Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space. We use rock physics models and Bayesian inversion to identify combinations of lithology, liquid water saturation, porosity, and pore shape consistent with the constrained mid-crust (∼11.5 to 20 km depths) seismic velocities and gravity near the InSight lander. A mid-crust composed of fractured igneous rocks saturated with liquid water best explains the existing data. Our results have implications for understanding Mars\' water cycle, determining the fates of past surface water, searching for past or extant life, and assessing in situ resource utilization for future missions.

There is limited research about how groups solve collective action problems in uncertain environments, especially if groups are confronted with unknown unknowns. We aim to develop a more comprehensive view of the characteristics that allow both groups and individuals to navigate such issues more effectively. In this article, we present the results of a new online experiment where individuals make decisions of whether to contribute to the group or pursue self-interest in an environment with high uncertainty, including unknown unknowns. The behavioral game, Port of Mars is framed as a first-generation habitat on Mars where participants have to make decisions on how much to invest in the shared infrastructure to maintain system health and how much to invest in personal goals. Participants can chat during the game, and take surveys before and after the game in order to measure personality attributes and observations from the game. Initial results suggest that a higher average social value orientation and more communication are the key factors that explain why some groups are more successful than others in surviving Port of Mars. Neither other attributes of players nor the group\'s communication content explain the observed differences between groups.

In this study, we conducted polymerase chain reaction (PCR) experiments using Escherichia coli (E. coli) and a Mars sand simulant (Mars Global Simulant MGS-1, Exolith Lab) to detect and analyze potential extraterrestrial life. The targeted DNA sequence is common among the bacterial kingdom on Earth. PCR experiments conducted after alkaline heat extraction, wherein samples with varying amounts of Mars sand simulant were compared, revealed that the simulant interfered with DNA detection. We then conducted PCR experiments following treatment with a sand DNA extraction kit on samples with various E. coli densities. DNA bands for a minimum E. coli density of 900 cells/(g sand) were confirmed, while no DNA bands were visible in the 90 cells/(g sand) sample with and without the Mars sand simulant. The total DNA mass contained in 900 cells was calculated to be 15.3 pg (i.e., 1.53 pg in 0.1 g sand sample we evaluated). We tested and compared the influence of the eluate of Mars sand simulant and DNA adsorption onto Mars sand simulant based on optical absorbance measurements. Our findings suggest that the mechanism by which the Mars sand simulant prevents PCR is through the adsorption of DNA onto the Mars sand simulant.

In recent years, extensive research has been dedicated to Mars exploration and the potential for sustainable interplanetary human colonization. One of the significant challenges in ensuring the survival of life on Mars lies in the production of food as the Martian environment is highly inhospitable to agriculture, rendering it impractical to transport food from Earth. To improve the well-being and quality of life for future space travelers on Mars, it is crucial to develop innovative horticultural techniques and food processing technologies. The unique challenges posed by the Martian environment, such as the lack of oxygen, nutrient-deficient soil, thin atmosphere, low gravity, and cold, dry climate, necessitate the development of advanced farming strategies. This study explores existing knowledge and various technological innovations that can help overcome the constraints associated with food production and water extraction on Mars. The key lies in utilizing resources available on Mars through in-situ resource utilization. Water can be extracted from beneath the ice and from the Martian soil. Furthermore, hydroponics in controlled environment chambers, equipped with nutrient delivery systems and waste recovery mechanisms, have been investigated as a means of cultivating crops on Mars. The inefficiency of livestock production, which requires substantial amounts of water and land, highlights the need for alternative protein sources such as microbial protein, insects, and in-vitro meat. Moreover, the fields of synthetic biology and 3-D food printing hold immense potential in revolutionizing food production and making significant contributions to the sustainability of human life on Mars.

Acetaminophen (APAP) overdose is the most common cause of acute liver failure (ALF) in the United States. Liver transplantation (LT) is potentially lifesaving for patients with ALF, but its feasibility in clinical practice is limited. Liver assist devices, such as the Molecular Adsorbent Recirculating System (MARS), are used in some centers as a \"bridge\" to liver transplantation or as a means of liver recovery, but their role in the treatment of ALF is not well-defined. We present the case of a 44-year-old man with APAP-associated ALF who experienced hepatic recovery after treatment with MARS.

Understanding the nature and preservation of microbial traces in extreme environments is crucial for reconstructing Earth\'s early biosphere and for the search for life on other planets or moons. At Rio Tinto, southwestern Spain, ferric oxide and sulfate deposits similar to those discovered at Meridiani Planum, Mars, entomb a diversity of fossilized organisms, despite chemical conditions commonly thought to be challenging for life and fossil preservation. Investigating this unique fossil microbiota can elucidate ancient extremophile communities and the preservation of biosignatures in acidic environments on Earth and, potentially, Mars. In this study, we use an innovative multiscale approach that combines the state-of-the-art synchrotron X-ray nanoimaging methods of ptychographic X-ray computed laminography and nano-X-ray fluorescence to reveal Rio Tinto\'s microfossils at subcellular resolution. The unprecedented nanoscale views of several different specimens within their geological and geochemical contexts reveal novel intricacies of preserved microbial communities. Different morphotypes, ecological interactions, and possible taxonomic affinities were inferred based on qualitative and quantitative 3D ultrastructural information, whereas diagenetic processes and metabolic affinities were inferred from complementary chemical information. Our integrated nano-to-microscale analytical approach revealed previously invisible microbial and mineral interactions, which complemented and filled a gap of spatial resolution in conventional methods. Ultimately, this study contributes to the challenge of deciphering the faint chemical and morphological biosignatures that can indicate life\'s presence on the early Earth and on distant worlds.

Jotun springs in Svalbard, Norway, is a rare warm environment in the Arctic that actively forms travertine. In this study, we assessed the microbial ecology of Jotun\'s active (aquatic) spring and dry spring transects. We evaluated the microbial preservation potential and mode, as well as the astrobiological relevance of the travertines to marginal carbonates mapped at Jezero Crater on Mars (the Mars 2020 landing site). Our results revealed that microbial communities exhibited spatial dynamics controlled by temperature, fluid availability, and geochemistry. Amorphous carbonates and silica precipitated within biofilm and on the surface of filamentous microorganisms. The water discharged at the source is warm, with near neutral pH, and undersaturated in silica. Hence, silicification possibly occurred through cooling, dehydration, and partially by a microbial presence or activities that promote silica precipitation. CO2 degassing and possible microbial contributions induced calcite precipitation and travertine formation. Jotun revealed that warm systems that are not very productive in carbonate formation may still produce significant carbonate buildups and provide settings favorable for fossilization through silicification and calcification. Our findings suggest that the potential for amorphous silica precipitation may be essential for Jezero Crater\'s marginal carbonates because it significantly increases the preservation potential of putative martian organisms.

Mars has been exposed to ionizing radiation for several billion years, and as part of the search for life on the Red Planet, it is crucial to understand the impact of radiation on biosignature preservation. Several NASA and ESA missions are looking for evidence of ancient life in samples collected at depths shallow enough that they have been impacted by galactic cosmic rays (GCRs). In this study, we exposed a diverse set of Mars analog samples to 0.9 Megagray (MGy) of gamma radiation to mimic 15 million years of exposure on the Martian surface. We measured no significant impact of GCRs on the total organic carbon (TOC) and bulk stable C isotopes in samples with initial TOC concentration > 0.1 wt. %; however, diagnostic molecular biosignatures presented a wide range of degradation that didn\'t correlate to factors like mineralogy, TOC, water content, and surface area. Exposure dating suggests that the surface of Gale crater has been irradiated at more than five times our dose, yet using this relatively low dose and \"best-case scenario\" geologically recalcitrant biomarkers, large and variable losses were nevertheless evident. Our results empasize the importance of selecting sampling sites at depth or recently exposed at the Martian surface.

The key building blocks for life on Mars could be preserved within potentially habitable paleo-depositional settings with their detection possible by utilizing mid-infrared spectroscopy; however, a definite identification and confirmation of organic or even biological origin will require the samples to be returned to Earth. In the present study, Fourier-transform infrared (FTIR) spectroscopic techniques were used to characterize both mineralogical and organic materials within Mars dust simulant JSC Mars-1 and ancient Antarctic cyanobacterial microbial mats from 1901 to 1904 Discovery Expedition. When FTIR spectroscopy is applied to cyanobacterial microbial mat communities, the resulting spectra will reflect the average biochemical composition of the mats rather than taxa-specific spectral patterns of the individual organisms and can thus be considered as a total chemical analysis of the mat colony. This study also highlights the potential difficulties in the detection of these communities on Mars and which spectral biosignatures will be most detectable within geological substrates. Through the creation and analysis of a suite of dried microbial mat material and Martian dust simulant mixtures, the spectral signatures and wavenumber positions of CHx aliphatic hydrocarbons and the C-O and O-H bands of polysaccharides remained detectable and may be detectable within sample mixtures obtained through Mars Sample Return activities.

Past and present habitability of Mars have been intensely studied in the context of the search for signals of life. Despite the harsh conditions observed today on the planet, some ancient Mars environments could have harbored specific characteristics able to mitigate several challenges for the development of microbial life. In such environments, Fe2+ minerals like siderite (already identified on Mars), and vivianite (proposed, but not confirmed) could sustain a chemolithoautotrophic community. In this study, we investigate the ability of the acidophilic iron-oxidizing chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans to use these minerals as its sole energy source. A. ferrooxidans was grown in media containing siderite or vivianite under different conditions and compared to abiotic controls. Our experiments demonstrated that this microorganism was able to grow, obtaining its energy from the oxidation of Fe2+ that came from the solubilization of these minerals under low pH. Additionally, in sealed flasks without CO2, A. ferrooxidans was able to fix carbon directly from the carbonate ion released from siderite for biomass production, indicating that it could be able to colonize subsurface environments with little or no contact with an atmosphere. These previously unexplored abilities broaden our knowledge on the variety of minerals able to sustain life. In the context of astrobiology, this expands the list of geomicrobiological processes that should be taken into account when considering the habitability of environments beyond Earth, and opens for investigation the possible biological traces left on these substrates as biosignatures.