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Most of the surface of Mars is covered with unconsolidated rocky material, known as regolith. High‐fidelity models of the dynamics of impacts in such material are needed to help with the interpretation of seismic signals that are now recorded by SEIS, the seismometer of InSight. We developed a numerical model for impacts on regolith, using the novel Hybrid Optimization Software Suite (HOSS), which is a Lagrangian code mixing finite and discrete element formulations. We use data from hypervelocity impact experiments performed on pumice sand at the NASA Ames Vertical Gun Range to identify and calibrate key model parameters. The model provides insight into the plastic‐elastic transition observed in the data and it also demonstrates that gravity plays a key role in the material response. Waveforms for receivers situated vertically below the impact point are correctly modeled, while more research is needed to explain the shallow receivers' signals. Plain Language Summary: The generation of seismic waves by meteorite impacts in unconsolidated materials, such as Mars regolith, is a complex dynamic process. We present a numerical model based on a novel method and show its potential to explain the main characteristics of shock and seismic waves generated by impacts at laboratory scales. Our goal is to use this model to help with the analysis of data recorded during the InSight mission. Key Points: We conduct a parametric study of a novel Lagrangian numerical model of shock waves in granular media, with application to Mars regolithWe validate this model with a laboratory experiment in pumice sand with an impact velocity of 0.98 km/sAmplitude of shock waves and transition to different regimes is explained by the model for the sensors placed vertically from the impact [ABSTRACT FROM AUTHOR]

This research aimed to investigate the viability and biodiversity of microbial communities within ancient Arctic permafrost after exposure to a gamma-radiation dose of 100 kGy at low temperature (− 50 °C), low pressure (1 Torr) and dehydration conditions. The main objective was to assess the possibility for long-term survival of Earth-bound microorganisms in the subsurface of Martian regolith or inside small space bodies at constant absorption and accumulation of the gamma radiation dose. Investigated microbial communities had shown high resistance to a simulated Martian environment. After irradiation the total count of prokaryotic cells and number of metabolically active bacterial cells remained at the control level, while the number of bacterial CFUs decreased by 2 orders of magnitude, and the number of metabolically active cells of archaea decreased threefold. Besides, the abundance of culturable bacteria after irradiation was kept at a high level: not less than 3.7 × 10 cells/g. Potential metabolic activity of irradiated microbial communities in general were higher than in the control sample. A fairly high biodiversity of bacteria was detected in the exposed sample of permafrost, although the microbial community structure underwent significant changes after irradiation. In particular, actinobacteria populations of the genus Arthrobacter, which was not revealed in the control samples, became predominant in bacterial communities following the exposure. The results of the study testify that long-term preservation of microbial life inside Martian permafrost is possible. The data obtained can also be evaluated from the perspective of the potential for discovering viable Earth-bound microorganisms on other objects in the Solar system and inside of small bodies in outer space. [ABSTRACT FROM AUTHOR]

The dual-reciprocating drill (DRD) is a biologically-inspired concept which has shown promise in planetary environments, requiring a lower overhead force than traditional rotary drilling techniques. By using two reciprocating backwards-facing teethed halves to grip the surrounding substrate, it generates a traction force that reduces the required overhead penetration force. Research into DRD has focused on the effects of operational and substrate parameters on performance compared to static penetration, with minimal study of the geometrical parameters which define the drill head. This paper presents the exploration of the effects of drill head design on drilling depth and power consumption. Sixteen variations of the original design were tested in planetary regolith simulants up to depths of 800 mm. The experiments showed relationships between final depth, total drill radius and cone shape, though the teeth design had a negligible effect on performance. These results can be used alongside the previous research to optimise the future design and operation of the DRD. Drill stem bending was seen to cause an increase in drilling speed and depth, leading to the exploration of the mechanics of diagonal drilling. This resulted in the proposal of a fully-integrated system prototype that incorporates both reciprocating and lateral motion mechanisms. [ABSTRACT FROM AUTHOR]

The identification of two nucleobases (adenine and hypoxanthine) by Surface-Enhanced Raman Scattering (SERS) on different mineral substrates was adopted as a test case to verify the capability of this analytical technique to detect trace amounts of organic or biological substances deposited over, or contained in, Martian regolith. Raman spectra were collected on polished samples of calcite, dolomite, magnesite, siderite, anhydrite, and gypsum, onto which traces of nucleobases were added. While spectroscopic features of the two nucleobases could not be observed in normal Raman spectrum, the addition of silver nanoparticles allowed easy identification of the vibrational bands characteristic of the two nucleobases. [ABSTRACT FROM PUBLISHER]

The landscape near Hanksville, Utah, contains a diversity of Mars analogue features. These included segmented and inverted anastomosing palaeochannels exhumed from the Late Jurassic Brushy Basin Member of the Morrison Formation that hosts abundant small carbonate concretions. The exhumed and inverted channels closely resemble many seen on the surface of Mars in satellite imagery and which may be visited by surface missions in the near future. The channels contain a wealth of palaeoenvironmental information and are potentially of astrobiological interest, but intrinsically difficult terrain would make their study challenging on Mars. We show that an un-exhumed channel feature can be detected geophysically, and this may allow their study in more easily accessed terrain. The concretion's morphology and surface expression parallel the haematite ‘blue berries’ that are strewn across the surface of Meridiani Planum on Mars. They are best developed in poorly cemented medium to coarse channel sandstones and appear to have formed during deep burial. [ABSTRACT FROM AUTHOR]

The configuration of a biologically fertile substrate for edible plant growth during long-term manned missions to Mars constitutes one of the main challenges in space research. Mars regolith amendment with compost derived from crew and crop waste in bioregenerative life support systems (BLSS) may generate a substrate able to extend crew autonomy and long-term survival in space. In this context, the aim of our work was threefold: first, to study the geochemistry and mineralogy of Mojave Mars Simulant (MMS-1) and the physico-chemical and hydraulic properties of mixtures obtained by mixing MMS-1 and green compost at varying rates (0:100, 30:70, 70:30, 100:0; v:v); secondly, to evaluate the potential use of MMS-1 as a growing medium of two lettuce (Lactuca sativa L.) cultivars; thirdly, to assess how compost addition may impact on sustainability of space agriculture by exploiting in situ resources. MMS-1 is a coarse-textured alkaline substrate consisting mostly of plagioclase, amorphous material and secondarily of zeolite, hematite and smectites. Although it can be a source of nutrients, it lacks organic matter, nitrogen, phosphorus and sulphur, which may be supplied by compost. Both cultivars grew well on all mixtures for 19 days under fertigation. Red Salanova lettuce produced a statistically higher dry biomass, leaf number and area than Green Salanova. Leaf area and plant dry biomass were the highest on 30:70 simulant:compost mixture. Nevertheless, the 70:30 mixture was the best substrate in terms of pore-size distribution for water-plant relationship and the best compromise for plant growth and sustainable use of compost, a limited resource in BLSS. Many remaining issues warrant further investigation concerning the dynamics of compost production, standardisation of supply during space missions and representativeness of simulants to real Mars regolith. Unlabelled Image • Coarse-textured alkaline simulant most consists of plagioclase and amorphous minerals • Simulant can be source of plant nutrients, but lacks of organic matter and nitrogen. • Bulk density and pH of simulant were lowered by increasing compost amendment. • Compost addition improved nutrient availability and hydraulic properties of simulant. • The highest plant dry biomass was produced on 30:70 simulant:compost mixture. [ABSTRACT FROM AUTHOR]

Carbon monoxide occurs at relatively high concentrations (≥800 parts per million) in Mars' atmosphere, where it represents a potentially significant energy source that could fuel metabolism by a localized putative surface or near-surface microbiota. However, the plausibility of CO oxidation under conditions relevant for Mars in its past or at present has not been evaluated. Results from diverse terrestrial brines and saline soils provide the first documentation, to our knowledge, of active CO uptake at water potentials (-41 MPa to -117 MPa) that might occur in putative brines at recurrent slope lineae (RSL) on Mars. Results from two extremely halophilic isolates complement the field observations. Halorubrum str. BV1, isolated from the Bonneville Salt Flats, Utah (to our knowledge, the first documented extremely halophilic CO-oxidizing member of the Euryarchaeota), consumed CO in a salt-saturated medium with a water potential of -39.6 MPa; activity was reduced by only 28% relative to activity at its optimum water potential of -11 MPa. A proteobacterial isolate from hypersaline Mono Lake, California, Alkalilimnicola ehrlichii MLHE-1, also oxidized CO at low water potentials (-19 MPa), at temperatures within ranges reported for RSL, and under oxic, suboxic (0.2% oxygen), and anoxic conditions (oxygen-free with nitrate). MLHE-1 was unaffected by magnesium perchlorate or low atmospheric pressure (10 mbar). These results collectively establish the potential for microbial CO oxidation under conditions that might obtain at local scales (e.g., RSL) on contemporary Mars and at larger spatial scales earlier in Mars' history.