp;J.P. Emery","doi":"10.1016/j.icarus.2025.116554","DOIUrl":"10.1016/j.icarus.2025.116554","url":null,"abstract":"<div><div>Material remaining from the formation of the outer Solar System congregated in the Kuiper Belt. Studying this material has provided key information about the formation of the Solar System, the distribution of planetary materials, and the compositions of different objects. Additional spectra of objects in the Kuiper Belt will provide further insight into Solar System formation and evolution. An important question is whether, and in what quantity, hydrated material formed in the outer Solar System. We address this question here with visible spectra of three Kuiper Belt Objects (KBOs) and one Centaur. We find moderately red spectral slopes for these four bodies, with no clear evidence for the 7000 Å feature due to Fe-rich phyllosilicates. These results extend the overall lack of detection of hydrated materials among KBOs and Centaurs. Although it is clear that hydrated silicates are not common in the outer Solar System, some hydration might be expected, and further observations will continue to refine its prevalence.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116554"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683298","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":"Insights for hydrated sulfuric acid on Europa's surface from a combined orbital – experimental approach.","authors":"T.W. Hayes ,&nbsp;S. Li","doi":"10.1016/j.icarus.2025.116543","DOIUrl":"10.1016/j.icarus.2025.116543","url":null,"abstract":"<div><div>Europa's non-water ice component may come from its interior ocean or from exotic processes (e.g. surface irradiation and/or impacts). We investigate these possible sources globally using all high spatial resolution (&lt;25 km/pixel) data acquired by the Near-Infrared Mapping Spectrometer (NIMS) onboard Galileo, which is more advantageous than previous studies that only used few selected high spatial resolution datasets, or those with global coverage yet low spatial resolution. We find that the slopes of NIMS spectra from 1.3 to 2.2 μm show the same hemispheric dichotomy displayed by incident radiation fluxes, with trailing hemisphere spectral slopes being much more negative, or “bluer”, than those of the leading hemisphere. Spectral slopes are also bluer locally in older terrains, further suggesting a surface exposure-age dependence. In our examined endmember library, only sulfuric acid octahydrate (H₂SO₄ • 8H₂O, “SAO”) can explain this blue slope. Water ice – SAO ice mixtures show blue slope strength increases with SAO abundance. We attribute the behavior of Europa's NIMS spectral slopes to indicate the likely presence of hydrated sulfuric acid. Weak blue slopes in Europa's endogenic features suggest minor SAO abundances.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116543"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683297","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":"The effects of measured slope on Martian lava flow modeling","authors":"Frances P. Russo ,&nbsp;Ian T.W. Flynn ,&nbsp;Sean I. Peters ,&nbsp;Michael S. Ramsey","doi":"10.1016/j.icarus.2025.116544","DOIUrl":"10.1016/j.icarus.2025.116544","url":null,"abstract":"<div><div>One of the most frequently used methods for modeling lava flows on Mars is commonly called the “standard rheologic approach” (SRA). This method requires measurements of the flow dimensions (e.g., width, length, thickness) and local topography (e.g., slope), which are used in equations of viscosity and yield strength, for example. Topography is a critical input for most lava flow models, a detailed analysis of how the input slope value affects the results using the SRA is needed. Here we present a topographic sensitivity analysis of SRA modeling, using the minimum, maximum, and one standard deviation of measured slope values. We investigated sixteen lava flows, fourteen south and two north of Arsia Mons, Mars. Depending on the input slope, a 5 % to 60 % change in viscosity, and a 5 % to 70 % change in yield strength was found. This viscosity range produced an inferred composition change from a basalt to an andesite for eight of the sixteen flows. We also tested a single flow using the SRA and derived slopes from MOLA, HRSC, and CTX digital elevation models (DEMs). The same compositional shift from a basalt to an andesite occurred with increasing DEM resolution. These results highlight the importance of testing the full range of possible slopes and using the highest resolution topographic dataset available to avoid inaccurate interpretation of flow composition. If only low to moderate DEM datasets are available, the results should be interpreted with caution.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116544"},"PeriodicalIF":2.5,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644946","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}

{"title":"The mineralogical composition of Jezero Crater Western Fan: Multigaussian modeling of Perseverance/SuperCam near-infrared observations and overview of major units","authors":"C. Royer ,&nbsp;F. Poulet ,&nbsp;R.C. Wiens ,&nbsp;F. Montmessin ,&nbsp;P. Beck ,&nbsp;O. Beyssac ,&nbsp;É. Clavé ,&nbsp;E. Dehouck ,&nbsp;T. Fouchet ,&nbsp;J.R. Johnson ,&nbsp;L. Mandon ,&nbsp;S. Bernard ,&nbsp;G. Caravaca ,&nbsp;S. le Mouélic ,&nbsp;C. Pilorget ,&nbsp;C. Quantin-Nataf ,&nbsp;S. Maurice ,&nbsp;A. Cousin","doi":"10.1016/j.icarus.2025.116538","DOIUrl":"10.1016/j.icarus.2025.116538","url":null,"abstract":"<div><div>The analysis of the mineralogical composition of rocks within the Jezero crater, Mars, enables the reconstruction of the aqueous activity history of the site, formed during the planet’s early epochs. Numerous secondary minerals resulting from aqueous alteration, as well as some primary minerals, are observable through near-infrared reflectance spectroscopy, as performed by the IRS/SuperCam instrument onboard the <em>Perseverance</em> rover. The characterization of these minerals, their distribution within geological units, as well as the composition of their assemblages, is crucial for deciphering the chemical, climatic, and geological history of the Jezero crater. In order to systematically study the growing number of IR spectra collected by the instrument, we have developed an automated method for extracting the characteristics of absorption bands, based on their modeling using a combination of Gaussian curves (MultiGM). The application of this method to the entire IRS dataset reveals a significant diversity of minerals distributed throughout the rover traverse, with a near-systematic presence of phyllosilicates in bedrocks, as well as increasingly frequent occurrences of carbonates on the delta, particularly within the Margin unit. These carbonates exhibit variable 2.5 <span><math><mi>μ</mi></math></span>m band positions attributed to different Fe and Mg compositions. The delta front presents the sole unit generally enriched in Fe/Mg sulfates (Yori Pass/Hogwallow Flats) accompanied by occurrences of bassanite (hydrated CaSO₄), whereas the presence of sulfates in other delta units and the crater floor is more sporadic and corresponds to fracture/vesicle fills. Finally, almost all the rocks analyzed with IRS/SuperCam are notably dominated by phyllosilicates signatures (Fe/Mg-smectites, serpentine), excepted for a few outcrops caping the Delta. This phyllosilicate presence witnesses the extended surficial (smectites) and hydrothermal (serpentine) aqueous alteration of Jezero’s rocks, either <em>in situ</em> or carried from the watershed.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116538"},"PeriodicalIF":2.5,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601006","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":"Stress analysis of asteroids during atmospheric entry and implications for the breakup criterion","authors":"Théo A. Rulko ,&nbsp;Aaditya Rau ,&nbsp;Grégoire Chomette ,&nbsp;Lorien Wheeler ,&nbsp;Donovan Mathias ,&nbsp;Jessie Dotson ,&nbsp;Raúl Radovitzky","doi":"10.1016/j.icarus.2025.116526","DOIUrl":"10.1016/j.icarus.2025.116526","url":null,"abstract":"<div><div>Observations of asteroid fragmentation upon atmospheric entry have been used as a basis to estimate asteroid mechanical strength by the simplifying assumption that strength corresponds to ram pressure at burst. However, it is unclear whether ram pressure is a good scalar measure of the stresses that induce fracture. In this work, we study the stress fields prior to break-up in idealized as well as representative irregular asteroids as they enter the atmosphere. We develop a model for elastic, homogeneous, monolithic asteroids subject to aerodynamic, inertial, and centrifugal loads applied via the Meteor Equations and modified Newtonian aerodynamic theory. We obtain an analytical solution to the elasticity boundary value problem for an idealized circular asteroid. Alongside it, detailed finite element solutions are used to both verify the analytical model and to quantify the effects of asteroid shape irregularity on the state of stress. We find that the stresses that drive brittle fracture in asteroids may be an order of magnitude lower than the ram pressure, which could have significant implications for strengths inferred from breakup observations. We also quantify the effect of the spin of the asteroid as it tumbles through the atmosphere and the regimes in which spin-induced stresses dominate. Finally, we find that asteroids with small shape variations are well-approximated as spheres, but that large shape irregularities, like at the necks of elongated or contact binary asteroids, may lead to the appearance of regions of tensile bending stress. Conclusions are drawn about the usefulness of the ram pressure alone as a measure of stress in asteroids.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116526"},"PeriodicalIF":2.5,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593525","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":"Measurement of the three-dimensional shape and size distribution of 17 lunar regolith simulants: Simulant shape and size inter-comparison and simulant shape comparison with Apollo 11 and Apollo 14 lunar regolith","authors":"O.L. Kafka ,&nbsp;N.H. Moser ,&nbsp;A.N. Chiaramonti ,&nbsp;E.J. Garboczi ,&nbsp;R.P. Wilkerson ,&nbsp;D.L. Rickman","doi":"10.1016/j.icarus.2025.116542","DOIUrl":"10.1016/j.icarus.2025.116542","url":null,"abstract":"<div><div>Lunar regolith simulants are manufactured in order to provide a higher volume, much less expensive and more available source of material, compared to real lunar regolith material, with which to test various instruments and machines designed to operate on the lunar surface. The particle size distribution and mineralogy of these materials is engineered but not the particle shape, although particle shape does play an important role in many engineering applications. Thus, the three-dimensional (3D) shape of these materials has rarely been characterized and never compared to each other and to real lunar regolith material. The focus of this paper is to provide 3D shape and size distribution of 17 different simulants, use this data to compare these materials against each other and provide these data in a NIST database. Over 1.1 M particles are in this database, with their 3D shape stored as STL files. The particle size range considered is roughly 7 μm to 1 mm. With the recent publication of 3D characterizations of lunar regolith material from the Apollo 11 and Apollo 14 missions, these characterizations are also compared to equivalent data for the real lunar regolith material. Both mare and highland simulants are studied using graphical comparisons as well as size and shape figure of merit analysis. This kind of 3D characterization provides the information that new engineering manufacturing techniques will need to enable the engineering of particle shape for new lunar regolith simulants, since the ability to make particle shape measurements relevant to manufacturing and use is a prerequisite for any such engineering. This database can also serve as a source of “digital twins” or “virtual simulants” for modeling studies both of individual particle properties and of packed particle geometry and properties.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"434 ","pages":"Article 116542"},"PeriodicalIF":2.5,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629610","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}