We are conducting a coordinated effort to investigate the sulfate-bearing deposits within several different chaos terrains on Mars, including Aram Chaos, Iani Chaos, Aureum Chaos, Aurorae Chaos, and Arsinoes Chaos. Previous studies focused on sulfate deposits at three locations within the equatorial chaos regions were all conducted prior to 2014 using different data sets [1-8]. Improved CRISM image processing using Map-Projected Targeted Reduced Data Record (MTRDR) images [9] have enabled more precise identification and discrimination of sulfates, as well as the acquisition of numerous additional CTX, HRSC, and HiRISE images that provide additional coverage of the morphologies and locations of sulfates within the equatorial chaos regions. We also used the lower resolution but larger spatial coverage of the CRISM mapping data to produce indicator vector maps [10] across the chaos region which allowed us to identify polyhydrated (PHS) and monohydrated (MHS) sulfate outcrops in between locations of targeted CRISM images. Orbital data that we are analyzing include: CRISM MTRDR images and mapping-data-derived mineral indicator GIS vectors specific to the sulfates; HiRISE images and derived Digital Terrain Models (DTMs); CTX images and mosaics; and HRSC images and DTMs.HiRISE and CTX images that cover the chaos regions were used to identify deposits that are generally brighter and smoother relative to the darker, hilly chaos terrain in which they occur. We mapped out the distribution of these light-toned deposits (LTDs) in ArcPro and determined they are more extensive than previously mapped. CRISM images were analyzed of the LTDs using spectral parameter maps corresponding to diagnostic mineralogies which indicate the presence of different types of sulfates. We identified sulfate-bearing units at all five chaos regions in association with the larger LTDs, with signatures of polyhydrated and monohydrated sulfates. At Aram Chaos, we identified ferric hydroxysulfate outcrops (FHS; Fe3+SO4OH) beyond what was mapped previously.There are both similarities and differences between the sulfates within the chaos regions. Similarities include the identification of PHS at all five chaos locations and MHS at four, with stratigraphic relationships showing the PHS are always above the MHS where they occur together. Differences include variations in the brightness and surface textures of each type of sulfate. By comparing the distribution, mineralogy, stratigraphy, and morphology of the sulfates within each of the five chaos regions, we hope to evaluate how the geologic setting of each chaos region may have affected the characteristics of each sulfate deposit that formed within it. References: [1] Glotch, T., and P. Christensen (2005), JGR doi:10.1029/2004JE002389; [2] Glotch, T., and A. Rogers (2007) JGR doi:10.1029/2006JE002863; [3] Masse, M. et al. (2008) JGR doi:10.1029/2008JE003131. [4] Noe Dobrea, E.Z. et al. (2008) Icarus doi:10.1016/ j.icarus. 2007.06.029; [5] Lichtenberg, K. A., et al. (2010) JGR doi:10.1029/2009JE003353; [6] Warner, N.H. et al. (2011) JGR doi/ 10.1029/2010JE003787; [7] Sefton-Nash, E. et al. (2012) Icarus, 221, 20-42; [8] Sowe, M. et al. (2012) Icarus, 218, 406-419; [9] Seelos, F. et al. (2024) Icarus, 419, 115612; [10] Cartwright, S. F. A. and F. P. Seelos (2023) AGU Mtg, Abs. #P51B-01.

Abstract Iron oxide-hydroxide minerals in Martian dust provide crucial insights into Mars’ past climate and habitability. Previous studies attributed Mars’ red color to anhydrous hematite formed through recent weathering. Here, we show that poorly crystalline ferrihydrite (Fe5O8H · nH2O) is the dominant iron oxide-bearing phase in Martian dust, based on combined analyses of orbital, in-situ, and laboratory visible near-infrared spectra. Spectroscopic analyses indicate that a hyperfine mixture of ferrihydrite, basalt and sulfate best matches Martian dust observations. Through laboratory experiments and kinetic calculations, we demonstrate that ferrihydrite remains stable under present-day Martian conditions, preserving its poorly crystalline structure. The persistence of ferrihydrite suggests it formed during a cold, wet period on early Mars under oxidative conditions, followed by a transition to the current hyper-arid environment. This finding challenges previous models of continuous dry oxidation and indicates that ancient Mars experienced aqueous alteration before transitioning to its current desert state.

Calcium sulfate minerals are found in multiple environments on Earth and Mars, with chloride (Cl) salts widely distributed on both planets. Low-temperature studies have explored geochemical processes, including the formation of transient liquid water and ion migration on Mars. Some Cl-salts (e.g., NaCl and CaCl2) can dissolve gypsum (CaSO42H2O) in certain environments, making gypsum-Cl salt interactions significant. Additionally, gypsum's geochemical transformation at high temperatures reveals dehydration pathways crucial for understanding Mars' aqueous history and potential for life. This study examines gypsum dehydration through (i) thermal analyses and (ii) interactions with Cl-salts over a temperature range of -90 to 400 degrees C. We applied three spectroscopic techniques (Raman, visible/near-infrared, and mid-IR) plus X-ray diffraction (XRD) to analyze these samples under variable conditions. This study also provides a low-temperature spectral data set for gypsum and gypsum-Cl salt mixtures, beneficial for orbital analyses. Our findings reveal that experimental (i) heating rates, (ii) temperature ranges, (iii) relative masses of gypsum and Cl-salts, and (iv) dehydration environments (e.g., in situ and in vacuo) influence Ca-sulfate phase formation. Although we find different results in some cases, this study demonstrates that changing experimental conditions affects the detectability and transformation of gypsum. Further, these results indicate that the geochemical environmental conditions on Mars play a role in gypsum's geochemical transformation to dehydrated components. This study also provides structural and chemical data for Ca sulfate assemblages from vibrational spectroscopy and XRD, which extends our knowledge of gypsum and related materials under variable conditions, thus aiding orbital and surface planetary analyses that may help to advance our understanding of planetary geochemistry on Mars.

Rare earth elements (REE) are a group of metals considered critical minerals for the energy transition and for numerous advanced technologies essential to modern society. However, despite continually increasing resource demand, REE accumulation processes (especially low-temperature processes) remain understudied and relatively poorly understood. Here, we investigate low-temperature REE behavior in the shallow, supra-permafrost regolith of three salt ponds (Don Juan Pond, VXE-6 Pond, and Brine Pond #1) in Antarctica's McMurdo Dry Valleys (MDV). We characterize REE distributions at five soil pit sites across the three separate salt pond basins. At the scale of an entire basin (i.e., at 100-m-scale) across three Don Juan Pond (DJP) soil pits, we document decreasing REE abundances toward the pond center (with the center of DJP being the most REE-depleted site in this study). This is compatible with an overall cross-basin trend of increased chemical leaching with increasing proximity to the center of DJP. At the scale of individual sediment profiles (i.e., at cm-scale) among all five soil pits, we document two soil pit locations where relative REE enrichment occurs at a clay-rich sediment interval: at the soil pit 300 m W of Don Juan Pond, the clay-enriched 10-12 cm depth interval has Sigma REE similar to 17 % higher than average for the soil pit, and at the VXE-6 Pond soil pit, the clay-enriched 4-7 cm interval has Sigma REE similar to 46 % higher than average. The clay-enriched, REE-enriched intervals are compatible with zones of active chemical alteration and concentration due to intermittent aqueous activity including supra-permafrost freeze-thaw cycling, pond fluctuations, and possible surface meltwaters. Overall, this work demonstrates the potential for limited water availability (and attendant leaching, aqueous alteration, and clay formation) in cold desert regions to nonetheless influence the mobility and concentration of regolith-hosted REE in the shallow subsurface. While MDV regolith-hosted REE are far below economic concentrations, Antarctic permafrost- and salt pond-associated geochemical processes may be relevant to understanding REE behavior (and REE accumulation) in desert and cold regions elsewhere on Earth, as well as to guiding future in-situ resource utilization in analogous planetary environments such as on Mars.

Intriguing outcrops in Ius Chasma provide a window into past aqueous processes in Valles Marineris, Mars. Hydrous sulfate minerals are abundant throughout this region, but one area in Ius Chasma includes phyllosilicates, opal, and additional materials with unusual spectral features. This study at Geryon Montes, an east-west horst that divides Ius Chasma into a northern and southern canyon, exploits recent advances in image calibration and feature extraction techniques for analysis of hyperspectral images acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Specifically, a unique spectral "doublet" feature with absorptions at 2.21-2.23 and 2.26-2.28 mu m is isolated at the border of phyllosilicate-bearing and sulfate-bearing regions in Ius Chasma and surveyed to characterize outcrops that may represent a changing climate on Mars. We document and map three distinct forms of this "doublet" material in relation to phyllosilicates and opal. Analyses of compositional maps derived from CRISM overlain on High Resolution Stereo Camera (HRSC) and High Resolution Imaging Science Experiment (HiRISE) imagery has revealed the presence of these hydrated outcrops along the wall rocks below a breach in the Geryon Montes, bordering a canyon containing abundant hydrated sulfates. Our investigation supports formation of these unique alteration phases through acid alteration of ancient smectites in the wall rock as the sulfate brine overflowed the south canyon of Ius Chasma at the breach in Geryon Montes and penetrated the deeper northern canyon.

Since leaving Vera Rubin ridge (VRr), the Mars Science Laboratory Curiosity rover has traversed though the phyllosilicate-bearing region, Glen Torridon, and the overlying Mg-sulfate-bearing strata, with excursions onto the Greenheugh Pediment and Amapari Marker Band. Each of these distinct geologic units were investigated using Curiosity's Mast Camera (Mastcam) multispectral instrument which is sensitive to iron-bearing phases and some hydrated minerals. We used Mastcam spectra, in combination with chemical data from Chemistry and Mineralogy, Alpha Particle X-ray Spectrometer, and Chemistry and Camera instruments, to assess the variability of rock spectra and interpret the mineralogy and diagenesis in the clay-sulfate transition and surrounding regions. We identify four new classes of rock spectra since leaving VRr; two are inherent to dusty and pyroxene-rich surfaces on the Amapari Marker Band; one is associated with the relatively young, basaltic, Greenheugh Pediment; and the last indicates areas subjected to intense aqueous alteration with an amorphous Fe-sulfate component, primarily in the clay-sulfate transition region. To constrain the Mg-sulfate detection capabilities of Mastcam and aid in the analyses of multispectral data, we also measured the spectral response of mixtures with phyllosilicates, hydrated Mg-sulfate, and basalt in the laboratory. We find that hydrated Mg-sulfates are easily masked by other materials, requiring >= 90 wt.% of hydrated Mg-sulfate to exhibit a hydration signature in Mastcam spectra, which places constraints on the abundance of hydrated Mg-sulfates along the traverse. Together, these results imply significant compositional changes along the traverse since leaving VRr, and they support the hypothesis of wet-dry cycles in the clay-sulfate transition. The clay-sulfate transition in Gale crater has long been hypothesized to record an environmental shift from "warm and wet" to "cold and dry." The paleolake that once filled Gale crater allowed phyllosilicates to form. As Mars became cooler and drier, sulfates were able to precipitate above the phyllosilicates. This mineralogic transition has been observed in other places on Mars, implying a global environmental change. Different hydrated Mg-sulfates can reveal characteristics of the paleoenvironment at the time of deposition and thus clarify the geologic history. The goals of this study are to (a) characterize potential sulfate-bearing rocks with the Curiosity rover's multispectral imaging instrument, Mastcam; and (b) constrain Mastcam's Mg-sulfate detection threshold using laboratory techniques. We identify three new rock spectral classes inherent to the clay-sulfate transition and one new class associated with the Greeneheugh pediment. Our laboratory results indicate that it would be challenging to detect Mg-sulfate with Mastcam unless it is nearly pure. New rock spectral classes correspond to unique geologic units. One supports the hypothesis of wet-dry cycles in the clay-sulfate transition Cross instrument analyses imply that Mg- and Fe- sulfates are significant in the amorphous component of the clay-sulfate transition region The spectral signature of hydrated Mg-sulfates in visible to near infrared reflectance spectra are easily masked by phyllosilicates and/or basalt

The mineralogy of paleolake sediment strata at the high elevation (~4300 m) Lejía depression in the Altiplano region of Chile reflect evolution of the lake geochemistry over time. This mineralogical study is part of a larger project characterizing the geochemistry and biology of several samples from a paleo terrace of the Lejía lake region. Visible/near-infrared (VNIR) reflectance measurements of several samples reveal variations in gypsum, carbonate, clays, iron oxides/hydroxides, and halite with depth. The spectral features are also consistent with abundant allophane or related poorly crystalline clay phases. Mg-calcite, gypsum, and poorly crystalline clays dominate the surface materials, while each of these components varies with depth at our study site. Sediments at Gale crater on Mars also include abundant poorly crystalline phases, phyllosilicates, gypsum, halite, and iron oxides/hydroxides. Thus, characterizing the spectral properties of paleolake sediments from the Lejía region may help constrain the spectral signatures of Gale crater sediments and other sites measured from orbit.Study Site. The broader Altiplano region of Chile provides an analog for Mars due to its extremely dry and salty conditions and this study was carried out as part of the SETI Institute team’s NASA Astrobiology Institute project (Cabrol et al., 2017). The Lejía region differs from others in the Chlean Altiplano due to its higher pH environment and the presence of clay minerals and carbonates in addition to the ubiquitous gypsum and halite otherwise characteristic of the Atacama region. Laguna Lejía is a shallow, salty lake spanning ~1 km in a depression between Láscar and other volcanoes in northern Chile where a larger glacial lake (10-15 km across) once stood (Grosjean et al., 1995). This high altitude basin is battered by winds and receives only limited precipitation, mostly from melting snow and ice from the surrounding mountains. Despite limited water, high UV radiation, and cold temperatures, zooplankton communities are present at Laguna Lejía (Muñoz-Pedreros et al., 2013). Further, genome-resolved metagenomics investigations are currently being developed to characterize the communities of microorganisms and their metabolisms in the paleo sediments of the Lejía lake (Lezcano et al., in preparation).Samples. The paleolake sediments investigated here were collected in 2018 from the upper 1 m of a lake terrace (Figure 1) adjacent to the current Lejía lake. The samples were kept frozen until studied. Extensive analyses are underway including X-ray diffraction (XRD), major element analyses, δ13C and δ15N isotope analyses, metagenomics, and lipid analyses (Lezcano et al., in preparation). XRD analyses determined the presence of albite, anorthite, Mg-calcite, gypsum, halite, andesine, muscovite, and quartz in many of these samples. Aliquots of 6 samples collected from different horizons were thawed, then air dried in the lab, gently crushed and dry sieved to

Solfataric alteration at the South Sulfur Bank of the former Kilauea caldera produced opal, Mg- and Fe-rich smectites, gypsum, and jarosite through silica replacement of pyroclastic Keanakako'i ash and leaching of basaltic lavas. This site on the island of Hawaii serves as an analog for formation of several minerals found in altered deposits on Mars. Two distinct alteration environments were characterized in this study, including a light-toned, high-silica, friable outcrop adjacent to the vents and a bedded outcrop containing alternating orange/tan layers composed of smectite, gypsum, jarosite, hydrated silica, and poorly crystalline ferric oxide phases. This banded unit likely represents the deposition of pyroclastic material with variations in chemistry over time that was subsequently altered via moderate hydrothermal and pedogenic processes and leaching of basaltic caprock to enhance the Si, Al, Mg, Fe, and Ca in the altered layers. In the light-toned, friable materials closest to the vents along the base of the outcrop, glassy fragments were extensively altered to opal-A plus anatase. Lab measurements of samples returned from the field were conducted to replicate recent instruments at Mars and provide further characterization of the samples. These include elemental analyses, sample texture, XRD, SEM, VNIR/mid-IR reflectance spectroscopy, TIR emittance spectroscopy, and Mossbauer spectroscopy. Variations in the chemistry and mineralogy of these samples are consistent with alteration through hydrothermal processes as well as brines that may have formed through rain interacting with sulfuric fumes. Silica is present in all altered samples, and the friable pyroclastic ash material with the strongest alteration contains up to 80 wt% SiO2. Sulfate mineralization occurred at the South Sulfur Bank through fumarolic action from vents and likely included solfataric alteration from sulfuric gases and steam, as well as oxidation of sulfides in the basaltic caprock. Gypsum and jarosite are typically present in different layers of the altered wall, likely because they require different cations and pH regimes. The presence of both jarosite and gypsum in some samples implies high-sulfate concentrations and the availability of both Ca2+ and Fe3+ cations in a brine percolating through the altered ash. Pedogenic conditions are more consistent with the observed Mg-smectites and gypsum in the tan layers, while jarosite and nontronite likely formed under more acidic conditions in the darker orange layers. Assemblages of smectite, Ca-sulfates, and jarosite similar to the banded orange/tan unit in our study are observed on Mars at Gale crater, Noctis Labyrinthus, and Mawrth Vallis, while high-silica outcrops have been identified in parts of Gusev crater, Gale crater, and Nili Patera on Mars.

The McMurdo Dry Valleys of Antarctica provide a testbed for alteration processes on Mars due to the cold, arid, and windy conditions. Analysis of three sediment cores collected from Don Juan Basin, Wright Valley, Antarctica, reveals that surface sediment formation is primarily dominated by physical alteration. Chemical alteration occurs sporadically in this region and is frequently indicated by the accumulation of sulfates and Cl-bearing salts. We investigated the effects of physical and chemical alteration in Don Juan Basin by considering major and trace element abundances in the sediments based on depth and location. Our results indicate inversely related chemical- and physical-alteration gradients with proximity to Don Juan Pond where the current center of the pond represents a more chemically altering environment and the perimeter a more physically altering one. Comparing calculated sulfate abundances for Don Juan Basin cores to rock and soil samples taken by the rover Curiosity at Gale crater, we observed that the core from within Don Juan Pond best matches Curiosity soil sulfate abundances. A new Chemical Index of Alteration equation that adjusts for salt dilution was also applied to the Antarctic cores and Curiosity rocks and soils. Our analysis indicates a significantly higher degree of chemical alteration than originally reported for most Antarctic and martian samples. Our investigation provides evidence for aqueous-based chemical alteration under cold, hyper-arid conditions in Don Juan Basin, Antarctica. Our work also demonstrates the analogous nature of terrestrial microenvironments to similar, local-scale sample sites on Mars, thereby supporting past or present chemical alteration on Mars.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) collected hyperspectral images of the Martian surface and atmosphere from September 27, 2006, through May 7, 2022. Over that time, nearly twenty scientific investigations were completed, most of which arose as a result of the findings from previous investigations. Two review papers published in 2009 (Murchie et al., 2009a, b) described the initial two-year investigation during MRO's Primary Science Phase, its key findings, and the CRISM data products that were developed and released to the community through that time. Here we describe the conduct and evolution of the CRISM investigation since then, which includes MRO's Extended Science Phase and first five Extended Missions. We document the physical changes in the instrument as it aged, including capabilities that were lost as well as new modes of operation not initially envisioned; the new science questions that were investigated and their key findings; anatomy of the extensive collection of data products that have been released to the Planetary Data System; the "final" radiometric calibration; high-order derived products produced from high-resolution targeted observations and global mapping campaigns; and data processing and analysis tools which have been developed and released by the CRISM team.

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.

We present an in-situ analysis of the reflectance of Visible Near Infrared (VNIR) and the petrologic texture of the surface of a relatively young lava flow at Jordan Craters, OR. Jordan Craters is a small young basaltic lava field in Oregon, USA which terminates in a lake, providing a wide variety of petrographic textures related to cooling rates and prolonged seasonal exposure to water, post-emplacement. Field VNIR measurements of 191 in-situ spots were used to calculate the overall reflectance between the bands 500-1000 nm (R500-1000) which serves as a proxy for glass abundance. Analyses were conducted on the surfaces of lava, spatter, and scoria from the vent, mid-portion, and margin of the flow. We assigned the 15 collected hand samples to five cooling environments based on their location and modal mineralogy. Crystal content was measured microscopically and compared with the spectra classification for 15 hand samples. Slower cooling environments had more crystals (30-60%) of plagioclase, olivine, Fe-oxides, and devitrified glass (15-30%) whereas faster cooling environments have higher proportions of vitreous glass (similar to 70%). In order from slowest cooling to fastest cooling the groups were lava interior, oxidized vent, flow margin, glassy vent, and mid-flow surface. Mid-flow indicates surfaces where inflation or breakouts of the top flows occurred at least five meters from the margin. Additionally, locations that were exposed to prolonged heat or environmental water had higher proportions of devitrification and Fe-oxide crystals. The values of R500-1000 mirrored the cooling histories of the hand samples with interior analyses having the highest values and vent samples having the lowest, though there was much scatter in the vent category due to lumping of oxidized and glassy together in the in-situ dataset. Our findings indicate that VNIR may be used to identify variations in petrologic texture across basaltic lava flows due to eruptive and emplacement conditions such as vent vs mid-flow surface or quickly cooled vs slowly cooled with careful sampling and sufficient number of analyses. This has implications for understanding the cooling dynamics of lava flow surfaces as well as furthering the study of lava flows as paleoenvironmental indicators.

Mars offers abundant raw materials that are of potential value for future human endeavors. Numerous vital elements can be found directly at the surface. 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. The natural geological variations in ore deposits can significantly impact viability of exploration sites and of the engineering architecture. Therefore, comprehension of these features is crucial for selecting and optimizing a particular technical design. This underlines the need for accurate resource exploration missions. Refinement and restructuring must be investigated to provide reliable fabrication systems since In Situ Resource Utilization (ISRU) is able to drastically cut down logistical dependence from Earth.Water is an essential requirement for an extended stay on Mars. It will serve as a consumable for astronauts and is needed for the production of propellant and oxygen, and for construction use. Water could even serve as radiation shielding if procurable in sufficient amounts. In contrast to subterranean ice, hydrated minerals offer a promising and reliable potential for water extraction directly at the surface of Mars and at lower latitudes. A large diversity of hydrated minerals such as phyllosilicates, hydrated silica, zeolites, and sulfates have been detected from orbit using visible near infrared (VIS-NIR) reflectance spectroscopy [1-3]. 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 (Fig. 1). We also present estimates of water volumes potentially retrievable from specific deposits and describe additional uses of the hydrated minerals for example as feedstock for a Bio-regenerative Life-Support System (BLSS).A BLSS architecture tends to be superior in terms of mass efficiency compared to non-bio-regenerative, i.e., chemical or physical life support systems, especially for protracted mission durations [4]. BLSS have the unique advantage of managing biological waste through biological processes exclusively. In addition, if higher plants are cultivated, they offer psychological comforts and nutritional benefits derived from the presence of plant life and as fresh food [5]. Thus, BLSS systems realized in the form of one or multiple greenhouses, are an indispensable component for sustaining a human presence on Martian terrain [6, 7]. Over the last 40 years, several studies have shown that crops can be efficiently grown on hydroponic or soilless media [8, 9]. In fact, crop cultivation in controlled environments can even meet or surpass record yields [10]. From 2018 to 2022, the EDEN ISS project from the German Aerospace Center operated a space-analog test facility greenhouse near the Neumayer III station in Antarctica, potentially resulting in the closest Mars analog we can find on Earth (Fig. 2). In the first year of operation, 268 kg of edible biomass was produced on the 12.5 m2 cultivation area of the greenhouse [11] with soilless media. Additional advantages include removing CO2 from the atmosphere, keeping water in a recycling loop, and producing oxygen. These findings demonstrate the importance of BLSS and can provide a scalable estimate of the potential contribution to logistics and required transport of materials for long duration crewed missions. [1] S.L. Murchie et al. (2009). A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter, J Geophys Res Planets 114. https://doi.org/10.1029/2009JE003342. [2] J.F. Mustard et al. (2008). Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument, Nature 454, 305–309. https://doi.org/10.1038/nature07097. [3] B.L. Ehlmann, C.S. Edwards (2014). Mineralogy of the Martian Surface, Annu Rev Earth Planet Sci 42, 291–315. https://doi.org/10.1146/annurev-earth-060313-055024. [4] C. Lasseur (2010). Melissa: The European project of a closed life support system, Gravitational and Space Biology 23 (2). [5] C. Mitchell (1994). Bioregenerative life-support systems, Am J Clin Nutr, 60 820S-824S. https://doi.org/10.1093/ajcn/60.5.820S. [6] M. Bamsey et al. (2009). Canadian advanced life support capacities and future directions, Advances in Space Research 44, 151–161. https://doi.org/10.1016/j.asr.2009.03.024. [7] H. Liu et al. (2021). Review of research into bioregenerative life support system(s) which can support humans living in space, Life Sci Space Res (Amst) 31, 113–120. https://doi.org/10.1016/j.lssr.2021.09.003. [8] J.F. Thomas, C.D. Raper (1983) Photoperiod Effects on Soybean Growth during the Onset of Reproductive Development under Various Temperature Regimes, Botanical Gazette 144, 471–476. http://www.jstor.org/stable/2474450. [9] Y. Tako (2001). Integration of Sequential Cultivation of Main Crops and Gas and Water Processing Subsystems Using Closed Ecology Experiment Facilities, https://doi.org/10.4271/2001-01-2133. [10] R.M. Wheeler, T.W. Tibbitts (1987). Utilization of potatoes for life support systems in space: III. Productivity at successive harvest dates under 12-H and 24-H photoperiods, Am Potato J 64, 311–320. https://doi.org/10.1007/BF02853523. [11] P. Zabel et al. (2020). Biomass Production of the EDEN ISS Space Greenhouse in Antarctica During the 2018 Experiment Phase, Front Plant Sci 11. https://doi.org/10.3389/fpls.2020.00656. Figure 1: Color-coded Mars Orbiter Laser Altimeter (MOLA) map showing the example regions in dashed white box. Figure 2: The EDEN ISS greenhouse in Antarctica with the Neumayer III station in the background (top). Cultivation area inside the test container (bottom).

Abstract Understanding past and present aqueous activity on Mars is critical to constraining martian aqueous geochemistry and habitability, and to searching for life on Mars. Assemblages of minerals observed at or near the martian surface include phyllosilicates, sulfates, iron oxides/hydroxides, and chlorides, all of which are indicative of a complex history of aqueous activity and alteration in the martian past. Furthermore, features observed on parts of the martian surface suggest present-day activity of subsurface brines and at least transient liquid water. Terrestrial analogs for younger and colder (Hesperian–Amazonian) martian geologic and climatic conditions are available in the McMurdo Dry Valleys (MDV) of Antarctica and provide opportunities for improved understanding of more recent aqueous activity on Mars. Here, we study the VXE-6 intermittent brine pond site from Wright Valley in the MDV region and use coordinated spectroscopy, X-ray diffraction, and elemental analyses to characterize the mineralogy and chemistry of surface sediments that have evolved in response to aqueous activity at this site. We find that brine pond activity results in mineral assemblages akin to aqueous alteration products associated with younger sites on Mars. In particular, surficial chlorides, a transition layer of poorly crystalline aluminosilicates and iron oxides/hydroxides, and a deeper gypsum-rich interval within the upper 10 cm of sediment are closely related at this Antarctic brine pond site. Activity of the Antarctic brine pond and associated mineral formation presents a process analog for chemical alteration on the martian surface during episodes of transient liquid water activity during the late Hesperian and/or more recently. Our results provide a relevant example of how aqueous activity in a cold and dry Mars-like climate may explain the co-occurrence of chlorides, clays, iron oxides/hydroxides, and sulfates observed on Mars.