Terrestrial Analogs Research Articles

Evaluating the Use of Unoccupied Aircraft Systems (UASs) for Planetary Exploration in Mars Analog Terrain

Planetary analog mission simulations are essential for testing science operations strategies and technologies. They also teach us how to use terrestrial analogs to inform studies of extraterrestrial environments. Unoccupied aircraft systems (UASs) have great potential for planetary surface exploration as demonstrated by the Mars 2020 Ingenuity helicopter and the in-development Dragonfly mission to Saturn’s moon Titan. Although applications of UAS technology for planetary exploration remain largely unexplored, simulated missions in planetary analog terrains can inform operational best practices. As part of the Rover–Aerial Vehicle Exploration Network project, we simulated a 12 sol UAS mission on Mars in the Holuhraun region of Iceland. The UAS had airborne imaging capability, as well as imaging, sampling, and geochemical analysis capabilities while landed. The mission evaluated the use of these instruments and developed operational strategies for using UASs to explore a planetary surface. Oblique airborne images were essential for mission planning and were used to scout large areas to identify both potential landing sites and targets for focused investigations. The airborne and landed data collected by the UAS allowed for detailed observations and interpretations not possible with analog orbital data sets, resulting in an improved scientific return for the simulated UAS mission compared to a premission analysis of only the analog orbital data. As a planetary exploration vehicle, a UAS is most advantageous for exploring large areas (many square kilometers) and is particularly useful when the terrain may be impassable to ground-based traverses (e.g., by rovers or humans).

An Endogenic Origin for Titan's Rampart Craters: Assessment of Explosion Mechanisms

AbstractRampart craters are a class of lakes or depressions in Titan's north polar region that have morphological attributes suggestive of an explosive origin. Two previous studies have proposed that rampart craters form via nitrogen or methane vapor explosions analogous to terrestrial maar explosions. We propose a new terrestrial analog for rampart craters: gas emission craters (GECs) found in permafrost zones. We evaluate the explosive origin of Titan's rampart craters by modeling the dispersal of material from an explosive vent. The dimensions of nine rampart craters with radar‐bright ramparts were used to model the explosion process. The model yields a range of explosion conditions (e.g., gas mass and reservoir depth) producing ejecta dispersal patterns matching the observed features. We find that gas masses of 1011–1014 kg are required to produce a rampart crater. We examine two explosion scenarios: (a) rapid, maar‐like vaporization and explosion of liquid nitrogen or methane, and (b) more gradual gas accumulation and explosion akin to a GEC driven by methane released from destabilizing clathrates. If Titan's crust is composed of pure water ice, the calculated gas pressures are consistent with a rapid, maar‐like explosion mechanism. If the subsurface is predominantly composed of organic materials or clathrate, either scenario may be plausible. Further research on the composition and tensile strength of Titan's subsurface are required to discriminate between hypotheses. Nevertheless, we conclude that explosive dispersal of ejecta from a vent can account for the morphologies of Titan's rampart craters and may contribute to atmospheric methane replenishment.

Morphological and Microbial Diversity of Hydromagnesite Microbialites in Lake Salda: A Mars Analog Alkaline Lake

ABSTRACTLake Salda, a terrestrial analog for the paleolake in Jezero Crater on Mars, hosts active, subfossil, and fossil hydromagnesite microbialites, making it an ideal location to study microbialite formation and subsequent processes. Our understanding of this record is still limited by an incomplete knowledge of the macro‐ and mesoscale morphotypes of microbialites, along with their spatial distribution and correlation with microbial and geochemical processes that influence microbialite formation. In this study, we investigated the spatial distribution, morphotypes, mineralogy, geochemistry, and microbial diversity of the microbialites and identified six distinct zones (Zone I to Zone VI) with major microbialite build‐ups in Lake Salda. Newly identified microbialites were classified based on the macro‐ and mesostructures. Our work shows that the lake contains stromatolites, thrombolites, stromatolitic thrombolites, dendrolites, and microbially induced sedimentary structures. At macroscale, Lake Salda microbialites exhibit hemispheres, stacked domes, and laterally linked columnar structures while minicolumns, knobs, mesoclots, laminae, and botryoidal structures are common at mesoscale. The macro‐ and mesoscale distribution of different microbialite types spatially correlates with microbial community composition and water depth. Deep‐growing microbialites with a low abundance of Cyanobacteria (∼1%–4%) and high abundance of Firmicutes (28%–93%) exhibit steeply convex lamination, producing finger‐like minicolumnar mesostructures. In contrast, shallow‐growing microbialites with a low abundance of Firmicutes (0%–5%) and high abundance of Cyanobacteria (11%–37%) have well‐preserved gently convex millimeter‐scale lamination, resulting in cauliflower mesostructures. Palygorskite ((Mg, Al)2Si4O10(OH)) is identified in the diatom‐rich microbial layer of the deep‐growing microbialites. Regardless of the microbialite types, hydromagnesite and aragonite are present in the extracellular polymeric substance (EPS)‐rich zone of the shallow and deep‐growing microbialites. Overall, environmental changes (e.g., water depth and, accommodation space) play a major role in the formation and spatial distribution of different microbialite morphologies at the macro‐ and mesoscale. Differences in the relative abundance of dominant microorganisms between mesostructured types suggest that mesomorphology may be influenced by changes in microbial diversity. Spatial variations in the microbialite morphotypes, along with the abundant presence of entombed biomass (e.g., mineralized filaments), may indicate areas that have a high potential for the preservation of biosignatures.

Graben systems and geological history of Mbokomu Mons region, Parga Chasmata, Venus

The relationship between chasmata (rift zones) and spatially associated volcanism (mons and coronae) on Venus has been extensively discussed but remains enigmatic. One region where these features are prominently displayed is along the 10,000 km long, WNW trending, Parga Chasmata, which connects Atla Regio with Themis Regio. The Mbokomu Mons area (located about 2200 km SE of Atla Regio) was selected for detailed study to provide insight into these relationships. More than 39,000 extensional lineaments (grabens, fissures and fractures) were mapped at 1:500,000 scale using full resolution Magellan Synthetic Aperture Radar (SAR) images and grouped into radiating, circumferential and linear systems. They are (except where noted) interpreted to represent the surface expression of underlying mafic dyke swarms, on the basis of associated volcanic features and terrestrial analogues. Radiating and/or circumferential swarms are associated with Mbokomu Mons and the four coronae in the surrounding area, Among Corona (AC), Repa Corona (RC) and two unnamed coronae (UC1 and UC2). Mbokomu Mons is unique among the tectono-magmatic features in this region of Parga Chasmata, in having both corona and mons characteristics. The initial Corona Phase consists of radiating and circumferential systems mainly preserved in an unflooded annular uplift, while the Mons Phase includes a second radiating swarm associated with a central edifice, and smaller circumferential fracture pattern near the summit that could overlie a magma reservoir. The plume or diapir that is interpreted to have been responsible for the initial Corona Phase is estimated to have had a radius of ∼150 km. Cross-cutting relationships indicate that Mbokomu Mons is younger than nearby Among, Oduduwa and Onenhtse coronae. All four centres are aligned along a WNW-trend parallel to the Parga Chasmata (rift system). Mbokomu Mons is located at, and its emplacement may be linked to, the intersection of this WNW-trending zone of weakness and the orthogonal Jokwa Linea rift system. Mbokumo Mons is also younger than the nearby parallel Penthesilia Fossa (PF) (part of the Great Dyke of Atla Regio).

Probable Concretions Observed in the Shenandoah Formation of Jezero Crater, Mars and Comparison With Terrestrial Analogs

AbstractThe Mars 2020 Perseverance Rover imaged diagenetic textural features in four separate sedimentary units in its exploration of the 25‐m‐thick Shenandoah formation at Jezero Crater, Mars, that we interpreted as probable concretions. These concretions were most abundant in the Hogwallow Flats member of the Shenandoah formation and were restricted to the light‐toned, platy, sulfur‐cemented bedrock at outcrop surfaces, whereas the finely laminated, darker toned, mottled and deformed strata lack concretions. The concretions also had a wide range of morphologies including concentric, oblate, urn, and spheroidal shaped forms that were not clustered, and ranged in size from ∼1 to 16 mm with a median of 2.65 mm. The elemental composition of the concretions compared to the bedrock had greater abundance of magnesium and calcium salts, silicates, and possibly hematite. We compared these Jezero Crater concretions to the geochemistry of concretions from previously published studies and from two new terrestrial analog sites (Gallup Formation, New Mexico and Torrey Pines, California). In addition, we measured organic carbon content of three terrestrial sedimentary analogs of increasing age that contain concretions (Torrey Pines (Pleistocene), Gallup Formation (∼89 Ma), and Moodies Group (∼3.2 Ga)). All measured concretions contained significant concentrations of organic carbon with the maximum organic carbon content (∼2 wt. % Total organic carbon) found in the Moodies Group concretions. Organic carbon abundances in terrestrial concretions was controlled more by the formation mechanism and relative timing of concretion development rather than deposit age. These findings suggested that concretions at Jezero Crater reflect local sites of enhanced biosignature preservation potential.

The astrobiological potential of the Makgadikgadi Basin, Botswana: Field analogue for planetary exploration

Terrestrial analogue sites have been crucial for studying Martian geology and mineralogy, integrating the direct evidence available from Mars through remote sensing and in situ measurements carried out by the instruments on board robotic missions. Studying readily available and accessible terrestrial analogues of Martian fossil or extant environments is considered the most efficient way to answer crucial scientific questions. These analogues offer opportunities to collect a range of geological and microbiological data. The Makgadikgadi Basin (MKB) in Botswana is one of such environments hosting a system of salt pans presenting striking similarities with Mars playa deposits. The MKB presents layered mounds, relict fan deltas with inverted channels, polygonal structures and evaporitic crusts harboring communities of extremophiles. The present-day MKB is predominantly fed by groundwater and local precipitations in an overall arid to semi-arid climate, characterized by high UV radiation and salinity, deposition of evaporitic minerals and authigenic clays. The shallow subsurface of the MKB pans is covered by diagenetic features (duricrusts) including silcretes and calcretes. These pans can serve as test beds for the physical and chemical characteristics of playa deposits on Mars and help improve our understanding of the conditions that might support life outside our planet.

Evidence for Glaciovolcanic, Phreatomagmatic Tuff Dominated Ridges at Pavonis Mons, Mars

AbstractHiRISE images and digital elevation models (DEMs) of outcrops in candidate Martian glaciovolcanoes provide more detailed evidence for glaciovolcanic processes than has previously been available for Mars. A group of ridges in the Pavonis Mons fan‐shaped glacial deposit features pervasive layering, evidence for local collapse and slumping, and steeper faces in the direction of paleoglacier flow inferred from other features in the deposit. After comparison with terrestrial analogs, we conclude that these ridges are excellent candidates for tephra‐dominated tindar, formed in phreatomagmatic subglacial eruptions. The englacial meltwater lakes required for a phreatomagmatic origin represent a rare example of voluminous surface water bodies in the Late Amazonian of Mars.

Laboratory testing of desiccation crack growth in terrestrial Martian analog environments using digital image correlation

The unique geologic features of raised ridges and polygonal cracks filled with multiple layers of cement observed in Gale and Jezero craters on Mars have origins that remain uncertain due to limited knowledge and measurement techniques. This study hypothesizes that these cracks result from the volumetric shrinkage of clay fabric due to dehydration and salinity fluctuations in ancient Martian lakes. The research aims to quantify the shrinkage of terrestrial simulants with varying mineral compositions analogous to those found at Gale Crater and Jezero Crater under diverse desiccation conditions. By simulating Martian regolith using the Rocknest soil simulant and examining historical aqueous conditions through sedimentary rock analogs, this study provides new insights into Martian geological structures. The extent and rate of shrinkage in simulant samples were quantified using ImageJ, while strain localization and propagation were measured using the Digital Image Correlation (DIC) technique until full desiccation crack patterns developed. Laboratory testing revealed that desiccation cracks tend to form polygonal patterns, which are patently similar to the polygonal patterns observed in some regions of Mars. However, not all simulants produced visible cracks, with some producing linear rather than polygonal patterns. Key findings indicate that higher temperatures result in wider and deeper cracks, while lower temperatures decrease crack density and length. Increased initial water content leads to more extensive cracking, with higher crack density and length per unit area. Sodium chloride and sodium sulfate significantly impact desiccation cracking, with low concentrations stabilizing the soil and high concentrations promoting extensive cracking. Smectite-rich samples exhibit extensive cracking, and tensile strain distribution during evaporation is non-uniform, influencing crack development based on sample properties and drying conditions. These insights enhance our understanding of polygonal crack formation on Mars, improving Mars sample return missions and informing the design of robust exploration equipment.

SEM/Raman spectroscopy of clathrites as analogs of authigenic carbonates in ocean worlds

AbstractThere is evidence from the near‐infrared observations of space missions of the presence of carbonates on the surface of several ocean worlds. However, their genesis remains unresolved. We investigate the hypothesis that these carbonates may be in the form of clathrites assuming that clathrate hydrates are stable phases in the crust and ocean of these ocean worlds. In order to support this, we studied a sample of a potential clathrite from the Hydrate Ridge cold seep (Cascadia Subduction Zone), the carbonate rock fossil of clathrate hydrates, as a terrestrial analogue. We characterised the mineralogy and texture of the sample by using a coupled confocal Raman microscope and scanning electron microscopy instrument with the aim of identifying possible geo‐ and biosignatures, which could be relevant for future missions of exploration to ocean worlds and Mars. Our results show that aragonite is the dominant mineral phase in the clathrite sample, but Mg‐calcite and dolomite were also identified. These three carbonates constitute a pattern related to clathrate hydrate formation and dissociation processes. Dolomite was defined as a biosignature of gas hydrate microbiomes because it was integrated within Mg‐calcite grains precipitated after clathrate hydrate dissociation. Nevertheless, no spectral changes were observed in Raman bands of carbonate minerals that would indicate the influence of clathrate hydrates in their genesis. We also observed that Raman band positions of the associated framboidal pyrites are a characteristic signature of the associated framboid‐like texture because its potential as biosignature may only be attributed by biochemical analysis.

Maskelynite- as seen in shocked Lonar target basalt, India, and martian and lunar meteorites

In this study, we investigate the mineralogical and petrochemical characteristics of maskelynite occurring in a shocked basalt boulder from a terrestrial impact crater on a basaltic target – the Lonar impact crater in India, and the martian and lunar meteorites. The majority of Lonar maskelynite experienced solid-state transformation and maintained almost a uniform chemical composition, consistent with the unshocked feldspar. The locally flow-like texture and marginal vesiculation in feldspathic glass are needed in interaction with the impact-melt. The vesiculated melt occasionally occurring at the margins of maskelynite is characterised by Na-loss due to the shock-induced volatility. A shock pressure of ≤42 GPa and at a temperature of ≤1000 °C appear consistent for the formation of Lonar vesiculated melt/ feldspathic glass. Under the impact-induced shock metamorphism, maskelynite samples from the moon retain both the crystalline and amorphous domains with a distinct chemical heterogeneity attributed to different shock metamorphism effects of the plagioclase. In contrast, the martian maskelynites exhibit a smooth, homogeneous composition. The estimated shock pressure is relatively higher at ∼42–45 GPa based on experiments and models. The difference in Si/Al ratio in lunar (1–1.3) and martian maskelynite (1.5–1.9) suggests its inherent difference in composition of the crust, whereas the Lonar maskelynite shows overlapping composition with the martian maskelynite contending Lonar basalt as a potential terrestrial analogue to the martian crust.

Low But Persistent Organic Carbon Content of Hyperarid River Deposits and Implications for Ancient Mars

AbstractMars has many well‐exposed fluvial ridges and fluvio‐deltaic basins; in two of these locations, the Curiosity and Perseverance rovers are currently searching for signs of habitability. The distribution of organic carbon that might persist in ancient fluvial deposits present on Mars is not well understood. In this study, we set out to assess the preservation potential of organic carbon in a hyperarid fluvial environment with observations and analyses of the Amargosa River in Death Valley, California (United States). The lower reaches of the Amargosa River in Badwater Basin are nearly devoid of plants and contain low gradient, meandering channels, making them a valuable terrestrial analog for early martian fluvial systems. We analyzed sediment taken from fluvial deposits exposed in cutbanks of two bends of a meandering channel. We found total organic carbon abundances that were on average 0.15% up to a meter below the surface. X‐ray diffraction and electron microscopy analyses revealed a suite of high redox potential mineral phases (including iron and manganese oxides) mixed with detrital and authigenic silicates, carbonate, and sulfate salts at or close to redox equilibrium with pore fluids in contact with the atmosphere. This finding highlighted that organic carbon can persist in fluvial deposits at low abundance despite oxidizing conditions and saturated sediments and suggested that ancient fluvial deposits on Mars may retain traces of organics in fine‐grained deposits if they are present during deposition.

Formation of the four terrestrial planets in the Jupiter–Saturn chaotic excitation scenario: fundamental properties and water delivery

The Jupiter–Saturn chaotic excitation (JSCE) scenario proposes that the protoplanetary disk was dynamically excited and depleted beyond ∼1–1.5 au in a few Myr, offering a new and plausible explanation for several observed properties of the inner solar system. Here, we expanded our previous work by conducting a comprehensive analysis of 37 optimal terrestrial planet systems obtained in the context of the JSCE scenario. Each optimal system harbored exactly four terrestrial planets analogs to Mercury, Venus, Earth, and Mars. We further investigated water delivery, feeding zones, and accretion history for the planet analogs, which allowed us to better constrain the water distribution in the disk. The main findings of this work are as follows: 1) the formation of four terrestrial planets with orbits and masses similar to those observed in our solar system in most of our sample, as evidenced by the dynamically colder and hotter orbits of Venus–Earth and Mercury–Mars analogs, and the high success rates of similar mutual orbital separations (∼40–85%) and mass ratios of the planets (∼70–90%) among the 37 systems; and 2) water was delivered to all terrestrial planets during their formation through the accretion of water-bearing disk objects from beyond ∼1–1.5 au. The achievement of Earth’s estimated bulk water content required the disk to contain sufficient water mass distributed within those objects initially. This requirement implies that Mercury, Venus, and Mars acquired water similar to the amount on Earth during their formation. Several of our planet analogs also matched additional constraints, such as the timing of Moon formation by a giant impact, Earth’s late accretion mass and composition, and Mars’s formation timescale.

Enceladus: Astrobiology Revisited

AbstractAstrobiology research seeks to understand how life begins and evolves, and to determine whether life exist elsewhere in the universe. The discovery of diverse ocean worlds has significantly expanded the number of planetary bodies in the Solar System that could potentially contain life. Of the recognized ocean worlds, Saturn's moon Enceladus stands out because it appears to meet all requirements to sustain life. For that reason, robotic mission concepts are being developed to determine whether Enceladus' ocean is inhabited. The theory of organic chemical evolution (OCE) represents an ideal framework to guide this exploration strategy, articulating investigations and associated measurements of organic matter in the subsurface ocean. Within this reference frame, the immediate priority with the lowest science risk would be to understand molecular and structural properties of bulk organic matter in the ocean, and search for metabolic precursors and biochemical building blocks, both free and bound. This could be supplemented with “high‐risk, high‐reward” searches for functional polymers, catalytic activity, and cell‐like objects with traits indicative of evolutionary adaptations. The theory of OCE provides a robust scientific foundation for the astrobiological exploration of ocean worlds, fostering a productive path to discovery with lower mission risk that could be implemented with existing technology. Strong synergies between astrobiology and Earth‐bound research could ensue from this exploration strategy particularly in the context of terrestrial analog studies and laboratory simulations.

Laboratory VIS–NIR reflectance measurements of heated Vesta regolith analogs: Unraveling the spectral properties of the pitted impact deposits on Vesta

AbstractPitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.

Geological history of the Atira Mons large shield volcano, Beta Regio, Venus.

Atira Mons is a large (∼300,000 km2) low-relief (1.8 km) shield volcano, with individual flows extending up to ∼700 km from the central caldera. It is located about 3000 km NW from the major plume center Beta Regio. Detailed mapping of the flows (at 1:500,000 scale, 10x more detailed than previous mapping) has identified fifty-three flow units which are grouped into eleven packages. Flow units are distinguished based on radar brightness, topography, morphology, continuity, structural modification, and sources, while flow packages group flows with clear stratigraphic relationship affinity.Cross-cutting relationships indicate a complex and multi-episodic eruption history with provisional identification of six mapped stages. The most voluminous flows are concentrated in the early stages, while the younger pulses, with a few exceptions, are shorter and less voluminous. A central caldera hosts the youngest volcanism with flows breaching its eastern side. Multiple stages of caldera collapse are indicated.The volume of the volcano is estimated using various methods and yields values range from ∼47,000 to ∼270,000 km3. The larger estimates are consistent with that of the magma volume of Large Igneous Provinces (LIP) on Earth. An appropriate terrestrial analogue is the Benham Rise Oceanic LIP in the western margin of the Philippine Sea, and particularly the Apolaki Caldera, which is the world's largest known basaltic caldera with a diameter of ∼150 km.

Linking cerebral hemodynamics and ocular microgravity-induced alterations through an in silico-in vivo head-down tilt framework

Head-down tilt (HDT) has been widely proposed as a terrestrial analog of microgravity and used also to investigate the occurrence of spaceflight-associated neuro-ocular syndrome (SANS), which is currently considered one of the major health risks for human spaceflight. We propose here an in vivo validated numerical framework to simulate the acute ocular-cerebrovascular response to 6° HDT, to explore the etiology and pathophysiology of SANS. The model links cerebral and ocular posture-induced hemodynamics, simulating the response of the main cerebrovascular mechanisms, as well as the relationship between intracranial and intraocular pressure to HDT. Our results from short-term (10 min) 6° HDT show increased hemodynamic pulsatility in the proximal-to-distal/capillary-venous cerebral direction, a marked decrease (-43%) in ocular translaminar pressure, and an increase (+31%) in ocular perfusion pressure, suggesting a plausible explanation of the underlying mechanisms at the onset of ocular globe deformation and edema formation over longer time scales.

Unveiling a Technosol-based remediation approach for enhancing plant growth in an iron-rich acidic mine soil from the Rio Tinto Mars analog site

This paper explores the potential of Technosols made from non-hazardous industrial wastes as a sustainable solution for highly acidic iron-rich soils at the Rio Tinto mining site (Spain), a terrestrial Mars analog. These mine soils exhibit extreme acidity (pHH2O = 2.1–3.0), low nutrient availability (non-acid cation saturation < 20 %), and high levels of Pb (3420 mg kg−1), Cu (504 mg kg−1), Zn (415 mg kg−1), and As (319 mg kg−1), hindering plant growth and ecosystem restoration. To address these challenges, the study systematically analyzed selected waste materials, formulated them into Technosols, and conducted a four-month pot trial to evaluate the growth of Brassica juncea under greenhouse conditions. Technosols were tailored by adding varying weight percentages of waste amendments into the mine Technosol, specifically 10 %, 25 %, and 50 %. The waste amendments comprised a blend of organic waste (water clarification sludge, WCS) and inorganic wastes (white steel slag, WSS; and furnace iron slag, FIS). The formulations included: (T0) exclusively mine Technosol (control); (T1) 60 % WCS + 40 % WSS; (T2) 60 % WCS + 40 % FIS; and (T3) 50 % WCS + 16.66 % WSS + 33.33 % FIS. The analyses covered leachate quality, soil pore water chemistry, and plant response (germination and survival rates, plant height, and leaf number). Results revealed a significant reduction in leachable contaminant concentrations, with Pb (26.16 mg kg−1), Zn (4.94 mg kg−1), and Cu (2.29 mg kg−1) dropping to negligible levels and shifting towards less toxic species. These changes improved soil conditions, promoting seed germination and seedling growth. Among the formulations tested, Technosol T1 showed promise in overcoming mine soil limitations, enhancing plant adaptation, buffering against acidification, and stabilizing contaminants through precipitation and adsorption mechanisms. The paper stresses the importance of tailoring waste amendments to specific soil conditions, and highlights the broader implications of the Technosol approach, such as waste valorization, soil stabilization, and insights for Brassica juncea growth in extreme environments, including Martian soil simulants.

Mount Etna as a terrestrial laboratory to investigate recent volcanic activity on Venus by future missions: A comparison with Idunn Mons, Venus

The recently selected missions to Venus have opened a new era for the exploration of this planet. These missions will provide information about the chemistry of the atmosphere, the geomorphology, local-to-regional surface composition, and the rheology of the interior. One key scientific question to be addressed by these future missions is whether Venus remains volcanically active, and if so, how its volcanism is currently evolving. Hence, it is fundamental to analyze appropriate terrestrial analog sites for the study of possibly active volcanism on Venus. To this regard, we propose Mount Etna - one of the most active and monitored volcanoes on Earth - as a suitable terrestrial laboratory for remote and in-situ investigations to be performed by future missions to Venus. Being characterized by both effusive and explosive volcanic products, Mount Etna offers the opportunity to analyze multiple eruptive styles, both monitoring active volcanism and identifying the possible occurrence of pyroclastic activity on Venus. We directly compare Mount Etna with Idunn Mons, one of the most promising potentially active volcanoes of Venus. Despite the two structures show a different topography, they also show some interesting points of comparison, and in particular: a) comparable morpho-structural setting, since both volcanoes interact with a rift zone, and b) morphologically similar volcanic fields around both Mount Etna and Idunn Mons. Given its ease of access, we also propose Mount Etna as an analog site for laboratory spectroscopic studies to identify the signatures of unaltered volcanic deposits on Venus.

Cohesion and shear strength of compacted lunar and Martian regolith simulants

Shear strength and cohesion of granular materials are important geotechnical properties that play a crucial role in the stability and behavior of lunar and Martian regolith, as well as their terrestrial analog materials. To characterize and predict shear strength and cohesion for future space missions, it is also important to understand the effects of particle size distribution and density on these fundamental geotechnical properties. Generalized equations have been established using empirical data from direct shear measurements of lunar and Martian regolith simulants to quantify the effects of particle size distribution and density on cohesion and shear strength. Preliminary results are also presented highlighting the effects of atmospheric absorbed water on shear strength and cohesion when conducting experiments in atmospheric conditions on Earth. The results of this study show that cohesion increases exponentially with bulk density, while the exponential growth constant is also dependent on particle size distribution. The presence of absorbed atmospheric water can also produce non-monotonic effects on the shear strength of regolith, and it's influence on shear strength varies based on sample density for Earth-based experiments and applications. Together, these results highlight the importance of particle size distribution, bulk density, and atmospheric water content on the shear strength and cohesion of lunar and Martian simulants. This study also establishes generalized equations for predictive, testing, and modeling efforts for future space missions.

Discovery of a geomorphological analog to Martian araneiforms in the Qaidam Basin, Tibetan Plateau

Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars. A gas erosion process driven by the seasonal sublimation of CO&lt;sub&gt;2&lt;/sub&gt; ice was proposed as an explanation for their formation, which cannot occur on Earth due to the high climatic temperature. In this study, we propose an alternative mechanism that attributes the araneiform formation to the erosion of upwelling salt water from the subsurface, relying on the identification of the first terrestrial analog found in a playa of the Qaidam Basin on the northern Tibetan Plateau. Morphological analysis indicates that the structures in the Qaidam Basin have fractal features comparable to araneiforms on Mars. A numerical model is developed to investigate the araneiform formation driven by the water-diffusion mechanism. The simulation results indicate that the water-diffusion process, under varying ground conditions, may be responsible for the diverse araneiform morphologies observed on both Earth and Mars. Our numerical simulations also demonstrate that the orientations of the saltwater diffusion networks are controlled by pre-existing polygonal cracks, which is consistent with observations of araneiforms on Mars and Earth. Our study thus suggests that a saltwater-related origin of the araneiform is possible and has significant implications for water searches on Mars.