1,339 research outputs found

    Nuclear rocket shielding methods, modification, updating, and input data preparation. Volume 5 - Two-dimensional, discrete ordinates transport technique Final progress report

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    Two dimensional, discrete ordinates transport technique for use with nuclear rocket shielding methods, modification, updating, and data input preparation - Vol.

    Using Technology to Better Characterize the Apollo Sample Suite: A Retroactive PET Analysis and Potential Model for Future Sample Return Missions

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    From 1969-1972 the Apollo missions collected 382 kg of lunar samples from six distinct locations on the Moon. Studies of the Apollo sample suite have shaped our understanding of the formation and early evolution of the Earth-Moon system, and have had important implications for studies of the other terrestrial planets (e.g., through the calibration of the crater counting record) and even the outer planets (e.g., the Nice model of the dynamical evolution of the Solar System). Despite nearly 50 years of detailed research on Apollo samples, scientists are still developing new theories about the origin and evolution of the Moon. Three areas of active research are: (1) the abundance of water (and other volatiles) in the lunar mantle, (2) the timing of the formation of the Moon and the duration of lunar magma ocean crystallization, (3) the formation of evolved lunar lithologies (e.g., granites) and implications for tertiary crustal processes on the Moon. In order to fully understand these (and many other) theories about the Moon, scientists need access to "new" lunar samples, particularly new plutonic samples. Over 100 lunar meteorites have been identified over the past 30 years, and the study of these samples has greatly aided in our understanding of the Moon. However, terrestrial alteration and the lack of geologic context limit what can be learned from the lunar meteorites. Although no "new" large plutonic samples (i.e., hand-samples) remain to be discovered in the Apollo sample collection, there are many large polymict breccias in the Apollo collection containing relatively large (approximately 1 cm or larger) previously identified plutonic clasts, as well as a large number of unclassified lithic clasts. In addition, new, previously unidentified plutonic clasts are potentially discoverable within these breccias. The question becomes how to non-destructively locate and identify new lithic clasts of interest while minimizing the contamination and physical degradation of the samples

    Nuclear rocket shielding methods, modification, updating, and input data preparation. Volume 1 - Synopsis of methods and results of analysis Final progress report

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    Analysis of data systems and computer programs for nuclear rocket shielding methods, modification, updating, and data input preparation - Vol.

    Meteoritic Material Recovered from the 07 March 2018 Meteorite Fall into the Olympic Coast National Marine Sanctuary

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    On 07 March 2018 at 20:05 local time (08 March 03:05 UTC), a dramatic meteor occurred over Olympic Coast National Marine Sanctuary (OCNMS) off of the Washington state coast (OCNMS fall, henceforth). Data to include seismometry (from both on-shore and submarine seismometers), weather radar imagery (Figure 1), and a moored weather buoy, were used to accurately identify the fall site. The site was visited by the exploration vessel E/V Nautilus (Ocean Exploration Trust) on 01 July 2018 [1] and by the research vessel R/V Falkor (Schmidt Ocean Institute) from 03-06 June 2019. Remotely operated vehicles (ROVs) from both vessels were used to search for meteorites and sample seafloor sediments. These expeditions performed the first attempts to recover meteorites from a specific observed fall in the open ocean. Analysis of weather radar data indicates that this fall was unusually massive and featured meteorites of unusually high mechanical toughness, such that large meteorites were disproportionately produced compared to other meteorite falls (Figure 2)[2-4]. We report the recovery of many (>100) micrometeorite-sized melt spherules and other fragments, and one small (~1mm3 ) unmelted meteorite fragment identified to date. Approximately 80% of the fragments were recovered from a single sample, collected from a round pit in the seafloor sediment. Melt spherules are almost exclusively type I iron-rich spherules with little discernible oxidation. Analyses are currently underway to attempt to answer the primary science question by identifying the parent meteorite type. Also, differences in the number and nature of samples collected by Nautilus and Falkor reveal a distinct loss rate to oxidation over the 15 months following the fall that is useful to inform future recovery efforts

    Application of remote sensing to study nearshore circulation

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    The research to use remote sensing techniques for studying the continental shelf is reported. The studies reported include: (1) nearshore circulation in the vincinity of a natural tidal inlet; (2) identification of indicators of biological activity; (3) remote navigation system for tracking free drifting buoys; (4) experimental design of an estuaring tidal circulation; and (5) Skylab support work

    Fieldpath Lunar Meteorite Graves Nunataks 06157, a Magnesian Piece of the Lunar Highlands Crust

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    To date, 49 feldspathic lunar meteorites (FLMs) have been recovered, likely representing a minimum of 35 different sample locations in the lunar highlands. The compositional variability among FLMs far exceeds the variability observed among highland samples in the Apollo and Luna sample suites. Here we will discuss in detail one of the compositional end members of the FLM suite, Graves Nunataks (GRA) 06157, which was collected by the 2006-2007 ANSMET field team. At 0.79 g, GRA 06157 is the smallest lunar meteorite so far recovered. Despite its small size, its highly feldspathic and highly magnesian composition are intriguing. Although preliminary bulk compositions have been reported, thus far no petrographic descriptions are in the literature. Here we expand upon the bulk compositional data, including major-element compositions, and provide a detailed petrographic description of GRA 06157

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