Planetary and Space Science最新文献

{"title":"Multiphase photoclinometry as applied to the lunar photometry with LROC NAC data","authors":"Sergey Velichko ,&nbsp;Viktor Korokhin ,&nbsp;Yuri Velikodsky ,&nbsp;Vadym Kaydash ,&nbsp;Yuriy Shkuratov ,&nbsp;Gorden Videen ,&nbsp;Tomasz Kwiatkowski ,&nbsp;Yehor Surkov","doi":"10.1016/j.pss.2024.105914","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105914","url":null,"abstract":"<div><p>An original method for photometric and geometric correction of LROC NAC data with high resolution (up to 0.5 m/pix) has been developed. The technique is based on photogrammetry and multiphase photoclinometry and allows us to obtain a longitudinal slope map and digital elevation model (DEM) with the resolution of LROC NAC CDR input images as well as to map parameters of model phase function. Obtained DEMs, requiring only LROC NAC images and LRO SPICE-kernels, exhibit significantly fewer defects and artifacts compared to existing DEMs, because they are derived from the same images they correct (self-orthorectification).</p><p>This method was used to study the area of the photometric anomaly, the Irregular Mare Patch (IMP) formation Ina. A zoning map of the correlation diagram of phase ratio vs. equigonal albedo shows significant differences in the optical (photometric) properties of the regolith for hummocky and blocky formations of the IMP Ina, compared to the surrounding areas, which indicates the different nature of their formation, age, and surface roughness, contradicting some models of the IMP formation. The analysis reveals the incompleteness or inconsistencies of previously proposed models of the IMP's formation mechanisms. The high-quality DEM of the Ina formation and surrounding area with a resolution of 0.5 m/pixel was constructed.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"246 ","pages":"Article 105914"},"PeriodicalIF":2.4,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140950568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 Hera Radio Science Experiment at Didymos","authors":"Edoardo Gramigna ,&nbsp;Riccardo Lasagni Manghi ,&nbsp;Marco Zannoni ,&nbsp;Paolo Tortora ,&nbsp;Ryan S. Park ,&nbsp;Giacomo Tommei ,&nbsp;Sébastien Le Maistre ,&nbsp;Patrick Michel ,&nbsp;Francesco Castellini ,&nbsp;Michael Kueppers","doi":"10.1016/j.pss.2024.105906","DOIUrl":"10.1016/j.pss.2024.105906","url":null,"abstract":"<div><p>Hera represents the European Space Agency's inaugural planetary defense space mission and plays a pivotal role in the Asteroid Impact and Deflection Assessment international collaboration with NASA DART mission that performed the first asteroid deflection experiment using the kinetic impactor techniques. With the primary objective of conducting a detailed post-impact survey of the Didymos binary asteroid following the DART impact on its small moon called Dimorphos, Hera aims to comprehensively assess and characterize the feasibility of the kinetic impactor technique in asteroid deflection while conducting an in-depth investigation of the asteroid binary, including its physical and compositional properties as well as the effect of the impact on the surface and shape of Dimorphos. In this work, we describe the Hera radio science experiment, which will allow us to precisely estimate critical parameters, including the mass, which is required to determine the momentum enhancement resulting from the DART impact, mass distribution, rotational states, relative orbits, and dynamics of the asteroids Didymos and Dimorphos. Through a multi-arc covariance analysis, we present the achievable accuracy for these parameters, which consider the full expected asteroid phase and are based on ground radiometric, Hera optical images, and Hera to CubeSats InterSatellite Link radiometric measurements. The expected formal uncertainties for Didymos and Dimorphos GM are better than 0.01% and 0.1%, respectively, while their J₂ formal uncertainties are better than 0.1% and 10%, respectively. Regarding their rotational state, the absolute spin pole orientations of the bodies can be recovered to better than 1°, and Dimorphos' spin rate to better than 10⁻³%. Dimorphos reconstructed relative orbit can be estimated at the sub-m level. Preliminary results, using a higher-fidelity dynamical model of the coupled motion between rotational and orbital dynamics, show uncertainties in the main parameters of interest that are comparable to those in standard radio science models. A first-order estimate of the expected uncertainty in the momentum transfer efficiency from DART's impact, obtainable with Hera, yields a value of about 0.25. This represents a significant improvement compared to current estimates. Overall, the retrieved values meet the Hera radio science requirements and goals, and remain valid under the condition that the system is determined to be in an excited but non-chaotic (or tumbling) state. The Hera radio science experiment will play an integral role in the exploration of the Didymos binary asteroid system and will provide unique scientific measurements, which, when combined with other observables such as optical images, altimetry measurements, and satellite-to-satellite tracking of the CubeSats, will support the mission's overarching goals in planetary defense and the deep understanding of binary asteroids.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"246 ","pages":"Article 105906"},"PeriodicalIF":2.4,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324000709/pdfft?md5=09ac1b58a380c16d497c010efa328906&pid=1-s2.0-S0032063324000709-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141050557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Assessing the survival of carbonaceous chondrites impacting the lunar surface as a potential resource","authors":"Samuel H. Halim ,&nbsp;Ian A. Crawford ,&nbsp;Gareth S. Collins ,&nbsp;Katherine H. Joy ,&nbsp;Thomas M. Davison","doi":"10.1016/j.pss.2024.105905","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105905","url":null,"abstract":"<div><p>The Moon offers a wide range of potential resources that may help sustain a future human presence, but it lacks indigenous carbon (C) and nitrogen (N). Fortunately, these elements will have been delivered to the Moon's surface by carbonaceous chondrite (CC) asteroid impactors. Here, we employ numerical modelling to assess the extent to which these materials may have sufficiently survived impact with the lunar surface to be viable sources of raw materials for future exploration. We modelled the impact of a 1 km diameter CC-like asteroid, considering impact velocities between 5 and 15 km s⁻¹, and impact angles between 15 and 60° to the horizontal. The most favourable conditions for the survival of C-rich, and especially N-rich materials, are those with the lowest impact velocities (≤10 km s⁻¹) and impact angles (≤15°). Impacts with velocities &gt;10 km s⁻¹ and angles &gt;30° were found not to yield any significant amount of surviving solid material, where bulk survival is defined as material experiencing temperatures less than the impactor material's estimated melting temperature (∼2100 K, based on a commonly adopted Equation of State for serpentine). Importantly, oblique and low velocity impacts result in concentrations of unmelted projectile material down-range from the impact site. For the canonical 1 km-diameter CC impactor considered here, with an impact angle ≤15° and velocity ≤10 km s⁻¹, this results in ∼10⁹–10¹⁰ kg of C and ∼10⁸–10⁹ kg of N being deposited a few tens of km down-range from the impact crater, where it might be accessible as a potential resource. Such low-velocity and oblique impacts have a low probability - we estimate that only ∼5 such impacts may have occurred on the Moon in the last 3 billion years (the number of impacts of smaller impactors will have been higher, but they will concentrate lower masses of potential resources). As the estimated C and N concentrations from such impacts greatly exceed those expected for ices within individual permanently shadowed polar craters, searching for these rare impact sites may be worthwhile from a resource perspective. We briefly discuss how this might be achieved by means of orbital infra-red remote-sensing measurements.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"246 ","pages":"Article 105905"},"PeriodicalIF":2.4,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324000692/pdfft?md5=15a887356e326c38a9cee5fe71427eb9&pid=1-s2.0-S0032063324000692-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140906674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Comet P/2003 T12 (SOHO): A possible fragment of comet 169P/NEAT?","authors":"Santiago Roland Alvarez,&nbsp;Andrea Sosa Oyarzabal","doi":"10.1016/j.pss.2024.105902","DOIUrl":"10.1016/j.pss.2024.105902","url":null,"abstract":"<div><p>This work provides insights into the possible origin of comet P/2003 T12 (SOHO) and the dynamics of comet fragmentation events. We studied the hypothesis of the origin of the comet P/2003 T12 (SOHO) as a fragment of the Jupiter family comet 169P/NEAT. We studied the recent dynamical evolution of the comet pair and determined the epochs of relative minimum distance and velocity as well as the similarity between the orbits using different criteria following Rożek et al. (2011) and Kholshevnikov et al. (2016). We generated 6000 clones of both comets with orbital elements compatible with the observational uncertainties of the actual orbits and found that their evolution is stable for the past <span><math><mo>∼</mo></math></span> 5000 years. We found four epochs where the relative distance and velocity exhibit simultaneous minima. We studied possible fragmentation events in these epochs by applying a simple break-up model for the generation of fictitious fragments at different relative speeds. Analyzing the orbital distance between the fragments, we found some fragments that exhibit noticeable stable behavior at a very low mutual orbital distance according to several distance definitions, which suggest that those fragments evolve in orbits very similar to that of the P/2003 T12 (SOHO). We conclude that comet P/2003 T12 (SOHO) could be a fragment of comet 169P/NEAT and the most likely epoch for such fragmentation would be at least 2000 years ago (around 94 A.D.), given that the fragments that best resemblance comet P/2003 T12 (SOHO) are found in this epoch.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"246 ","pages":"Article 105902"},"PeriodicalIF":2.4,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140757462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Mapping the spatial distributions of oxide abundances and Mg# on the lunar surface using multi-source data and a new ensemble learning algorithm","authors":"Chaofa Bian ,&nbsp;Kefei Zhang ,&nbsp;Yunzhao Wu ,&nbsp;Suqin Wu ,&nbsp;Yu Lu ,&nbsp;Hongtao Shi ,&nbsp;Huaizhan Li ,&nbsp;Dongsheng Zhao ,&nbsp;Yabo Duan ,&nbsp;Ling Zhao ,&nbsp;Huajing Wu","doi":"10.1016/j.pss.2024.105894","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105894","url":null,"abstract":"<div><p>The spatial distribution of oxide abundances and Mg# (Mg/(Mg + Fe)) on the lunar surface is of great significance for in-depth understanding the origin and evolution of the Moon. China's Chang’E−5 (CE-5) mission returned young lunar soils for the first time, providing a new ground truth for the inversion of oxide abundances. In this study, the relationship between multi-source remote sensing data (including Chang’E−1 Interference Imaging Spectrometer (CE-1 IIM) data and the new global Christiansen feature (CF) product, named IIM-CF data), and the abundances of six oxides (FeO, TiO₂, MgO, SiO₂, Al₂O₃ and CaO) measured at 40 lunar sampling sites including CE-5 were analyzed. The use of IIM-CF data as the input features of the selected inversion models for obtaining the abundances of oxides, and the oxide abundances measured at the 40 sampling sites were used as the ground truth. The models selected for this investigation contain three typical algorithms − random forest (RF), extreme gradient boosting (XGBoost) and partial least squares regression (PLSR), and a new method integrates RF, XGBoost and PLSR together named RXP was developed in this study. The modeling results of the abundances of the six oxides derived from the above four algorithms show that the RXP algorithm outperforms the other three algorithms. The distributions of the six oxides and Mg# on the lunar surface covering the range from 70° N to 70° S (70° N/S) with a resolution of about 200 m/pixel were generated using the proposed RXP algorithm. Our results indicate that, compared with the result of a single data source, the use of IIM-CF data improved the accuracy of the modeling of oxide abundances and Mg#. It is expected that the CE-5 samples can bring additional references to the studies of the inversion for the oxides of the lunar surface and deepen our understanding over this issue.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"245 ","pages":"Article 105894"},"PeriodicalIF":2.4,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140619052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Preliminary spectroscopic investigation of a potential Mars analog site: Lake Bagno dell’Acqua, Pantelleria, Italy","authors":"Enrico Bruschini ,&nbsp;Marco Ferrari ,&nbsp;Cristina Mazzoni ,&nbsp;Stefano Fazi ,&nbsp;Francesco Latino Chiocci ,&nbsp;Ilaria Mazzini ,&nbsp;Giovanna Costanzo ,&nbsp;Simone De Angelis ,&nbsp;Maria Cristina De Sanctis ,&nbsp;Francesca Altieri ,&nbsp;Jeremy Brossier ,&nbsp;Eleonora Ammannito","doi":"10.1016/j.pss.2024.105893","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105893","url":null,"abstract":"<div><p>In this study, we characterize the mineralogy and microbiology of a suite of samples from the Bagno dell’Acqua alkaline (pH ≥ 9) lake in Pantelleria, Italy. The aim of the present characterization is the assessment of the lake as a Martian analog site. Nineteen samples were characterized by a combination of VNIR reflectance spectroscopy, micro-Raman (μ-Raman) spectroscopy, and fluorescence microscopy. In addition, DNA extraction was performed on three selected samples to identify the bacteria phyla and to quantify their abundance. The samples were collected as push cores inside the lake and as loose sediments taken along the eastern and southeastern lake's shore. The samples underwent three thermal cycles (between 343 K and 473 K) to remove excess water and organic matter. The VNIR spectra were measured on each sample after each thermal cycle to check the variation of the spectral features as a function of thermal treatment. The mineralogical content of our push core samples is dominated by the presence of Mg-smectite clays always associated with the remanence of K-feldspars and Ca-carbonates while in the sediments we observe also additional minor phases like pyroxene (aegirine NaFe³⁺Si₂O₆), hematite (Fe₂O₃), anatase (TiO₂), and volcanic glass. Two organic phases were detected by μ-Raman spectroscopy. One phase was attributable to carotenoids, in line with the high abundance of Bacterial Phyla that can synthesize these molecules. The second phase appeared to be visually indistinguishable from the inorganic matrix and is therefore attributed to EPS (Extracellular Polymeric Substances) forming a biofilm and extensively observed by fluorescent microscopy. The peculiar chemistry of the waters, the presence of Mg-smectite in the sediments of Lake Bagno dell’Acqua associated with Ca-carbonates and sediments derived by biological activity makes Lake Bagno dell’Acqua a very interesting and promising Martian analog site.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"245 ","pages":"Article 105893"},"PeriodicalIF":2.4,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140619053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"An observational investigation of very low frequency radio emissions originating from meteors","authors":"Paraksh M. Vankawala ,&nbsp;Robert A. Marshall ,&nbsp;Denis Vida ,&nbsp;Peter Brown","doi":"10.1016/j.pss.2024.105892","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105892","url":null,"abstract":"<div><p>This study presents results from five months of meteor observations that included simultaneous and nearby very low frequency (VLF) wave detections. We explore the plausibility of VLF emissions from meteors resulting in the documented phenomena of simultaneous optical and audio signatures with meteor events. Most previous attempts to observe VLF emissions from meteors have been limited in duration and/or in area covered during observations. With the extended duration and an observational network of three cameras and two VLF receivers across Colorado, an exhaustive approach was taken to detect meteor VLF emissions. The <span><math><mo>∼</mo></math></span>650 events collected were closely inspected for any signs of emissions, with an emphasis on brighter meteors and fireballs. The VLF data was filtered using interference mitigation techniques to eliminate spurious signals that could obscure the VLF signals of interest. By comparing the VLF spectral content at the time of meteors and during control times, we search for very small changes in the signal that would be statistically correlated with meteor observation times. Despite these efforts, no VLF emissions have been detected that cannot be attributed to other sources. Most commonly, lightning-generated sferics coincident with the time of meteor events lead to false attributions to meteors.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"245 ","pages":"Article 105892"},"PeriodicalIF":2.4,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140551321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Optical polarization studies of latex beads in aqueous solution: An analog for radar scattering in icy regolith","authors":"Antoine Bourget ,&nbsp;Parvathy Prem ,&nbsp;David Blewett ,&nbsp;Michael G. Daly ,&nbsp;Isaac B. Smith","doi":"10.1016/j.pss.2024.105891","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105891","url":null,"abstract":"&lt;div&gt;&lt;p&gt;This study presents low phase angle &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;mtext&gt;–&lt;/mtext&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; measurements of polarimetric properties of icy planetary regolith analog materials acquired using the custom-built Multi-Axis- Goniometer-Instrument (MAGI). We present same sense &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and opposite sense &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; backscatter circular polarization coefficients, circular polarization ratio &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and degree linear polarization &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; of spherical latex (non-dye) beads of varying sizes and volume concentrations (v/v) in aqueous solutions (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) in water. We also present measurements of alumina powder in air at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;064&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Measurements showed that at a low incidence angle &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, backscatter is dominated by surface specular single-bounce scattering, that hides other scattering processes. At high &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;15&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; incidence angle, surface single-bounce surface scattering becomes negligible, allowing for the detection of diffuse, dihedral (multiple bounces) scattering. We find that classical Mie alumina particles &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; enhance subsurface scattering due to a larger void space relative to larger Mie particles &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;30&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, that cause the radar signal to scatter forward off small imperfections, maintaining the polarization properties of the signal and generating high &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Latex beads, representing impurities, demonstrate the impact of isotropic and anisotropic scattering on radar signatures. This study also found that the scattering medium’s anisotropy correlates to the size of the beads, while the void space of the medium inversely correlates with the bead size and the volume concentration (v/v) of the beads. Rayleigh beads, due to isotropic scattering from the reduced scattering cross-section and higher transparency relative to larger impurities, generate subsurface single bounce scatter","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"244 ","pages":"Article 105891"},"PeriodicalIF":2.4,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324000552/pdfft?md5=c513602ff4b1c6ccdd84378188bdef1d&pid=1-s2.0-S0032063324000552-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Synthesizing lunar regolith-geopolymer emulating lunar positive temperature regime","authors":"Usman Javed ,&nbsp;Faiz Uddin Ahmed Shaikh ,&nbsp;A.K.M. Samsur Rahman","doi":"10.1016/j.pss.2024.105890","DOIUrl":"https://doi.org/10.1016/j.pss.2024.105890","url":null,"abstract":"<div><p>The development of lunar habitat using lunar regolith is a captivating research area for constructing lunar bases, especially after the discovery of polar ice, and molecular water on the lunar south pole. The aim of this research is to synthesize a robust lunar regolith geopolymer by fine-tuning the concentration and ratios of alkaline activators while implementing curing under lunar positive thermal regime. The geopolymer was synthesized containing lunar highlands simulant (LHS-1) and mare regolith simulant (LMS-1) at the lowest water content using sodium (Na) and potassium (K) based alkaline activators emulating positive temperature regime collected by Diviner Lunar Radiometer Experiment (DLRE). The maximum compressive strength of 41.23 MPa was achieved for highlands regolith simulant-based geopolymer containing a Na-activator with the lowest water-to-precursor ratio of 0.23. The surplus alkali cations in the geopolymer paste matrix resulted in the formation of carbonation products after reacting with atmospheric carbon dioxide. K-activator geopolymer resulted in Kalicinite which has lower thermal stability and dissolution in water, whereas sodium carbonate formed in Na-activator-based geopolymer engrained and embedded precursor particles alongside sodium-calcium aluminosilicate hydrate (N-(C)-A-S-H) gel forming more densified microstructure. Conclusively, lunar regolith geopolymer has the potential for the construction of lunar habitat. However, this study recommends synthesizing geopolymer in vacuum conditions, emulating freeze-thaw cycles for a more precise estimation of microstructural developments and evaluating other critical properties.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"244 ","pages":"Article 105890"},"PeriodicalIF":2.4,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324000540/pdfft?md5=6b6a1a8d9adc16907dcbe93963814616&pid=1-s2.0-S0032063324000540-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140180103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Laboratory reflectance spectra of enstatite and oldhamite mixtures for comparison with Earth-based reflectance spectra of asteroid 2867 Šteins and Mercury","authors":"Kathrin Markus ,&nbsp;Gabriele Arnold ,&nbsp;Lyuba Moroz ,&nbsp;Daniela Henckel ,&nbsp;Harald Hiesinger","doi":"10.1016/j.pss.2024.105887","DOIUrl":"10.1016/j.pss.2024.105887","url":null,"abstract":"<div><p>The reflectance spectra of synthetic oldhamite (CaS), synthetic enstatite (Mg₂Si₂O₆), and their mixtures have been studied in the spectral range from 0.3 μm to 16 μm. The spectrum of enstatite is very bright, with a steep slope in the ultraviolet (UV) and an almost neutral slope in the visible (VIS) and near-infrared (NIR). The mid-infrared (MIR) region is characterized by the Christiansen feature, Reststrahlen bands and the Transparency feature. The oldhamite spectrum shows a red slope in the UV and VIS and an absorption band at 0.41 μm. The absorption band has a relative depth of 11.4%. In the MIR, the oldhamite spectrum is much brighter than the enstatite spectrum and shows several broad absorption bands. The spectra of the mixtures show an intermediate behavior between the two endmembers. The absorption band at 0.41 μm is visible in the spectra of all mixtures, even in the spectrum of the mixture with only 1 vol% oldhamite. In the MIR, the spectra of the mixtures with ≤10 vol% oldhamite are very similar to the spectrum of pure enstatite. Changes in the spectral characteristics such as reflectance or band depths do not follow simple linear trends but show two distinct trends: One for mixtures with ≤10 vol% oldhamite and one for mixtures with ≥20 vol% oldhamite. Changes occur significantly faster in the spectra of mixtures with ≤10 vol% than in those with ≥20 vol% oldhamite.</p><p>Reflectance spectra of the E[II]-type asteroid 2867 Šteins are flat and almost featureless but show an absorption band at 0.49 μm, which is attributed to oldhamite. Comparison of the laboratory spectra in the VIS and MIR with spectra of Šteins gives an upper limit for the oldhamite content on its surface of 40 %vol. Hence, Šteins probably consists of aubrite-like material with virtually FeO-free enstatite as the major constituent and an oldhamite abundance of &lt;40 vol%. Šteins and other E[II]-type asteroids likely formed through igneous processes on a larger now destroyed body, where an immiscible CaS-melt formed within a silicate melt.</p><p>The surface of Mercury is also linked to FeO-poor silicates like enstatite. Oldhamite and other sulfides are linked to the formation of hollows on Mercury. Mixtures of enstatite and oldhamite could therefore serve as suitable model analog for the surface of Mercury. Contrasting trends at ∼7–8.5 μm in the MIR reflectance spectra of oldhamite and enstatite could be used as an indicator for the presence of oldhamite in spectral data that will be collected by the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument onboard the ESA/JAXA BepiColombo mission to Mercury.</p></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"244 ","pages":"Article 105887"},"PeriodicalIF":2.4,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0032063324000515/pdfft?md5=01c413c13634abbe7c1dd2a3e96d1293&pid=1-s2.0-S0032063324000515-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140201139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}