The Martian lava plains are characterized by their extensive, low-relief surfaces, which are the result of numerous basaltic eruptions and feature a variety of volcanic landforms, including vents, cones, pits, and skylights. The combination of these features and impact craters yields a significant understanding of the planet's geological past and subsurface composition. However, the flat terrain presents a challenge to detailed morphometric analyses, while the unavailability of high-resolution Digital Elevation Models (DEMs) complicates the precise estimation of radar-based thicknesses and dielectric constants. To address these challenges, we investigated an ∼8,030 km2 area northwest of Ascraeus Mons within the Tharsis Region. Prior research documented Amazonian volcanic features in this region; however, precise thickness and permittivity values remained undetermined owing to insufficient surface features and limited exposures. An enhanced, multi-scale neighborhood analysis method, adapted from terrestrial and Martian applications, was utilized to define the boundaries of a shallow lava flow sequence and identify three previously unmapped volcanic vents. Subsequently, all available subsurface sounding radar data in the region were analyzed using a simplified method. The results demonstrate that shallow, low-relief lava flows overlie a series of laterally consistent subsurface units, suggesting that volcanic and sedimentary processes occurred in multiple phases. The combination of our unique morphometric methodology using radar sounding showcases the characterization of morphologically subtle features despite the constraints of available data. This study offers a methodological framework for the investigation of other low-relief Martian regions, enhancing our understanding of the planet's volcanic and stratigraphic evolution.
This study presents a large-scale mapping framework for identifying and characterizing periodic decameter aeolian landforms on Mars using CTX mosaics and machine learning. To test whether the mapped features align with the current aeolian regime, we mapped barchan slipfaces and used Global Climate Model (GCM) outputs to characterize present-day aeolian activity across an extended region, encompassing the Thaumasia and Bosporos planae as well as the lowlands located in the northwestern edge of Noachis Terra. Morphology and data clustering allowed us to define eight regional units, presenting distinct sets of aeolian landforms. The spatial distribution of these units is influenced by long-wavelength topography, with the Thaumasia highlands and Coprates rise forming a major divide. The bedforms in Thaumasia and Bosporos planae are morphologically simpler and possibly younger. Yet, their trend deviates by 35° from the orientation of GCM-predicted bedforms forming under current surface conditions. In addition, the units located in the eastern lowlands display complex morphologies and paleo-wind streaks indicative of multi-phase aeolian imprints. These features imply an ancient southeast–northwest paleo-wind regime, opposing the current southeastward transport trend. These major discrepancies may reflect several reorganizations of Mars' atmospheric circulation in the past. Our systematic mapping results underscore the richness and complexity of Mars' aeolian record, revealing extensive and continuous patches of likely ancient wind-shaped landforms. Our results suggest that a considerable number of multi-generational aeolian imprints (i.e., wind-formed features created over multiple periods) may have been preserved on the surface of Mars, under the form of decameter-scale aeolian landforms.
The lunar south polar region has been a focus of human exploration due to its potential rich water-ice and mineral resources. However, scientific exploration of this area based on spectral data is limited due to challenging lighting conditions and complex topography. In this work, we used the Moon Mineralogy Mapper (M3) and Lunar Orbiter Laser Altimeter (LOLA) reflectance data to construct a hyperspectral cube in the lunar 83°–90°S region. Mineralogical abundance maps of the four major lunar minerals were derived from M3 data at a spatial resolution of ∼193 m/pixel. Quantitative mineral maps of four common lunar minerals, including high-calcium pyroxene (HCP), low-calcium pyroxene (LCP), olivine, and plagioclase, were derived from the M3 data, with abundance ranges consistent with those from the Kaguya Spectral Profiler (SP) data. The high-resolution mineral maps enhance the identification of mineral distribution details, such as purest anorthosite enrichment in the crater wall and floor of the Shackleton Crater. Comprehensive analysis of the mineral abundance maps reveals geological characteristics and potential effects of impact events, with particular emphasis on Artemis III mission landing site candidates. Pyroxene enrichment detected in the De Gerlache-Kocher Massif region may present an opportunity to collect South Pole-Aitken ejecta materials.
Fluid-assisted metasomatism was prevalent on Vesta, but the timing and source(s) of aqueous activities remain elusive. Here, we report an absolute 207Pb/206Pb isochron age (4,169 ± 85 Ma) of apatites from a plagioclase-rich eucrite clast within the Jikharra 001 eucrite. Petrographic, mineralogical, and geochemical characteristics demonstrate that apatite veins in the clast formed during fluid-assisted metasomatism on Vesta. The elevated 87Sr/86Sr ratios observed in the bulk clast and plagioclase grains suggest the incorporation of fluid from primitive sources, probably carbonaceous chondrites. The slightly negative oxygen isotopic composition (Δ17O = −0.275 ± 0.013‰) of the clast further indicates a largely carbonaceous chondrite source. Impacts from carbonaceous chondrites are the probable origin of Veneneia. Evidence from apatite veins in the Jikharra 001 is consistent with a carbonaceous fluid source and may constrain the age of Veneneia to the late heavy bombardment, approximately 4.1–4.2 Ga.
Atmospheric hydrogen chloride (HCl, or hydrochloric acid) has strong links to volcanic activity on Earth. If it is present in the atmosphere of Mars, it could hint at active magmatic processes, or the outgassing from the remnants of recently dormant volcanoes. It has been sought in the Martian atmosphere using terrestrial telescopes and was a target for the ExoMars Trace Gas Orbiter (TGO) mission. Since it was found by TGO, the terrestrial telescopes have returned to their hunt, and the recent study by Faggi et al. (2025), https://doi.org/10.1029/2025je009105 presents the results of a multi-year campaign to study the global distribution of HCl across the Martian surface. In this commentary, we will examine the importance of HCl, its context in the broader chloride cycle on Mars, how we have gotten to this point, and the implications the new study has on our understanding of its origins.
Impact-generated hydrothermal systems are considered potentially habitable environments on Mars, Earth, and other planetary bodies for microbial life. However, there is an ongoing debate regarding what geological features on Mars provide definitive evidence for such systems. Although earlier studies have modeled hydrothermal processes in Martian craters, they often lacked integration with shock physics hydrocodes to constrain initial impact conditions. The importance of this two-code coupling was demonstrated by successfully replicating alteration signatures in the Earth's Haughton impact structure. In this study, we use a similar two-code approach, combining the iSALE hydrocode with the HYDROTHERM hydrothermal model to simulate the full evolution of impact-generated hydrothermal systems. We apply this method to craters the size of Jezero (∼50 km) and Gale (∼154 km) in diameter. Although Jezero's interior is largely buried, our results align with hypothesized hydrothermal vents and alteration minerals near central uplifts in similarly sized exposed craters, such as Toro and Auki. Furthermore, our models correspond to alteration patterns observed by the Curiosity in the lower layers of Mount Sharp, which may represent remnants of impact-driven hydrothermal activity. A key finding is that these systems may persist much longer than previously estimated. Our simulations suggest that a Jezero-sized system could remain habitable for thermophiles for approximately 720,000 years, whereas a Gale-sized system could persist for nearly 2 million years. Additionally, simulations under unsaturated crustal conditions reveal that air-dominated near-surface layers can suppress vertical fluid flow, enabling deep subsurface alteration without producing detectable mineral signatures at the surface.
The current volcanic output of Venus is unknown. In the 2030s, the VenSAR (Venus Synthetic Aperture Radar) instrument onboard the European Space Agency's (ESA) EnVision mission will estimate the global volcanic mass flux by looking for new flows with radar imaging at resolutions of 10 or 30 m/pixel, which can be compared with the 1990s-era Magellan data (100–300 m/pixel). Based on eruptions on Earth and Io, we make suggestions for measuring the Venusian global eruptive flux. We do not need to observe small eruptions with Eruption Magnitude (based on mass) <3 because (at least on Earth) they produce <10% of the aggregate erupted mass. Assuming that the size–frequency distribution of Earth lava flows and domes holds on Venus and is augmented to include flows 75% longer as predicted for the Venus surface, we find that all Eruption Magnitude ≥3 eruptions are detectable by VenSAR–VenSAR imaging and >80% by VenSAR–Magellan. However, only 80% of eruptions may produce a detectable change in radar backscatter based on our examination of 24 basaltic terrestrial lava flows from 2014 to 2023 from the ESA Sentinel-1a/b satellites. From observed Earth basaltic flows, thickness will rarely be measured on Venus due to low vertical accuracy. If VenSAR images 20%–40% of the most active volcanoes (as planned), it could detect 79%–92% of the flux if the Eruption Magnitude–frequency distribution is similar to Earth and Io. A few eruptions could then be extrapolated to a global flux, but this is dependent on quantifying the largest eruption, so targeting the right volcanoes is critical.
Lunar and Martian lava tubes will offer stable temperatures and radiation protection, making them potential habitats for extraterrestrial life. The Martian atmosphere, containing gases like H2, CO, and CH4, could serve as an energy source for microbes. To address the knowledge gap concerning microbial communities and their survival strategies in Earth's lava tubes, which serve as analogs on Mars, we conducted a study at the Shishan Volcanic Group located in Haikou City, Hainan Province. Through field surveys, microcosm experiments, and multi-omics analyses, we explored the microbial composition and survival mechanisms within these environments. The results revealed that bacterial communities were predominantly composed of Pseudomonadota, Actinomycetota, and Bacillota, while archaeal communities were primarily represented by Thermoproteota and Thermoplasmatota. Bacteria had significantly higher abundance and diversity than archaea, and were positively correlated with low organic matter content. Additionally, the pmoA gene, associated with methane metabolism, was found to be highly abundant, which aligns with the observed high methane oxidation rates. Exposure to 10 ppm CH4 downregulated methane monooxygenase, hydrogenase, and CO dehydrogenase expression, indicating microbial adaptation to low-concentration trace gases for energy. Genomic analyses show that some bacteria use both the energy-efficient reductive TCA cycle and the high-energy Calvin-Benson cycle to fix carbon dioxide while oxidizing trace gases. This metabolic versatility may provide a competitive advantage over archaea, potentially contributing to the high abundance of bacteria within lava tubes. These findings from Mars-analog lava tubes provide insights into extraterrestrial life survival strategies, advancing our understanding of astrobiology.
Bonestell Crater in Acidalia Planitia and a ∼13 km-diameter crater to the northwest preserve geomorphic and thermophysical evidence of Amazonian-aged glacial activity. In Bonestell, lobate deposits along the northwestern rim and a cirque-like depression along the southeastern rim display steep scarps, lineated textures, and polygonal surface patterns consistent with debris-covered ice and periglacial modification. The cirque depression contains thrust-like ridges and compressional structures resembling terrestrial glacial cirques, interpreted as a remnant of polythermal glaciation, where cold- and warm-based ice likely coexisted. Thermal inertia values across these deposits range from ∼300 to 800 J·M−2 K−1·s−1/2, suggesting a downslope transition from poorly consolidated sediment to indurated material. CRISM spectra reveal hydrated minerals and altered silicates consistent with episodic basal melting or volatile-driven alteration. In contrast, the unnamed northwest crater hosts clear examples of rock glaciers. Multiple lobate flows descend from alcoves along the crater walls, exhibiting convex-upward profiles, degraded termini, and compressive ridges that closely resemble terrestrial debris-covered glaciers. HiRISE image data show flow-parallel lineations and banding indicative of internal deformation and sublimation-driven modification. Spectral unmixing of THEMIS ROTO data acquired from multiple viewing geometries fit modeled mixtures of sand and indurated crust with thermal inertia values ∼600 J·M−2 K−1·s−1/2, consistent with debris-coated ice. These results demonstrate that mid-latitude ice in the region is preserved in diverse forms, including cirques, rock glaciers, and debris-mantled ice masses. Their co-occurrence indicates that Amazonian glaciation was not singular nor isolated but regionally extensive and capable of producing transient wet-based conditions that locally sustained liquid water and habitable environments.
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