Planetary and Space Science最新文献

{"title":"A composite phase function for cometary dust comae","authors":"Ivano Bertini ,&nbsp;Jean–Baptiste Vincent ,&nbsp;Raphael Marschall ,&nbsp;Fiorangela La Forgia ,&nbsp;Alessandra Mura ,&nbsp;Laura Inno ,&nbsp;Stavro Ivanovski ,&nbsp;Michael Küppers ,&nbsp;Cecilia Tubiana ,&nbsp;Vladimir Zakharov","doi":"10.1016/j.pss.2025.106164","DOIUrl":"10.1016/j.pss.2025.106164","url":null,"abstract":"<div><div>Comets represent the most preserved planetesimals we can nowadays study and dust is one of their major components. Once emitted in the coma, cometary dust particles represent anisotropic scatterers of the incident solar light and their nature can be investigated with remote sensing studies. Among them, the measurement of the phase function curve has a key importance in several scientific aspects. It can be inverted with theoretical and laboratory studies to derive hints on the intimate nature of the emitted dust. It is also needed in adjusting cometary dust production rates for phase angle effects when data obtained throughout large time intervals are correlated. Finally, it is useful for space instruments planning since it provides inputs for optimal exposure times for remote sensing sensors which observe the coma spanning a large range of phase angles during close approaches. This will be particularly valuable in the framework of the future ESA Comet Interceptor mission which is going to fly-by a Dynamically New Comet entering our Inner Solar System for the very first time, carrying instruments which will image the coma with different observing geometries and phase angles in a short amount of time. In order to provide an useful tool to address the aforementioned scientific topics, we used available literature data to build a new composite phase function for cometary dust comae. This was obtained fitting Henyey–Greenstein functions to the original data of 11 comets and then connecting them in a continuous way as all data values were coming from a single average comet. We then fitted our result with a compound Henyey–Greenstein curve and compared it with previous models which were not including recent literature data constituting fine follow-ups of comets at small and large phase angles. The main difference is found in the description of the forward scattering surge, where our model depicts intensity one order of magnitude larger than previous ones. This finding is extremely important since it shows that the choice of the model may have severe consequences when interpreting, or instrumentally planning, forward scattering data.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"265 ","pages":"Article 106164"},"PeriodicalIF":1.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580289","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":"Preparing for the 2061 return of Halley’s comet. A rendezvous mission with an innovative imaging system","authors":"Cesare Barbieri ,&nbsp;Alessandro Beolchi ,&nbsp;Ivano Bertini ,&nbsp;Vania Da Deppo ,&nbsp;Elena Fantino ,&nbsp;Roberto Flores ,&nbsp;Claudio Pernechele ,&nbsp;Chiara Pozzi","doi":"10.1016/j.pss.2025.106165","DOIUrl":"10.1016/j.pss.2025.106165","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The return of Comet 1P/Halley will promote a worldwide interest for ground and space observations of a celestial body of outstanding scientific and cultural interest. In addition to remote observations, space will open the possibility of &lt;em&gt;in situ&lt;/em&gt; study, similarly to what was done during the passage of 1986. In this paper, we first discuss the scientific motivations for a rendezvous mission capable to overcome the limitations of the flyby missions that took place at that time. In the second part, we describe an example of a rendezvous trajectory that can be carried out with existing power and propulsion technologies, i.e., with radioisotope thermoelectric generators and a Hall effect thruster. Furthermore, the transfer is made possible by the gravitational assistance of a giant planet. The resulting mission concept, nicknamed HCREM (Halley Comet REndezvous Mission), selected from a number of cases treated in a previous paper of ours (Beolchi et al., 2024), will be capable to reach the comet beyond the distance of Saturn, when the sublimation of super-volatile species (e.g. CO and CO&lt;sub&gt;2&lt;/sub&gt;) will be ongoing, and well before the onset of the sublimation of water (expected to occur around 4 AU, namely at larger heliocentric distance than Mars). Following a direct transfer from Earth, a gravity assist with Jupiter inserts the spacecraft into the cometary orbital plane with retrograde motion. Electric propulsion modifies the trajectory so that the spacecraft reaches the target with zero relative velocity. After the rendezvous, the spacecraft will accompany the comet before, around and after perihelion, which will happen in July 2061, until the outbound crossing of the ecliptic and possibly even later. Given the large heliocentric distances reached by the spacecraft, our concept mission does not foresee the implementation of solar panels. In this way, some shortcomings deriving from the adoption of this technology onboard the Rosetta mission to comet 67P are avoided and operations can occur even inside the dense dust coma at short distance from the nucleus. In the third part of the paper, an innovative imaging system with a very large field of view of approximately 100°is proposed. This optical system allows the simultaneous capture of both details of the cometary surface and the surrounding space within a single image frame. For several degrees outside the borders of the nucleus, it allows following the trajectories of chunks and clouds ejected by pits or fractures, all phenomena crucial to the understanding of the cometary activity. In the conclusions, we stress that a concerted effort is needed in the current decade to plan and approve a rendezvous mission to 1P. Indeed, the scenario here described requires launching before 2040, less than 15 years from now. Later launches with existing rockets imply a severe loss of scientific knowledge, because the spacecraft will not be able to reach the comet before the onset of water subli","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"265 ","pages":"Article 106165"},"PeriodicalIF":1.8,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563147","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":"Seismic wave experiments in granular media with applications to asteroids","authors":"Thomas Gallot,&nbsp;Camila Sedofeito,&nbsp;Alejandro Ginares,&nbsp;Gonzalo Tancredi","doi":"10.1016/j.pss.2025.106153","DOIUrl":"10.1016/j.pss.2025.106153","url":null,"abstract":"<div><div>Observational data support the view of asteroids as granular systems. Characterizing their mechanical properties is crucial for space mission planning, assessing Earth’s impact risks, and understanding solar system origins. In this context, we present a laboratory-scale experiment aimed at examining wave propagation in granular media. Our findings demonstrate that the propagation of observed waves at 500 Hz shows significant attenuation with an estimated value of <span><math><mrow><mi>α</mi><mo>=</mo><mrow><mo>(</mo><mn>1</mn><mo>.</mo><mn>8</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>2</mn><mo>)</mo></mrow></mrow></math></span> Np/m. Additionally, we observe an increase in wave speed with confining pressure, which follows a dependency on <span><math><msup><mrow><mi>p</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math></span>, interpreted as mesoscopic nonlinear elasticity. This indicates that a confined granular medium behaves as a nonlinear consolidated medium. Furthermore, we establish the equivalence of propagation properties between impact and vibration by supporting our experimental data analysis with numerical simulations. Applying our findings to model wave propagation in a low-gravity setting involving Dimorphos’ mass and geometry, our laboratory-based approach offers a cost-effective alternative to in situ measurements.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"265 ","pages":"Article 106153"},"PeriodicalIF":1.8,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570642","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":"Demonstration of the low-temperature carbothermal process for producing oxygen from lunar regolith: Terrestrial test campaign","authors":"Alice Dottori ,&nbsp;Ivan Troisi ,&nbsp;Michèle Roberta Lavagna","doi":"10.1016/j.pss.2025.106154","DOIUrl":"10.1016/j.pss.2025.106154","url":null,"abstract":"<div><div>The solid-gas carbothermal reduction is one of the processes available for extracting oxygen from the lunar regolith, a crucial capability for supporting lunar exploration and establishing a sustainable human presence on the Moon’s surface. This article presents the findings of the experimental campaign conducted at the Politecnico di Milano, which confirmed the feasibility of the process. Water is extracted from dry regolith, and the production of carbon oxides is monitored to gather data on the process. The campaign studied the influence of various parameters to enhance water and oxygen production, including reaction temperatures, regolith granularity and mass, solid-to-gas ratio, processing duration, and others. The extracted water is collected in a condensation stage, while the evolution of the gaseous mixture is monitored using gas chromatography, and the exhaust batch of simulant is analysed through SEM and XRD. These analyses provided qualitative and quantitative assessments of the reaction’s effectiveness, yielding important information about the impact of changing parameters. The study concludes by proposing a set of process parameters to serve as a baseline for future implementation of the low-temperature carbothermal process on the lunar surface.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"266 ","pages":"Article 106154"},"PeriodicalIF":1.8,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631754","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":"He+ ions in the vicinity of mercury observed by the MESSENGER and BepiColombo spacecraft","authors":"Markus Fränz ,&nbsp;Harald Krüger ,&nbsp;Jim M. Raines ,&nbsp;Austin N. Glass ,&nbsp;Daniel J. Gershman ,&nbsp;Fabio Prencipe ,&nbsp;Norbert Krupp ,&nbsp;Lina Z. Hadid ,&nbsp;Dominique Delcourt ,&nbsp;Sae Aizawa ,&nbsp;Shoichiro Yokota ,&nbsp;Yuki Harada ,&nbsp;Yoshifumi Saito","doi":"10.1016/j.pss.2025.106152","DOIUrl":"10.1016/j.pss.2025.106152","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was launched in 2004, and between March 2011 and April 2015 it was the first spacecraft in orbit around Mercury. The Fast Imaging Plasma Spectrometer (FIPS) instrument on board MESSENGER measured the ion composition in the vicinity of Mercury and in the inner solar system.&lt;/div&gt;&lt;div&gt;We aim to determine the origin of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions in the inner solar system and in the environment of Mercury, continuing earlier work by Gershman et al., (2013).&lt;/div&gt;&lt;div&gt;We have analyzed measurements of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions made by the FIPS instrument during the interplanetary cruise phase of MESSENGER and its entire orbital mission at Mercury. We determined the spatial distributions of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions in the regions sampled by MESSENGER during that period and compare the spectra to a similar observation by the Mass Spectrum Analyzer instrument which is part of the Mercury Plasma Particle Experiment (MPPE-MSA) onboard BepiColombo. We consider two possible sources of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;: (1) interstellar neutral helium ionized close to Mercury and (2) solar He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions converted close to or at the surface of Mercury. We also compare the observed densities with a simple model of the ionization of the interstellar helium flow.&lt;/div&gt;&lt;div&gt;The FIPS data show a continuous evolution of the He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; energy spectra from solar wind towards Mercury - changing from a shape typical for pick-up ions to a thermalized spectrum. This could mean that interstellar He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; is concentrated at Mercury by increased electron impact ionization close to the planet. We find a remarkably similar high mean ratio of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;/He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions in the upstream solar wind and in the inner magnetosphere, while the ratio is reduced in the magnetosheath.&lt;/div&gt;&lt;div&gt;Outside Mercury’s magnetosphere the source of He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; ions is interstellar helium, while inside the planet’s magnetosheath and the magnetosphere both interstellar helium and solar wind helium may be of similar magnitude. The observed median upstream He&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; densities are in good quantitative agreement with a si","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"265 ","pages":"Article 106152"},"PeriodicalIF":1.8,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557312","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":"A sliding window method considering image shadow to detect Mars rock from MRO HiRISE datasets","authors":"Na Sun ,&nbsp;Yongjiu Feng ,&nbsp;Xiaohua Tong ,&nbsp;Pengshuo Li ,&nbsp;Rong Wang ,&nbsp;Yuhao Wang ,&nbsp;Yuze Cao ,&nbsp;Zilong Cao ,&nbsp;Xiong Xu ,&nbsp;Yusheng Xu ,&nbsp;Shijie Liu","doi":"10.1016/j.pss.2025.106155","DOIUrl":"10.1016/j.pss.2025.106155","url":null,"abstract":"<div><div>Rock distribution is a crucial factor in landing site selection for Mars exploration. Typically, rocks in flat Martian terrains are characterized by clear boundaries and distinct shadows. We developed a new method (named SSW-ROCK) for rock detection from HiRISE images using the shadow (S) and sliding window technique (SW). SSW-ROCK uses shadows to define the minimum bounding rectangle in the direction of illumination, establishing an initial sliding window based on this rectangle. The window is then slid to the termination position according to the predefined conditions. The rock size can be obtained by fitting the ellipse with the positions of the initial and termination windows. The rock height is estimated using the shadow length along the illumination direction. We used five HiRISE images of Mars between 65° N −70° N for rock detection and detected 532,284 rocks with maximum diameters &gt;1.5 m. We selected accuracy assessment areas in each of the five images and extracted the rocks manually. The SSW-ROCK results were assessed for accuracy using the manual results as a benchmark. In the assessment, we proposed two evaluation metrics, PS and PM: PS measures the proportion of SSW-ROCK results with center points within the range of manual results, while PM measures the proportion of manual results with center points within the range of SSW-ROCK results. Accuracy assessments in five selected areas showed that the mean for both PS and PM exceeded 77 %. Additionally, the dimensions detected by the SSW-ROCK method for known Mars landers closely match their actual sizes. These experiments demonstrate that the SSW-ROCK method is effective for rock detection in flat Martian terrains.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"265 ","pages":"Article 106155"},"PeriodicalIF":1.8,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481490","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":"A simulator of the MAJIS instrument onboard the JUICE mission: Description and application to operational and scientific cases","authors":"C. Royer ,&nbsp;P. Haffoud ,&nbsp;Y. Langevin ,&nbsp;F. Poulet ,&nbsp;D. Bockelée-Morvan ,&nbsp;E. D’Aversa ,&nbsp;M. Cisneros-González ,&nbsp;D. Grassi ,&nbsp;N. Ligier ,&nbsp;G. Piccioni ,&nbsp;J. Carter ,&nbsp;F. Tosi ,&nbsp;M. Vincendon ,&nbsp;F. Zambon ,&nbsp;V. Zakharov ,&nbsp;M. Gilles ,&nbsp;B. Seignovert","doi":"10.1016/j.pss.2025.106147","DOIUrl":"10.1016/j.pss.2025.106147","url":null,"abstract":"<div><div>The MAJIS (Moons And Jupiter Imaging Spectrometer) instrument, part of the JUICE (JUpiter ICy moons Explorer) mission, is a crucial tool for investigating the composition and dynamics of Jupiter’s atmosphere, and the surfaces and exospheres of its icy moons. To optimize observational planning and assess instrument performance, we have developed a radiometric simulator that accurately models MAJIS expected signal from various Jovian system targets. This simulator incorporates instrumental parameters, the spacecraft trajectory, observational constraints, and Jupiter’s radiation environment. It provides essential outputs, including Signal-to-Noise Ratio (SNR) predictions and optimized instrument settings for different observational scenarios. By simulating both radiometric performance and de-spiking strategies to mitigate the impact of Jupiter radiation belt, the tool aids in refining observation strategies throughout the MAJIS operations. Several scientific applications demonstrate the simulator capabilities, from mapping the surfaces of Ganymede and Europa to detecting exospheric emissions and atmospheric composition on Jupiter. This simulator is a critical asset for maximizing MAJIS scientific return and ensuring optimal data acquisition during MAJIS exploration of the Jovian system. Study cases are presented for illustrating the capability of the simulator to model scenarios such as high-resolution mapping of Ganymede, exosphere characterization and hotspot detection on Io and Europa. These simulations confirm the potential of MAJIS for detecting key spectral features with high signal to noise ratio so as to provide major contributions to the main goals of the mission: habitability and compositional diversity in the Jovian system.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"264 ","pages":"Article 106147"},"PeriodicalIF":1.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307983","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":"Stability of adenine in interaction with saponite in a simulated hydrothermal impact-generated system and its implications for astrobiology","authors":"L. Ramírez-Vázquez ,&nbsp;A.A. Duarte-Ruiz ,&nbsp;M.G. Santiago-Santos ,&nbsp;G. Cordero Tercero ,&nbsp;J.A. Cruz-Castañeda","doi":"10.1016/j.pss.2025.106151","DOIUrl":"10.1016/j.pss.2025.106151","url":null,"abstract":"<div><div>For astrobiological studies related to the chemical evolution of organic molecules, it is essential to establish a plausible geological context, either on early Earth or at another viable site within the solar system. Impact-generated hydrothermal systems may have provided an ideal environment for prebiotic chemical reactions before the origin of life.</div><div>In this study, we simulated the conditions of such systems using saponite, a clay mineral identified as a product of hydrothermal alteration in impact craters that once hosted hydrothermal activity. Adenine was chosen as the model organic molecule due to its biological relevance and its known abiotic formation, as evidenced by its detection in certain meteorites. The interaction between saponite and adenine was investigated by analyzing adsorption kinetics and isotherms, revealing that adsorption is favored at acidic pH (3.5), as under these conditions, approximately 97 % of the adenine is adsorbed. The interaction between the molecule and the clay was observed through spectroscopic techniques such as XRD, FRX, Raman and ATR-FTIR, UV–vis spectrophotometry, and HPLC-UV chromatographic. Additionally, thermolysis experiments were conducted on aqueous adenine solutions and adenine-saponite mixtures. The results indicate that saponite plays a protective role, preventing adenine decomposition at temperatures ranging from 100 °C to 200 °C across a pH range of 3.5–8.9. These processes are critical for astrobiology, as they demonstrate how some clay minerals could have concentrated and preserved prebiotic organic molecules on early Earth, Mars, or planetesimals, facilitating the emergence of life.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"264 ","pages":"Article 106151"},"PeriodicalIF":1.8,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272294","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":"New insights into the origin of ice: chronological implication from 14 permanently shadowed craters on Mercury","authors":"S. Bertoli ,&nbsp;E. Martellato ,&nbsp;G. Cremonese ,&nbsp;M. Massironi ,&nbsp;A. Lucchetti ,&nbsp;M. Pajola ,&nbsp;P. Borin ,&nbsp;P. Cambianica ,&nbsp;E. Simioni","doi":"10.1016/j.pss.2025.106150","DOIUrl":"10.1016/j.pss.2025.106150","url":null,"abstract":"<div><div>The polar regions of Mercury are characterised by areas known as permanently shadowed regions (PSRs), which provide stable thermal conditions for water ice over geological timescales. Both Earth-based radar measurements and data from the NASA/MESSENGER spacecraft identified the area encompassing the PSRs with reflectance properties indicative of both water ice and other volatiles.</div><div>In this work, we employ crater counting absolute model age determination on both ejecta and crater floor materials of fourteen northern polar craters yielding cold traps and ice. Our findings unravel younger ages for the floors than for the associated ejecta, prompting further investigation into the role of ice as the mechanisms responsible for rejuvenating polar crater floors. Notably, a correlation emerges between the age of craters and the accumulation of ice within PSRs. Indeed, older craters tend to accumulate more ice within the PSRs, measured in terms of area. These correlations may be attributed to the two primary processes allowing ice continuous accumulation: micrometeorite flux and solar wind implantation. Considering the limiting factors for these processes, which are impact velocity and gardening, respectively, it is estimated that over approximately 3.7 billion years (the age of the oldest craters in this study), a substantial amount of ice would have accumulated at the poles. Two of the analyzed craters do not follow the trend and this might signify episodic delivery of ice resulting from asteroidal and/or cometary impacts. Thus, we propose that both steady-state accumulation and episodic delivery processes should be considered when analyzing the presence of ice in PSRs.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"264 ","pages":"Article 106150"},"PeriodicalIF":1.8,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144279223","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":"Comparative analysis of mask R-CNN and U-Net architectures using ResNet as backbone for lunar crater detection","authors":"Mimansa Sinha ,&nbsp;Sanchita Paul ,&nbsp;Mili Ghosh Nee Lala","doi":"10.1016/j.pss.2025.106140","DOIUrl":"10.1016/j.pss.2025.106140","url":null,"abstract":"<div><div>Automated detection of lunar craters is crucial for advancing planetary science, enabling efficient geological mapping, surface age estimation, and resource identification. This study compares Mask R-CNN (instance segmentation) and U-Net (semantic segmentation) architectures using ResNet as the backbone for lunar crater detection. Key novelty is comparing model performance in both a Geospatial context (ArcGIS Pro environment) and non-Geospatial environment a method not heretofore attempted. Training and validation were conducted using Geocoded Chandrayaan-2 TMC-2 DEM data, employing a new strategy that facilitates accurate localization and precise detection of small, morphologically complex craters. Mask R-CNN achieved a precision of 91 %, a recall of 85 %, and an Intersection over Union (IoU) of 87 %, excelling in detecting intricate crater edges and identifying crater diameters with accurate geolocation information. However, it struggled to detect craters with less depth or degraded rims. Conversely, U-Net demonstrated superior recall (93 %) but moderate precision (85 %), making it efficient for broader crater localization tasks. U-Net excelled at identifying perfectly shaped craters but faced challenges in detecting larger and very small craters. Mask R-CNN identified previously uncatalogued craters, particularly those smaller than 1 km in diameter, while U-Net excelled at detecting a greater number of overlapping and nested craters, showcasing their complementary strengths. These findings underscore the potential of deep learning to enhance lunar research and future planetary exploration.</div></div>","PeriodicalId":20054,"journal":{"name":"Planetary and Space Science","volume":"264 ","pages":"Article 106140"},"PeriodicalIF":1.8,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184329","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}