Mars Analog Environment Research Articles

Rapid Destruction of Lipid Biomarkers Under Simulated Cosmic Radiation.

Understanding how organics degrade under galactic cosmic rays (GCRs) is critical as we search for traces of ancient life on Mars. Even if the planet harbored life early in its history, its surface rocks have been exposed to ionizing radiation for about four billion years, potentially destroying the vast majority of biosignatures. In this study, we investigated for the first time the impact of simulated GCRs (using gamma rays) on several types of lipid biosignatures (including hopane C30, sterane C27, alkanes, and fatty acids [FAs]) in both the presence and absence of salts (NaCl, KCl, and MgCl2). We measured that the lipids degraded 6-20 times faster than amino acids in similar conditions; moreover, when irradiated in the presence of a salt substrate, degradation was at least 4-6 times faster than without salt, which suggests that salty environments that are often preferred targets for astrobiology warrant caution. We detected radiolytic by-products only for FAs-in the form of alkanes and aldehydes. These results expand our understanding of the degradation of organic molecules in Mars analog environments and underscore the urgent need to direct rover missions to sampling sites protected from GCRs, for example, sites on Mars that have been recently exposed by a wind scarp retreat or meteoritic impact.

Comparing Rover and Helicopter Planetary Mission Architectures in a Mars Analog Setting in Iceland

The Rover–Aerial Vehicle Exploration Network project field-tested planetary mission operations within a Mars analog environment in Iceland using stand-alone rover and helicopter architectures. Mission planning, implementation, and results are reported for the rover mission and briefly summarized for the helicopter mission. The outcomes of both missions are subsequently compared. Field implementation occurred from 2022 July to August at the Holuhraun lava flow. The rover science operations team executed a 14 sol (Martian day) mission that achieved mission, science, and sampling goals, including the contextualization, acquisition, and planned caching of two eolian and two rock samples. The helicopter science operations team executed a plan of comparable length but emphasized different science goals given long-range flight capabilities and landing limitations. The resolution and targetability of the rover payload enabled more detailed analyses, whereas the helicopter was better able to map flow-scale morphologies. The rover’s exploration was limited by daily mobility duration limits and hazardous terrain, whereas the helicopter’s exploration was constrained by landing site hazards. Resource limitations resulted from lengthier rover drives and data-volume-intensive helicopter imaging surveys. Future missions using combined rover–helicopter architectures should account for each spacecraft’s resource needs and acknowledge system strengths in different geologic settings. Both missions served to establish operations strategies and mission outcomes to be applied to future combined rover and helicopter mission architectures, while the helicopter mission also evaluated strategies and outcomes for future stand-alone airborne missions. Findings in this work are relevant to future missions seeking to optimize strategies for planetary mission operations.

The Atacama Rover Astrobiology Drilling Studies (ARADS) Project.

With advances in commercial space launch capabilities and reduced costs to orbit, humans may arrive on Mars within a decade. Both to preserve any signs of past (and extant) martian life and to protect the health of human crews (and Earth's biosphere), it will be necessary to assess the risk of cross-contamination on the surface, in blown dust, and into the near-subsurface (where exploration and resource-harvesting can be reasonably anticipated). Thus, evaluating for the presence of life and biosignatures may become a critical-path Mars exploration precursor in the not-so-far future, circa 2030. This Special Collection of papers from the Atacama Rover Astrobiology Drilling Studies (ARADS) project describes many of the scientific, technological, and operational issues associated with searching for and identifying biosignatures in an extreme hyperarid region in Chile's Atacama Desert, a well-studied terrestrial Mars analog environment. This paper provides an overview of the ARADS project and discusses in context the five other papers in the ARADS Special Collection, as well as prior ARADS project results.

Linear Ion Trap Mass Spectrometer (LITMS) Instrument Field and Laboratory Tests as Part of the ARADS Field Campaigns.

The highly compact Linear Ion Trap Mass Spectrometer (LITMS), developed at NASA Goddard Space Flight Center, combines Mars-ambient laser desorption-mass spectrometry (LD-MS) and pyrolysis-gas chromatography-mass spectrometry (GC-MS) through a single, miniaturized linear ion trap mass analyzer. The LITMS instrument is based on the Mars Organic Molecule Analyser (MOMA) investigation developed for the European Space Agency's ExoMars Rover Mission with further enhanced analytical features such as dual polarity ion detection and a dual frequency RF (radio frequency) power supply allowing for an increased mass range. The LITMS brassboard prototype underwent an extensive repackaging effort to produce a highly compact system for terrestrial field testing, allowing for molecular sample analysis in rugged planetary analog environments outside the laboratory. The LITMS instrument was successfully field tested in the Mars analog environment of the Atacama Desert in 2019 as part of the Atacama Rover Astrobiology Drilling Studies (ARADS) project, providing the first in situ planetary analog analysis for a high-fidelity, flight-like ion trap mass spectrometer. LITMS continued to serve as a laboratory tool for continued analysis of natural Atacama samples provided by the subsequent 2019 ARADS final field campaign.

Jack Dwayne Farmer April 18, 1947-February 22, 2023.

Jack Dwayne Farmer April 18, 1947-February 22, 2023.

Planetary Mapping Using Deep Learning: A Method to Evaluate Feature Identification Confidence Applied to Habitats in Mars-Analog Terrain.

The goals of Mars exploration are evolving beyond describing environmental habitability at global and regional scales to targeting specific locations for biosignature detection, sample return, and eventual human exploration. An increase in the specificity of scientific goals-from follow the water to find the biosignatures-requires parallel developments in strategies that translate terrestrial Mars-analog research into confident identification of rover-explorable targets on Mars. Precisely how to integrate terrestrial, ground-based analyses with orbital data sets and transfer those lessons into rover-relevant search strategies for biosignatures on Mars remains an open challenge. Here, leveraging small Unmanned Aerial System (sUAS) technology and state-of-the-art fully convolutional neural networks for pixel-wise classification, we present an end-to-end methodology that applies Deep Learning to map geomorphologic units and quantify feature identification confidence. We used this method to assess the identification confidence of rover-explorable habitats in the Mars-analog Salar de Pajonales over a range of spatial resolutions and found that spatial resolutions two times better than are available from Mars would be necessary to identify habitats in this study at the 1-σ (85%) confidence level. The approach we present could be used to compare the identifiability of habitats across Mars-analog environments and focus Mars exploration from the scale of regional habitability to the scale of specific habitats. Our methods could also be adapted to map dome- and ridge-like features on the surface of Mars to further understand their origin and astrobiological potential.

Sulfur Cycling as a Viable Metabolism under Simulated Noachian/Hesperian Chemistries.

Water present on the surface of early Mars (>3.0 Ga) may have been habitable. Characterising analogue environments and investigating the aspects of their microbiome best suited for growth under simulated martian chemical conditions is key to understanding potential habitability. Experiments were conducted to investigate the viability of microbes from a Mars analogue environment, Colour Peak Springs (Axel Heiberg Island, Canadian High Arctic), under simulated martian chemistries. The fluid was designed to emulate waters thought to be typical of the late Noachian, in combination with regolith simulant material based on two distinct martian geologies. These experiments were performed with a microbial community from Colour Peak Springs sediment. The impact on the microbes was assessed by cell counting and 16S rRNA gene amplicon sequencing. Changes in fluid chemistries were tested using ICP-OES. Both chemistries were shown to be habitable, with growth in both chemistries. Microbial communities exhibited distinct growth dynamics and taxonomic composition, comprised of sulfur-cycling bacteria, represented by either sulfate-reducing or sulfur-oxidising bacteria, and additional heterotrophic halophiles. Our data support the identification of Colour Peak Springs as an analogue for former martian environments, with a specific subsection of the biota able to survive under more accurate proxies for martian chemistries.

Abiotic Nitrous Oxide Production From Sediments and Brine of Don Juan Pond, Wright Valley Antarctica, at Mars Analog Temperatures (−40°C)

AbstractThe presence of biogenic gases such as oxygen, methane, and nitrous oxide (N2O) in the atmospheres of extraterrestrial bodies has been postulated as a biosignature of life. Abiotic N2O production was documented recently in Don Juan Pond (DJP), Antarctica, a cold, hypersaline Mars analog environment. Here we quantify the temperature‐driven kinetics of abiotic N2O production and combine this with stable isotope labeling to demonstrate that N2O is produced from DJP sediment and brine at Mars‐analog temperatures down to at least −40°C. Further, we show that at any given temperature, N2O production is controlled by the availability of reduced Fe‐bearing minerals rather than nitrate. We conclude that abiotic N2O production is possible on Mars and on other extraterrestrial bodies and exoplanets. Thus, the presence of atmospheric N2O on these bodies should not be taken by itself as an indicator of microbial life.

Nitrogen Cycling and Biosignatures in a Hyperarid Mars Analog Environment.

The hyperarid Atacama Desert is a unique Mars-analog environment with a large near-surface soil nitrate reservoir due to the lack of rainfall leaching for millennia. We investigated nitrogen (N) cycling and organic matter dynamics in this nitrate-rich terrestrial environment by analyzing the concentrations and isotopic compositions of nitrate, organic C, and organic N, coupled with microbial pathway-enzyme inferences, across a naturally occurring rainfall gradient. Nitrate deposits in sites with an annual precipitation of <10 mm carry atmospheric δ15N, δ18O, and Δ17O signatures, while these values are overprinted by biological cycling in sites with >15 mm annual precipitation. Metagenomic analyses suggest that the Atacama Desert harbors a unique biological nitrogen cycle driven by nitrifier denitrification, nitric oxide dioxygenase-driven alternative nitrification, and organic N loss pathways. Nitrate assimilation is the only nitrate consumption pathway available in the driest sites, although some hyperarid sites also support organisms with ammonia lyase- and nitric oxide synthase-driven organic N loss. Nitrifier denitrification is enhanced in the “transition zone” desert environments, which are generally hyperarid but see occasional large rainfall events, and shifts to nitric oxide dioxygenase-driven alternative nitrifications in wetter arid sites. Since extremophilic microorganisms tend to exploit all reachable nutrients, both N and O isotope fractionations during N transformations are reduced. These results suggest that N cycling on the more recent dry Mars might be dominated by nitrate assimilation that cycles atmospheric nitrate and exchanges water O during intermittent wetting, resulting stable isotope biosignatures could shift away from martian atmospheric nitrate endmember. Early wetter Mars could nurture putative life that metabolized nitrate with traceable paleoenvironmental isotopic markers similar to microbial denitrification and nitrification stored in deep subsurface.

Organic Material Distribution in Mars-Analog Volcanic Rocks, as Determined with Ultraviolet Laser-Induced Fluorescence Spectroscopy.

Understanding the distribution of trace organic material in a rocky environment is a key to constraining the material requirements for sustaining microbial life. We used an ultraviolet laser-induced fluorescence (LIF) spectroscopy instrument to characterize the distribution of organic biosignatures in basalts collected from two Mars-analog environments. We correlated the fluorescence results with alteration-related sample properties. These samples exhibit a range of alteration conditions found in the volcanic environments of Hawai'i Volcanoes National Park, Hawai'i (HI), and Craters of the Moon National Monument, Idaho (ID), including fumarolic systems. LIF mapping of the sample surfaces and interiors showed a heterogeneous distribution of areas of highly fluorescent material (point[s]-of-interest [POIs])-with fluorescence characteristics indicative of organic material. Results suggest that POIs are associated with secondary alteration mineral deposits in the rock's vesicles, including zeolites and calcite. Scanning electron microscopy with electron-dispersive X-ray spectroscopy was used to characterize the mineralogy present at POIs and support the evidence of carbon-bearing material. Overall, samples collected proximate to active or relict meteoric fumaroles from Hawai'i were shown to contain evidence for organic deposits. This suggests that these minerals are measurable spectroscopic targets that may be used to inform sample-site selection for astrobiology research.

Stable Carbon Isotope Depletions in Lipid Biomarkers Suggest Subsurface Carbon Fixation in Lava Caves

AbstractLava caves, formed through basaltic volcanism, are accessible conduits into the shallow subsurface and the microbial life residing there. While evidence for this life is widespread, the level of dependence of these microbial communities on surface inputs, especially that of organic carbon (OC), is a persistent knowledge gap, with relevance to both terrestrial biogeochemistry and the characterization of lava caves as Mars analog environments. Here, we explore carbon cycling processes within lava caves at Lava Beds National Monument, CA. We interrogate a range of cave features and surface soils, characterizing the isotopic composition (δ13C) of bulk organic and inorganic phases, followed by organic geochemical analysis of the distribution and δ13C signatures of fatty acids derived from intact polar lipids (IPLs). From these data, we estimate the carbon sources of different sample types, finding that surface soils and mineral‐rich speleothems incorporate plant‐derived biomass (δ13CVPDB ∼ −30‰), whereas biofilms are dominated by strongly 13C‐depleted lipids (minimum δ13CVPDB −45.4‰) specific to bacteria, requiring a significant proportion of their biomass to derive from in situ fixation of inorganic carbon from previously respired OC. Based on the prevalence and abundance of these 13C‐depleted lipids, we conclude that biofilms here are fueled by in situ chemolithoautotrophy, despite relatively high concentrations of dissolved OC in colocated cave waters. This unexpected metabolic potential mirrors that found in other deep subsurface biospheres and has significant positive implications for the potential microbial habitability of the Martian subsurface.

Quantifying Preservation Potential: Lipid Degradation in a Mars-Analog Circumneutral Iron Deposit.

Comparisons between the preservation potential of Mars-analog environments have historically been qualitative rather than quantitative. Recently, however, laboratory-based artificial maturation combined with kinetic modeling techniques have emerged as a potential means by which the preservation potential of solvent-soluble organic matter can be quantified in various Mars-analog environments. These methods consider how elevated temperatures, pressures, and organic-inorganic interactions influence the degradation of organic biomarkers post-burial. We used these techniques to investigate the preservation potential of deposits from a circumneutral iron-rich groundwater system. These deposits are composed of ferrihydrite (Fe5HO8 · 4H2O), an amorphous iron hydroxide mineral that is a common constituent of rocks found in ancient lacustrine environments on Mars, such as those observed in Gale Crater. Both natural and synthetic ferrihydrite samples were subjected to hydrous pyrolysis to observe the effects of long-term burial on the mineralogy and organic content of the samples. Our experiments revealed that organic-inorganic interactions in the samples are dominated by the transformation of iron minerals. As amorphous ferrihydrite transforms into more crystalline species, the decrease in surface area results in the desorption of organic matter, potentially rendering them more susceptible to degradation. We also find that circumneutral iron-rich deposits provide unfavorable conditions for the preservation of solvent-soluble organic matter. Quantitative comparisons between preservation potentials as calculated when using kinetic parameters show that circumneutral iron-rich deposits are ∼25 times less likely to preserve solvent-soluble organic matter compared with acidic, iron-rich environments. Our results suggest that circumneutral iron-rich deposits should be deprioritized in favor of acidic iron- and sulfur-rich deposits when searching for evidence of life with solvent extraction techniques.

Fatty Acid Preservation in Modern and Relict Hot-Spring Deposits in Iceland, with Implications for Organics Detection on Mars.

Hydrothermal spring deposits host unique microbial ecosystems and have the capacity to preserve microbial communities as biosignatures within siliceous sinter layers. This quality makes terrestrial hot springs appealing natural laboratories to study the preservation of both organic and morphologic biosignatures. The discovery of hydrothermal deposits on Mars has called attention to these hot springs as Mars-analog environments, driving forward the study of biosignature preservation in these settings to help prepare future missions targeting the recovery of biosignatures from martian hot-spring deposits. This study quantifies the fatty acid load in three Icelandic hot-spring deposits ranging from modern and inactive to relict. Samples were collected from both the surface and 2-18 cm in depth to approximate the drilling capabilities of current and upcoming Mars rovers. To determine the preservation potential of organics in siliceous sinter deposits, fatty acid analyses were performed with pyrolysis-gas chromatography-mass spectrometry (GC-MS) utilizing thermochemolysis with tetramethylammonium hydroxide (TMAH). This technique is available on both current and upcoming Mars rovers. Results reveal that fatty acids are often degraded in the subsurface relative to surface samples but are preserved and detectable with the TMAH pyrolysis-GC-MS method. Hot-spring mid-to-distal aprons are often the best texturally and geomorphically definable feature in older, degraded terrestrial sinter systems and are therefore most readily detectable on Mars from orbital images. These findings have implications for the detection of organics in martian hydrothermal systems as they suggest that organics might be detectable on Mars in relatively recent hot-spring deposits, but preservation likely deteriorates over geological timescales. Rovers with thermochemolysis pyrolysis-GC-MS instrumentation may be able to detect fatty acids in hot-spring deposits if the organics are relatively young; therefore, martian landing site and sample selection are of paramount importance in the search for organics on Mars.

Microbial community distribution in variously altered basalts: Insights into astrobiology sample site selection

Terrestrial basalts represent ecological niches with the potential for microbial habitability. However, little is known about how gradients of physical and/or chemical alteration may impact the distribution of microbial biomass. If higher abundances of microbial biomass are associated with identifiable alteration features, i.e. visible from orbit or rover, such features would become an important tool in the selection of astrobiology targets for future life-detection missions. To examine the associations between biomass abundance and basalt alteration processes, phospholipid fatty acid (PLFA) biomarker analysis was used to assess microbial biomass in basalts representative of distinct alteration categories collected from two Mars analog environments: Craters of the Moon National Monument and Preserve (COTM), Idaho and Hawai’i Volcanoes National Park (HVNP), Hawai’i. PLFA concentration was generally highest in field categorized high-temperature alteration (syn-emplacement) samples within COTM, particularly in those that may have also undergone some degree of secondary weathering. Basalts from HVNP showed more variable biomass abundances, with no clear trend between altered and unaltered basalts. HVNP fumarolic deposits (both active and relict fumarole-associated samples) generally had consistently detectable biomass although temperature appeared to play a role in abundance with the highest temperate fumarole exhibiting the lowest PLFA concentration. PLFA profiles generally had high proportions of brPLFA (including biomarkers of iron- and sulfur-reducing bacteria) and indicated that basalts were dominated by heterotrophic organisms, however no clear trend between community biomarker composition and alteration type or extent was identified. Heterogeneity of microbial biomass within terrestrial basalts suggests that identification of distinct alteration features clearly linked to high biomass (biomarkers) is challenging but that altered materials (syn-emplacement and secondary weathering) and fumarolic deposits are likely promising astrobiology targets.

Unraveling biogeochemical phosphorus dynamics in hyperarid Mars‐analogue soils using stable oxygen isotopes in phosphate

With annual precipitation less than 20mm and extreme UV intensity, the Atacama Desert in northern Chile has long been utilized as an analogue for recent Mars. In these hyperarid environments, water and biomass are extremely limited, and thus, it becomes difficult to generate a full picture of biogeochemical phosphate-water dynamics. To address this problem, we sampled soils from five Atacama study sites and conducted three main analyses-stable oxygen isotopes in phosphate, enzyme pathway predictions, and cell culture experiments. We found that high sedimentation rates decrease the relative size of the organic phosphorus pool, which appears to hinder extremophiles. Phosphoenzyme and pathway prediction analyses imply that inorganic pyrophosphatase is the most likely catalytic agent to cycle P in these environments, and this process will rapidly overtake other P utilization strategies. In these soils, the biogenic δ18 O signatures of the soil phosphate (δ18 OPO4 ) can slowly overprint lithogenic δ18 OPO4 values over a timescale of tens to hundreds of millions of years when annual precipitation is more than 10mm. The δ18 OPO4 of calcium-bound phosphate minerals seems to preserve the δ18 O signature of the water used for biogeochemical P cycling, pointing toward sporadic rainfall and gypsum hydration water as key moisture sources. Where precipitation is less than 2mm, biological cycling is restricted and bedrock δ18 OPO4 values are preserved. This study demonstrates the utility of δ18 OPO4 values as indicative of biogeochemical cycling and hydrodynamics in an extremely dry Mars-analogue environment.

The Limits, Capabilities, and Potential for Life Detection with MinION Sequencing in a Paleochannel Mars Analog.

No instrument capable of direct life detection has been included on a mission payload to Mars since NASA's Viking missions in the 1970s. This prevents us from discovering whether life is or ever was present on Mars. DNA is an ideal target biosignature since it is unambiguous, nonspecific, and readily detectable with nanopore sequencing. Here, we present a proof-of-concept utilization of the Oxford Nanopore Technologies (ONT) MinION sequencer for direct life detection and show how it can complement results from established space mission instruments. We used nanopore sequencing data from the MinION to detect and characterize the microbial life in a set of paleochannels near Hanksville, UT, with supporting data from X-ray diffraction, reflectance spectroscopy, Raman spectroscopy, and Life Detector Chip (LDChip) microarray immunoassay analyses. These paleochannels are analogs to martian sinuous ridges. The MinION-generated metagenomes reveal a rich microbial community dominated by bacteria and containing radioresistant, psychrophilic, and halophilic taxa. With spectral data and LDChip immunoassays, these metagenomes were linked to the surrounding Mars analog environment and potential metabolisms (e.g., methane production and perchlorate reduction). This shows a high degree of synergy between these techniques for detecting and characterizing biosignatures. We also resolved a prospective lower limit of ∼0.001 ng of DNA required for successful sequencing. This work represents the first determination of the MinION's DNA detection limits beyond ONT recommendations and the first whole metagenome analysis of a sinuous ridge analog.

The Dallol Geothermal Area, Northern Afar (Ethiopia)-An Exceptional Planetary Field Analog on Earth.

The Dallol volcano and its associated hydrothermal field are located in a remote area of the northern Danakil Depression in Ethiopia, a region only recently appraised after decades of inaccessibility due to severe political instability and the absence of infrastructure. The region is notable for hosting environments at the very edge of natural physical-chemical extremities. It is surrounded by a wide, hyperarid salt plain and is one of the hottest (average annual temperatureDallol: 36–38°C) and most acidic natural systems (pHDallol ≈0) on Earth. Spectacular geomorphologies and mineral deposits produced by supersaturated hydrothermal waters and brines are the result of complex interactions between active and inactive hydrothermal alteration of the bedrock, sulfuric hot springs and pools, fumaroles and geysers, and recrystallization processes driven by hydrothermal waters, degassing, and rapid evaporation.The study of planetary field analog environments plays a crucial role in characterizing the physical and chemical boundaries within which life can exist on Earth and other planets. It is essential for the definition and assessment of the conditions of habitability on other planets, including the possibility for biosignature preservation and in situ testing of technologies for life detection. The Dallol area represents an excellent Mars analog environment given that the active volcanic environment, the associated diffuse hydrothermalism and hydrothermal alteration, and the vast acidic sulfate deposits are reminiscent of past hydrothermal activity on Mars. The work presented in this paper is an overview of the Dallol volcanic area and its hydrothermal field that integrates previous literature with observations and results obtained from field surveys and monitoring coupled with sample characterization. In so doing, we highlight its exceptional potential as a planetary field analog as well as a site for future astrobiological and exploration programs.

Evidence for Biotic Perchlorate Reduction in Naturally Perchlorate-Rich Sediments of Pilot Valley Basin, Utah.

The presence of perchlorate on Mars suggests a possible energy source for sustaining microbial life. Perchlorate-reducing microbes have been isolated from perchlorate-contaminated soils and sediments on the Earth, but to date, never from an environment that is naturally enriched in perchlorate. The arid Pilot Valley paleolake basin in Utah is a Mars analog environment whose sediments are naturally enriched with up to ∼6.5 μg kg-1 perchlorate oxyanions. Here, we present results of field and laboratory studies indicating that perchlorate-reducing microorganisms co-occur with this potential electron acceptor. Biogeochemical data suggest ongoing perchlorate reduction; phylogenetic data indicate the presence of diverse microbial communities; and laboratory enrichments using Pilot Valley sediments show that resident microbes can reduce perchlorate. This is the first article of the co-existence of perchlorate-reducing microbes in an environment where perchlorate occurs naturally, arguing for Pilot Valley's utility as an analog for studying biogeochemical processes that may have occurred, and may yet still be occurring, in ancient martian lacustrine sediments.

Where to Look? Predictive Perception With Applications to Planetary Exploration

Planetary rovers exploring the surface of Mars rely on vision-based localization and navigation algorithms to estimate their state and plan their motion during autonomous traverses. The accurate estimation of rover's motion enables safe navigation across environments with potentially hazardous terrain that would otherwise require careful human intervention. The accuracy of these vision-based localization and navigation methods are directly related to the amount of visual texture observed by the rover's sensors. This poses a challenge for Mars navigation, where texture-limited surfaces such as smooth sand is prevalent. To overcome this issue, we propose making use of a rover's ability to actively steer its visual sensors with the goal of maximizing actionable visual information content. This letter answers the question of where and when to look by presenting a method to predict the sensor trajectory that maximizes rover localization performance. This is accomplished through an online search of possible trajectories using synthetic, future camera views created from observed data. Proposed trajectories are quantified and chosen based on expected localization performance. We validate our algorithm in a high-fidelity simulation of a Mars-analogue environment and show how intelligently choosing where to look during a traverse can increase navigation accuracy compared to traditional fixed-sensor configurations.

Evaluation of the Tindouf Basin Region in Southern Morocco as an Analogue Site for Soil Geochemistry on Noachian Mars

Locations on Earth that provide insights into processes that may be occurring or may have occurred throughout martian history are often broadly deemed "Mars analog environments." As no single locale can precisely represent a past or present martian environment, it is important to focus on characterization of terrestrial processes that produce analogous features to those observed in specific regions of Mars or, if possible, specific time periods during martian history. Here, we report on the preservation of ionic species in soil samples collected from the Tindouf region of Morocco and compare them with the McMurdo Dry Valleys of Antarctica, the Atacama Desert in Chile, the martian meteorite EETA79001, and the in situ Mars analyses from the Phoenix Wet Chemistry Laboratory (WCL). The Moroccan samples show the greatest similarity with those from Victoria Valley, Beacon Valley, and the Atacama, while being consistently depleted compared to University Valley and enriched compared to Taylor Valley. The NO3/Cl ratios are most similar to Victoria Valley and Atacama, while the SO4/Cl ratios are similar to those from Beacon Valley, Victoria Valley, and the Atacama. While perchlorate concentrations in the Moroccan samples are typically lower than those found in samples of other analog sites, conditions in the region are sufficiently arid to retain oxychlorines at detectable levels. Our results suggest that the Tindouf Basin in Morocco can serve as a suitable analogue for the soil geochemistry and subsequent aridification of the Noachian epoch on Mars.