The paper presents pioneering data on the comparative study of impact glasses from the Zhamanshin crater and lunar regolith (delivered by the Luna 16, 20, and 24 probes). The data were acquired using ...analytical techniques of ultrahigh spatial resolution. Many of the melt and condensate impact glasses, both terrestrial and lunar, are similar in inner structure and composition, which were controlled primarily by the physics of the impacts and similar compositions of the targets.
In preparation for the upcoming Luna 27 mission to the south polar region of the Moon, the Package for Resource Observation and in-Situ Prospecting for Exploration Commercial exploitation and ...Transportation (PROSPECT) is undergoing a series of tests to ensure its suitability for polar regolith and volatile analysis. A lunar regolith simulant, NU-LHT-2M, was used for geotechnical validation and volatile extraction testing. Therefore, the physical, chemical/mineralogical, and spectral properties of separate batches of this simulant have been characterised to better understand the results of the instrument laboratory testing phase. Here we compare measurements from two different batches of the simulant to Apollo bulk regolith samples in order to understand the suitability and representativeness of the simulant to the properties of surface highlands regolith. Based on our measurements, we recommend that the physical, mineralogical, and spectral properties of simulants be analysed both before and after space instrument testing campaigns. These bookended measurements would allow for a more detailed understanding of the test phase, including: how the simulants have been altered by the test and, therefore, how the lunar surface may be affected by mission extraction and sampling processes.
The Luna structure of India has been rumored to be an impact crater for more than a decade without any convincing evidence. This structure (1.5–1.8 km) is prominently visible in the low-lying Banni ...Plains of the tectonically active Kutch Basin as a circular morphological feature with a less-prominent rim. Luna area is strewn with melt-like rocks having high specific gravity and displaying wide range of magnetic properties. It contains minerals like wüstite, kirschsteinite, ulvöspinel, hercynite, and fayalite. The whole rock analysis denotes PGE enrichment, with notably higher average concentrations of Ru (19.02 ppb), Rh (5.68 ppb), Pd (8.64 ppb), Os (6.03 ppb), Ir (10.63 ppb) and Pt (18.31 ppb). The target is not exposed at Luna, owing to the overlying thick sequence of Quaternary sediments. The mineralogical and geochemical signatures points to an impact into a target, which is rich in clay with elevated calcium and silica (sand/silt) content. Geochemical data suggests an iron or stony-iron meteorite as the potential projectile at Luna. The silt layer containing plant remnants, underlying the strewn layer, yielded a radiocarbon age of 6905 years, making Luna the biggest crater to result from an iron bolide within the last 10,000 years.
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•Confirmation of Luna as an impact crater uptick the limited numbers of crater in India.•Characteristic mineral of meteorites like wüsite, kirschsteinite, hercynite, and ulvöspinel were identified.•Luna samples have one of the highest Ir values amongst the different terrestrial impactites.•Geochemistry confirms iron bolide as the potential impactor.•An age of <6.9 ka and 1.8 km diameter makes Luna the largest crater within the last 10 ka.
Abstract
Collective identities, as literature suggests, are constructed via an emphasis on sameness within a group and in the downplaying of internal difference. This study, however, found that ...collective agency, and resultingly, collective identity, was fueled just as much by a careful negotiation of difference as it was a group's core similarities. Based on interviews with Palestinian, Israeli, and international activists involved in two Palestinian-led coalitions in Israel/Palestine, the study shows how uneven privileges and other differences, could be leveraged for the benefit of the coalitions, particularly through assessing what each ethno-national group brought to the collective. When members enacted their closely negotiated and distinct roles, the coalition's sense of “we” was further solidified. Indeed, as this article illustrates, difference as well as unequal privileges, can be perceived as a defining feature of a strategically constructed collective identity and the reason for a partnership, not simply a problem to be managed.
High mountain lakes and their catchments are remote ecosystems in areas with low anthropogenic disturbance. High mountain lakes integrate changes in the atmosphere and catchment areas (e.g., acid ...rain, airborne pollutants, climate change). The present research analyses long-term datasets of meteorological and limnological variables representing two tropical high mountain lakes, El Sol and La Luna, in Central Mexico to identify the impacts of anthropogenic disturbance (i.e., sentinels of global/climate change). The 54-year meteorological analysis showed marked interannual variability with no statistically significant air temperature or rainfall trends. However, from 2000 to 2018, the air temperature increased by 0.5 °C. Accordingly, the lake water temperature increased (Lake El Sol: 0.8 °C, Lake La Luna: 0.6 °C). Although the rainfall displayed no change, the water level decreased in both lakes (1.5 m), most likely associated with increased evapotranspiration. Unexpectedly, the dissolved inorganic nitrogen (DIN) concentration in the lakes decreased. The initial acid pH rose to close neutrality in Lake La Luna and to alkaline values in Lake El Sol. The latter may be a consequence of the lowered SOx and NOx emissions from governmental regulations promulgated to control atmospheric pollution beginning in 2000 and probably resulting in less acidic deposition. An additional explanation for the lakes' deacidification is the increased deposition of alkaline ions derived from activities at the volcano slopes. Since the atmospheric supply is the primary nitrogen source to high mountain lakes, the DIN concentration decline could reflect the reduction in atmospheric HNO3. Thus, Lakes El Sol and La Luna evidenced global change. Both lakes are inside the same crater and are subjected to similar influences; thus, they showed similar responses to global change (increasing lake water temperatures, declining water levels, higher pH value, and lower DIN concentrations). Nevertheless, their differences (e.g., catchment size, surface area, water volume, water depth, trophic status) influenced the magnitude of the impacts, with higher pH increases recorded in Lake El Sol and higher DIN concentrations in Lake La Luna.
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•Air temperature and rainfall were affected by teleconnection indices.•While the air and water temperature increased, the lakes' water levels decreased.•DIN decreased by the reduction of atmospheric acid precursors.•The atmospheric acid precursors reduction increased pH in the lakes.•The global change affected both lakes similarly but with a different magnitude.
Proyecto FOCARIS, habitar la Luna Eid-Macheh-Sánchez, Yasmina; García-Valverde, Juanjo; Martínez-Frías, Jesús ...
Informes de la construcción,
03/2023, Letnik:
75, Številka:
569
Journal Article
Recenzirano
Odprti dostop
Contar con nuevos hábitats frente a la colonización de otros planetas surge de la motivación innata en los seres humanos de “traspasar fronteras”, llevando implícita la persecución del avance ...científico, tecnológico y sociocultural por medio del estudio y puesta en marcha de nuestras capacidades junto a la búsqueda de desarrollo. Así, Stephen Hawking encontraba necesario “ir donde nadie ha ido nunca aún”, con el fin de poder sobrevivir frente a “peligros y desastres” múltiples. En este sentido, proyectar y construir en base a las necesidades de máxima seguridad, confort, y mínimo consumo energético se hace necesario para cumplir, como decía Alvar Aalto (pionero en la arquitectura moderna), con “las plenas exigencias de una sociedad positiva”. Reflexiones estas, que ayudaron a plantear uno de los diez hábitats finalistas de un concurso internacional para el diseño de un futuro hábitat extraterrestre pensado con el fin de albergar vida humana en nuestro satélite, la Luna, denominada FOCARIS.
We review constraints on the magnitude and possible causes of discrepancies, or at least major disparities, among global and near‐global data sets for lunar highland surface composition. When ...compared with data from other sources, reported mafic mineral abundance results from the Kaguya Spectral Profiler (Kaguya SP) spectral reflectance method for four Apollo 16 soils appear systematically low by a factor of 0.6, or an even more extreme factor (~1/3) if viewed in relation to the soils’ nonglass or CIPW mineralogy. Also, whether evaluated on a global median basis or on the basis of site‐by‐site comparison (for Apollo 16, Luna 20, and Apollo 17), the compositions found by the Kaguya SP technique show discrepancy, or at least disparity, versus other mafic abundance observations by that same factor of ~1/3. Spectral reflectance does not supply a simple bulk analysis of the target soil. The reflectance mineralogical signal is preponderantly determined by the nonglass fraction, and especially the masswise subordinate 10–20 µm grain size fraction. Literature data show that in anorthositic lunar soil, chemical composition is fractionated, more extremely anorthositic, for the nonglass component compared to the glass component. Also, the grain size fraction (10–20 μm) that most closely matches bulk reflectance has a significantly higher abundance of impact/agglutinitic glass than does the coarser material that dominates the soil mass. The Kaguya SP mafic abundance calibration needs adjustment by a factor of nearly 3 if results are to be interpreted as indicative of the mineralogy of the underlying crust. A claimed detection of several hundred lunar 500 m scale purest anorthosite (PAN; ≥98 vol% plagioclase) locales among millions of spectral reflectance observations is dubious, in part because with large data sets, compositional extremes are inevitably exaggerated as a byproduct of analytical uncertainty. Preponderance of PAN composition is rare among terrestrial layered intrusive anorthosites and is neither required nor expected for the flotation crust of a global magma ocean. Buoyant flotation and compaction would not suffice to yield pure plagioclase unless adcumulus growth was negligible, and trace element contents of ferroan anorthosites show that their mafic silicate components are for the most part of adcumulus, not “trapped melt,” derivation. A PAN‐dominated crust would imply a curiously fractionated (low) thorium/aluminum ratio for the crust, an implausibly high mantle/crust Th concentration ratio, and an oddly low Th/Al for the bulk Moon. Remote sensing techniques for planetary regolith composition are not easy to calibrate, particularly near the extremes of composition‐space and sensitivity.
The Late Heavy Bombardment Bottke, William F; Norman, Marc D
Annual review of earth and planetary sciences,
08/2017, Letnik:
45, Številka:
1
Journal Article
Recenzirano
Heavily cratered surfaces on the Moon, Mars, and Mercury show that the terrestrial planets were battered by an intense bombardment during their first billion years or more, but the timing, sources, ...and dynamical implications of these impacts are controversial. The Late Heavy Bombardment refers to impact events that occurred after stabilization of the planetary lithospheres such that they could be preserved as craters and basins. Lunar melt rocks and meteorite shock ages point toward a discrete episode of elevated impact flux between ∼3.5 and ∼4.0-4.2 Ga, and a relative quiescence between ∼4.0-4.2 and ∼4.4 Ga. Evidence from Precambrian impact spherule layers suggests that a long-lived tail of terrestrial impactors lasted to ∼2.0-2.5 Ga. Dynamical models that include populations residual from primary accretion and destabilized by giant planet migration can potentially account for the available observations, although all have pros and cons. The most parsimonious solution to match constraints is a hybrid model with discrete early, post-accretion and later, planetary instability-driven populations of impactors.
A partir del uso de la metodología del Análisis de Eventos de Protesta (AEP) y de la Teoría de las Oportunidades Políticas, el presente artículo realiza un análisis descriptivo de las acciones ...colectivas registradas durante los primeros siete meses de gestión del gobierno de Rodrigo Chaves Robles en Costa Rica. Particularmente, se discute cómo se comporta la protesta social en contextos de “luna de miel”, un concepto utilizado para referirse al período de alto nivel de aprobación presidencial al comienzo de la administración. El principal hallazgo es que el inicio de la administración Chaves Robles ha sido la menos conflictiva de los últimos ocho años, lo que podría deberse a un marco de menores oportunidades políticas para la protesta social y la organización del descontento en este periodo. Sin embargo, las primeras medidas concretas de Chaves, especialmente aquellas en contra de los derechos laborales y lesivas para la institucionalidad pública, poco a poco han contribuido a un paulatino repunte en los niveles de la protesta social, en especial, entre agosto y octubre del 2022.
The influence of the particle size distribution (PSD) on the band broadening and the efficiency of packed columns is investigated on both theoretical and practical viewpoints. Each of the classical ...contributions to mass transfer kinetics, those due to longitudinal diffusion, eddy dispersion, and solid–liquid mass transfer resistance are measured and analyzed in terms of their expected and observed intensity as a function of the PSD of mixtures of the commercially available packing materials, 5 and 3
μm Luna-C
18(2) particles (Phenomenex, Torrance, CA, USA). Six 4.6
mm
×
150
mm columns were packed with different mixtures of these two materials. The efficiencies of these columns were measured for a non-retained and a retained analytes in a mixture of acetonitrile and water. The longitudinal diffusion coefficient was directly measured by the peak parking method. The solid–liquid mass transfer coefficient was measured from the combination of the peak parking method, the best model of effective diffusion coefficient and the actual PSDs of the different particle mixtures measured by Coulter counter experiments. The eddy diffusion term was measured according to a recently developed protocol, by numerical integration of the peak profiles. Our results clearly show that the PSD has no measurable impact on any of the coefficients of the van Deemter equation. On the contrary and surprisingly, adding a small fraction of large particles to a batch of small particles can improve the quality of the packing of the fine particles. Our results indirectly confirm that the success of sub-3
μm shell particles is due to the roughness of their external surface, which contributes to eliminate most of the nefarious wall effects.
