•Abiotic formation of organic compounds was studied experimentally.•Fischer-Tropsch-type (FTT) processes resulted in biomarker-like alkyl lipids.•FTT-derived alkanes, alkanols and alkanoic acids are ...described in detail.•Abiotic and biologically-derived organics are compared.•Analyses of extraction residues revealed existence of a potential FTT polymer.
Lipid biomarkers are commonly used for tracking life through Earth’s history and are also gaining in importance in the search for extraterrestrial life. However, some lipids may also be formed in-situ via abiotic Fischer-Tropsch-type (FTT) reactions. These processes have been considered as a source of prebiotic organic matter. Here we report on a FTT synthesis experiment performed under hydrothermal conditions, focusing on more complex, previously undescribed FTT reaction products that may potentially mimic biological signals. The experiment was carried out in stainless steel reactors by heating aqueous solutions of oxalic acid mixed with montmorillonite to 175 °C for 3 days. Organic extracts of the products and extraction residues were analyzed by gas chromatography–mass spectrometry (GC–MS) and combustion-infrared detection, attenuated total reflectance Fourier transform infrared spectroscopy and pyrolysis GC–MS. FTT reactions led to a number of biomarker-like lipids such as linear and methyl-branched alkanes and alkanols as well as n-alkanoic acids. However, FTT reactions a priori produce unimodal chain length distributions and isomeric mixtures of methyl-branched compounds, as opposed to biolipids which typically show preferences of individual homologs and/or isomers. Experimental maturation of an immature kerogen demonstrated how these biological signatures may pass into unimodal distributions similar to FTT reaction products by thermal overprint. Therefore, discrimination of biologically derived compounds from FTT organics may become increasingly problematic with ongoing thermal maturation. Extraction residues of FTT reaction products contained organic material, possibly in form of an organic polymer. However, it remains to be tested whether these residual organics can evolve into kerogen-like material.
In this paper we describe a method to compute spatial scales for images acquired by NASA's Mars Curiosity rover (Mars Science Laboratory, MSL). The method is based on the assumption that the rover ...stands on an infinite plane that may have any orientation with respect to the local gravity vector. While not new, it is the first time that this method is systematically applied to Martian images acquired by a lander. A continuously run software pipeline processes the images acquired by the rover within a 20 m radius, adds approximate scalebars to the raw images, and generates, whenever possible, rectified (warped) versions of those images. The products of this software pipeline and the chemical compositions of relevant rover science targets from NASA's Planetary Data System archive, are made available to the public via the Approximate Scale for Images and Chemistry website, which has been developed in collaboration with the Planetary Data System Analyst's Notebook for the MSL mission. Hyperlinks connect the two resources.
Plain Language Summary
We developed a software pipeline that calculates the spatial scale of images acquired by NASA's Mars Curiosity rover. The software pipeline is linked to a new website: the Approximate Scale for Images and Chemistry, in which the scalebar products are paired with information about the shape, size, color, and chemical composition of the imaged site, obtained by the rover suite of instruments. The images mimic the vantage point of human eyes and are therefore well‐suited to inspire field geologists (including those mainly working on Earth) to interpret Martian geologic features.
Key Points
A systematic method to generate approximate scalebars for obliquely acquired Martian landscape images was developed
A newly created Approximate Scale for Images and Chemistry (ASIC) website links images, color, spatial scale, and chemistry, as returned by NASA's Curiosity rover in Gale crater
The ASIC website is complementary and strongly linked to the Analyst's Notebook, the data resource for Martian/lunar landed missions
The objective of the Phoenix mission is to determine if Mars' polar region can support life. Since liquid water is a basic ingredient for life, as we know it, an important goal of the mission is to ...determine if liquid water exists at the landing site. It is believed that a layer of Martian soil preserves ice by forming a barrier against high temperatures and sublimation, but that exposed ice sublimates without the formation of the liquid phase. Here we show possible independent physical and thermodynamical evidence that besides ice, liquid saline water exists in areas disturbed by the Phoenix Lander. Moreover, we show that the thermodynamics of freeze‐thaw cycles can lead to the formation of saline solutions with freezing temperatures lower than current summer ground temperatures on the Phoenix landing site on Mars' Arctic. Thus, we hypothesize that liquid saline water might occur where ground ice exists near the Martian surface. The ideas and results presented in this article provide significant new insights into the behavior of water on Mars.
► We investigate Apollinaris Mons for signs of ancient hydrothermal activity. ► The region shows extensive evidence for volcanic and hydrologic activity. ► We report on various putative signs of ...magma–water interaction in the area. ► The Apollinaris Mons fan deposits may be thicker than previously estimated. ► Numerous mounds around the volcano could be of exobiological significance.
A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly hydrothermal activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5–2
km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. 1993. Icarus 104, 301–323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma–water interaction or, alternatively, volatile-rich magmas early in the volcano’s history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation.
The findings point to a site of extensive volcanic and hydrologic activity with possibly a period of magma–water interaction and hydrothermal activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures.
The Panoramic Camera (Pancam) on the Mars Exploration Rover mission has acquired in excess of 20,000 images of the Pancam calibration targets on the rovers. Analysis of this data set allows estimates ...of the rate of deposition and removal of aeolian dust on both rovers. During the first 150–170 sols there was gradual dust accumulation on the rovers but no evidence for dust removal. After that time there is ample evidence for both dust removal and dust deposition on both rover decks. We analyze data from early in both rover missions using a diffusive reflectance mixing model. Assuming a dust settling rate proportional to the atmospheric optical depth, we derive spectra of optically thick layers of airfall dust that are consistent with spectra from dusty regions on the Martian surface. Airfall dust reflectance at the Opportunity site appears greater than at the Spirit site, consistent with other observations. We estimate the optical depth of dust deposited on the Spirit calibration target by sol 150 to be 0.44 ± 0.13. For Opportunity the value was 0.39 ± 0.12. Assuming 80% pore space, we estimate that the dust layer grew at a rate of one grain diameter per ∼100 sols on the Spirit calibration target. On Opportunity the rate was one grain diameter per ∼125 sols. These numbers are consistent with dust deposition rates observed by Mars Pathfinder taking into account the lower atmospheric dust optical depth during the Mars Pathfinder mission.
After the Swiss government's decision to decommission its five nuclear power plants by 2035, energy production from wind, biomass, biogas and photovoltaic is expected to increase significantly. Due ...to its many aspects of a direct democracy, high levels of public acceptance are necessary if a substantial increase in new renewable energy power plants is to be achieved in Switzerland. A survey of 502 citizens living near 19 biogas plants was conducted as the basis for using structural equation modeling to measure the effects of perceived benefits, perceived costs, trust towards the plant operator, perceived smell, information received and participation options on citizens’ acceptance of “their” biogas plant. Results show that local acceptance towards existing biogas power plants is relatively high in Switzerland. Perceived benefits and costs as well as trust towards the plant operator are highly correlated and have a significant effect on local acceptance. While smell perception and information received had a significant effect on local acceptance as well, no such effect was found for participation options. Reasons for the non-impact of participation options on local acceptance are discussed, and pathways for future research are presented.
•Acceptance of biogas plants by local residents in Switzerland is relatively high.•Local acceptance is highly affected by perceived outcomes and citizens’ trust.•Smell perception increases perceived costs and reduces perceived benefits and trust.•Information offers reduce perceived costs and increase trust and perceived benefits.•Participation offers do not have any effect on local acceptance.
Hydropower remains, by a wide margin, the largest source of renewable electricity around the world, and hydropower dams supply a greater source of commercial energy than the world's fleet of nuclear ...power plants. Yet far less attention has been paid to the political, security, and governance elements underlying the continued use and growth of hydropower. Theorists from many disciplines—political geography, security studies, development studies, economics, public policy, and governance—have questioned both the proper role and ostensible benefits from the generation of electricity from large-scale hydroelectric dams, but have tended to approach the problem on a case-by-case basis. In this study, we provide the first systematic, cross-comparative assessment of five hypotheses about global hydropower states, using World Bank data from 1980 to 2010 and a research design which incorporates five reference classes of countries. Based on regression and comparative country analyses, we find tentative statistical evidence that hydropower countries do seem to perform worse on a series of security, economic development, and governance metrics.
•We provide a multidimensional assessment of global hydropower states.•We find that hydropower countries perform worse on a series of security and economic metrics.•They also perform worse on development and governance metrics.
Our study offers a comparative assessment of the economic, sociopolitical and environmental implications of the world's largest source of renewable electricity, hydropower. Theorists from many ...disciplines have questioned both the proper role and ostensible benefits from the generation of electricity from large-scale hydroelectric dams. In this study, we use 30 years of World Bank data from 1985 to 2014 and a research design with three mutually exclusive reference classes of countries: major hydropower producers, members of OPEC and all other countries. This is precisely so our analysis moves away from 'dam-centric' or single case study approaches to comparative analysis at the international scale. We examine and test six separate hypotheses related to (a) military conflict, (2) poverty, (3) economic growth, (4) public debt, (5) corruption and (6) greenhouse gas emissions.
Our analysis lends statistical support to the idea that there is such a thing as a 'hydroelectric resource curse', although effects were not always significant and varied from small, medium to large. The possible benefits of hydroelectricity-improved energy access, economic development and positive spillover effects-are real, but they are all too frequently constrained. Planners, investors and researchers may therefore need to rethink their underlying assumptions about how they evaluate hydropower's risk.
PDF
