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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 developedA 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 craterThe ASIC website is complementary and strongly linked to the Analyst's Notebook, the data resource for Martian/lunar landed missions [ABSTRACT FROM AUTHOR]

Laser‐induced breakdown spectroscopy, as utilized by the ChemCam instrument onboard the Curiosity rover, detected enhanced abundances of the element copper. Since landing in Gale crater (6 August 2012), 10 enhancements in copper abundance were observed during 3007 Martian days (sols) of rover operations and 24 km of driving (as of 20 January 2021). The most prominent ones were found in the Kimberley area on the crater floor (Aeolis Palus) and in Glen Torridon (GT) on the lower flanks of Aeolis Mons (Mt. Sharp). Enhancements in copper record the former existence of modestly acidic and oxidizing fluids, which were more oxidizing in Kimberley than in GT. Of the two main types of bedrock in the lowest part of GT, Mg‐rich "coherent" and K‐rich "rubbly" (named based on their outcrop expression), copper was detected only in coherent, not in rubbly bedrock. The difference between these two types of bedrock may be due to difference in provenance. Alternatively, based on a recently developed lacustrine‐groundwater mixing model, we suggest that rubbly bedrock was altered by modestly acidic, shallow‐subsurface lake water that leached out both copper and manganese, while coherent bedrock was affected by dominantly alkaline fluids which would be consistent with its mineralogical composition (including siderite) as returned by the CheMin instrument onboard the rover. Higher up in GT, ChemCam data indicated significant gradients in the copper concentration in coherent bedrock on a local scale of only a few meters, which suggests a different alteration style and possibly different types of diagenetic fluids. Plain Language Summary: Gale crater, Mars, about 152‐km in diameter and 3.6 Ga in age, has a central mound that is partly of sedimentary origin. To date (July 2022), the NASA rover Curiosity has been exploring the crater floor and the lower‐most 600 m (in elevation) of sediments of that mound. ChemCam, an instrument mounted on top of the remote‐sensing mast utilizing Laser‐Induced Breakdown Spectroscopy, has been measuring chemical composition and specifically copper abundances along the rover traverse. We identified 10 areas of copper enhancement along Curiosity's traverse. In the Kimberley formation on the crater floor, copper was identified in a manganese‐rich sandstone. Later on, some 350 m above Kimberley, high copper abundances were detected in magnesium‐rich mudstone and in iron‐rich sandstone in the Jura and Knockfarril Hill member, respectively. Following earlier work about copper in Gale crater (Payré et al., 2019, https://doi.org/10.1016/j.icarus.2018.12.015), we postulate a copper‐rich source region north of Gale crater and suggest that copper‐rich detrital material delivered to these areas in Gale crater. Taking into account the chemical and mineralogical composition of these types of bedrock, we conclude that copper was mobilized by later acidic and oxidizing fluids. Key Points: High copper abundances (200–400 ppm) are found in specific areas along the rover traverseIn the Jura member in Glen Torridon (GT), copper is detected only in coherent bedrock, not in rubbly bedrockIn the Knockfarril Hill member in GT, there is evidence for the redistribution of copper and iron by acidic, oxidizing fluids [ABSTRACT FROM AUTHOR]

The clay‐rich Glen Torridon region of Gale crater, Mars, was explored between sols 2300 and 3007. Here, we analyzed the diagenetic features observed by Curiosity, including veins, cements, nodules, and nodular bedrock, using the ChemCam, Mastcam, and Mars Hand Lens Imager instruments. We discovered many diagenetic features in Glen Torridon, including dark‐toned iron‐ and manganese‐rich veins, magnesium‐ and fluorine‐rich linear features, Ca‐sulfate cemented bedrock, manganese‐rich nodules, and iron‐rich strata. We have characterized the chemistry and morphology of these features, which are most widespread in the higher stratigraphic members in Glen Torridon, and exhibit a wide range of chemistries. These discoveries are strong evidence for multiple generations of fluids from multiple chemical endmembers that likely underwent redox reactions to form some of these features. In a few cases, we may be able to use mineralogy and chemistry to constrain formation conditions of the diagenetic features. For example, the dark‐toned veins likely formed in warmer, highly alkaline, and highly reducing conditions, while manganese‐rich nodules likely formed in oxidizing and circumneutral conditions. We also hypothesize that an initial enrichment of soluble elements, including fluorine, occurred during hydrothermal alteration early in Gale crater history to account for elemental enrichment in nodules and veins. The presence of redox‐active elements, including Fe and Mn, and elements required for life, including P and S, in these fluids is strong evidence for habitability of Gale crater groundwater. Hydrothermal alteration also has interesting implications for prebiotic chemistry during the earliest stages of the crater's evolution and early Mars. Plain Language Summary: The NASA Curiosity rover explored the ancient lakebed rocks within the Glen Torridon region of Mars from January 2019 to January 2021. The rover observed many signs that the bedrock was changed by groundwater, especially in the higher elevations along the rover's path. We used data from the rover's ChemCam instrument to record chemistry, and images from four cameras on the rover to look for physical changes to the rocks. When the rock in Glen Torridon was altered by groundwater, it introduced a variety of physical and chemical changes to the rock, and the amount of some elements (sodium, calcium, iron, magnesium, or manganese) increased in the rocks in association with these physical changes to the rocks. We can use these changes in the rock's characteristics to determine the type of water that changed these rocks on Mars (its chemical composition, its temperature, acidic vs. basic, oxidizing vs. reducing) at the time that the changes occurred. We found that many types of groundwater mixed at different times to cause changes to the rocks. At least one of the groundwater types was warmer than what was previously expected and could be related to the impact that formed the crater. Key Points: Glen Torridon in Gale crater underwent multiple generations of diagenesis of the bedrock that widely varies in chemistry and morphologyOne hypothesis suggests an initial enrichment of elements occurred during the Gale's post‐impact hydrothermal alteration phase of evolutionWe estimate that at least one type of vein in Glen Torridon required warm temperatures, and highly reducing and alkaline fluid to form [ABSTRACT FROM AUTHOR]

Author(s): Walter Goetz (corresponding author) [1]; Preben Bertelsen [2]; Charlotte S. Binau [2]; Haraldur P. Gunnlaugsson [3]; Stubbe F. Hviid [1]; Kjartan M. Kinch [3]; Daniel E. Madsen [2]; Morten [...]

Papillomavirus late gene expression is tightly linked to the differentiation state of the host cell. Levels of late mRNAs are only in part controlled by regulation of the late promoter, other posttranscriptional mechanisms exist that reduce the amount of late mRNA in undifferentiated cells. Previously we described a negative regulatory element (NRE) located upstream of the human papillomavirus type 16 late poly(A) site. We have delineated the NRE to a 79-nt region in which a G+U-rich region was the major determinant of NRE activity. UV-crosslinking assays identified a prominent nuclear protein of 65 kda as the only factor in close contact with the NRE, and a complex of at least five proteins, including the 65-kDa protein, was enriched on NRE-RNA. Binding of the 65-kDa protein was depleted by preincubation with poly(U) Sepharose in high salt, a property characteristic of the U2 small nuclear ribonucleo-protein auxiliary factor U2A[F.sup.65] and bacterially expressed U2A[F.sup.65] exhibited NRE binding. The 65-kDa protein bound to the G+U-rich NRE 3[prime] half which shows homology to the B2P2 sequence a known U2A[F.sup.65] binding site in the [Alpha]-tropomyosin gene, and the G+U-rich element can be replaced by B2P2 in the binding assay. Treatment of cells with phorbol 12-myristate 13-acetate reduced binding of the 65-kDa protein, induced NRE binding of a cytoplasmic protein, and relieved the NRE block on reporter gene expression.

The Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2020 rover (to be landed in March 2021) utilizes pyrolysis gas chromatography–mass spectrometry (GC-MS) with the aim to detect organic molecules in martian (sub-) surface materials. Pyrolysis, however, may thermally destroy and transform organic matter depending on the temperature and nature of the molecules, thus altering the original molecular signatures. In this study, we tested MOMA flight-like pyrolysis GC-MS without the addition of perchlorates on well-characterized natural mineralogical analog samples for Oxia Planum, the designated ExoMars 2020 landing site. Experiments were performed on an iron-rich shale (that is rich in Fe-Mg-smectites) and an opaline chert, with known organic matter compositions, to test pyrolytic effects related to heating in the MOMA oven. Two hydrocarbon standards (n-octadecane and phytane) were also analyzed. The experiments show that during stepwise pyrolysis (300°C, 500°C, and 700°C), (1) low-molecular-weight hydrocarbon biomarkers (such as acyclic isoprenoids and aryl isoprenoids) can be analyzed intact, (2) discrimination between free and complex molecules (macromolecules) is principally possible, (3) secondary pyrolysis products and carryover may affect the 500°C and 700°C runs, and (4) the type of the organic matter (functionalized vs. defunctionalized) governs the pyrolysis outcome rather than the difference in mineralogy. Although pyrosynthesis reactions and carryover clearly have to be considered in data interpretation, our results demonstrate that pyrolysis GC-MS onboard MOMA operated under favorable conditions (e.g., no perchlorates) will be capable of providing important structural information on organic matter found on Mars, particularly when used in conjunction with other techniques on MOMA, including derivatization and thermochemolysis GC-MS and laser desorption/ionization–MS. [ABSTRACT FROM AUTHOR]

Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of the earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds). The Magadi cherts contain low organic carbon (< 0.4 wt %) that occurs in the form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both extractable (bitumen) and non-extractable organic matter (kerogen) were analyzed. The bitumens contain immature "biolipids" like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids, and alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring "geolipids" such as n -alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties (C 20 and C 25 chains) in kerogen pyrolysates indicate rapid sequestration of some archaeal lipids into kerogen while hydrothermal alteration was active. We posit that such early sequestration may enhance the resistance of molecular biosignatures against in situ hydrothermal and post-depositional alteration. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth. [ABSTRACT FROM AUTHOR]

Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds) - important analogs for Archean cherts. The Magadi cherts contain low organic carbon (< 0.4 wt.%) that occurs in form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both, extractable (bitumen) and non-extractable organic matter (kerogen) was analyzed. The bitumens contain immature "biolipids" like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids and - alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring "geolipids" such as n-alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties in some of the kerogens indicate that a fast sequestration of microbial lipids into kerogen must have occurred while hydrothermal alteration was active. We posit that such early sequestration may enhance the survival of molecular biosignatures during in-situ hydrothermal (and post-depositional) alteration through deep time. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions, and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth. [ABSTRACT FROM AUTHOR]

Abstract: The Panoramic Cameras on NASA's Mars Exploration Rovers have each returned more than 17,000 images of their calibration targets. In order to make optimal use of this data set for reflectance calibration, a correction must be made for the presence of air fall dust. Here we present an improved dust correction procedure based on a two‐layer scattering model, and we present a dust reflectance spectrum derived from long‐term trends in the data set. The dust on the calibration targets appears brighter than dusty areas of the Martian surface. We derive detailed histories of dust deposition and removal revealing two distinct environments: At the Spirit landing site, half the year is dominated by dust deposition, the other half by dust removal, usually in brief, sharp events. At the Opportunity landing site the Martian year has a semiannual dust cycle with dust removal happening gradually throughout two removal seasons each year. The highest observed optical depth of settled dust on the calibration target is 1.5 on Spirit and 1.1 on Opportunity (at 601 nm). We derive a general prediction for dust deposition rates of 0.004 ± 0.001 in units of surface optical depth deposited per sol (Martian solar day) per unit atmospheric optical depth. We expect this procedure to lead to improved reflectance‐calibration of the Panoramic Camera data set. In addition, it is easily adapted to similar data sets from other missions in order to deliver improved reflectance calibration as well as data on dust reflectance properties and deposition and removal history. [ABSTRACT FROM AUTHOR]

Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover, lowers the freezing temperature of water. Moreover, perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere-soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower. [ABSTRACT FROM AUTHOR]

369 randomly selected freshmen. (1962) at the University of New Mexico were sent a questionnaire related to college attrition, and the attitudes of withdrawees and continuers. were compared regarding teachers,. `counselors, facilities, and various personal experiences and conditions that might lead to withdrawal. The results failed to support reasons. for attrition commonly cited in the literature. Only 5 items distinguished the groups' reaction to the college environment. In fact, the continuers were more negative toward the college environment than the withdrawees. Only 3 reasons generally related to attrition differentiated the groups: withdrawees felt that problems of marriage, family finance, and general unhappiness were somewhat more important than did the continuers. These findings indicate that the real causes for college withdrawal have yet to be discovered. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]