Martian Regolith Simulant Research Articles

Microstructural and mechanical properties of high-strength geopolymer based on Martian soil simulant

Geopolymers made from simulated Martian regolith would suffer from exhibit poor engineering properties, rendering them unsuitable as base materials. To improve the mechanical properties of geopolymers, this study prepared a new Martian soil simulant named DH-1. DH-1- based geopolymers were synthesized using Al2O3 (Al group) and metakaolin (MK group) as modifying agents. The durability of geopolymers with ultraviolet (UV) radiation was assessed under simulated Martian atmospheric conditions. The results indicated that the UCS and FS of both the Al and MK groups increased with curing time, with maximum UCS and FS of 55.27 MPa and 15.16 MPa, respectively. The UCS and FS of the Al and MK groups exhibited a two-phase change. The inflection points for rapid to slow in the UCS and FS occurred on day 28 for the Al group and day 14 for the MK group. The addition of Al2O3 and metakaolin promoted the replacement of silicon atoms by aluminum atoms in the silica-oxygen group, producing more gels product. After UV irradiation, the UCS and FS of the geopolymer decreased by 13 % and 44 %, respectively. Furthermore, the geopolymers underwent carbonation, with new cracks forming due to the combined effects of UV exposure, causing strength reduction.

A Lab-scale Investigation of the Mars Kieffer Model

The Kieffer model is a widely accepted explanation for seasonal modification of the Martian surface by CO2 ice sublimation and the formation of a “zoo” of intriguing surface features. However, the lack of in situ observations and empirical laboratory measurements of Martian winter conditions hampers model validation and refinement. We present the first experiments to investigate all three main stages of the Kieffer model within a single experiment: (i) CO2 condensation on a thick layer of Mars regolith simulant; (ii) sublimation of CO2 ice and plume, spot, and halo formation; and (iii) the resultant formation of surface features. We find that the full Kieffer model is supported on the laboratory scale as (i) CO2 diffuses into the regolith pore spaces and forms a thin overlying conformal layer of translucent ice. When a buried heater is activated, (ii) a plume and dark spot develop as dust is ejected with pressurized gas, and the falling dust creates a bright halo. During plume activity, (iii) thermal stress cracks form in a network similar in morphology to certain types of spiders, dendritic troughs, furrows, and patterned ground in the Martian high south polar latitudes. These cracks appear to form owing to sublimation of CO2 within the substrate, instead of surface scouring. We discuss the potential for this process to be an alternative formation mechanism for “cracked” spider-like morphologies on Mars. Leveraging our laboratory observations, we also provide guidance for future laboratory or in situ investigations of the three stages of the Kieffer model.

A comparison of additive manufactured to injection molded Martian regolith based polymer matrix composites

The completed study investigated the creation of Martian regolith simulant composite parts using injection molding and additive manufacturing. Traditional manufacturing techniques such as injection molding are not feasible on the Martian surface therefore in-situ processes must be developed using additive manufacturing processes to prepare habitats prior to having a human presence on the surface. The goal of this study was to investigate the impacts of additive manufacturing on the material property values between parts made using traditional injection molding and additive manufacturing. Martian regolith simulant composite pellets were created by combining a Martian regolith simulant at 40 wt% loading with polypropylene via twin screw extrusion. This material was then used to create test specimens using injection molding and additive manufacturing. Samples underwent tensile, flexural, Izod impact, and immersion density tests according to ASTM International and standardized test instructions. Additive manufactured parts saw a nearly 40% reduction in tensile and flexural strength with more than double the tensile modulus when compared to injection molded parts. The flexural modulus for additive manufacturing was around 36% that of the injection molded part with a minor decrease in density of around 13%. The collected test results suggested that while there were differences in the material property values between the manufacturing processes, a more interesting foaming behavior of the extrudite was observed during the additive manufacturing process resulting in an extremely rough and pitted surface. This rough surface finish was a stark comparison to the smooth injection molded parts. This observed foaming behavior in the polymeric composite material during thermal processing prompted the theory that thermal releases from the Martian regolith simulant was the most likely cause of the observed differences. Pellet surface moisture tests, Martian regolith simulant thermogravimetric analyses, and literature reviews of thermal decomposition of the Martian regolith simulant constituents revealed that most likely olivine releases oxygen and hydrated silica releases water during the thermal processing of the Martian regolith simulant composite. During a closed mold process such as injection molding, these volatile gases are forced out of the part by the pressures of the molding process, but in an open to atmosphere process such as additive manufacturing these gases foam to the surface during cooling leaving the part with an inferior surface finish.

Characterization of a Simulated Martian Regolith Ecosystem by Proton Nuclear Magnetic Resonance (NMR) Relaxometry and Fourier Transform Infrared (FT-IR) and Visible (VIS)-Near-Infrared (NIR) Spectroscopies

Of the various Martian soil simulant mixes developed by NASA and Jet Propulsion Laboratory (JPL), three types were chosen that have the closest features to those of the Martian regolith to be analyzed. The characterization of the Martian regolith types was performed the advanced methods of 1H nuclear magnetic resonance (NMR) relaxometry, Fourier transform infrared (FT-IR) spectroscopy and visible (VIS)-near-infrared (NIR) spectroscopy, as well as classical methods such as pH, the electrical conductivity, and the total dissolved solids. These analyses showed that trace water, nitrogen, phosphorus and potassium are present in the Martian regolith simulant. A Martian Garden has been built with the Martian soils, in which various vegetables have been seeded. Among the Fourier Transform infrared (FT-IR) spectra acquired for the plants, a high degree of similarity was observed, which indicates that the substrate ‘Martian regolith simulant of terrestrial soil’ does not significantly influence the structure of the radish, peas and bean leaves, stems, or roots. Nevertheless, the results of 1D 1H nuclear magnetic resonance (NMR) relaxometry indicate that the substrate presents a high influence on the water dynamics in plant pores at the level of roots, stems and leaves and in bound water. A Marsarium was designed and built, where all types of Martian and terrestrial soils were introduced, together with a family of ants. The ants adapted to the imposed conditions, as they dug tunnels in the soils.

Effect of vermicompost on rhizobiome and the growth of wheat on Martian regolith simulant

As humanity embarks on the journey to establish permanent colonies on Mars, ensuring a reliable source of sustenance will be crucial. Therefore, detailed studies regarding crop cultivation using Martian simulants are of great importance. This study aimed to grow wheat on substrates based on soil and Martian simulants, with the addition of vermicompost, to investigate the differences in wheat development. Basic physical and chemical properties of substrates were examined, including determination of macro- and microelements as well as their microbiological properties. Plant growth parameters were also determined. The addition of vermicompost positively affected wheat grown on soil, but the effect on plants grown on substrate with Martian simulants was negligible. Comparing the microbiological and chemical components, it was observed that plants can defend themselves against the negative effects of growth on the Martian simulants, but their success depends on having the PGPR (Plant growth-promoting rhizobacteria) present, which can provide the plant with additional nitrogen. The presence of beneficial symbiotic microbiota will allow the wheat to wait out the negative growth time rather than adapt to the regolith environment.

Martian Regolith Simulant-Based Geopolymers with Lithium Hydroxide Alkaline Activator

As humanity envisions the possibility of inhabiting Mars in the future, the imperative for survival in the face of its challenging conditions necessitates the construction of protective shelters to mitigate the effects of radiation exposure and the absence of atmospheric pressure. The feasibility of producing geopolymers using the Martian regolith simulant MGS-1 (as precursor) for potential building and infrastructure projects on Mars in the future is investigated in this paper. Various alkaline activators, such as sodium hydroxide (NaOH), lithium hydroxide (LiOH·H2O) and sodium silicate (Na2SiO3), are employed to investigate their efficiency in activating the precursor. The influence of alkali type and concentration on the mechanical performance of the synthesized geopolymers is examined. Geopolymer samples are oven-cured for 7 days at 70 °C before a compressive strength test. It is found that through the hybrid use of LiOH·H2O and NaOH with optimal concentrations, metakaolin and milled MGS-1 as precursors, geopolymer mixtures with a compressive strength of 30 ± 2 MPa can be developed. The present test results preliminarily demonstrate the potential of Martian regolith simulant-based geopolymers as suitable construction and building materials for use on Mars.

Assessing the feasibility of laser induced breakdown spectroscopy for detecting nitrogen in martian surface sediments

Despite the detection of fixed nitrogen in meteorites and directly on Mars' surface, the abundance and distribution of nitrogen sequestered in the martian crust remains unknown. Given that nitrogen is a bioessential element that is required for the synthesis of amino acids, nucleic acids, and other organic molecules vital for life, this gap in knowledge is one of the most important challenges in constraining martian habitability. Laser-induced breakdown spectroscopy (LIBS) has the capability to detect N in natural rock samples and is available as a stand-off survey instrument on multiple currently active Mars rovers, creating an immediate opportunity to map the stratigraphic distribution of N within diverse depositional settings. However, little has been published regarding the detection of N with LIBS.To lay a foundation for N detection on Mars using LIBS, we synthesized a comprehensive suite of samples with variable amounts of nitrogen (as nitrate or ammonium) in either a Mars regolith simulant or a clay matrix. We present baseline spectra of N emission in Mars-relevant matrices and identify spectral interferences. Our results indicate that 17 diagnostic N emission lines are reliably detectable from mineral-bound N against a basaltic background, but only four lines exhibit sufficient sensitivity to be detected across a range of N concentrations and within all tested matrices. To elucidate optimized strategies for quantification, we present an iterative series of PLS models. We find that prediction accuracy is improved by restricting the compositional range of the training set, normalizing the data, subtracting baseline continuum emission, and simultaneously modeling the emission behaviour of multiple diagnostic N lines at once. We observe that the prediction uncertainty increases (worsens) from 8.4% to 29.9% if models are used to predict N in samples with a dissimilar matrix than those used during training, suggesting poor generalizability outside the training range. Consequently, future work should focus on developing a larger, more diverse training set that encompasses the range of N concentrations and phases expected to be encountered on Mars, which may be used to train generalizable models. Overall, this work demonstrates that LIBS is a promising tool for determining the abundance of N sequestered in martian surface materials and lays a foundation for future development.

A Comparison of Different Protocols for the Extraction of Microbial DNA Inhabiting Synthetic Mars Simulant Soil.

Compared with typical Earth soil, Martian soil and Mars simulant soils have distinct properties, including pH > 8.0 and high contents of silicates, iron-rich minerals, sulfates, and metal oxides. This unique soil matrix poses a major challenge for extracting microbial DNA. In particular, mineral adsorption and the generation of destructive hydroxyl radicals through cationic redox cycling may interfere with DNA extraction. This study evaluated different protocols for extracting microbial DNA from Mars Global Simulant (MGS-1), a Mars simulant soil. Two commercial kits were tested: the FastDNA SPIN Kit for soil ("MP kit") and the DNeasy PowerSoil Pro Kit ("PowerSoil kit"). MGS-1 was incubated with living soil for five weeks, and DNA was extracted from aliquots using the kits. After extraction, the DNA was quantified with a NanoDrop spectrophotometer and used as the template for 16S rRNA gene amplicon sequencing and qPCR. The MP kit was the most efficient, yielding approximately four times more DNA than the PowerSoil kit. DNA extracted using the MP kit with 0.5 g soil resulted in 28,642-37,805 16S rRNA gene sequence reads and 30,380-42,070 16S rRNA gene copies, whereas the 16S rRNA gene could not be amplified from DNA extracted using the PowerSoil kit. We suggest that the FastDNA SPIN Kit is the best option for studying microbial communities in Mars simulant soils.

Near Room Temperature Production of Segregated Network Composites of Carbon Nanotubes and Regolith as Multifunctional, Extra-Terrestrial Building Materials.

Constructing a semi-permanent base on the moon or Mars will require maximal use of materials found in situ and minimization of materials and equipment transported from Earth. This will mean a heavy reliance on regolith (Lunar or Marian soil) and water, supplemented by small quantities of additives fabricated on Earth. Here it is shown that SiO2-based powders, as well as Lunar and Martian regolith simulants, can be fabricated into building materials at near-ambient temperatures using only a few weight-percent of carbon nanotubes as a binder. These composites have compressive strength and toughness up to 100 MPa and 3 MPa respectively, higher than the best terrestrial concretes. They are electrically conductive (>20Sm-1) and display an extremely large piezoresistive response (gauge factor >600), allowing these composites to be used as internal sensors to monitor the structural health of extra-terrestrial buildings.

Assessment of Fertility Dynamics and Nutritional Quality of Potato Tubers in a Compost-Amended Mars Regolith Simulant.

Mars exploration will foresee the design of bioregenerative life support systems (BLSSs), in which the use/recycle of in situ resources might allow the production of food crops. However, cultivation on the poorly-fertile Mars regolith will be very challenging. To pursue this goal, we grew potato (Solanum tuberosum L.) plants on the MMS-1 Mojave Mars regolith simulant, pure (R100) and mixed with green compost at 30% (R70C30), in a pot in a cold glasshouse with fertigation. For comparison purposes, we also grew plants on a fluvial sand, pure (S100) and amended with 30% of compost (S70C30), a volcanic soil (VS) and a red soil (RS). We studied the fertility dynamics in the substrates over time and the tuber nutritional quality. We investigated nutrient bioavailability and fertility indicators in the substrates and the quality of potato tubers. Plants completed the life cycle on R100 and produced scarce but nutritious tubers, despite many critical simulant properties. The compost supply enhanced the MMS-1 chemical/physical fertility and determined a higher tuber yield of better nutritional quality. This study demonstrated that a compost-amended Mars simulant could be a proper substrate to produce food crops in BLSSs, enabling it to provide similar ecosystem services of the studied terrestrial soils.

Effect of struvite on the growth of green beans on Mars and Moon regolith simulants

Abstract When humans are going to live on the Moon or Mars, food production and reusing waste products as manure will be essential for their survival. This calls for a circular sustainable agricultural ecosystem for food production. Earlier experiments have shown that crop growth is possible on simulant regoliths though there are several challenges. One of them is the shortage of nitrate or ammonium in the regoliths. Moreover, phosphate is not easily available. This could be solved by the application of human feces as manure. The goal of this experiment was to test if human urine-based struvite (MgNH4PO4) could fertilize Mars and Moon regolith simulants and lead to a higher yield of green beans. Three “soils” were examined: Mars regolith simulant (MMS), Moon regolith simulant (JSC 1A), and Earth potting soil with and without struvite. Forty grams of struvite were added, besides 10% (volume) organic matter. The experiment was conducted in tenfold. Length of plants was recorded, and beans were harvested when ripe and at the end of the experiment, three and a half months after the start. The struvite treatment yielded a significantly higher bean harvest. Plants on potting soil and Moon soil simulant with struvite addition reached the same height and were higher than the control plants. The plants on Mars soil simulant were smaller but still taller than the control. It can be concluded that the addition of struvite had a significant positive effect on the production of green beans on potting soil and Mars and Moon soil simulant.

Determination of inorganic and organic carbons in a Martian soil simulant under the Martian CO2 atmosphere using LIBS coupled with machine learning

Carbon plays a crucial role in the search for extraterrestrial life and serves as an indicator for the habitability and the paleoatmospheric CO2 reservoir on Mars. Previous exploration missions provided evidence of carbon on Mars with different chemical speciation using various instruments including laser-induced breakdown spectroscopy (LIBS). Quantitative determination with LIBS onboard Mars rovers is still precluded because of the important contribution of the atmospheric carbon in the LIBS plasma, in addition to matrix effects omnipresent for elemental determination with LIBS of geological materials. In this work, we performed a series of LIBS experiments in a simulated Martian atmosphere using samples prepared with a Martian soil simulant mixed with various carbonates and organic C-bearing materials. Convoluted influences on LIBS spectra due to the ambient gas and the different chemical speciation of carbon were observed for inorganic and organic C-bearing materials, which explains the unsatisfactory performance for a univariate regression model based on a carbon-related emission line. In particular, the influence of ambient gas was observed more important for inorganic carbon brought into the samples with carbonates. Multivariate models were then developed based on a back-propagation neural network (BPNN), for ensembles of samples with inorganic and organic carbons respectively, and then for the fusion of the two ensembles. The results showed respective limits of detection (LODs) of 0.247 wt%, 1.022 wt% and 0.873 wt%, and respective root mean square errors of prediction (RMSEPs) of 0.036 wt%, 0.133 wt%, and 0.062 wt% for the three collections of samples. Moreover, the model training process is investigated in detail in order to understand the way in which the most significant spectral features are selected, processed and mapped to the carbon concentrations of the samples by a neural network.

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.

A micromechanical model for estimating the shear modulus and damping ratio of loose sands under low stresses. Application to a Mars regolith simulant

The dynamic properties of loose sands under low stresses have been poorly investigated because of the higher order of magnitude of stress levels in terrestrial geotechnical structures. However, low densities and low stresses prevail in the sandy surface deposits of some other rocky planets, making low stress conditions relevant for extra-terrestrial soil mechanics. This is the case of Mars, on the surface of which a seismometer has been placed during the InSight mission. In this context, a dynamic shear rheometer was used to measure the shear modulus and damping ratio of a Martian regolith simulant under very low stresses to improve the interpretation of the InSight dataset on surface materials. This paper also revisits the grain contact stiffness and the overall modulus of a random packing of identical spheres, based on the Hertz-Mindlin contact theory. A micromechanical model accounting for the effects of both grain roughness and slipping in the soil degradation curve is proposed. The results of the model show a good agreement with experimental data, capturing the non-linear transition from low to high-shear strains. The model hence provides a new framework for a better understanding of the behaviour of granular materials in low gravity (extra-terrestrial) conditions.

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.

Intercropping on Mars: A promising system to optimise fresh food production in future martian colonies.

Future colonists on Mars will need to produce fresh food locally to acquire key nutrients lost in food dehydration, the primary technique for sending food to space. In this study we aimed to test the viability and prospect of applying an intercropping system as a method for soil-based food production in Martian colonies. This novel approach to Martian agriculture adds valuable insight into how we can optimise resource use and enhance colony self-sustainability, since Martian colonies will operate under very limited space, energy, and Earth supplies. A likely early Martian agricultural setting was simulated using small pots, a controlled greenhouse environment, and species compliant with space mission requirements. Pea (Pisum sativum), carrot (Daucus carota) and tomato (Solanum lycopersicum) were grown in three soil types ("MMS-1" Mars regolith simulant, potting soil and sand), planted either mixed (intercropping) or separate (monocropping). Rhizobia bacteria (Rhizobium leguminosarum) were added as the pea symbiont for Nitrogen-fixing. Plant performance was measured as above-ground biomass (g), yield (g), harvest index (%), and Nitrogen/Phosphorus/Potassium content in yield (g/kg). The overall intercropping system performance was calculated as total relative yield (RYT). Intercropping had clear effects on plant performance in Mars regolith, being beneficial for tomato but mostly detrimental for pea and carrot, ultimately giving an overall yield disadvantage compared to monocropping (RYT = 0.93). This effect likely resulted from the observed absence of Rhizobia nodulation in Mars regolith, negating Nitrogen-fixation and preventing intercropped plants from leveraging their complementarity. Adverse regolith conditions-high pH, elevated compactness and nutrient deficiencies-presumably restricted Rhizobia survival/nodulation. In sand, where more favourable soil conditions promoted effective nodulation, intercropping significantly outperformed monocropping (RYT = 1.32). Given this, we suggest that with simple regolith improvements, enhancing conditions for nodulation, intercropping shows promise as a method for optimising food production in Martian colonies. Specific regolith ameliorations are proposed for future research.

Survival of Environment-Derived Opportunistic Bacterial Pathogens to Martian Conditions: Is There a Concern for Human Missions to Mars?

The health of astronauts during space travel to new celestial bodies in the Solar System is a critical factor in the planning of a mission. Despite cleaning and decontamination protocols, microorganisms from the Earth have been and will be identified on spacecraft. This raises concerns for human safety and planetary protection, especially if these microorganisms can evolve and adapt to the new environment. In this study, we examined the tolerance of clinically relevant nonfastidious bacterial species that originate from environmental sources (Burkholderia cepacia, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens) to simulated martian conditions. Our research showed changes in growth and survival of these species in the presence of perchlorates, under desiccating conditions, exposure to ultraviolet radiation, and exposure to martian atmospheric composition and pressure. In addition, our results demonstrate that growth was enhanced by the addition of a martian regolith simulant to the growth media. Additional future research is warranted to examine potential changes in the infectivity, pathogenicity, and virulence of these species with exposure to martian conditions.

Wave Velocities and Poisson Ratio in a Loose Sandy Martian Regolith Simulant Under Low Stresses: 1. Laboratory Investigation

AbstractWave velocity measurements were performed on Fontainebleau sand samples used as a Martian regolith simulant to investigate the elastic properties of the surface material at the InSight landing site on Mars (Elysium Planitia). Loose samples (density 1.4 Mg/m3, density index 6%) were prepared by using the pluviation method to mimic the low regolith density at the InSight landing site. A novel device derived from triaxial testing was designed to measure wave velocities at low stresses along a horizontal cylindrical specimen. Four tests were made, in which the confining stress was applied by applying a vacuum between 1 and 80 kPa. Wave velocities were measured by using bender elements under stresses as low as 1.75 kPa, a very low value compared to the standard stress ranges generally considered in terrestrial geotechnics (&gt;10 kPa). The changes in compression and shear wave velocities obey a standard power law, with two slightly different exponents for Vp and Vs, indicating a not perfectly elastic behavior. Data showed greater variability below 5 kPa, indicating some limitations of the bender element technique in this range. A slight decrease in Poisson ratio was detected below 5 kPa, which certainly deserves more investigation. This investigation is useful to better analyze the data of the InSight mission, both in terms of wave propagation at the surface and to interpret some in situ elastic tests carried out with the scoop. These data are interpreted in the light of a granular contact mechanics theory in a companion paper.

Development of Sensitive Methods for the Detection of Minimum Concentrations of DNA on Martian Soil Simulants.

Several methods used for the quantification of DNA are based on UV absorbance or the fluorescence of complexes with intercalator dyes. Most of these intercalators are used in gels to visualize DNA and its structural integrity. Due to many extraterrestrial samples, such as meteorites or comets, which are likely to contain very small amounts of biological material, and because the ability to detect this material is crucial for understanding the origin and evolution of life in the universe, the development of assays that can detect DNA at low limits and withstand the rigors of space exploration is a pressing need in the field of astrobiology. In this study, we present a comparison of optimized protocols used for the fast and accurate quantification of DNA using common intercalator dyes. The sensitivity of assays exceeded that generated by any commercial kit and allowed for the accurate quantification of minimum concentrations of DNA. The methods were successful when applied to the detection and measurement of DNA spiked on soil samples. Furthermore, the impact of UV radiation as a harsh condition on the surface of Mars was assessed by DNA degradation and this was also confirmed by gel electrophoresis. Overall, the methods described provide economical, simple-step, and efficient approaches for the detection of DNA and can be used in future planetary exploration missions as tests used for the extraction of nucleic acid biosignatures.

Interaction between a Martian Regolith Simulant and Fungal Organic Acids in the Biomining Perspective.

The aim of this study was to evaluate the potential of Aspergillus tubingensis in extracting metals from rocks simulating Martian regolith through biomining. The results indicated that the fungal strain produced organic acids, particularly oxalic acid, in the first five days, leading to a rapid reduction in the pH of the culture medium. This acidic medium is ideal for bioleaching, a process that employs acidolysis and complexolysis to extract metals from rocks. Additionally, the strain synthesized siderophores, molecules capable of mobilizing metals from solid matrices, as verified by the blue CAS colorimetric test. The secretion of siderophores in the culture medium proved advantageous for biomining. The siderophores facilitated the leaching of metal ions, such as manganese, from the rock matrix into the acidified water solution. In addition, the susceptibility of the Martian regolith simulant to the biomining process was assessed by determining the particle size distribution, acid composition after treatment, and geochemical composition of the rock. Although the preliminary results demonstrate successful manganese extraction, further research is required to optimize the extraction technique. To conclude, the A. tubingensis strain exhibits promising abilities in extracting metals from rocks through biomining. Its use could prove useful in future in situ mining operations and environmental remediation efforts. Further research is required to optimize the process and evaluate its feasibility on a larger scale.