Icarus最新文献

{"title":"Near-Earth Asteroid orbit determination with Physics-Informed Extreme Learning Machine","authors":"Xiuyu Chen ,&nbsp;Kai Tang ,&nbsp;Qingfeng Zhang ,&nbsp;Zhenliang Tian ,&nbsp;Yong Yu","doi":"10.1016/j.icarus.2026.116962","DOIUrl":"10.1016/j.icarus.2026.116962","url":null,"abstract":"<div><div>The Physics-Informed Extreme Learning Machine (PIELM) is a single-hidden-layer feedforward neural network. It integrates the rapid training capability of Extreme Learning Machines (ELM) with the physics-informed strength of Physics-Informed Neural Networks (PINN), ensuring solutions consistent with physical laws and measurements. This synergy makes PIELM well-suited for solving the complex orbit determination problem. In this study, we extended the PIELM framework to Near-Earth Asteroid (NEA) orbit determination, proposing a comprehensive and operational strategy. Our approach is specifically designed to account for unique NEA characteristics, notably incorporating light-time correction into the measurement model. A statistical analysis using a large number of real NEA observations was conducted to assess PIELM’s accuracy in NEA orbit determination. The results demonstrate that although PIELM’s precision does not yet match the traditional least-squares method, it achieves sufficient accuracy for most scenarios covered in this study. Notably, PIELM does not require any prior orbit guess and demonstrates performance comparable or superior to the classical Laplace method in Initial Orbit Determination (IOD). This capability is vital for NEA discovery and recovery in the upcoming data-intensive survey era.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116962"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074887","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":"Validation of SPH code Spheral to model interacting solid bodies in a supersonic flow","authors":"Veronika A. Korneyeva ,&nbsp;Jason M. Pearl ,&nbsp;Kathryn M. Kumamoto ,&nbsp;J. Michael Owen ,&nbsp;Cody D. Raskin ,&nbsp;Megan B. Syal ,&nbsp;Nicholaus J. Parziale ,&nbsp;Stuart J. Laurence","doi":"10.1016/j.icarus.2026.116964","DOIUrl":"10.1016/j.icarus.2026.116964","url":null,"abstract":"<div><div>Contemporary discussions of planetary defense involve analyzing the risks posed by smaller sized, 20 to 200 m diameter, asteroids which are capable of breaking up in the atmosphere and generating a blast wave. Consequence assessments for this size class of asteroids are performed through fast-running analytic or semi-analytic models which are informed by high-fidelity hydrocode simulations of asteroid entry and breakup. However, insufficient historical data necessitates validating the independent physical processes which dominate airburst events. The Fluid Solid Interface Smoothed Particle Hydrodynamics solver was previously used by Pearl et al. in 2023 to model the Chelyabinsk airburst and is used here to perform a series of validation simulations. The first effort involves modeling a cylinder in a hypersonic flow and comparing the bow shock geometry to that predicted by analytic theory. The second effort involves modeling the separation of two spherical bodies in supersonic flow and validating against experimental footage. Combined, these exercises demonstrate the ability of the code to model the flight-path of interacting solid bodies in a hypersonic flow.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116964"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074892","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":"Investigation of the dynamics and origin of the NEA pair 2021 PH27 and 2025 GN1","authors":"Albino Carbognani ,&nbsp;Marco Fenucci ,&nbsp;Toni Santana-Ros ,&nbsp;Clara E. Martínez-Vázquez ,&nbsp;Marco Micheli","doi":"10.1016/j.icarus.2026.116939","DOIUrl":"10.1016/j.icarus.2026.116939","url":null,"abstract":"<div><div>We analyse the association between the NEAs 2021 PH27 and 2025 GN1, which share similar heliocentric Keplerian elements and the same taxonomic classification. First, we confirm the spectral similarity by getting independent colours measurements of 2025 GN1 and confirming that they are both X-type. From numerical integration of the orbits up to 100 kyr in the past, taking into account relativistic corrections, we found that the two asteroids experienced five similar flybys with Venus, but none of them were closer than the Roche limit. The perihelion distance also reached values between 0.1 and 0.08 au about 17/21 kyr and 45/48 kyr ago, but still well outside the Roche limit with the Sun. So, the origin of the pair by tidal disruption of a progenitor rubble-pile asteroid appears unlikely. On the other hand, we found periods lasting several thousand years where the perihelion was below 0.1 au, and this can lead to thermal fracturing of the surface. We found that the rotation period of the primary and the mass ratio secondary/primary make the pair indistinguishable from the binary systems known among the NEAs, and the YORP effect can double the rotation period of 2021 PH27 in <span><math><mrow><mn>150</mn><mo>±</mo><mn>50</mn></mrow></math></span> kyr. So it is plausible that the pair was formed by the rotational disintegration of a rubble-pile asteroid due to anisotropic gas emission or the YORP effect, which formed a binary system that later dissolved due to the internal dynamics of the pair. We are unable to give a value for the separation age; we can only say that it occurred more than 10.5 kyr ago and may have occurred between 17/21 kyr ago during the last and longer phase of lower perihelion distance. In this scenario, little meteoroids released in space due to the fragmentation event are still near the pair’s orbit and can generate a meteor shower in Venus’ atmosphere.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116939"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035954","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":"Radiatively coupled equatorial waves in Mars’ Aphelion Cloud Belt: Wavenumber–frequency analysis in Mars GCM simulations","authors":"Márton Mester ,&nbsp;R. John Wilson ,&nbsp;Melinda A. Kahre","doi":"10.1016/j.icarus.2026.116967","DOIUrl":"10.1016/j.icarus.2026.116967","url":null,"abstract":"<div><div>We investigate the influence of radiatively active water–ice clouds on tropical wave variability in Mars’ Aphelion Cloud Belt using Mars general circulation model simulations. Wavenumber–frequency spectral and empirical orthogonal function analyses reveal four primary categories of variability: fast eastward- and westward-propagating waves, slow eastward and westward oscillations associated with the Tropical Cloud Oscillation (TCO), and the diurnal westward-propagating wavenumber-1 tide (DW1). When water–ice clouds are radiatively active, the spectrum of tropical variability is dominated by a 13-sol, eastward-propagating wavenumber-1 mode and a 7-sol, westward-propagating wavenumber-2 mode. Both exhibit vertically coherent, quasi-barotropic structures in the cloud field but distinct baroclinic signatures in temperature, indicating partial dynamical coupling between thermal and microphysical variability. By contrast, simulations without radiatively active clouds display more distinct Kelvin and Rossby wave-like bands and qualitatively different spatial structures among slow waves. Radiative feedbacks redistribute energy and concentrate the spectral distribution to a discrete set of wave modes, and promote vertically extended, hemispherically coupled wave modes. The slow TCO-related variability is particularly sensitive to cloud radiative effects. With radiatively active clouds, the long-period spectral wave band forms a robust three-state oscillation involving alternating cloudiness over Tharsis and Syrtis Major — consistent with observations. However, in the absence of radiative feedbacks, the variability collapses into a single, slowly propagating mode confined to Tharsis. These results demonstrate that radiatively active water–ice clouds fundamentally reshape the spectrum and structure of Martian tropical waves. By introducing vertically distributed diabatic heating and enhancing thermal–microphysical coupling, cloud radiative effects sustain the large-scale, seasonally modulated oscillations that characterize the tropical cloud regime on Mars.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116967"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035953","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":"Crossing boundaries: Brachinites and their diverse asteroidal origins","authors":"B.G. Rider-Stokes ,&nbsp;F.A. Davies ,&nbsp;T.H. Burbine ,&nbsp;E. MacLennan ,&nbsp;R.C. Greenwood ,&nbsp;S.L. Jackson ,&nbsp;M. Anand ,&nbsp;D. Sheikh ,&nbsp;M.M. Grady","doi":"10.1016/j.icarus.2026.116965","DOIUrl":"10.1016/j.icarus.2026.116965","url":null,"abstract":"<div><div>Brachinite meteorites are typically linked to the olivine-rich A-type asteroids. In this study, however, they appear to exhibit unexpected spectral diversity. Spectroscopic analysis of seven meteorites from the brachinite clan reveals two distinct populations in band parameters, overlapping with both the A-type and S-complex asteroids. This dual association shows that a single meteorite group can originate from multiple asteroid taxonomies. Notably, one S-complex-like specimen, Northwest Africa (NWA) 14,635, displays band parameters similar to those of asteroid (65803) Didymos, the target of the European Space Agency's (ESA) ongoing Hera mission. These results underscore the value of spectroscopic characterization of poorly understood meteorite groups and identifying potential analogs that are highly relevant for current and future mission planning.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116965"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035947","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":"Hyper Spectral Range Index: Detection and quantification of H2O vapor in the Martian atmosphere with PFS/MEx","authors":"M. Es-sayeh ,&nbsp;S. Bauduin ,&nbsp;L. Clarisse ,&nbsp;B. Franco ,&nbsp;M. Smith ,&nbsp;M. Giuranna","doi":"10.1016/j.icarus.2026.116951","DOIUrl":"10.1016/j.icarus.2026.116951","url":null,"abstract":"<div><div>This paper introduces a framework scheme for the detection and quantification of trace species in planetary hyperspectral datasets. The method, only used for terrestrial purposes yet, relies on a Hyperspectral Range Index (HRI) to quantify the target gas spectral signature with respect to the climatological background. The HRI is subsequently converted to a total column using an artificial feed-forward neural network built from radiative transfer (RT) model simulations. Importantly, we also provide an appropriate uncertainties characterization. The method has been applied to the Planetary Fourier Spectrometer (PFS) instrument onboard Mars Express (MEX) to retrieve H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O vapor column amount. Nine Martian years of PFS/LWC (Long Wavelength Channel) measurements have been processed to acquire a data set of H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O vapor total columns, analyzed, and compared to similar products from other retrieval methods. The results are comparable to those from standard retrieval methods but were achieved at a significantly reduced computational cost, demonstrating the method’s suitability for analyzing large observational datasets.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116951"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074886","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 “A dual-branch automatic classification network for lunar simple crater degradation grades integrating image and morphological parameters” [Icarus 445 (2026) 116863]","authors":"Shuai Shao,&nbsp;Meng Xiao,&nbsp;Zhizhong Kang,&nbsp;Teng Hu,&nbsp;Zhen Cao,&nbsp;Yingnan Zhang,&nbsp;Jinhao Cai,&nbsp;ZhongLu Lei,&nbsp;Haoxiang Hu","doi":"10.1016/j.icarus.2026.116972","DOIUrl":"10.1016/j.icarus.2026.116972","url":null,"abstract":"","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116972"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074893","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":"Far ultraviolet carbon emissions in the Mars aurora: Brightness, intensity ratios and seasonal dependence","authors":"J.C. Gérard ,&nbsp;L. Soret ,&nbsp;B. Hubert ,&nbsp;R. Lillis ,&nbsp;S. Jain ,&nbsp;J. Deighan","doi":"10.1016/j.icarus.2025.116919","DOIUrl":"10.1016/j.icarus.2025.116919","url":null,"abstract":"<div><div>Neutral carbon emissions have been observed in Far Ultraviolet spectra (FUV) of the Martian aurora with the Emirates Mars Ultraviolet Spectrometer (EMUS) instrument on board the Emirates Mars Mission (EMM). Oxygen emissions at 130.4 and 135.6 nm have been used to map the auroral morphology and its dependence on solar wind parameters. The CI emissions at 156.1 and 165.7 nm are excited by collisions between energetic electrons and CO₂, CO and C. We present Monte Carlo simulations of the altitude distributions of both features showing that electron collisions with ambient CO₂ molecules are the dominant source, followed by collisions on CO, while direct impact on C atoms is several orders of magnitude smaller. Since the C atom fragments resulting from dissociation are produced with a speed exceeding by far the thermal velocity, the optical depth is negligible. Consequently, the 156.1 and 165.7 nm photons are not self-absorbed, and the calculation of the emission rates does not require consideration of radiative transfer, unlike the OI 130.4 nm triplet. We present calculations of the efficiency of the carbon emissions for a range of incident auroral electrons energies. We illustrate the energy dependence of the intensity ratios between the oxygen 130.4 and 135.6 nm and the carbon 165.7 nm emissions. These ratios may be used to remotely characterize the spatial distribution of the incident electron energies in spectral FUV maps of the aurora.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"448 ","pages":"Article 116919"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145882258","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":"Boulder motions on asteroid Ryugu induced by thruster gas disturbance by Hayabusa2","authors":"Naoya Sakatani ,&nbsp;Shingo Kameda ,&nbsp;Kosuke Kitsunai ,&nbsp;Hiroshi Kikuchi ,&nbsp;Shota Kikuchi ,&nbsp;Yuto Takei ,&nbsp;Yuya Mimasu ,&nbsp;Osamu Mori ,&nbsp;Toru Kouyama ,&nbsp;Tomokatsu Morota ,&nbsp;Eri Tatsumi ,&nbsp;Yuichiro Cho ,&nbsp;Manabu Yamada ,&nbsp;Yasuhiro Yokota ,&nbsp;Moe Matsuoka ,&nbsp;Chikatoshi Honda ,&nbsp;Hidehiko Suzuki ,&nbsp;Masahiko Hayakawa ,&nbsp;Kazuo Yoshioka ,&nbsp;Kazunori Ogawa ,&nbsp;Seiji Sugita","doi":"10.1016/j.icarus.2025.116916","DOIUrl":"10.1016/j.icarus.2025.116916","url":null,"abstract":"<div><div>JAXA's Hayabusa2 spacecraft executed several low-altitude (down to &lt;25 m) operations during its proximity maneuvers on asteroid Ryugu. Analysis of images acquired during the ascent (i.e., soon after thruster gas injection) revealed that many surface boulders were in motion on Ryugu. While previous studies documented boulder movement resulting from physical contact, such as the Hayabusa2 touchdowns and NASA's OSIRIS-REx sampling operations, this study uniquely confirms movement induced by remote disturbance through thruster gas. Boulder movement was analyzed using a series of Optical Navigation Camera (ONC) images taken during the DO-S01 operation, where the greatest number of boulders displayed movement over an extended period among the low-altitude descents by Hayabusa2. 74 moving boulders were identified, and the largest one was approximately 40 cm in diameter. The maximum velocity was 1.7 cm/s. The momentum imparted to the rock from the thruster injection pressure exceeded the observed momentum, suggesting that the boulder motion was induced directly by thruster gas, and subsequent friction with the surface decelerated the boulders. Notably, the observations revealed sustained boulder motion lasting more than 10 min, during which the trajectories of some boulders changed, suggesting multiple bouncing on the asteroid surfaces. This observation implies a significant restitution coefficient for boulder motion on microgravity asteroids, allowing for multiple bouncing. However, shadow measurements indicate minimal or zero leap height. This indicates that a mode of motion akin to rolling on the surface should not be ruled out either. Comparison between moving and stationary boulders showed that the numbers of the moving boulders relative to the stational is lower for smaller size. This suggests that the inertia of larger boulders, making them harder to stop, has stronger effect than the ease of acceleration in smaller boulders. These findings on the characteristics of motion are pivotal for predicting the dynamical response of surface materials after physical disturbances on asteroids. This understanding is crucial for deciphering the mode of surface renewal in near-Earth asteroids and for planning expected proximity observations of near-Earth objects (e.g., OSIRIS-APEX and RAMSES missions).</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"448 ","pages":"Article 116916"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145882260","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":"Instantaneous thermally-driven erosion can explain dearth of dark near-Sun asteroids","authors":"Georgios Tsirvouils ,&nbsp;Mikael Granvik ,&nbsp;Leonard Schirner ,&nbsp;Athanasia Toliou ,&nbsp;Jooyeon Geem ,&nbsp;Axel Hagermann","doi":"10.1016/j.icarus.2026.116942","DOIUrl":"10.1016/j.icarus.2026.116942","url":null,"abstract":"<div><div>Recent models of the near-Earth asteroid population show that asteroids must be super-catastrophically destroyed when they evolve to orbits with perihelion passages well inside of Mercury’s orbit. The heliocentric distances at which the disruptions typically occur are tens of solar radii, which is too far from the Sun for asteroids to be destroyed by sublimation and tidal disruption. The typical disruption distance also appears to be larger for darker asteroids. Here, by carrying out irradiance experiments in vacuum that replicate the conditions in the near-Sun environment, we show that CI meteorite simulants are destroyed within minutes when exposed to the level of solar irradiance encountered at heliocentric distances of up to about 0.2 au. Our results provide an explanation for the scarcity of dark, carbonaceous asteroids with perihelion distances less than 0.2 au, and for the observed mass-loss rate of the asteroid-like object 322P/SOHO 1 assuming its composition is similar to CI carbonaceous chondrites.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"448 ","pages":"Article 116942"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973571","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}