Abstract Spectral and hyperspectral data provide essential information on the surface composition of rocky planetary bodies, through which we can reconstruct and understand their origin and geologic evolution. In this field, applications of advanced tools, such as machine learning‐based algorithms, are steadily increasing. This study presents a newly developed, open‐source, Python‐based tool and workflow for the identification and mapping of spectral units with CRISM near‐infrared (NIR) data using unsupervised machine‐learning (clustering) techniques. Data pre‐processing, dimensionality reduction, clustering, and visualization are integrated into an interactive user‐friendly environment. The tool employs two different established clustering algorithms: K‐means and Gaussian Mixture Models. Dimensionality reduction methods include the use of projection‐based and manifold‐based dimensionality reduction techniques, respectively Principal Component Analysis (PCA) and Uniform Manifold Approximation and Projection (UMAP). We showcase the abilities of the tool on a set of selected CRISM images. We identify multiple spectral units, from which we retrieve spectral signatures ranging from mafic minerals, with broad absorption bands, to Fe/Mg phyllosilicates and sulfates, which exhibit multiple narrow absorption features. Results highlight how clustering methods can support and enhance the findings derived from classical analysis of spectral parameters, for instance, by highlighting subtle spectral variations. Moreover, with minor tuning and modifications, the tool can be applied to different spectral ranges as well as to spectral or hyperspectral data from other planetary surfaces.

Spectral and hyperspectral data provide essential information on the surface composition of rocky planetary bodies, through which we can reconstruct and understand their geologic evolution and environmental history. The study of compositional data is commonly approached through the definition and mapping of spectral parameters such as band depths, band areas, and spectral slopes. Applications of more advanced tools, such as machine learning-based automatic detection systems are steadily increasing in the planetary science field. We present a newly developed, Python-based, open source tool to perform unsupervised clustering on CRISM near-infrared (NIR) hyperspectral data. The tool employs two different algorithms: k-Means and Gaussian Mixture Models. Data can be fed to these algorithms following some pre-processing steps and dimensionality reduction, which include the use of projection-based and manifold-based dimensionality reduction techniques (Principal Component Analysis and Uniform Manifold Approximation and Projection). With this tool, we identify and cluster a great variety of spectral signatures, ranging from mafic minerals with broad absorption bands to Fe/Mg phyllosilicates and sulfates, which exhibit multiple narrow absorption features. We showcase the abilities of the tool on a set of selected CRISM images. Results highlight how automated clustering methods can greatly support and enhance the findings derived from classic analysis of spectral parameters. Moreover, with minor tuning and modifications, the tool can be broadly applied both to different spectral ranges and to spectral or hyperspectral data from any planetary surface.

Carbonates on Mars provide key evidence of past environmental conditions because they can form through alteration of ultramafic rocks by liquid water in a dense CO2–rich atmosphere. We searched for carbonates by examining the 2.3, 2.5, and 3.5 µm absorption bands in 540 CRISM near-infrared hyperspectral cubes. The detected carbonates are best described as Fe–Mg solid solutions within the siderite–magnesite series, likely formed under reducing conditions and preserved despite later acidic, oxidizing environments. We identify new carbonate-rich deposits associated with clay-bearing terrains, revealing a more widespread co-occurrence of carbonates and clays than previously recognized, partly because carbonates can be spectrally masked by clays. Their association suggests formation in neutral to mildly alkaline waters early in Mars’ history, implying prolonged aqueous alteration, sustained liquid water, and environments potentially favorable for microbial life. These findings expand the known distribution of carbonates and highlight promising targets for future biosignature exploration.

This study presents a novel theoretical model based on Smoothed Particle Hydrodynamics (SPH) to simulate volatile emissions triggered by drilling operations on Mars, specifically focusing on the ESA Rosalind Franklin rover’s subsurface exploration of Oxia Planum. The model captures early time interactions between vapor, water ice, dust, and atmospheric carbon dioxide, accounting for thermal and dynamical interactions, and phase transitions dynamics during drilling. The three dimensional borehole and drill geometry are explicitly modeled, along with realistic temperature profiles derived from Martian surface and subsurface conditions. Vapor is assumed to originate from sublimation of water ice due to drill-induced heating. The simulations investigate how different initial volatile compositions, icy grain sizes, and borehole depths influence material redistribution. Results show that the distribution of ice is mainly governed by sublimation and recondensation cycles. When smaller icy grains are considered, water vapor tends to condense efficiently on colder surfaces, forming thin ice layers on the drill rod. Larger icy grains, instead, form more slowly and experience weaker atmospheric drag, occasionally enabling a small fraction to escape the borehole. Moreover, the presence of carbon dioxide alters the vertical motion of dust, constraining it to remain stuck at the bottom of the borehole. The presented model provides a tool to constrain the early-time dynamics of drilling-induced volatile release on Mars and offers a modular framework adaptable to other planetary environments, like the Moon.

MAJIS is the Moons and Jupiter Imaging Spectrometer onboard ESA’s Jupiter Icy Moons Explorer (JUICE) mission. It covers the spectral range from 0.5 to 5.56 µm through two spectral channels: the VIS-NIR channel (0.495–2.35 µm) and the IR channel (2.28–5.56 µm), with up to 640 spectral samples per channel. The main scientific goals of MAJIS are to investigate the surface composition and physical properties of the Jovian icy satellites by detecting ices, salts, organics, and rocky materials [1].The JUICE mission was launched in April 2023 and will arrive at Jupiter in July 2031. During the cruise phase, JUICE performed observations of the Moon and Earth thanks to a double flyby (Lunar-Earth Gravitational Assist, LEGA) in August 2024, reaching a minimum altitude of 750 km for the Moon and 6100 km for Earth. This provided a unique opportunity to validate MAJIS’s technical and scientific performance after launch [2, 3].On the Moon, MAJIS observed equatorial regions in Mare Tranquillitatis, Mare Fecunditatis, and neighbouring highland terrains, confirming its capability to detect and map lunar mineralogical diversity and soil maturity [2, 4]. Here, we focus on regions including Duke Island and the Ruin Basin in Mare Tranquillitatis, and the Messier Crater rays in Mare Fecunditatis. Detections of glass, pyroxene and olivine in other locations are also discussed. This work has been developed under the ASI-INAF agreement n. 2023-6-HH.0. [1] Poulet et al., 2024, SSR. [2] Poulet et al., 2026, Ann. Geo., submitted. [3] Langevin et al., 2026, Ann. Geo., submitted. [4] Zambon et al., 2026, Ann. Geo., submitted.

Shallow lunar subsurface characterization is a key requirement for future exploration activities, particularly for in situ resource utilization and the identification of protected environments for human and robotic operations. This work presents the preliminary design and performance assessment of an orbital very high frequency (VHF) radar sounder tailored to the detection of subsurface water ice deposits and lava tubes at depths relevant to exploration. The analysis combines physically based modeling of acquisition geometry, electromagnetic properties, and surface roughness with quantitative evaluation of signal-to-noise and signal-to-clutter ratios. Results indicate that surface clutter constitutes the primary limitation for subsurface detectability in orbital sounding, thereby driving both instrument design and mission geometry. Quantitative performance bounds are derived for penetration depth and spatial resolution, providing guidance for identifying regions where subsurface access may be achieved with reduced operational risk. One-dimensional electromagnetic simulations further demonstrate the advantages of operating in the VHF regime. While lower-frequency systems retain sensitivity to some subsurface interfaces, their limited vertical resolution prevents reliable separation of closely spaced structures, such as the roof and floor of lava tubes. In contrast, the proposed VHF sounder enables clear separation of multiple subsurface interfaces, allowing geometric characterization of cavities and improved discrimination of ice-bearing layers. These results establish the feasibility and relevance of a VHF orbital radar sounder as a dedicated tool for shallow lunar subsurface investigations in support of future exploration missions.

Mapping the global distribution of carbonate minerals on the Martian surface is a prerequisite for understanding the aqueous and atmospheric evolution of Mars, as these minerals represent a principal sink for atmospheric CO₂ and direct tracers of past liquid water activity. To date, the orbital data from CRISM offers our best opportunity for detecting the diagnostic vibrational signatures of these minerals; however, studies have focused almost entirely on the weak short-wave infrared (SWIR) overtone and combination bands near 2.3 and 2.5 µm [1,2]. These features can be spectrally degenerate with co-occurring phyllosilicates and are not always strong enough to reveal smaller or less exposed deposits, leaving a significant fraction of the carbonates undetected.The strongest spectroscopic signatures of carbonates lie in the mid-wave infrared (MWIR): the fundamental absorptions at 3.4 and 3.9 µm [2]. These features remain largely unexploited in CRISM data, due to the limited spectral range of the instrument, which does not fully cover the 3.9 µm band, and to the superposition of reflected solar radiance and planetary thermal emission in the 3–4 µm window, which renders band depth estimation challenging.To overcome this issue, we developed a dual-band detection framework based on two independent pipelines processing the SWIR and MWIR parts of the spectrum. While the SWIR pipeline works similarly to conventional detection methods, refining the 2.5 µm overtone absorption, the MWIR pipeline has to deal with the presence of thermal emission. Each pipeline produces a spatially filtered detection map with fully propagated, SNR-anchored uncertainties.In particular, the MWIR pipeline operates on the atmospherically corrected datacube and treats the observed signal as the sum of a reflected solar continuum, a surface thermal contribution, and channel noise. The solar continuum is estimated using an iteratively reweighted least-squares (IRLS) fit to a band-masked window between 1.8–2.6 µm, which serves as a robust estimator with a well-defined per-pixel noise level, avoiding the limitations that affect classical shoulder-based approaches. Using these residuals, the thermal contribution is estimated by a constrained Planck greybody fit in the 3–4 µm window, with temperature values restricted to a realistic Martian daytime range. Instrumental artifacts are subsequently identified and filtered both at the channel level and in map space before proceeding with the final detection step.The SWIR pipeline uses a pre-processed atmospherically corrected and denoised datacube, where thermal emission is absent. The 2.5 µm overtone is isolated with an iterative continuum fit and sub-pixel band-centre localisation, while band absorption is quantified via a Gaussian-kernel-weighted band-depth integration. SNR, band-centre location, and amplitude of the detected absorption serve as criteria for distinguishing carbonates from overlapping phyllosilicates and sulphates [3].As a first demonstration, the framework is applied to a single CRISM observation, FRT000186FA at Nili Fossae, a scene chosen for its close proximity to Jezero Crater, where carbonate presence has been independently established both from orbit [4] and in situ by the Perseverance rover [5,6]. Both pipelines detect a spatially coherent area of elevated absorption,with detection maps consistent in spatial extent and structure. Figure 1: Band depth integral at 2.5 µm (SWIR pipeline) for CRISM observation FRT000186FA (Nili Fossae). Figure 2: Band depth integral at 3.9 µm (MWIR pipeline, thermal-corrected) for CRISM observation FRT000186FA (Nili Fossae). Nili Fossae serves here as a validation benchmark, with the framework designed for systematic application across a geologically diverse sample of CRISM observations, moving toward a more complete carbonate inventory of Mars. This work is funded by the Italian Space Agency (ASI) [ASI-INAF n.23-3-HH.0][1] Harner, P.L., & Gilmore, M.S. (2015). Visible–near infrared spectra of hydrous carbonates, with implications for the detection of carbonates in hyperspectral data of Mars. Icarus 250, 204-214. http://dx.doi.org/10.1016/j.icarus.2014.11.037 [2] Bishop, J.L., et al. (2021). Spectral properties of anhydrous carbonates and nitrates. Earth and Space Science, 8, e2021EA001844. https://doi.org/10.1029/2021EA001844 [3] Plebani, E., et al. (2022). A machine learning toolkit for CRISM image analysis. Icarus 376, 114849. https://doi.org/10.1016/j.icarus.2021.114849 [4] Ehlmann, B.L., et al. (2008). Orbital Identification of Carbonate-Bearing Rocks on Mars. Science 322, 1828-1832. https://doi.org/10.1126/science.1164759 [5] Clavé, E., et al. (2023). Carbonate detection with SuperCam in igneous rocks on the floor of Jezero Crater, Mars. JGR Planets 128, e2022JE007463. https://doi.org/10.1029/2022JE007463[6] Clavé, E., et al. (2026). In Situ Carbonation of Sedimentary and Igneous Rocks of Ultramafic Composition in Jezero Crater, Mars. JGR Planets 131, e2025JE009107. https://doi.org/10.1029/2025JE009107

Introduction:Permanently shadowed regions (PSRs) of the Moon are thought to act as cold traps for volatiles, due to their extremely low temperatures (

The emission of volatiles from the surface and subsurface of planetary bodies can provide fundamental knowledge concerning their formation, evolution, and structure. There are a variety of physical processes that shape the structural, kinematic and thermal behavior of the released material. We simulate Enceladus' plumes outgassing from a surface fracture, characterizing their dynamical and thermal behavior by introducing an advanced numerical model, that adopts the Smoothed Particle Hydrodynamics (SPH) approach. We target and discuss the challenging implementation of several important microscopic phenomena that can alter the macroscopic properties of the simulated plume. Indeed, we consider the dynamical interaction with solid boundaries, the phase transitions, the solar radiation, the thermal interaction with Enceladus' surface, the viscous drag coupling and the gravitational attraction. We run simulations with two values of the icy grains size, to explore the role of such parameter in the considered effects. The simulations results are consistent with the expected physical behavior and the observed properties of Enceladus' plumes. We discuss the role of the processes in shaping the velocity, temperature, and density distributions for the vapor and ice components. We calculate the amount of mass loss from the surface fracture, obtaining values consistent with previous estimates. Similarly occurs for the ice deposition rate near the fracture, over the surface of Enceladus. The good agreement between our results and the current knowledge about Enceladus' plumes supports the strength of an SPH based approach to study the emission of volatiles from the surface and subsurface of planetary objects. Such a model offers a unique tool in the investigation of the occurring phenomena, as well as for predicting and comparing with observations.

NASA’s Curiosity rover recently discovered decimeter-sized clasts of nearly pure native sulfur within the Gediz Vallis channel in Gale crater, representing the first detection of elemental sulfur on Mars. The origin of this material remains uncertain, as native sulfur on Earth typically forms in volcanic, hydrothermal, or evaporitic environments. Here, we investigate a formation mechanism in which sulfur-rich material is melted by a meteoritic impact, producing molten sulfur that subsequently flows and solidifies at the surface. Geological mapping of the Gediz Vallis region reveals a partially breached crater (~390 m in diameter) located upstream of the sulfur-bearing deposits, within a light-toned yardangs unit. We interpret this structure as a candidate source crater, where impact-generated melt may have escaped through the breach and flowed a few kilometers downslope before solidifying. Production of melt in the context of such a small impact crater is qualitatively supported by the observations of impact melt pools associated with small craters on Lunar basaltic surfaces.To assess whether the volume of melt produced could be comparable to the native sulfur deposit at Geidz Vallis, we performed numerical simulations using the iSALE shock-physics code. We modeled vertical impacts of dunite projectiles into a basaltic target at velocities of 5, 7, 10 km/s, the size of the asteroid being empirically adjusted to reproduce the observed crater size. Because a dedicated high-pressure equation of state for sulfur is unavailable, sulfur was treated as a minor component of the target, and shock propagation was assumed to be controlled by the basaltic matrix. Sulfur melting was then evaluated a posteriori using reconstructed thermodynamic properties derived from experimental shock data and melting curves.From tracer-based shock pressure histories, we estimated the total mass of sulfur melted (liquid plus vapor), the fraction retained within the crater as a melt pool, and the amount potentially lost to vaporization. Our results show that total melt production increases with impact velocity, while only about 20–25% of the melted sulfur is retained within the crater after excavation. For sulfur concentrations typical of minor components, the retained melt mass is insufficient to explain the volume inferred from Curiosity observations. However, extrapolation to sulfur-rich substrates (≥ 50% sulfur fraction) would yield melt pool masses comparable in order of magnitude to Curiosity’s inferred mass, even under conservative assumptions regarding vaporization and ejected melt.These results suggest that impact-induced melting of sulfur-rich materials is a possible mechanism for producing native sulfur deposits on Mars, provided that the light-toned yardangs unit is significantly enriched in sulfur. However, a model incorporating a dedicated sulfur equation of state is critical to further test this hypothesis, whereas in situ rover observations as Curiosity approaches the yardangs unit shall reveal its nature and composition.

Abstract. The Moons and Jupiter Imaging Spectrometer (MAJIS) instrument onboard the ESA Jupiter Icy Moon Explorer (JUICE) mission acquired the first hyperspectral data of the lunar surface since Chandrayaan-1/Moon Mineralogy Mapper (M3), Cassini/VIMS, and the more recent Chandrayaan-2/Imaging Infrared Spectrometer (IIRS). In this study, we present a mineralogical and spectral analysis of a portion of the lunar nearside, including Mare Tranquillitatis, Mare Fecunditatis, and adjacent highland terrains, as observed by MAJIS. Due to high-phase and high-incidence illumination conditions, our analysis primarily focuses on two specific MAJIS observations. MAJIS spectra reveal prominent absorption features near 1 and 2 μm, indicative of both low- and high-calcium pyroxenes, confirming the dominance of mafic minerals—particularly in mare regions and fresh impact craters along with associated ejecta, such as those from Maskelyne G and Messier/Messier A. These areas are characterised by deeper absorption bands compared to surrounding terrains. Variations in spectral slopes are also observed and are associated with both surface maturity and compositional differences, consistent with the spectral characteristics of the observed regions retrieved by previous instruments. We apply thermal emission correction to investigate potential features above 2.6 μm, to discriminate possible absorption bands in the MAJIS infrared spectral range. Nevertheless, further work is required to fully explore this spectral range. Finally, comparison with datasets from previous missions demonstrates strong consistency in derived spectral parameters, validating the performance of MAJIS for lunar mineralogical studies. These findings highlight MAJIS’ capability to characterise both composition and maturity of the lunar surface, while also emphasising its potential for future investigations in the Jovian system.

Extensive research over the past two decades has shown that early Mars likely had a warmer, wetter climate with widespread water activity. Ferromagnesian (Fe,Mg-rich) clay deposits are compelling markers of these ancient environments, helping reconstruct Mars' hydrologic evolution, assess past habitability, and guide future exploration. This study analyzes hyperspectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA's Mars Reconnaissance Orbiter, focusing on regions along the Martian crustal dichotomy-where clay deposits occur at the boundary between the ancient southern highlands and the younger northern lowlands. We systematically surveyed similar to 1500 CRISM targeted observations (1-2.6 mu m) to identify ferromagnesian clays, distinguish them from other hydrated minerals, and characterize compositional differences between Fe- and Mg-rich species using diagnostic absorptions around 1.4, 2.3, and 2.4 mu m. Results reveal spatial variations in clay mineralogy: Fe-rich nontronites are prevalent around Mawrth Vallis, while Mg-rich saponites are more locally distributed in Nili Fossae and Libya Montes. Oxia Planum-the Rosalind Franklin rover landing site-exhibits more compositionally intermediate clays such as vermiculites and ferrosaponites. These differences may reflect variations in the iron and magnesium abundance or in the iron oxidation state. Moreover, a recurring absorption near 2.5 mu m suggests co-occurring carbonates like magnesite and siderite, increasing the potential for biosignature preservation. These findings refine our understanding of Mars' aqueous history and offer an important mineralogical context for future rover and sample return missions. They also emphasize the need for a next-generation orbital imaging spectrometer to succeed CRISM and extend its legacy.

The Lunar-Earth Gravitational Assist (LEGA) of 19-20 August 2024 marked the first in-flight opportunity beyond functional checks to perform MAJIS (Moons and Jupiter Imaging Spectrometer) observations on-board the ESA's Jupiter Icy Moons Explorer (JUICE) spacecraft. This unique double flyby involved sequential close approaches to the Moon and Earth, offering an unprecedented configuration to evaluate MAJIS under high radiance, rapidly changing geometric, and operationally constrained conditions. A total of 24 hyperspectral image cubes were acquired (5 targeting the Moon and 19 the Earth) providing a dataset of approximately 7.5 Gbit. This work presents the primary goal of this observation campaign, which was to verify key aspects of MAJIS performance, including radiometric and spectral calibration, straylight behavior, geometric alignment, the use of onboard browse products, and interference tests with other JUICE instruments. This event also enabled assessment of thermal behavior and susceptibility to electromagnetic interference, and provided a first operational benchmark for MAJIS and a basis for refining future observation strategies and data analyses during JUICE's cruise and science phases. In addition, despite limited spatial and temporal coverage of the observations, the analyses presented here and in a series of companion papers of the special issue "The first-ever lunar-Earth flyby: a unique test environment for JUICE" demonstrated the instrument's ability to characterize mineralogical features on the Moon and atmospheric constituents on Earth. Observations include detection of mafic minerals (some associated to fresh excavated materials), thermal emission, and emissivity variations on the Moon at spatial scale of 100-200 m. Characterization of atmospheric absorption features, thermal brightness, icy cloud properties are captured for the Earth at km-scale and briefly discussed in the framework of the atmospheric biosignatures relevant to exoplanet habitability studies. Near-coincident acquisitions with other JUICE instruments and Earth-orbiting spectrometers provided valuable inter-calibration and cross-validation opportunities.

Sulfur is abundant on Mars and oxidized, resulting from massive early volcanism and aqueous activity as recorded by extensive sulfate-bearing terrains. Yet, a recent observation by NASA’s Curiosity rover indicates native sulfur is also preserved in the geological record and questions sources and mechanisms required to form such a deposit. A breached circular depression located within the light-toned Yardang unit upstream of the native sulfur deposit was proposed as a possible source. In this context, we test the possibility that a meteoritic impact on a sulfur-rich substrate can generate enough molten sulfur to account for the deposit. Given molten sulfur is expected to segregate from silicates, this process should lead to the formation of pure native sulfur accumulations. Here, we use the iSALE shock-physics code to estimate the amount of liquid sulfur segregating from the shocked material following vertical asteroid impacts on a sulfur-rich basaltic target. The impact parameters (mass, velocity) were varied and adjusted to match the diameter of the circular depression observed within the light-toned Yardang unit (390m). To overcome the lack of a high-pressure equation of state for sulfur, we model shock propagation in a basaltic matrix considering sulfur as a minor component. The amount of molten sulfur is then estimated in a second step using available thermodynamic constraints for the native element. Our simulations demonstrate that the meteoritic impact may produce an amount of molten sulfur consistent with Curiosity observations only for a significantly sulfur-enriched impact substrate (S > 10 wt%). We find that impact velocity is an important factor: lower velocities favor the retention of a liquid melt pool, while higher velocities promote ejection and extensive vaporization. This study establishes meteoritic impact as a viable mechanism to produce deposits of pure native sulfur from sulfur-bearing soils on Mars.

Equatorial Layered Deposits (ELDs) are sedimentary landforms found at equatorial latitudes of Mars showing repetitive bedding and commonly associated with hydrous minerals. These deposits are important archives of Mars' past aqueous conditions yet in most cases their formation mechanisms are still debated and elusive. Here we provide a detailed characterization of the mineralogy and stratigraphy of three different exposures of ELDs in Meridiani Planum, where such formations are found within small impact craters and are dated back to the Noachian-Hesperian boundary. Our analysis highlights a varying degree of mixture between polyhydrated Mg sulfates and Fe/Mg phyllosilicates within the beds of all three chosen targets, with several alternating strata of sulfate-rich and phyllosilicate-rich materials. In one case, Al-phyllosilicates are also found along with their Fe/Mg counterpart. This is a much more varied mineral assemblage than previously reported for ELDs in this area. We propose a formation mechanism which explains the observed interbedding as a result of surface ponding of groundwaters, aqueous alteration of atmospherically-sourced basaltic materials and water table/pH oscillations (wet/dry cycles) leading to recurrent sulfate precipitation. Our findings show how local environments play a substantial role in recording small-scale variations of complex aqueous processes, generally not observed at regional and global scales on Mars.

Since the Juno spacecraft started orbiting around Jupiter in 2016, our understanding of the planet has continued to expand. One of the mission’s primary scientific objectives was to delve into the mechanisms governing the complex aurorae at Jupiter’s poles, leading to significant progress. The Jovian InfraRed Auroral Mapper (JIRAM), on board the Juno mission and composed of an imager and a spectrometer, strongly contributed to advancing in the field. Throughout the mission, the imager has provided detailed monitoring of auroral morphology in the infrared, while the spectrometer has enabled us to derive the temperature and concentration of H ${}_{3}^{+}$ and the distribution of CH _4 across the planet. Despite the extended data volume provided by the spectrometer, only a small fraction of its observations have been analyzed so far, due to the intricate nature of JIRAM spectra, which pose challenges in modeling the observed signal. As new scientific goals have emerged, further investigation into these data is needed to enhance their characterization. In this study, we present several sensitivity tests on JIRAM spectra, with a specific emphasis on observations taken at nadir. Our aim is to characterize the criticalities of these data and assess the implications for further data analyses using inversion techniques. This research is intended as a valuable reference for future JIRAM spectra exploitation, outlining strategies used to address challenges arising from the nature of the data and identifying areas that still require further investigation.

Fractures are ubiquitous in rocks, representing the mechanical stresses exerted on geological materials. They are also of considerable biological interest because of their pivotal role in facilitating fluid circulation within the subsurface. The search for signs of life beyond Earth drives the European Space Agency (ESA) ExoMars Rosalind Franklin (RF) rover mission, which selected the phyllosilicate-rich region of Oxia Planum (latitude 16 °-19 ° N, longitude 23 ° 28 ° W), Mars, as its landing site. In this context, the identification and characterization of fractures are critical in guiding the search for potential biosignatures. Fracture patterns, with spacings ranging from meters to tens of meters, are observable in the region through the Mars Reconnaissance Orbiter (MRO) HiRISE camera, which provides high-resolution optical remote sensing imagery at a resolution of 30 cm per pixel. While the ExoMars team conducted a geological survey focused on the "one-sigma" landing ellipse (approximately 66.75 × 5 km, corresponding to a 67% probability of landing), we initiated a systematic mapping of fractures using HiRISE data through a grid-based mapping approach (1 km by 1 km). Our 1:50,000 scale map represents the current understanding of the spatial distribution of fractures across the "three-sigma" landing ellipse (approximately 115 × 15 km, with a 99% probability of touchdown). Fractures are classified into three categories based on their visibility at 1:5,000 map scale: clearly observable, barely observable, and not observable. By using open geospatial formats, we ensure that datasets produced at different times and in different contexts remain comparable. In this study, we compare our map of fractures with the existing geological map of the Rosalind Franklin landing site, highlighting similarities and differences. By implementing a grid-based mapping approach, we aim to extrapolate additional information and extend the current understanding of the region, providing critical information to support the surface operations of the RF rover. This extended dataset will contribute to the planning of rover exploration activities, provide a framework for testing geological hypotheses about the formation and evolution of Oxia Planum, and facilitate the identification of astrobiologically significant terrains with the potential to preserve biosignatures.Acknowledgments: This work is supported by the ASI-INAF Mars Exploration agreement code 2023-3-HH 0.

Since the Juno spacecraft started orbiting around Jupiter in 2016, our understanding of the planet has continued to expand. One of the mission’s primary scientific objectives was to delve into the mechanisms governing the complex aurorae at Jupiter’s poles, leading to significant progress. The Jovian InfraRed Auroral Mapper (JIRAM), on board the Juno mission and composed of an imager and a spectrometer, strongly contributed to advancing in the field. Throughout the mission, the imager has provided detailed monitoring of auroral morphology in the infrared, while the spectrometer has enabled us to derive the temperature and concentration of H 3 + and the distribution of CH 4 across the planet. Despite the extended data volume provided by the spectrometer, only a small fraction of its observations have been analyzed so far, due to the intricate nature of JIRAM spectra, which pose challenges in modeling the observed signal. As new scientific goals have emerged, further investigation into these data is needed to enhance their characterization. In this study, we present several sensitivity tests on JIRAM spectra, with a specific emphasis on observations taken at nadir. Our aim is to characterize the criticalities of these data and assess the implications for further data analyses using inversion techniques. This research is intended as a valuable reference for future JIRAM spectra exploitation, outlining strategies used to address challenges arising from the nature of the data and identifying areas that still require further investigation.

Transport and mixing of gas species are of particular interest in planetary environments, where interactions among multiple species can occur within confined or porous media. In this work, we present a novel smoothed particle hydrodynamics (SPH) approach for modelling the mixing of binary gas species. The model treats each gas as a separate fluid governed by its own set of Euler equations, coupled through collisional momentum and energy exchange terms derived from a kinetic relaxation model based on the Boltzmann equation. The numerical scheme employs a first-order operator splitting approach combined with a two-step Euler integrator. In this setup, the hydrodynamic evolution is first computed using standard SPH techniques to handle pressure forces. This is followed by a separate correction step that accounts for interspecies collisional exchanges. Such a decoupled treatment enables the use of a larger time-step dictated by hydrodynamics rather than the typically much smaller collisional time-scale, enhancing computational efficiency. The model achieves good accuracy in reproducing the equilibration of density and temperature in a range of molecular mass ratios. Its modular structure supports natural extensions to polyatomic mixtures and enables the inclusion of additional physics, such as gas-solid interactions with dust and ice. These features make the method particularly well-suited for applications involving confined, multicomponent gas systems, such as those expected during the ESA ExoMars mission.

Introduction: it is generally acknowledged that Mars’ past surface conditions were very different from what we observe today. The presence of fluvio-lacustrine morphological features and a widespread hydrous mineralogy on older surfaces indicate that water-rich conditions were common during the first billion years of the history of Mars [1]. In particular, the presence of Fe/Mg phyllosilicates on Noachian surfaces (4.1-3.7 b.y. old) indicates that aqueous alteration of the crust at that time was happening at circumneutral pH conditions [2].The nature of Mars’ climate started to change around 3.7 b.y. ago, at the beginning of the Hesperian period (3.7-3.0 Ga), where we have indications that the environment had become drier and acidic. Evaporites, primarily sulfate-rich salts, are the major alteration mineralogy observed on Hesperian surfaces [1] and the occurrence of water-related morphologies decreased abruptly [3]. Most of the local and regional records of the stratigraphic variability induced by this major climate change event are still unclear and poorly constrained but offer valuable information for assessing the possibility for life’s origin and endurance on Mars.Objective: we focus our investigations on the equatorial region of Mars called Meridiani Planum. This area is well-known for showing signs of a rich and varied aqueous activity spanning through the Noachian and the Hesperian. In particular, a thick sequence of layered sediments rich in sulfates and clays [4] is observed, potentially retaining key information on the climate and environment in which they deposited.Datasets and methods: We select several areas within the northern part of Meridiani Planum which show presence of layered sediments rich in hydrous minerals. Mineralogy and stratigraphy are investigated combining spectral information from the CRISM instrument with high resolution images and DEMs from CTX and HiRISE. Results and discussion: Stratigraphic analysis has evidenced that sulfates (polyhydrated and monohydrated Mg sulfates) are commonly observed at the bottom of the stratigraphic sequence, while clays (Fe/Mg phyllosilicates) are deposited on top, with no evidence of tectonic-structural phenomena that could have overturned the original stratigraphic sequence. The clays observed here therefore do not belong to the Noachian units of Meridiani planum but were formed later, after the sulfates were deposited. The transition between an environment which favors abundant sulfate deposition to one that favors Fe/Mg clays is recording a climatic transition which does not follow the general clay-to-sulfate trend observed at large scales on Mars [1], implying an additional level of complexity to the geologic history of Meridiani. It is essential to assess if similar stratigraphic sequences are observed elsewhere on Mars, to define whether this phenomenon is confined to this region or is evidence of larger scale, if not global, events.Acknowledgements: This project is partially funded by Europlanet RI20-24 GMAP project (research grant agreement No. 871149). References: [1] J. Bibring et al. (2006), Science, 312. [2] S. L. Murchie et al. (2009), JGR-Planets, 114 (E2). [3] B. Hynek, et al. (2010), JGR-Planets, 115 (E9). [4] J. Flahaut et al. (2015), Icarus, 248, 269-288.