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Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space. We use rock physics models and Bayesian inversion to identify combinations of lithology, liquid water saturation, porosity, and pore shape consistent with the constrained mid-crust (∼11.5 to 20 km depths) seismic velocities and gravity near the InSight lander. A mid-crust composed of fractured igneous rocks saturated with liquid water best explains the existing data. Our results have implications for understanding Mars' water cycle, determining the fates of past surface water, searching for past or extant life, and assessing in situ resource utilization for future missions.

Members of the family Trichomeriaceae, belonging to the Chaetothyriales order and the Ascomycota phylum, are known for their capability to inhabit hostile environments characterized by extreme temperatures, oligotrophic conditions, drought, or presence of toxic compounds. The genus Knufia encompasses many polyextremophilic species. In this report, the genomic and morphological features of the strain FJI-L2-BK-P2 presented, which was isolated from the Mars 2020 mission spacecraft assembly facility located at the Jet Propulsion Laboratory in Pasadena, California. The identification is based on sequence alignment for marker genes, multi-locus sequence analysis, and whole genome sequence phylogeny. The morphological features were studied using a diverse range of microscopic techniques (bright field, phase contrast, differential interference contrast and scanning electron microscopy). The phylogenetic marker genes of the strain FJI-L2-BK-P2 exhibited highest similarities with type strain of Knufia obscura (CBS 148926T) that was isolated from the gas tank of a car in Italy. To validate the species identity, whole genomes of both strains (FJI-L2-BK-P2 and CBS 148926T) were sequenced, annotated, and strain FJI-L2-BK-P2 was confirmed as K. obscura. The morphological analysis and description of the genomic characteristics of K. obscura FJI-L2-BK-P2 may contribute to refining the taxonomy of Knufia species. Key morphological features are reported in this K. obscura strain, resembling microsclerotia and chlamydospore-like propagules. These features known to be characteristic features in black fungi which could potentially facilitate their adaptation to harsh environments.

Since November 2021, the Tianwen-1 mission has activated its scientific instrument, the Mars Ion and Neutral Particle Analyzer (MINPA), to detect particles within Martian space. To evaluate the reliability of the plasma parameters from the MINPA measurements, in this study, we analyze and reduce the background signal (or noise) appearing in the MINPA data and then calculate the plasma moments based on the noise-reduced data. Remarkably, our findings reveal a strong correlation between the velocity measurements from MINPA and those from the Solar Wind Ion Analyzer (SWIA) onboard the MAVEN spacecraft, underscoring MINPA's accuracy. Similarly, temperature measurements correlate with SWIA data, albeit with a tendency towards underestimation and greater variability. A significant limitation, however, is MINPA's 2 π field of view (FOV), which restricts its ability to observe ions omnidirectionally, leading to a substantial underestimation of number density and thermal pressure compared to SWIA measurements. Addressing this challenge necessitates a sophisticated approach that fully accommodates the FOV constraints to derive accurate values for these parameters. Moreover, our comprehensive investigation into the noise origins traced it back to electronic noise within MINPA's circuitry. This study confirms MINPA's operational efficacy and potential to yield dependable plasma parameters with further procedures and contributes valuable insights for the design of future scientific instruments. [ABSTRACT FROM AUTHOR]

The Industrial Internet of Things (IIoT) attributes to intelligent sensors and actuators for better manufacturing and industrial operations. At the same time, IIoT devices must be secured from the potentially catastrophic effects of eventual attacks, and this necessitates real-time prediction and preventive strategies for cyber-attack vectors. Due to this, the objective of this investigation is to obtain a high-accuracy intrusion detection technique with a minimum payload. As the experimental process, we have utilized the IIoT network security dataset, namely WUSTL-IIOT-2021. The feature selection technique Particle Swarm Optimization (PSO) and feature reduction techniques such as Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and t-distributed stochastic neighbor embedding (t-SNE) are applied. Additionally, the Generalized Additive Model (GAM) and Multivariate Adaptive Regression Splines (MARS) are used to detect payloads that can interfere with the normal operation of an application. Both PSO and PCA combined with MARS have produced predictive results with an exceptional accuracy of 100%. Yet, the trained Machine Learning (ML) model is quantized with 4-bit and 8-bit, and it is deployed on Azure IoT Edge to simulate edge devices. Experimental results show that the latency of the model was reduced by 25% on quantization. [ABSTRACT FROM AUTHOR]

ABSTRACT The sedimentary fill of Gale crater on Mars is dominated by lacustrine strata that are the focus of investigations into surface processes, climate change and habitability early in the planet's history. This study focuses on the lower part of the explored portion of the Murray formation on Aeolis Mons (Mount Sharp) in the Pahrump Hills and Hartmann's Valley field areas. At Pahrump Hills, sedimentary features and geochemical attributes of exposed mudstones suggest accumulation in an underfilled lake basin in which lake levels, shorelines and salinities fluctuated greatly at various temporal scales. The immediately superjacent stratigraphic interval, designated by the rover team as the Hartmann's Valley member, has previously been interpreted as an aeolian‐deposited sandstone interval. This fresh examination of all available data, however, suggests that the Hartmann's Valley member is strongly dominated by the same mudstone facies that compose most of the underlying Pahrump Hills member. The one novel facies element encountered in the Hartmann's Valley member are undulose bedded to convex bodies of mudstone that are oriented roughly north–south, suggestive of sediment supply from a northern fluvial source. Mudstones analogous in scale and character to these undulose mudstones occur on Earth in multiple modern and ancient lacustrine successions, and are related to deposition of prodelta mud lobes. The mudstones of the Hartmann's Valley member record a continuation of the underfilled evaporitive lake system proposed previously for the underlying Pahrump Hills member but with somewhat more variable environmental conditions. Hartmann's Valley mudstones contain more abundant matrix CaSO4, suggesting more severe evaporitic conditions, whereas the interbedded undulose bedded mudstones signify intermittent freshening and buildout of mud‐dominated deltas into the lake. The textural similarities between Pahrump Hills and Hartmann's Valley strata suggest that the Gale lacustrine system operated at a stable depositional mode with similar environmental parameters during both stratigraphic intervals. [ABSTRACT FROM AUTHOR]

On 2022‐02‐15, solar eruptions caused one of the most intensive Solar Particle Events (SPEs) in Solar Cycle 25 observed at various heliospheric locations. This study focuses on the enhancements of energetic proton flux observed by multiple detectors located at the orbit and on the surface of Mars. We carry out the first analysis by the Mars Energetic Particle Analyzer (MEPA) instrument on board the Chinese Tianwen‐1 spacecraft (TW‐1) at Mars orbit which also serves to validate the instrument's capability to measure protons of up to 100 MeV. We reconstruct the event spectrum up to 1 GeV and further model the event doses at Mars's orbit and surface which are then validated against the corresponding dosimetry data. Our study utilizes all available radiation detectors at Mars, advances our understanding of Mars's radiation environment induced by large SPEs, and emphasizes the necessity of continuous and synergistic radiation monitoring at Mars. Plain Language Summary: There is a growing interest in exploring Mars in the coming decades. However, a significant obstacle that remains is the presence of space radiation, which poses a considerable and unavoidable threat to crew health, especially during long‐term stays in future Martian habitats. Of particular concern are sporadic energetic particle events caused by strong solar eruptions, which can increase radiation levels in deep space and near Mars to potentially dangerous levels. Notably, a SEP event on 15 February 2022 has caused the first significant radiation enhancement at Mars in Solar Cycle 25 as observed by ESA's Trace Gas Orbiter, Chinese Tianwen‐1 orbiter as well as NASA's Mars Atmosphere and Volatile Evolution spacecraft and the Curiosity rover. By combining data from measurement and modeling techniques, we reconstruct the energy spectrum of this SEP event to understand the potential radiation hazards at Mars. Key Points: A major solar particle event (SPE) was simultaneously measured by multiple detectors both on the surface and in orbit of MarsThe first analysis of a SPE at Mars measured by the Tianwen‐1 Mars orbiter serves to verify its capacity in high‐energy particle detectionWe compare the radiation measurements, both on the surface and in orbit of Mars, with results derived from data‐based models [ABSTRACT FROM AUTHOR]

The mixed Fe(II)/Fe(III) mineral magnetite [Fe3O4] of various stoichiometric and non‐stoichiometric compositions have been reported in Martian soils and rocks by several rover missions. Magnetite is an important paleomagnetic indicator mineral and can serve as a 'biogeobattery' as a consequence of its magnetic properties and the mixed valence state of iron in its structure. Here, we assess the extent of oxidative weathering of magnetite in presence of chlorate and bromate containing solutions that are likely important oxidants on Mars. Oxyhalogen species, chlorate and bromate, produced non‐stoichiometric magnetite [Fe(II)/Fe(III) < 0.5] in Mars‐relevant, near‐neutral pH fluids; no other ferric minerals were produced. The same results were observed in highly acidic fluids with or without oxyhalogens. Owing to its resistance to extensive oxidation, magnetite can serve as an important archive of geochemical, paleomagnetic, and astrobiological information in samples that will be returned by the Mars Sample Return mission. Plain Language Summary: Magnetite is an iron oxide that contains both Fe(II) and Fe(III) in its crystal structure. The Fe(II) to Fe(III) ratio in an ideal (i.e., stoichiometric) magnetite is 0.5, that decreases as Fe(II) in its structure oxidizes to Fe(III) thereby forming non‐ideal (i.e., non‐stoichiometric) magnetite. Owing to its unique structure, magnetite can serve as an important paleomagnetic indicator mineral and a source of energy for microorganisms. Therefore, understanding the survivability of magnetite in presence of the harsh oxidizing chemical environment on Mars is important. Here, we conduct laboratory experiments in Mars‐like fluids to test the reactivity of magnetite in presence of strong and effective oxidants that have previously been shown to be active on Mars. Our results show that magnetite is resistant to extensive oxidation in presence of chlorate and bromate solutions to an extent that is much greater than other Fe(II) minerals like iron sulfides, and forms non‐stoichiometric magnetite making it a useful target for analyses of samples from the Mars Sample Return mission aimed at understanding Mars' magnetic history and habitability. Key Points: Magnetite shows resistance to oxidation by oxyhalogen compounds (chlorate and bromate) in Mars‐relevant fluidsNon‐stoichiometric magnetite on Mars may be formed by aqueous alteration of stoichiometric magnetite by oxyhalogen compoundsMagnetite likely preserves geochemical, paleomagnetic and astrobiological information and is an important target mineral in Mars return samples [ABSTRACT FROM AUTHOR]

The RIMFAX ground‐penetrating radar (GPR) on Mars2020 Perseverance Rover is the first GPR operated on the Martian surface since February 2021, searching for stratigraphy beneath the Jezero crater. During its operations, GPR detected several strong reflectors extending from the exposed section of the Séitah formation down to depths of 15 m, with derived relative permittivity of ∼9.0 consistent with low‐porosity mafic rocks. We reprocessed all the SHAllow RADar (SHARAD) observations at a higher resolution and combined repeat‐passes coherently and/or incoherently for clutter mitigation. We then examined the bright returns searching for subsurface structures. The reprocessed data did not show any shallow reflectors like those detected by RIMFAX. We investigated possible factors influencing the lack of shallow reflectors in SHARAD radargrams, including the properties of the older volcanic lithologies and the significant variability of subsurface reflectors within the SHARAD km‐wide spatial footprint, which prevents the formation of coherent reflections. Plain Language Summary: The detection of subsurface sequences by RIMFAX beneath the Jezero crater has sparked renewed debate about the possibility of detecting the boundaries between the crater's units from orbit using the Shallow Radar instrument. We have taken full advantage of the entire SHARAD coverage to examine the near‐subsurface regions beneath the Jezero crater, looking for subsurface returns. The detection of the reflectors recorded by SHARAD may be compromised by the spurious radar returns, which tend to mask the subsurface signals. Therefore, advanced processing specifically designed for resolution improvement and clutter mitigation have been applied to the entire sounder data set prior to searching for interfaces. Despite the signal enhancements, our survey of 56 observations found no returns from the subsurface stratigraphy. The lack of detections may be ascribed to several aspects, including the properties of the rough ancient materials that characterize the crated floor and the physical limitations of the orbital observations. Key Points: RIMFAX‐detected interfaces are within SHARAD's ranges; however, no reflector can be identified in standard radar data at overlap regionsResolution improvements and clutter mitigation techniques still highlight a lack of detectable subsurface reflectionsRough surface, volume scattering and attenuation over older volcanics (>1.5 Ga) significantly inhibits orbital data interpretation [ABSTRACT FROM AUTHOR]

During the development activities of SuperCam Calibration Target, target intended for one of the two first Raman instruments to be deployed on another planetary body, our group developed a laboratory instrument that could simulate to some extent the Raman capabilities of one of such instruments and could provide data with similar quality. The use of this kind of laboratory instruments has demonstrated its utility in the evaluation of potential calibration targets or anticipating the science outcome that an instrument could provide. The present work describes our laboratory setup to support SuperCam, evaluating similarities between both instruments, despite of differences in the hardware. Evaluation of data gathered by SuperCam on Mars and the availability of one replica of SuperCam's Calibration Target allowed the comparison on the same set of targets, demonstrating how similar Signal-to-Noise Ratio (SNR) could be achieved from both instruments. The higher energy per pulse on SimulCam is compensated by a greater analytical footprint and the use of smaller collection optics. The results show how spectra obtained at representative distances of SuperCam are comparable. Operational principles are also comparable in terms of time resolution, and close in terms of spectral resolution. This similarity has allowed different science support works using SimulCam data, as well as the support to Mars detections using our setup. We provide examples of this support that will be shared with the community in different papers, as well as examples of possible operations activities that could benefit from experiments performed with SimulCam. We show how this setup can complement the two laboratory replicas in Los Alamos and Toulouse in providing support data to different experiments. [ABSTRACT FROM AUTHOR]

• Infiltration rates under low gravities were agreed with 1G based predictions. • The air entrapped little in fine porous media may have prevented the infiltration rate reduction. • The infiltration theory is applicable to fine uniform porous media under low gravities. The applicability of the theory of water infiltration in porous media under low gravities is controversial. We evaluated the hypothesis that infiltration under low gravities can be simulated from horizontal infiltration experiments under 1G. Parabolic flights provided low gravity conditions, assuming in the space station (µG), on the moon (0.19 G), and Mars (0.38 G). We measured infiltration rates in uniform particle-size porous media. No significant differences existed between infiltration rates under low gravities and ground-based predictions, i.e. the 1G condition. The air was entrapped little in this study, which may have prevented the infiltration rate reduction reported in previous studies. We concluded that the current infiltration theory adequately simulated water infiltration in fine uniform porous media under low gravity conditions. [ABSTRACT FROM AUTHOR]

Understanding the interaction between Mars and the solar wind is crucial for comprehending the atmospheric evolution and climate change on Mars. To gain a comprehensive understanding of the Martian plasma environment, global numerical simulations are essential in addition to spacecraft observations. However, there are still discrepancies among different simulation models. This study investigates how these discrepancies stem from the considered physical processes and numerical implementations. We compare two global multispecies MHD models: the "Sun model" based on the BATS‐R‐US code and the "Sakata model" based on a newly developed multifluid model MAESTRO. By employing the same typical upstream conditions and the same neutral atmosphere for current Mars, along with similar numerical implementations such as inner boundary conditions, we obtain simulation results that exhibit unprecedented agreement between the two models. The dayside results are nearly identical, especially along the subsolar line, indicating the robustness of MHD models to predict dayside interaction under given upstream conditions and ionosphere assumptions. The escape rates of planetary ions are also in good agreement. However, discrepancies remain in the terminator and nightside regions. Detailed numerical implementations, including inner boundary conditions, magnetic field divergence control methods, and radial resolutions, are shown to influence certain aspects of the results greatly, such as magnetotail configuration and ion diffusion. Key Points: The same physical assumptions are employed for two different global multispecies MHD modelsThe results for the dayside interaction and planetary ion escape are in unprecedented good agreementDetails of the numerical implementations influence the results, especially on the nightside [ABSTRACT FROM AUTHOR]

In this paper we address two problems associated with data‐limited dynamic spacecraft exploration: data‐prioritization for transmission, and data‐reduction for interpretation, in the context of ESA ExoMars rover multispectral imaging. We present and explore a strategy for selecting and combining subsets of spectral channels captured from the ExoMars Panoramic Camera, and attempt to seek hematite against a background of phyllosilicates and basalts as a test case scenario, anticipated from orbital studies of the rover landing site. We compute all available dimension reductions on the material reflectance spectra afforded by 4 spectral parameter types, and consider all possible paired combinations of these. We then find the optimal linear combination of each pair whilst evaluating the resultant target‐vs.‐background separation in terms of the Fisher Ratio and classification accuracy, using Linear Discriminant Analysis. We find ∼50,000 spectral parameter combinations with a classification accuracy >95% that use 6‐or‐less filters, and that the highest accuracy score is 99.6% using 6 filters, but that an accuracy of >99% can still be achieved with 2 filters. We find that when the more computationally efficient Fisher Ratio is used to rank the combinations, the highest accuracy is 99.1% using 4 filters, and 95.1% when limited to 2 filters. These findings are applicable to the task of time‐constrained planning of multispectral observations, and to the evaluation and cross‐comparison of multispectral imaging systems at specific material discrimination tasks. Plain Language Summary: Specially designed cameras used by Mars rovers can see not just with the red, green and blue colors of trichromatic vision, but through a dozen or so distinct color channels, some of which extend into the near‐infrared. This super‐human color vision allows for the distinction of a greater diversity of materials, such as types of rocks and soils, than 3‐color vision. This extra color information requires extra data, but there is a limit to the data than can be transmitted from Mars back to Earth each day. If only some of these colors can be transmitted, then which should be chosen? And once transmitted, how should these channels be combined and contrast‐stretched to best convey the content of the scene? That is the problem we address in this paper. We have used mathematical methods from linear algebra to efficiently trial >200,000 possible combinations and contrast stretches of the 12 available color channels of the ExoMars rover Panoramic Camera to find the best combination that uses the smallest number of channels, for finding the water‐related mineral hematite at the landing site of the ExoMars rover. We've found that only 2–6 channels are needed for an accuracy of >99%. Key Points: Method for ranking the ability of multispectral channel combinations to separate target from background material reflectance spectraUsed to seek minimal number of spectral channels needed by the ExoMars Rover PanCam multispectral imager to find hematite at Oxia PlanumFind ∼50,000 combinations with >95% accuracy using six‐or‐less channels, and find that >99% accuracy can be achieved with 2 channels [ABSTRACT FROM AUTHOR]

The Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory Curiosity rover primarily measures neutrons that have undergone interactions with rocks and materials in the rover's local environment. As the rover ascends Aeolis Mons, it may encounter more extreme local topography (e.g., cliffs, gullies, canyons). We present three parts of the rover's traverse in which local topography, expressed as the average local relief relative to the rover, is moderately to strongly correlated with an increase in passive thermal neutron count rates. These increases in count rates are consistent with results from radiation transport models of the instrument's performance near simulated topographic features. Additional DAN measurements in areas of high average local relief (>0.25 m) within 5 m of the instrument could bolster this correlation. DAN's sensitivity to topography in its passive mode could be utilized as a new measurement capability and has implications for the operation of future landed missions carrying neutron spectrometers (e.g., VIPER, MoonRanger, Lunar‐VISE). Key Points: Three sections of the MSL rover traverse exhibit increased thermal neutron count rates correlated with increased average local reliefThe magnitude of the increase in relative neutron count rates near topography is dependent upon the source and the nearby hydrogen contentFuture measurements from missions with neutron instruments could use this sensitivity to measure hydration of nearby high relief features [ABSTRACT FROM AUTHOR]

Natural opal is a widespread mineral formed by the aqueous alteration of silicate rocks. It occurs as a mixture of silica nano-to-micro-structures (e.g., nanograins, spheres) and silica hydrogel cement, with variations in the proportions of these components leading to significant differences in the physico-chemical properties of opals. However, the detailed process of their formation in nature and the influence of the mixing ratio are not fully understood, as opal has not been yet synthesized under geologically relevant conditions. This study aims to develop a method of opal synthesis in conditions close to continental weathering conditions (<50 °C, ambient pressure) using relevant chemicals that could be employed to gain insight into the processes that give rise to opal on Earth and Mars. Our synthesis method enabled us to synthesize opal-A with different mixing ratios, of which four were then studied to determine the effect on the material's properties. Changes in the proportion of the hydrogel cement affect the porosity and the total water content, as well as the proportion of "water" species (H2O and OH). Moreover, the synthetic opal obtained with a 1:1 ratio shows the closest similarity to natural opal-AG. Finally, our results support the hypothesized multistage process for opal formation in nature. [ABSTRACT FROM AUTHOR]

This study presents the development of a so‐called Turbulent Kinetic Energy (TKE)‐l, or TKE‐l, parameterization of the diffusion coefficients for the representation of turbulent diffusion in neutral and stable conditions in large‐scale atmospheric models. The parameterization has been carefully designed to be completely tunable in the sense that all adjustable parameters have been clearly identified and the number of parameters has been minimized as much as possible to help the calibration and to thoroughly assess the parametric sensitivity. We choose a mixing length formulation that depends on both static stability and wind shear to cover the different regimes of stable boundary layers. We follow a heuristic approach for expressing the stability functions and turbulent Prandlt number in order to guarantee the versatility of the scheme and its applicability for planetary atmospheres composed of an ideal and perfect gas such as that of Earth and Mars. Particular attention has been paid to the numerical stability and convergence of the TKE equation at large time steps, an essential prerequisite for capturing stable boundary layers in General Circulation Models (GCMs). Tests, parametric sensitivity assessments and preliminary tuning are performed on single‐column idealized simulations of the weakly stable boundary layer. The robustness and versatility of the scheme are assessed through its implementation in the Laboratoire de Météorologie Dynamique Zoom GCM and the Mars Planetary Climate Model and by running simulations of the Antarctic and Martian nocturnal boundary layers. Plain Language Summary: In planetary atmospheres, turbulent motions actively contribute to the mixing of quantities such as heat, momentum, and chemical species. Such motions are not resolved in coarse‐grid atmospheric models and have to be parameterized. The parameterization of turbulent mixing should ideally be based on physical laws and sufficiently sophisticated to realistically represent the full spectrum of motions over the full range of stability encountered in the atmospheres. However, it also necessarily contains a number of closure parameters not always well identified and whose values are determined empirically—thereby questioning the universality of the parameterization and its potential application over the full globe or even to other planets—or adjusted to guarantee the numerical stability of the model. This study presents the design of a turbulent mixing parameterization that can be fully calibrated and applied in planetary atmospheres such as that of Mars. We then calibrate the parameterization on an idealized simulation set‐up and test its robustness and performance by running simulations of the Antarctic and Martian atmospheres. Key Points: A simple TKE‐l turbulent diffusion scheme is developed in a semi‐heuristic way for applications in models of the Earth and Mars atmospheresAll adjustable parameters are clearly identified and the number of parameters is minimized to thoroughly assess the parametric sensitivityOnce tuned on GEWEX Atmospheric Boundary Layer Study 1 1D simulations, the scheme is able to capture the Antarctic and Martian stable boundary layers in 3D simulations [ABSTRACT FROM AUTHOR]

This study explores the impact of butadiene rubber (BR) crystallization on the low-temperature properties of butadiene/silicone (VMQ) rubber blends (BR/VMQ) designed for Martian applications. Two types of BR, semi-crystalline high-cis Buna CB24 and amorphous Buna CB550, were blended with VMQ, and their mechanical and thermal properties were evaluated. Kinetics of vulcanization, static mechanical properties, dynamical mechanical analysis, thermal shrinkage, and differential scanning calorimetry were utilized. The research demonstrates that the semi-crystalline BR improves mechanical properties but induces greater shrinkage at low temperatures. Conversely, using amorphous BR provided more consistent mechanical properties across the Martian temperature range and reduced material shrink by 6.71% for samples with carbon black, by 8.36% for samples with silica, and by 11.63% for unfilled samples. Future research will be required to evaluate the impact of volume change on the sealing properties of the BR/VMQ blends. [ABSTRACT FROM AUTHOR]

Identifying surface sites with significant astrobiological potential on Mars requires a comprehensive understanding of past geological processes and conditions there, including the shallow subsurface region. Numerical modelling could distinguish between regions dominated by erosion and those characterized by sediment accumulation in ancient wet environments. The target area of Jezero Crater is relatively well explored and thus is an ideal site to evaluate model calculations; however, important works are still missing on expectations related to its shallow subsurface. In this work, the best available approaches were followed, and only surface morphology was considered (supposedly formed by the last fluvial episode). The shallow subsurface became an important target recently, and this model could provide new inputs in this area. Erosion–accumulation models are suitable for terrestrial surface features, but few have been applied to Mars. This work addresses this challenge using the SIMWE (SIMulated Water Erosion) model on the Jezero Crater delta, the landing site of the Perseverance rover. For calculations, the average grain size according to the THEMIS TI data was applied to the target area. The flow depth varied between 1.89 and 34.74 m (average of 12.66 m). The water-filled channel width ranged from 35.3 to 341.42 m. A flow velocity of 0.008–11.6 m/s, a maximum erosion rate of 5.98 g/m2/h, and a deposition 4.07 g/m2/h were estimated. These calculated values are close to the range of estimations from other authors assuming precipitation of 1–20 mm/h and discharges of 60–400 m3/s. The model was able to distinguish between erosion- and accumulation-dominated areas about 1 m above Jezero Crater's delta that are not visible from above. This model helps to identify the accumulation-dominated areas with the finest grain size with good preservation capability for the shallow but invisible subsurface. [ABSTRACT FROM AUTHOR]

GeoAI has emerged as an exciting interdisciplinary research area that combines spatial theories and data with cutting-edge AI models to address geospatial problems in a novel, data-driven manner. Although GeoAI research has flourished in the GIScience literature, its reproducibility and replicability (R&R), fundamental principles that determine the reusability, reliability, and scientific rigor of research findings, have rarely been discussed. This article aims to provide an in-depth analysis of this topic from both computational and spatial perspectives. We first categorize the major goals for reproducing GeoAI research, namely, validation (repeatability), learning and adapting the method for solving a similar or new problem (reproducibility), and examining the generalizability of the research findings (replicability). Each of these goals requires different levels of understanding of GeoAI, as well as different methods to ensure its success. We then discuss the factors that might cause the lack of R&R in GeoAI research, with an emphasis on (1) the selection and use of training data; (2) the uncertainty that resides in the GeoAI model design, training, deployment, and inference processes; and more important (3) the inherent spatial heterogeneity of geospatial data and processes. We use a deep learning-based image analysis task as an example to demonstrate the results' uncertainty and spatial variance caused by different factors. The findings reiterate the importance of knowledge sharing, as well as the generation of a "replicability map" that incorporates spatial autocorrelation and spatial heterogeneity into consideration in quantifying the spatial replicability of GeoAI research. [ABSTRACT FROM AUTHOR]

A climatological survey of Martian ionospheric plasma density irregularities was conducted by exploring the in-situ measurements of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. The irregularities were first classified as enhancement, depletion, and oscillation. By checking the simultaneous magnetic field fluctuation, the irregularities have been classified into two types: with or without magnetic signatures. The classified irregularities exhibit diverse global occurrence patterns, as those with magnetic signatures tend to appear near the periphery of the crustal magnetic anomaly (MA), and those without magnetic signatures prefer to appear either inside of the MA or outside of the MA, depending on the type and solar zenith angle. Under most circumstances, the irregularities have a considerable occurrence rate at altitudes above the ionospheric dynamo height (above 200 km), and the magnetization state of the ions seems irrelevant to their occurrence. In addition, the irregularities do not show dependence on magnetic field geometry, except that the enhancement without magnetic signatures favors the vertical field line, implying its equivalence to the localized bulge. Other similarities and discrepancies exist in reference to previous studies. We believe this global survey complements previous research and provides crucial research clues for future efforts to clarify the nature of the Martian ionospheric irregularities. [ABSTRACT FROM AUTHOR]

The present study involves the development of a new method, a range-dependent multivariate adaptive regression splines–genetic algorithm (RD-MARS-GA), for monthly streamflow prediction. The results of the RD-MARS-GA model are compared with standard MARS, Gaussian process regression, principal component regression, M5 model tree and random forest. The input data utilized in the study combine satellite and ground-based datasets. Monthly data from the Treene, Schaale, and Wandse rivers in Northern Germany were used as case studies. The satellite datasets used were sourced from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG GPM) and Moderate Resolution Imaging Spectroradiometer Evapotranspiration (MODIS). A comparison of the results reveals that the RD-MARS-GA can improve the forecasting accuracy of the MARS model across all watersheds at different temporal scales. The RD-MARS-GA model surpassed the other regression models and improved the root mean square accuracy of the MARS model by 12.8%, 26.7% and 18.5% in predicting one-month-ahead streamflow of the rivers Treene, Schaale, and Wandse, respectively. [ABSTRACT FROM AUTHOR]

The three largest impact craters, the remains of which have been found on Earth to date, had diameters of about 200 km immediately after formation. The search for traces of larger impact structures continues. This paper presents the results of numerical modeling of the formation of terrestrial impact craters larger than those already found. It is shown that the inferred geothermal gradient significantly influences the initial geometry of the impact melt region, which may facilitate the search for the remains of deeply eroded ancient impact structures. [ABSTRACT FROM AUTHOR]

The installation of planetary and lunar human outposts might be an important step for future solar system exploration by both public space agencies and private companies. Humans living and working in these artificially created habitats will possibly depend, among other life support approaches, on bio-regenerative life support systems to produce and recycle oxygen and water, and to produce food. A variety of natural resources suitable life support can be readily found on Mars, and to a lesser extent on the Moon. Instead of launching all resources (e.g., water, propellant, food and other materials) from Earth, it could potentially be much more cost effective to send automated machinery to harvest resources from the Martian surface and atmosphere in preparation for the arrival of humans. The exploration of these natural resource deposits, the concentration of the raw materials contained in them, and the feasibility of mining and refinement are open questions that require further consideration. Here we address the concept of harvesting resources in situ by reviewing the potential of several large deposits of hydrated minerals found on the surface of Mars thanks to previous orbital detections. We also present estimates of water volumes potentially retrievable from specific deposits and describe additional uses of the hydrated minerals for example as fertilizer for food production. • Hydrated sulfate deposit contains important resources for landed crews. • Bio-regenerative Life-Support Systems could reduce logistics from Earth to Mars. • Several regions on Mars bear large exploitable resource potential. • Water is abundantly available in selected deposits. • Prolonged human presence on Mars could profit from the use of local resources. [ABSTRACT FROM AUTHOR]

Aerobraking represents a valuable option for interplanetary missions thanks to its capability of reducing the orbital semi-major axis through multiple atmospheric passages, thus with limited fuel consumption. However, due to structural and thermal loads the spacecraft undergoes, mission risks and ground operations costs increase. This study aims to tackle this aerobraking drawback by enhancing its autonomy. The main activities required for aerobraking execution, including atmospheric prediction, orbital state estimation, and orbit control, are tailored for onboard execution. Regarding orbit control, two different methodologies, differentiated by working principle and prediction horizon breadth, are investigated. The first plans orbit control manoeuvres based on the prediction of the atmospheric conditions for a single upcoming pericentre, while the second schedules and optimizes the manoeuvres considering the recent atmospheric conditions experienced by the spacecraft and the altitude trend of multiple upcoming pericentres. The whole operational concept is tested within a simulated environment, with the primary objective of accurately reproducing the intense atmospheric variations of the Martian atmosphere, which represents the most challenging aspect during aerobraking execution. The numerical testing, involving the simulation of different aerobraking regimes under varied conditions, shows that the natural dynamics of the orbital motion can be exploited to minimize both fuel consumption for orbit control manoeuvres and spacecraft load variations, thus enabling more efficient aerobraking and more stable flight conditions, even with the limited predictive capabilities that characterize onboard resources. Both control logics permit the aerobraking execution without exceeding the maximum allowed thermal limits, hence showing their effectiveness. Furthermore, a Monte Carlo analysis conducted on a complete aerobraking simulation reveals a 25.5% reduction in propellant consumption and a 9.4% reduction in heat rate variability when the orbit control decision process uses information relative to multiple future pericentres. [ABSTRACT FROM AUTHOR]

The Tropical Cloud Oscillation (TCO) in the Martian atmosphere is a shift of clouds in the northern spring and summer tropical cloud belt between the eastern and western hemispheres on an intra‐seasonal timescale of about 10–40 sols. The TCO is a significant intraseasonal variation and may strongly affect the Martian general circulation, water cycle, and dust cycle. We examine TCOs using multiple data sets with a focus on the clouds observed in Mars Daily Global Maps during Mars Year (MY) 29–35. One or more TCO cycles are observed in each MY and the phenomenon is most prominent during Ls = 135°–185°. Space‐time spectral analysis shows a variety of waves which appear to follow the theoretical dispersion relationships of equatorial waves, such as Kelvin waves, Rossby waves, and Mixed Rossby Gravity waves. The TCO appears to be controlled by zonal wavenumber one traveling waves with Kelvin and Rossby wave characteristics and exhibits a fine‐scale latitudinal structure that requires modeling with sufficient resolution. Issues with current data assimilation products for use in studies of Martian equatorial waves due to this fine‐scale structure are discussed. Plain Language Summary: During martian northern spring and summer, a relatively thick water ice cloud belt is observed in the tropics (approximately 25°S–25°N), which modifies large‐scale circulation, global water transport and the atmospheric dust cycle. We report on a Tropical Cloud Oscillation (TCO) that is a periodic shift in the thickness of this cloud belt between the eastern and western hemispheres on timescales (about 10–40 Mars days) longer than that of weather but shorter than that of seasons. Since the TCO involves changes in clouds and implies changes in circulation, it may also modulate the dust and water cycles. We examine TCOs using image data for Mars Year 29–35 (late 2007 through early 2021). One or more TCO cycles are observed in each Mars Year and the phenomenon is most prominent in late northern summer. A wide variety of atmospheric waves are found during TCOs; however, the most important are equatorial waves traveling eastward and westward with one peak and one trough around the planet. These waves have narrow latitudinal length scales and thus require high resolution numerical models to simulate and properly represent in data assimilation products. Key Points: The Martian tropical cloud belt exhibits eastern—western zonal oscillations that are most prominent in late northern summerTropical Cloud Oscillations are controlled by large‐scale low frequency equatorial Kelvin and Rossby wavesEquatorial wave dynamics may have an important effect on the Martian water and dust cycles [ABSTRACT FROM AUTHOR]

The Curiosity Rover has been exploring the Gale Crater using the on‐board Navigation Camera to monitor the line‐of‐sight (LOS) dust extinction within the crater. Previous studies of the line‐of‐sight extinction have shown an annual trend where a minimum in extinction occurs around Ls = 100° and a maximum occurs around Ls = 300°. However, past studies have been constrained to images acquired only between 10:00 and 14:00 local time, limiting our understanding of the variation of dust extinction in Gale Crater throughout the day. Here, using a method that corrects for variable lighting geometry, we reanalyze the line‐of‐sight images captured throughout the mission to include images acquired in the early morning and late afternoon. Additionally, we update the line‐of‐sight record to include over 1,000 additional sols of the mission through sol 3,663, which updates our record of extinction in Gale to the end of Mars Year 36—a period of almost 5.5 Mars Years. Using images taken throughout the sol, we examine the diurnal trend in dust extinction, where a maximum is seen around solar noon. This diurnal trend is observed throughout the year, with a larger diurnal variation observed during the southern summer. Additionally, the geographic homogeneity in dust loading is quantified, with higher dust loading observed in the western portion of the line‐of‐sight images, corresponding with the north‐western portion of the crater rim. These observations suggest that dust lifting from the surface and vertical mixing are factors in the diurnal, seasonal, and geographic dynamics observed in the extinctions. Plain Language Summary: The Curiosity Rover has used its Navigation Camera to image the northern rim of Gale Crater for over 3,000 martian days. These images are used to calculate the amount of airborne dust between the rover and the crater rim. Past studies using these images found that the amount of dust was lowest during southern‐hemisphere winter and highest during southern‐hemisphere summer. In this work, a new method to find the amount of dust was used, allowing us to use images taken throughout the day for the first time. The entire set of crater rim images was reanlayzed using the new method, including new images captured up to sol 3,663. We find a daily cycle, where the amount of dust in the air is lowest in the morning and evening, and highest around noon. In addition, there is more airborne dust between the rover and the crater rim on the western side of the image compared with the center and eastern side. This suggests that dust is moving within the Gale Crater on short timescales, where dust lifting from the surface likely plays a key role in the diurnal trend, in combination with air outside the crater mixing with air within the crater. Key Points: The line‐of‐sight dust extinction is calculated through 3,663 sols using the Mars Science Laboratory's Navigation CameraDiurnally, the dust extinction peaks at solar noon, with lower values in the morning and eveningThe diurnal variation is higher during the dustier southern summer and lower during the southern winter when dust extinction is at a minimum [ABSTRACT FROM AUTHOR]

Our understanding of the paleoclimate of Mars and the dominant forcing functions that drive large‐scale changes largely remains a mystery. However, the Martian Polar Layered Deposits (PLD) offer a promising avenue for unraveling the planet's recent paleoclimate history. Despite recent progress to detect a climate signal in the PLD, definitive evidence of a correlation between the stratigraphic record and Mars' recent orbital history remains elusive. We utilized new and updated techniques, including high‐resolution stratigraphic reconstruction from High Resolution Imagine Science Experiment stereo imagery and digital terrain models, combined with a technique of variable dip correction to account for three dimensional bedding orientations. Signal processing methods, such as wavelet and Fourier analysis, were applied to perform detailed time‐series analysis. These analyses revealed a quasi‐periodic signal indicative of fine bedding at a scale of approximately 2 m. Based on previously proposed deposition rates, these fine layers appear to correspond to timescales centering around 4,000 years. This suggests that the meter‐scale layers may not be the result of orbital forcing and hint at an unknown sub‐Milankovitch climate forcing mechanism. We discuss potential exogenic causal mechanisms, such as cyclic variations in solar activity, and endogenic factors, including large‐scale changes in dust distribution. Understanding the formation processes of these fine layers may significantly enhance our knowledge of Martian climate history and its driving forces. Plain Language Summary: In this paper, we investigate the presence, distribution, and significance of small‐scale layers in the northern polar layered deposits (PLD) of Mars. Solar radiation is a key variable in determining the long‐term evolution and stability of the polar caps, and it is closely linked to changes in the planet's orbit, such as precession, eccentricity, and obliquity. We argue that the thickness and periodicity of these fine layers reflect a causal mechanism that cannot be attributed solely to climate changes resulting from the long‐term evolution of Mars' orbit. Based on proposed accumulation rates of the polar ice, we suggest that the quasi‐periodic bedding may represent a climate signal occurring on timescales several orders of magnitude shorter than those of the orbit changes in Mars, centering around 4,000 years. These observations help to characterize and better understand the PLD and their formation. Key Points: Meter‐scale bedding is widespread throughout Mars northern polar layered depositsUsing image and topographic data, we show that the fine bedding is quasi‐periodic within a confined range of wavelengths from 1.5 to 3 mUnder previous deposition rate estimates, meter‐scale bedding corresponds to ∼ ${\sim} $4,000‐year, sub‐Milankovitch timescales [ABSTRACT FROM AUTHOR]

The lithosphere of Mars accommodates horizontal shortening through folding and faulting, producing landforms described as wrinkle ridges or lobate scarps. Despite this nomenclature, we lack a deep understanding of the drivers of morphological differences observed between landform types. This study aims to develop a quantitative model for shortening landform classification based on surface morphology, subsurface architecture, and strain accommodation, facilitating interpretations of where and how lithospheric stresses are recorded. We developed this model by mapping 100 shortening landforms in a Geographic Information System, recording 12 unique geomorphic parameters such as length and asymmetry, and estimating the strain of each landform. We conducted a Discriminant Function Analysis (DFA) using surface morphometrics. This DFA produced a predictive linear function for categorizing wrinkle ridges and lobate scarps and for quantifying which landforms were exemplars within those categories. The three most influential variables on the surface morphometry DFA were the maximum width, forelimb slope, and back limb length. We then modeled the subsurface structural geology of 50 landforms using MOVE Structural Geology Modeling Software and conducted a second DFA based on subsurface metrics. DFA was most influenced by the dip and depth of the lower ramp base. When both surface morphology and subsurface geometry are input into single DFA, wrinkle ridges and lobate scarps can be distinguished quantitatively 96% of the time. Our results also show that lobate scarps accommodate more strain and imply that studies should consider landform type when interpreting local, regional, and global geological stress histories. Plain Language Summary: The tectonic structures of a planet record its geologic history. Some of these structures, such as those classified as lobate scarps and wrinkle ridges, account for the horizontal shortening of the planet's surface. These two groups of shortening structures are observed on the surface of almost every rocky planet. Planetary geologists have historically assumed that wrinkle ridges and lobate scarps represent different types or amounts of shortening based on differences in their visual morphologies. In this work, we mapped 100 of these landforms on Mars and quantified their surface characteristics. We then further analyzed 50 landforms using a structural geology modeling software to assess their subsurface fault and fold geometries. Using the parameters we measured, we applied a statistical analysis called a Discriminant Function Analysis to quantify and learn about the differences between these landform types. We find that lobate scarps are rooted by faults that extend deeper into the subsurface than faults that underly wrinkle ridges, and that because of the greater variability in landform characteristics, lobate scarps may represent a range of stages in the formation of these landforms while wrinkle ridges developed entirely during one phase of the geologic history of Mars. Key Points: Shortening landforms on Mars were analyzed at the surface and subsurface to quantify their morphometrics and structural geometriesTraditional definitions of lobate scarps and wrinkle ridges are end member descriptions of landforms that exist across a morphological spectrumLobate scarps are fault‐dominated structures while wrinkle ridges are fold‐dominated structures [ABSTRACT FROM AUTHOR]

The scarce carbonate record on the Martian surface is one of the fundamental unsolved issues for paleoclimate and environmental evolution. Whether carbonates first formed and then dissolved due to a transition in global environments or whether Mg–Fe carbonates never extensively formed due to geochemical kinetics thresholds remains unknown. In this study, we experimentally examined the preservation potential of siderite in Mars‐relevant fluids, including ultrapure water, H2O2, NaClO4, NaClO3, NaCl, Na2SO4, NaHCO3, and Na2SiO3 solutions, at 277 K. The effects of the water/rock ratio at WR10 and WR100 on dissolution rates were also investigated. We found that siderite dissolution and subsequent oxidation and hydrolysis of leached Fe did not substantially acidify the solutions. The siderite dissolved relatively rapidly in the chloride and chlorate solutions and slowly in the silica or bicarbonate solutions. In a circum‐neutral to slightly alkaline aqueous environment with oxidative species, the mobility of leached Fe was limited, leading to the formation of goethite or lepidocrocite, which clustered on the siderite surface. The longest lifetime of 1‐mm siderite grains was found in the Na2SiO3 solution at WR100, which was estimated to range from 198 ka to 198 Ma. Water‐limited, silica‐rich, and oxidative aqueous environments benefit siderite preservation on the Martian surface. Our results support that the lack of voluminous siderite on Mars may be primarily due to the inhibition of its formation rather than alteration and dissolution after its presence, consistent with the recent detection of Mg–Fe carbonate at Gale Crater and Jezero Crater. Plain Language Summary: Despite the predominant carbon dioxide atmosphere, the distribution of carbonate outcrops on Mars detected to date is very limited. The discrepancy between the CO2‐dominant atmosphere and scarce carbonate records is one of the key issues for understanding the paleoclimate and environmental evolution of Mars. We experimentally investigated the preservation potential of siderite in eight Mars‐relevant fluids under water‐limited versus water‐abundant scenarios at 277 K. We found that water‐limited conditions, silica‐rich environments, and the presence of oxidants in aqueous environments generally benefit siderite preservation. The longest lifetime of 1‐mm siderite grains is present in silica‐rich solutions, estimated to range from 198 ka to 198 Ma. In a neutral to alkaline aqueous environment with oxidative species, the mobility of leached iron is limited, and the Fe precipitates are mainly in the form of goethite or lepidocrocite, accumulating on the siderite surface. Martian aqueous environments can efficiently preserve siderite. Therefore, the lack of voluminous siderite on Mars may be because siderite was never extensively formed rather than altered and dissolved after its presence. Key Points: Siderite dissolves relatively fast in chloride‐ and chlorate‐fluids and slowly in silica‐ and bicarbonate‐fluidsWater‐limited, silica‐rich, and oxidative aqueous environments favor siderite preservation on the Martian surfaceThe scarcity of voluminous siderite on Mars may be due to the inhibition of its formation rather than its dissolution after its presence [ABSTRACT FROM AUTHOR]

The Thermal Evolved Gas Analyzer (TEGA) analysis of surface and icy subsurface Phoenix landing site soils consisted of low (300–700°C) and high (>700°C) temperature CO2 evolutions that were attributed to organic carbon (83–1,484 μgC/g) and Ca‐rich carbonate (1.1–2.6 wt.%). Total carbon abundances ranged from 1,143 to 4,905 µgC/g, which is the highest soil carbon concentration so far detected on Mars. Low temperature CO2 was attributed to oxidized organic C (e.g., oxalates, acetates), while hydrocarbon combustion was indicated in two soils by the detection of coevolved CO2 and O2 (perchlorate). Combustion reactions may have prevented the detection of hydrocarbon masses in the Phoenix landing site soils. Organic C was likely derived from meteoritic and igneous/hydrothermal sources, but microbiological sources cannot be excluded. CO2 evolved at high temperatures was consistent with Ca‐rich carbonate along with possible minor contributions from macromolecular organic carbon and mineral/glass vesicle CO2. Carbon detected in the Phoenix landing site soil and other landing site soils and sands (e.g., Gale/Jezero craters) would be consistent with global organic C and carbonate in soils and sand across Mars. However, oxidizing water thin films derived from the near‐surface ice in the Phoenix soils favor Ca‐carbonate over Fe‐carbonate, which is likely more stable in the ice‐free regions of Mars (e.g., Gale/Jezero craters). The global carbon budget on Mars inferred from these results emphasizes that Mars Sample Return should yield carbon bearing soil/rock that would allow the identification of the origin of carbon and any possible connections to ancient martian microbiology. Plain Language Summary: The Phoenix Lander's Thermal Evolved Gas Analyzer (TEGA) analyzed surface and subsurface icy soils of the martian northern plains in 2008. The TEGA instrument heated scooped soils to 1,000°C and measured evolved gases (e.g., CO2, O2, H2O) to quantify the presence of volatile bearing phases (e.g., organics, carbonates, salts). Some TEGA results have been previously published; however, this report describes unreported TEGA results. The TEGA instrument detected low (300–700°C) and high (>700°C) temperature CO2 evolutions that were attributed to organic carbon and Ca‐rich carbonate. Total carbon abundances as high as 4,905 µgC/g were detected which is the highest soil carbon concentration detected on Mars to date. Organic C sources include meteoritic and igneous/hydrothermal sources, but microbiological origins cannot be excluded. Ca‐rich carbonate may have been inherited from local sediments or was derived from dissolved CO2 reactions with the soil in migrating water thin‐films from subsurface ice. The carbon detections at the Phoenix and other landing sites suggest that Mars Sample Return of surface soil/rock should contain carbon that can be used to identify the origin(s) of carbon. Key Points: Phoenix landing site soils have the highest soil carbon concentration (up to 4,905 µgC/g) of any soil measured on MarsOrganic C (83–1,484 μgC/g) was likely derived from meteoritic sources with possible contributions from igneous/hydrothermal sourcesCa‐carbonate (1.1–2.6 wt.%) was inherited from local sediments or derived from soil reactions with dissolved CO2 in water thin‐films [ABSTRACT FROM AUTHOR]

Terra Sirenum, a region of Noachian highlands southwest of the Tharsis volcanic complex, is unique in the number, proximity, and diversity of orbital detections of secondary minerals, as the sole region found to date hosting large‐scale deposits of all of Mars' major salts (chlorides, sulfates, carbonates) as well as diverse hydrated silicates. We combine mineralogical information, high‐resolution imagery, and elevation models to investigate the geologic context of these secondary minerals to understand the sources of water and ions for each type of deposit and their spatial/temporal relationships. Carbonates, where present, are part of Noachian basement rocks exposed through cratering and do not appear associated with evaporative sequences. Numerous small detections of the acid sulfate minerals alunite and jarosite mirror the dominant clay cation in the localities they are found—Al phyllosilicates and Fe phyllosilicates, respectively—suggesting in situ formation. We interpret a previously discovered kaolinite‐rich unit overlying Fe/Mg clays across northeast Terra Sirenum as remnants of a widespread ash unit rather than a pedogenic weathering sequence. Sulfate and chloride detections are decoupled, with sulfates in topographic lows likely precipitated from volcanism‐associated groundwaters, while chloride detections are consistent with surface water runoff, in some instances clearly post‐dating volcanic units capping sulfate detections. Volcanic resurfacing of craters in the region is progressively younger from west to east, and crater statistics‐based ages indicate localized sulfate‐ and chloride‐forming processes continue to occur from ∼3.5 to ∼1.4 Ga. We hypothesize that their decoupling points to disconnected, episodic surface and groundwater reservoirs, perhaps separated by a permafrost layer. Plain Language Summary: A major question is how Mars evolved from a water‐rich planet to a dry planet. We study a region southwest of Mars' largest volcanoes with multiple types of water‐related minerals. We use their detections to infer the properties of the water that deposited them and imagery to understand if/how the minerals are related to each other. Chlorides (e.g., table salt) are found in ponds and channels over a wide elevation range. Sulfates are present only in deep basins with signs of volcanic activity. On Earth, sulfates and chlorides are often together, forming during evaporation of a body of water; however, on Mars, the occurrences seem to be separated, which suggests different water sources and that groundwater with sulfur added from volcanic gases was involved in sulfate formation. The deposits both get progressively younger, as young as ∼2 billion years ago, toward the large volcanic region. Furthermore, aluminum clays on top of iron/magnesium clays in this area have been previously interpreted as weathering sequences, which implies a large volume of water. Instead, we find most aluminum clays are part of a volcanic ash layer deposited on top of older iron/magnesium clays, which needs a smaller amount of water to create the observed layering. Key Points: Thick, layered deposits with Al clays in upper strata thin with distance from Arsia Mons, suggesting volcanic ash parent lithologiesChlorides are decoupled from sulfates in deep basins; sulfates likely precipitated from upwelling groundwater with magmatic volatilesAssociated volcanic units have ages pointing to episodic volcanic springs and surface melt waters into the early Amazonian [ABSTRACT FROM AUTHOR]

The paper addresses the possibility of a young Mars having had a massive moon, which synchronized the rotation of Mars, and gave Mars an initial asymmetric triaxiality to be later boosted by geological processes. It turns out that a moon of less than a third of the lunar mass was capable of producing a sufficient initial triaxiality. The asymmetry of the initial tidal shape of the equator depends on timing: the initial asymmetry is much stronger if the synchronous moon shows up already at the magma‐ocean stage. From the moment of synchronization of Mars' rotation with the moon's orbital motion, and until the moon was eliminated (as one possibility, by an impact in the beginning of the Late Heavy Bombardment), the moon was sustaining an early value of Mars' rotation rate. Key Points: A synchronous moon of 1/3 of the lunar mass could create Mars' present triaxiality and asymmetry, when the lithosphere was absent or weakVolcanism near the frozen tidal bulges was, hypothetically, more active than in other provinces. Hence Tharsis and Syrtis MajorThe putative moon perished in the Late Heavy Bombardment, Phobos and Deimos being remnants of its large fragment destroyed later [ABSTRACT FROM AUTHOR]

A comprehensive modeling study has been conducted to investigate space weather effects at Mars during the 10 September 2017 solar flare, utilizing an integrated framework that combines the global magnetohydrodynamic (MHD) model and Mars Global Ionosphere‐Thermosphere Model (MGITM). This is the first time the thermosphere‐ionosphere‐magnetosphere system is self‐consistently simulated under realistic, time‐varying conditions. Our simulations align well with observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN). Recognizing that complexities due to highly disturbed upstream conditions and rotating crustal fields obscure solar flare effects in orbit‐to‐orbit comparisons, we perform controlled simulations of nonflare and flare cases and exploit their contrast to quantify spatiotemporal variations in flare impact. Our results highlight pronounced and rapid dayside ionospheric perturbations, contrasting with weaker and delayed nightside responses. Notably, in the topside ionosphere, O2+ ${\mathrm{O}}_{2}^{+}$ and CO2+ ${\mathrm{O}}_{2}^{+}$ densities increase primarily on the dayside below ∼ ${\sim} $300 km altitude, peaking with an increase of 20%–30%. The O+ ${\mathrm{O}}^{+}$ density shows a more significant increase of up to ∼ ${\sim} $50%, extending into the magnetosphere and nightside via plasma transport, increasing its total loss rate by 14%. We observe distinct altitude‐dependent patterns in dayside electron density enhancements in percent, characterized by a weakening with altitude and a rapid decay below ∼ ${\sim} $150 km in line with the flare development, and a gradual intensification between ∼ ${\sim} $150–300 km due to plasma transport and flare‐induced atmospheric upwelling. Earlier Mars Global Surveyor observations were limited to the low‐altitude pattern due to atmospheric expansion and missed the higher altitude variations observed by MAVEN. Plain Language Summary: This study investigates the impact of a powerful X8.2‐class solar flare on 10 September 2017 at Mars. Using an integrated modeling framework that combines two state‐of‐the‐art global models, our simulations provide insights into distinct altitude‐dependent patterns of flare‐induced ionospheric density enhancements, pronounced day‐night asymmetry, and a moderate increase in ion escape. Key findings include rapid variations in ionospheric density enhancements at lower altitudes, with a gradual intensification at higher altitudes due to plasma transport and atmospheric upwelling. These findings contribute to a better understanding of how solar flares impact the space environment of unmagnetized or weakly‐magnetized planets like Mars. Key Points: The solar flare causes pronounced and rapid dayside ionospheric perturbations and weaker and delayed effects on the nightsideO2+ and CO2+ densities increase by 20%–30% above 150 km on the dayside, while O+ increases by up to 50% and over larger spacePercentage increase of dayside e− densities decreases with altitude and decays fast below ∼150 km, and rises and decays slowly above that [ABSTRACT FROM AUTHOR]

This exploratory study investigates changes in the autonomic cardiac system of young analog astronauts in a hostile, confined, and isolated environment. It uses linear and nonlinear indices of heart rate variability (HRV) during a Mars analog mission to assess how HRV varies under day and night stressors. This study is guided by the hypothesis that significant HRV changes occur based on adaptation days, aiming to offer insights into autonomic nervous system (ANS) adaptation to environmental stressors. Over five days in August 2022, five analog astronauts faced adverse conditions in the Mojave Desert, simulating Martian conditions. Electrocardiograms were recorded daily for five minutes during morning and evening sessions to extract short-term RR time series. HRV parameters were analyzed using both time- and frequency-domain indices and nonlinear measures. Significant differences in HRV parameters across days highlight the mission environment's impact on autonomic cardiac function. Morning measurements showed significant changes in average RR intervals and heart rate, indicating ANS adaptation. Nonlinear indices such as detrended fluctuation analysis and approximate entropy also showed significant differences, reflecting shifts in autonomic function. The Borg scale indicated reduced perceived exertion over time, aligning with HRV changes. Increased vagal activity during Mars analog adaptation under confinement/isolation may be crucial for cardiovascular adaptation and survival in future space flights. [ABSTRACT FROM AUTHOR]

We use the crystallinity of hydrated silica, represented by the 1.4 μm absorption position in orbiter spectroscopic data, as a proxy for the longevity of water–rock interaction in the Syrtis Major region. Geological maps and crater size–frequency distribution analyses are employed to contextualize mineral detections and estimate surface ages. Hydrated silica is detected within two distinct geological units: a younger "volcanic terrain" (vt) unit (∼2.4 Ga) and an older "highland terrain" (ht) unit (3.5–3.7 Ga). Hydrated silica in the vt unit typically has a band position <1.41 μm, consistent with amorphous opal‐A, suggesting these younger terrains have experienced limited interaction with water. In contrast, hydrated silica in the older highlands typically has a band position >1.41 μm, indicating opal‐CT, suggesting that these deposits have had more time to interact with water, while also producing accessory minerals such as kaolinite and Fe/Mg phyllosilicates. Plain Language Summary: This study explores the interactions between water and rocks in a region on Mars known as Syrtis Major by investigating a mineral‐like substance called hydrated silica. The structure of hydrated silica helps us estimate the extent of water interaction and its effects on the rocks. We used satellite data to locate this mineral across Syrtis Major and infer its crystal structure. Furthermore, we developed detailed geological maps and estimated surface ages to understand the geological context. We found that hydrated silica is located in two different types of areas: (a) a younger volcanic region; and (b) an older highland region. In the younger volcanic areas, it appears that less crystalline hydrated silica formed by interaction with small amounts of water, possibly during later volcanic activity. In the older highlands, more crystalline hydrated silica likely interacted with water for a longer duration or in larger amounts. This information aligns with the idea that the older highlands experienced more extensive or long‐lasting interactions with water compared to the younger volcanic regions. It provides insights into different wet periods in Mars' past, aiding our understanding of the planet's geological history and the role water played in shaping its surface. Key Points: We analyzed the crystallinity of hydrated silica in Syrtis Major to infer the extent and longevity of water–rock interactionAmorphous silica is found in young volcanic terrains within Nili and Meroe Paterae and more crystalline silica in the older highlandsOlder highland regions likely underwent a longer interaction with water compared to younger volcanic terrains [ABSTRACT FROM AUTHOR]

The properties of the first kilometers of the Martian atmospheric Planetary Boundary Layer have until now been measured by only a few instruments and probes. InSight offers an opportunity to investigate this region through seismoacoustics. On six occasions, its seismometers recorded short low‐frequency waveforms, with clear dispersion between 0.4 and 4 Hz. These signals are the air‐to‐ground coupling of impact‐generated infrasound, which propagated in an low‐altitude atmospheric waveguide. Their group velocity depends on the structure of effective sound speed in the boundary layer. Here, we conduct a Bayesian inversion of effective sound speed up to 2,000 m altitude using the group velocity measured for events S0981c, S0986c and S1034a. The inverted effective sound speed profiles are in good agreement with estimates provided by the Mars Climate Database. Differences between inverted and modeled profiles can be attributed to a local wind variation in the impact→station direction, of amplitude smaller than 2 m/s. Plain Language Summary: The Martian Planetary Boundary Layer corresponds to the first few kilometers of the atmosphere. The InSight lander offers the opportunity to investigate its properties via the coupling of seismic and acoustic waves. Impact‐generated infrasound waves were recorded for the first time on Mars by the seismometers of the InSight mission. These infrasound waves propagated in an atmospheric waveguide in the first kilometers above the Martian surface, and thus present a frequency‐dependent group velocity. This frequency‐dependence, also known as a dispersion relation, is influenced by the structure of the speed of sound in the waveguide. Here, we use group velocity measured for events S0981c, S0986c and S1034a to invert the variations of effective sound speed between 0 and 2,000 m altitude. For the three events, the inverted profiles are in good agreement with estimates provided by the Mars Climate Database using global climate modeling. The differences between inverted and modeled profiles can be attributed to a local variation in wind in the impact→station direction, with magnitude smaller than 2 m/s. Key Points: InSight recorded impact‐generated infrasound on Mars. Their group velocity is sensitive to the structure of the atmospheric boundary layerWe conduct a Bayesian inversion of effective sound speed profiles with altitude based on group velocities measured for three impact eventsThe inverted profiles provide an indirect measurement of the Martian boundary layer, and validate models of the Mars Climate Database [ABSTRACT FROM AUTHOR]

It is commonly believed that because of the direct solar wind interaction with the Martian atmosphere/ionosphere, the planet could have lost a significant part of its atmosphere. Closed field lines of the crustal magnetic field can weaken a transport of the ionospheric ions to the tail. Reconnection of the interplanetary magnetic field lines draping around Mars and the crustal magnetic field can also lead to a presense of sunward fluxes of planetary ions that might affect the total ion loss. The LatHyS (LATMOS Hybrid Simulation) three‐dimensional multispecies hybrid model is used here to characterize sunward fluxes of O+ ions and the magnetic field topology at Mars. It is shown that although reconnection between the interplanetary magnetic field (IMF) and the crustal magnetic fields strongly modifies the field topology, then sunward ion fluxes are rather small and do not significantly change the total ion loss. Plain Language Summary: Although Mars has no a global intrinsic magnetic field and solar wind interacts directly with the planetary atmosphere/ionosphere, the existence of strong but localized crustal magnetic field modifies the field topology around Mars. As a result, the Martian magnetosphere contains elements of the intrinsic and the induced magnetospheres. Reconnection between the interplanetary magnetic field and the crustal magnetic field can generate the plasma flows toward the planet and decrease the ionospheric losses, which is very important for the evolution of the Mars atmosphere/ionosphere. We have performed the numerical simulations of these potential effects and shown that the sunward ion fluxes are significantly less than the losses induced by the solar wind impact on the Martian ionosphere. Key Points: Hybrid simulations show a drastic change of the field topology at altitudes less than ∼1,000 km due to crustal field sourcesAlthough the magnetic field topology is modified, the sunward fluxes do not essentially affect the total ion lossSunward fluxes of oxygen ions in the tail vary between ∼5% and ∼20% compared to the anti‐sunward fluxes [ABSTRACT FROM AUTHOR]

Depleted shergottites record unique information about the primary composition and differentiation of the mantle of Mars. Their petrology, geochemistry, and cosmic ray exposure and crystallization ages suggest that most of them were excavated by a single young impact in the Amazonian‐aged lava flows of the Tharsis and Elysium volcanic provinces. However, the difficulties of deriving consistent model ages for individual craters and inadequate evaluation of 3‐7 km craters capable of ejecting martian meteorites have not been settled. Here we perform detailed geological investigations and crater statistics in patches of impact melt deposits for potential source craters of depleted shergottites with D > 3 km, especially those in the Tharsis and Elysium volcanic provinces. By excluding the effect of heterogeneous textures across ejecta deposits, which hinder straightforward extraction of superposed production populations, our systematically updated model ages reveal that Chakpar crater at the northern flank of Ascraeus Mons is the best‐fit candidate. The local context of this crater permits establishing a link between the meteorites and specific lava flows. The long‐lived volcanic center here may experience an eruption and/or local deposition hiatus for about 1.8 billion years, and abundant subsurface water existed when the impact occurred at about 1.1 million years. [ABSTRACT FROM AUTHOR]

Mars has experienced drastic environmental evolution in terms of pH, redox, and desiccation. NASA's Curiosity rover discovered that the sediments of the Pahrump Hills member of the Murray formation in Gale Crater contained different redox states of Fe oxides. To interpret the observations, understanding the factors that control iron redox states within early Gale lakes on Mars is needed. Here, we present the results of a one-dimensional geochemical model of a closed-basin lake that considers the Fe(II) photo-oxidation reaction. Depending on the source of Fe(II) (groundwater vs. river flow), lake pH, advection rate, and atmospheric composition, we defined four types of chemical profiles in the lake; namely, Fe(II) dominated, Fe(III) dominated, carbonate precipitating, and redox-stratified profiles. The Fe(III) dominated profile corresponds to the end member case in which photo-oxidation effectively oxidizes the supplied Fe(II). The redox-stratified profile, interpreted as an intermediate condition between Fe(III) dominated profile and Fe(II) dominated profile, appears in broad parameter set when Fe(II) is supplied from the groundwater, typically with a low to moderate Fe(II) input flux at acidic to alkaline pH (pH 5–9) conditions; however, the low water flux due to the nature of the groundwater may be unable to explain the measured abundance of Fe oxides in the sediments. Another endmember case, the Fe(II) dominated profile, which would also be expected to generate mixed valence Fe oxides, occurs when the pH is acidic (pH 4–5); nevertheless, the acidic pH is inconsistent with the mineral assemblages of the sediments. Carbonate precipitating profiles were limited to the case in which Fe(II) is supplied by groundwater with high Fe input flux and alkaline pH of 8–9. These results may imply either the Fe(II) input flux was high enough for the redox-stratified case or Fe(II) photo-oxidation was suppressed by turbidity or by dusty/cloudy atmosphere, or possibly that Fe(II) oxides found in the Pahrump Hills member are, at least partly, of detrital origin. Although numerous other factors (ex., effect of lake depth, variable pH throughout the lake water, detailed chemical speciation) remain unconsidered, the diverse profiles in Fe redox resulting from Fe(II) photo-oxidation reaction sheds light on interpreting the variety and the evolution of redox condition on early Mars. [ABSTRACT FROM AUTHOR]

In the present research, an attempt is made to use four machine learning technique techniques such as artificial neural network combined with particle swarm optimization (ANN-PSO), adaptive neuro-fuzzy inference system (ANFIS), multivariate adaptive regression splines (MARS), and M5Tree machine learning (ML) approaches to model the scour depth. A total of 534 live bed scouring (LBS) experimental and field datasets are collected for bridge pier scouring from the previously published literature, and a gamma test has been performed to identify the best input parameter combination. A total of 36 combinations were tested in the gamma test, five distinct input combinations such as pier width to flow depth (b/y), approach flow velocity to sediment incipient velocity (V/Vc), critical Froude number (Frc), pier width to median sediment size (b/d50), geometric standard deviation of bed material (σg) were selected based on the lowest gamma value and Vratio. The developed models have been validated using field datasets of Pearl River, Mississippi, USA, by Mueller and Wagner (2005) and Ganga River, Patna, India, by Kumar and Singh (2022) and compared with six other existing scour depth predictive models. Results indicate that the proposed M5Tree scour depth prediction model (R2 = 0.9196, RMSE = 0.0837) provided better accuracy for all combinations of input variables (b/y, V/Vc, Frc, b/ d50, σg) compared to other ML models. The developed M5Tree model was successfully applied to the field condition for Ganga River, Patna, India and Pearl River, Mississippi, USA, and the mean absolute percentage error (MAPE) value is found to be less than 12% and the coefficient of determination (R2) more than 0.98. [ABSTRACT FROM AUTHOR]

Background: The Andean Altiplano hosts a repertoire of high-altitude lakes with harsh conditions for life. These lakes are undergoing a process of desiccation caused by the current climate, leaving terraces exposed to extreme atmospheric conditions and serving as analogs to Martian paleolake basins. Microbiomes in Altiplano lake terraces have been poorly studied, enclosing uncultured lineages and a great opportunity to understand environmental adaptation and the limits of life on Earth. Here we examine the microbial diversity and function in ancient sediments (10.3–11 kyr BP (before present)) from a terrace profile of Laguna Lejía, a sulfur- and metal/metalloid-rich saline lake in the Chilean Altiplano. We also evaluate the physical and chemical changes of the lake over time by studying the mineralogy and geochemistry of the terrace profile. Results: The mineralogy and geochemistry of the terrace profile revealed large water level fluctuations in the lake, scarcity of organic carbon, and high concentration of SO42--S, Na, Cl and Mg. Lipid biomarker analysis indicated the presence of aquatic/terrestrial plant remnants preserved in the ancient sediments, and genome-resolved metagenomics unveiled a diverse prokaryotic community with still active microorganisms based on in silico growth predictions. We reconstructed 591 bacterial and archaeal metagenome-assembled genomes (MAGs), of which 98.8% belonged to previously unreported species. The most abundant and widespread metabolisms among MAGs were the reduction and oxidation of S, N, As, and halogenated compounds, as well as aerobic CO oxidation, possibly as a key metabolic trait in the organic carbon-depleted sediments. The broad redox and CO2 fixation pathways among phylogenetically distant bacteria and archaea extended the knowledge of metabolic capacities to previously unknown taxa. For instance, we identified genomic potential for dissimilatory sulfate reduction in Bacteroidota and α- and γ-Proteobacteria, predicted an enzyme for ammonia oxidation in a novel Actinobacteriota, and predicted enzymes of the Calvin–Benson–Bassham cycle in Planctomycetota, Gemmatimonadota, and Nanoarchaeota. Conclusions: The high number of novel bacterial and archaeal MAGs in the Laguna Lejía indicates the wide prokaryotic diversity discovered. In addition, the detection of genes in unexpected taxonomic groups has significant implications for the expansion of microorganisms involved in the biogeochemical cycles of carbon, nitrogen, and sulfur. EPcqnK6xUD66cr6MUL2q3U Video Abstract [ABSTRACT FROM AUTHOR]

Mars lacks a global intrinsic dipole field but possesses localized crustal fields, making it unique in the solar system. Recent observations revealed that electrons can be injected into the crustal fields, and exhibit drift-dispersed bursts due to the magnetic drift motion, which are characterized by increases or decreases in energy over time in the energy spectrum. However, the source of the drift-dispersed electrons and the mechanism of their injection into the crustal fields remains unclear. Here, by leveraging data from the Mars Atmosphere and Volatile EvolutioN mission, along with test-particle simulations, we reveal that the source of dispersed electrons is the precipitating electrons injected into the crustal fields via open field lines. These electrons display as dispersionless bursts near the source location, and as dispersed bursts as they drift away from the source. Thus, the dispersed electrons represent a later stage in the evolution of dispersionless electrons. This evolutionary process closely mirrors that observed within Earth's dipole field, affirming that the crustal fields function similarly to a mini-magnetosphere. [ABSTRACT FROM AUTHOR]

Introduction We evaluated the risk factors associated with gastrointestinal disorders (GD) among the soldiers of the Army and Marine Aviation community (AMAC) using an exposomic approach. Specifically, we aimed to determine the medical and operational factors associated with reported GD in the Military Health System. Methods Longitudinal data were obtained from the Medical Assessment and Readiness System (MARS) housed at Womack Army Medical Center, Fort Liberty, NC, for a retrospective cohort study that included 79,249 active duty United States AMAC active duty service members (ADSMs) from October 2015 to December 2019. Multivariable mixed-effects logistic regression was used to assess the relationship between the incidence occurrence of GD and variables including rank, service time, deployment, Armed Forces Qualification Test score, education, tobacco use, alcohol use, age, gender, race, ethnicity, body mass index (BMI), and marital status. Results The incidence of GD included 22,813 person-years of observations with a rate of 2.2 per 100 person-years and a period prevalence of 3.2%. GD was independently associated with rank, service time, and deployment (all P  < 0.05). Conclusion The high-risk categories associated with GD in the AMAC included age, BMI, race (not ethnicity), marital status, and service time. Our data also show that deployment time, not geographical location, was associated with a higher risk of GD. Together, these analyses suggest that White ADSMs older than 33 years of age who have experienced marriage, longer service time, and deployments appear to have a higher risk of GDs. Our assessment shows the utility of using an exposomic approach to create a member-specific, big data-informed personalized clinical algorithm of health outcomes. [ABSTRACT FROM AUTHOR]

European Space Agency's Mars Express (MEX) has been orbiting Mars for 20 years and its instruments have provided a plethora of observations of atmospheric dust and clouds. These observations have been analysed to produce many unique views of the processes leading to dust lifting and cloud formation, and a full picture of the climatologies of dust and clouds has emerged. Moreover, the orbit of MEX enables viewing the planet at many local times, giving a unique access to the diurnal variations of the atmosphere. This article provides an overview of the observations of dust and clouds on Mars by MEX, complemented by the Trace Gas Orbiter that has been accompanying MEX on orbit for some years. [ABSTRACT FROM AUTHOR]

In this work, we derive a simple method for calibrating Raman bandwidths for the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument onboard NASA's Perseverance rover. Raman bandwidths and shapes reported by an instrument contain contributions from both the intrinsic Raman band (IRB) and instrumental artifacts. To directly correlate bandwidth to sample properties and to compare bandwidths across instruments, the IRB width needs to be separated from instrumental effects. Here, we use the ubiquitous bandwidth calibration method of modeling the observed Raman bands as a convolution of a Lorentzian IRB and a Gaussian instrument slit function. Using calibration target data, we calculate that SHERLOC has a slit function width of 34.1 cm–1. With a measure of the instrument slit function, we can deconvolve the IRB from the observed band, providing the width of the Raman band unobscured by instrumental artifact. We present the correlation between observed Raman bandwidth and intrinsic Raman bandwidth in table form for the quick estimation of SHERLOC Raman intrinsic bandwidths. We discuss the limitations of using this model to calibrate Raman bandwidth and derive a quantitative method for calculating the errors associated with the calibration. We demonstrate the utility of this method of bandwidth calibration by examining the intrinsic bandwidths of SHERLOC sulfate spectra and by modeling the SHERLOC spectrum of olivine. [ABSTRACT FROM AUTHOR]

On Earth, carbonate minerals are widely used as recorders of the geological environments in which they formed. Here, we present a method designed to retrieve the crystal chemistry of Fe‐Mg carbonate minerals using infrared remote sensing or Raman spectroscopy. We analyzed a suite of well‐characterized Fe‐Mg carbonate minerals for which Raman spectra were obtained in two different laboratories, and IR spectra were measured in reflectance and transmission from the visible range to 25‐μm. We built calibration lines for the dependence of fundamental and harmonic vibrational modes position to the Mg# (defined as Mg# = 100 × Mg/(Mg + Fe + Ca + Mn)). These calibrations should enable retrieval of Mg# based on spectroscopic observations with a typical accuracy of 10. We discuss the framework of applicability of these calibrations and apply them to a typical CRISM spectrum of carbonates from the Nilli Fossae region of Mars. Key Points: Fundamental FeMg carbonate mode position have a linear dependence to Mg# for Fe‐Mg carbonate mineralHarmonic bands at 2.3 and 2.5 also have a linear dependence of their position with Mg# for Fe‐Mg carbonate mineralsWe present calibration curves of Mg# versus fundamental and harmonic vibration position than can be used to retrieve crystal chemistry [ABSTRACT FROM AUTHOR]

Interest in the exploration of other planets has led to the success of Ingenuity (Mars helicopter)'s first flight in the Martian atmosphere. Despite this achievement, the flight of aircraft under ultra-low air density, such as Mars, is still limited. A flapping-wing aircraft that mimics nature's flyers can provide an alternative solution to conventional aircraft. Successful flapping flight on Mars, where the air density is very thin, requires an understanding of aerodynamics, and prediction of the dynamic changes of the flapping wing under very-low air density. In this paper, we constructed a simple dynamic model that can predict the changes in aerodynamics and dynamic behavior under various low air densities. The predicted changes were compared with the measured ones in a chamber that could simulate the low air density with a modified flapping-wing system based on our flapping-wing micro-air-vehicle (FW−MAV) models, the KUBeetle. Both prediction and measurement showed that when the air density decreased, the flapping frequency tended to increase due to drag reduction, even without consuming additional power. The model reasonably predicted a large decrease in the lift for the 10 % air density, where the flapping frequency increased by 10 %. Under the 50 % and 25 % low air densities, the measured lift coefficients did not change much. However, under the 10 % air density, the lift coefficient decreased by about 16 % due to less wing rotation and wing twist. While the aerodynamic power was predicted to decrease significantly due to the large decrease in aerodynamic forces under low air density, an increase in the angular velocity and peak angular acceleration caused an increase in the inertial power. Therefore, the amount of reduction in the measured mechanical power consumption under the 10 % air density was relatively small, compared to that under the 100 % air density. This work may provide insights into the design of an FW−MAV for the ultra-thin air density, such as Mars. • The proposed dynamic model reasonably predicted the flapping motion under low air density. • The measured flapping frequency increased by about 15 % under the 10 % air density, consuming about 9 % less power. • The reduction in measured power consumption under low air density was small, due to the large inertial power. • The measured lift coefficient decreased by about 16 % under the 10 % air density, due to less wing Q4 rotation and wing twist. [ABSTRACT FROM AUTHOR]

A significant challenge for interplanetary small satellites is fully propulsive orbit insertion due to limited total velocity change capabilities. At destinations with significant atmospheres, this challenge can be circumvented via aerocapture, a technique that uses a single atmospheric pass to convert a hyperbolic approach trajectory into a captured elliptical orbit. This paper investigated small satellite aerocapture at Mars with the morphable entry system, a deployable entry vehicle concept that uses shape morphing for trajectory control. A Monte Carlo dispersion analysis was conducted to assess the vehicle's robustness with respect to uncertainties in entry state, atmospheric density, and vehicle aerodynamics. Under the combined effects of these uncertainties, the morphable entry system achieved a 100% aerocapture success rate. Furthermore, the total velocity change required to place the vehicle on the target orbit for 99% of the simulated trajectories was 166.5 m/s, which is within the current capabilities of small satellite propulsion systems. The results suggest that the morphable entry system is a viable option for smallsat aerocapture at Mars. • Morphable entry system (MES) uses shape-morphing for aerocapture trajectory control. • MES achieved 100% aerocapture success rate at Mars. • MES may be a viable option for small satellite aerocapture at Mars. [ABSTRACT FROM AUTHOR]

The Chandler period of Mars is a new parameter determined from observational data that characterizes the properties of the planetary interior. Numerical modeling of the period of the Chandler wobble of Mars was performed for a number of internal structure models that satisfy not only geodetic data (moment of inertia, tidal Love number k2), but also data obtained during a seismic experiment in the years 2019–2022. To reconcile the theoretical and observed values of the Chandler wobble, it is necessary to take into account the inelasticity of the mantle. To take into account the viscoelastic behavior of the interior, the Andrade rheological model was used. It is demonstrated how the value of the Chandler period depends on the rheological model parameters. [ABSTRACT FROM AUTHOR]

Nakhlites (clinopyroxene-rich cumulates) and chassignites (dunites) are two types of meteorites that were emplaced onto — and subsequently ejected from— the surface of Mars together, but their petrogenetic history has been difficult to discern. We studied the primary magmatic history preserved in zoning patterns of cumulus phases from a suite of nakhlites and chassignites. Samples studied include nakhlites Northwest Africa (NWA) 11013, NWA 10645, Governador Valadares, Caleta el Cobre 022, Nakhla, Miller Range 090032, and NWA 817, as well as chassignites NWA 2737 and Chassigny. In nakhlite and chassignite olivine, phosphorous (P) preserves primary magmatic signatures, and P 2 O 5 ranges from ∼<0.01–0.21 wt %; in nakhlite pyroxene, chromium (Cr) zoning corresponds to Cr 2 O 3 abundances between ∼0.03 and 0.36 wt %. We find that nakhlite pyroxene cores uniformly formed rapidly for a time at high crustal pressures, and then slowly at near-equilibrium under lower crustal pressures. Pyroxene in the nakhlites were then stored through multiple injections of magma prior to remobilization, eruption, and final crystallization. Nakhlite olivine cores are morphologically heterogenous throughout the suite, but all record rapid initial crystallization prior to equilibrium formation, followed by resorption in changing magma compositions. Both olivine and pyroxene in the nakhlites are antecrysts, as they initially formed in a different magma than that in which they erupted. Chassignites underwent very rapid initial undercooling, and record later changes in magma conditions, resulting in thin elemental oscillatory zoning patterns in olivine grains. Together, the cumulus phases of the nakhlite and chassignite suite, combined with petrological evidence from martian shergottite meteorites, suggest that significant magmatic undercooling is the rule rather than the exception for martian magmatic systems. This may relate to the stalling of magmas within the thicker crust of Mars, fostering crystal storage with significant temperature differences between injected magmas and crystal mushes. [ABSTRACT FROM AUTHOR]

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