Nitrate is common in Mars sediments owing to long-term atmospheric photolysis, oxidation, and potentially, impact shock heating. The Atacama Desert in Chile, which is the driest region on Earth and rich in nitrate deposits, is used as a Mars analog in this study to explore the potential effects of high nitrate levels on growth of extremophilic ecosystems. Seven study sites sampled across an aridity gradient in the Atacama Desert were categorized into 3 clusters—hyperarid, middle, and arid sites—as defined by essential soil physical and chemical properties. Intriguingly, the distribution of nitrate concentrations in the shallow subsurface suggests that the buildup of nitrate is not solely controlled by precipitation. Correlations of nitrate with SiO2/Al2O3 and grain sizes suggest that sedimentation rates may also be important in controlling nitrate distribution. At arid sites receiving more than 10 mm/yr precipitation, rainfall shows a stronger impact on biomass than nitrate does. However, high nitrate to organic carbon ratios are generally beneficial to N assimilation, as evidenced both by soil geochemistry and enriched culturing experiments. This study suggests that even in the absence of precipitation, nitrate levels on a more recent, hyperarid Mars could be sufficiently high to benefit potentially extant Martian microorganisms.

In this study, we conducted a survey among a large sample of U.S. adults to assess attitudes and beliefs about the causes of homelessness, policies to address homelessness, and programs for homeless individuals. In 2016, we surveyed a national sample of 541 adults from 47 different U.S. states using Amazon Mechanical Turk. Of the total sample, 78% reported that homelessness was a problem in their communities and 60% believed homelessness would increase in the next 5 years. The majority expressed compassion for homeless individuals and endorsed structural, intrinsic, and health factors as causes of homelessness. Most participants (73%–88%) believed the federal government should dedicate more funds and policies for homeless individuals. These attitudes were substantially more likely to be reported by participants who were female, lower income, Democrat, and personally exposed to homelessness. Most Americans care about homelessness as a major problem but there are divergent perspectives on solutions to address homelessness based on gender, income level, and political affiliation.

Phosphorus (P) is a crucial bioelement for life on Earth, as it is utilized in the formation of ATP/GTP, genetic materials (DNA/RNA), cell membrane phospholipids, and sugar phosphates formed as intermediate products during sugar metabolism (George et al., 2018). Due to the role P plays in the cycle of life, it is critical to understand P uptake and utilization pathways and their interaction with other key nutrients, such as carbon (C) and nitrogen (N). This is especially true in extreme environments, where organisms are often forced to find novel adaptation strategies for survival and C:N:P ratios may be atypical (Huang et al., 2018; Tian, Chen, Zhang, Melillo, & Hall, 2010). These environments also act as a unique analogue for investigating the potential for life on other planets including Mars, where in the planet's early history active hydrology promoted the release of nutrients making P bioavailable (Komatsu & Ori, 2000;

1] The Solar Wind Ion Detectors (SWIDs) on the Chang'E-1 spacecraft, while orbiting the Moon, occasionally observed two continuous flux peaks with energies not exceeding 8 and 4 times that of the prevailing solar wind proton energy. These form parallel curves (PCs) with an energy ratio of 2 in the energy-time spectrogram. The fluxes of the two curves are comparable, around 10 −5 ∼ 10 − 4 of the solar wind flux. The pitch angle distribution of PC particles is concentrated around 90°. The velocity space distribution of PC particles shows distinct double-ring feature, suggesting the existence of a pickup ion species with m/q = 2. Pickup ions from local interstellar medium, the inner sources and the lunar exosphere are investigated. We conclude that this observation may be the first in situ evidence for H 2 + ions in the lunar exosphere, thus providing new insights on the evolution and fate of solar wind hydrogen in the solar system. Citation: Wang, X.-D., et al. (2011), Detection of m/q = 2 pickup ions in the plasma environment of the Moon: The trace of exospheric H 2 + , Geophys. Res. Lett., 38, L14204,