Stable isotope systematics of the martian regolith

The geologic history of a planetary body is recorded within its rock record. As such, meteorites provide an opportunity to answer questions about the geologic history of other planetary bodies. NWA 7034 and its paired stones represents a new class of martian meteorites that are the first examples of the martian surface available for analysis in terrestrial laboratories. Regolith breccia samples are composed of rock fragments from a diverse array of lithologic sources. As such, they consist of several lithologies that are not represented by other martian meteorites, providing an opportunity to further expand our understanding of Mars. The stable isotopic systematics of these martian regolith breccia (MRB) samples represents an opportunity to expand our understanding of geological processes and geochemical cycling on Mars, particularly those invoked of incorporating crustal or surficial deposits. A powerful tool when studying the isotope systematics of complex geological materials are SIMS techniques, as they offer unparalleled capability for the in situ isotopic analysis of samples at the microscale. The aims of this thesis were twofold: first to develop a high-resolution SIMS technique to be able to analyse the 16O, 17O, 18O isotopic compositions of achondrite materials, more specifically martian meteorites, and secondly, to assess the stable isotope (O and S) systematics of MRB samples with high-resolution, high-precision in situ microscale techniques (i.e., /\17O, /\33S and /\36S of MRB lithologies). First, I develop an analytical protocol whereby SIMS three O isotope measurements can be used to robustly distinguish achondrite (parent body) population values, including main-group pallasites (ca.-0.2permil) and martian meteorites (ca.+0.3permil), from the TFL (zero) to levels of analytical precision better than 0.10 permil. Then, it is applied to (1)samples of the SNC clan, (2)lithologies within ALH84001 and (3) MRB lithologies. The results of these analyses show (1)all SIMS isotopic analysis of SNC silicates lie within error of the MFL, and replicate whole-rock bulk analyses of the MFL; (2)The ALH84001 lithologies show more diversity than the SNCs, and evidence that the apparent variations within Fe-rich carbonates and silicate host rock within the specimen can be resolved during isotopic analysis with the in situ SIMS technique (3)MRB samples show non-uniform /\17O, with the lithologies assessed exhibiting a variation of more than 2permil. Also, several distinct /\17O compositions are seen in the rocks, with some feldspars (those with cryptoperthite textures), the matrix, and gabbroic clasts being significantly enriched, while pyroxene, oxide, and phosphate lithologies lie on the MFL. This may suggest interactions with distinct O sources, and maybe different geological processing. Lastly, I measure the 33S-MIF and 36S-MIF compositions of MRB sulphide minerals using SIMS isotopic analysis to address questions about the S source of these minerals to assess the distribution of S-MIF signatures in martian samples and inform our understanding of S cycling on Mars. Results suggest that MRB sulpides contain a heterogenous distribution of S-MIF signatures. The isotopic analysis of MRB sulphide grains do not show a uniform 33S composition, with heterogeneities spanning a 0.73permil range and show positive, near-0 and negative /\33S values within the same grain. However, the mostly +sign of 33-SMIF signatures suggests that at some point in its history the early martian atmospheric environment was favourable for MIF photochemical processing. This study shows that MRBs are isotopically heterogenous with variable O-MIF and S-MIF signatures that may record evidence of secondary planetary geological processes not documented in other martian rocks. Understanding these signatures has implications for atmosphere-regolith-crustal exchange interactions and increasing our understanding of the geologic history and evolution of Mars

Research and Technology Operating Plan. Summary: Fiscal year 1976 research and technology program

A compilation of the summary portions of each of the Research and Technology Operating Plans (RTOP) used for management review and control of research currently in progress throughout NASA was presented. The document is arranged in five sections. The first one contains citations and abstracts of the RTOP. This is followed by four indexes: subject, technical monitor, responsible NASA organization, and RTOP number

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 24)

Abstracts are provided for 167 patents and patent applications entered into the NASA scientific and technical information system during the period July 1983 through December 1983. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application

Geophysical study of four possible impact structures localized in the Parnaíba basin and geological/geophysical detail of the Serra da Cangalha structure/TO

Orientadores: Alvaro Penteado Crósta, Eder Cassola MolinaAcompanhado de 2 mapas (folhas soltas dobradas), acondicionados em bolsoTese (doutorado) - Universidade Estadual de Campinas, Instituto de GeociênciasResumo: A Bacia sedimentar do Parnaíba abriga em seus domínios diversas estruturas circulares, das quais algumas têm sua origem atribuída a impactos meteoríticos sem que, no entanto, haja evidências comprobatórias. Esta tese aborda um estudo das assinaturas geofísicas das estruturas de São Miguel do Tapuio (SMT), Santa Marta (SM), Riachão (Ria) e Serra da Cangalha (SdC) utilizando dados aerogeofísicos de baixa resolução com o intuito de compará-las com outras crateras meteoríticas similares. Aborda também estudos geofísicos, utilizando dados aéreos de alta resolução e terrestres das estruturas de SdC e Ria, além de estudos geológicos de detalhe da estrutura de SdC, duas feições circulares com diâmetros de ~13 km (SdC) e ~4 km (Ria) localizadas nos estados de Tocantins e Maranhão, respectivamente. Os resultados fornecidos pelos métodos geofísicos mostram que a estrutura de SMT exibe alto magnético e assinatura gravimétrica variável, características estas não compatíveis com o padrão de estruturas de impacto similares; SM apresenta anomalia magnética negativa e gravimétrica positiva, características compatíveis com origem por impacto; Ria exibe altos magnético e gravimétrico na região central, e anomalia gamaespectrométrica circular com abundância de K, Th e U em sua porção central. Apesar da assinatura gravimétrica de Ria não ser claramente diagnóstica, a assinatura magnética é semelhante às de crateras de impacto similares. A estrutura de SdC apresenta anomalia gravimétrica da ordem de 1 mGal e dados aeromagnéticos mostram que o embasamento está a uma profundidade média de ~1,9 km, diminuindo para cerca de 500 a 1000 metros em sua porção central. Dados gamaespectrométricos revelam altos valores de K, Th e U no núcleo soerguido e alto Th e U na região externa próximo ao limite da cratera. Do ponto de vista morfo-estrutural SdC é constituída por núcleo soerguido que tem ~5,8 km de diâmetro e que possui em seu interior proeminente colar com ~3 km de diâmetro. Dados estruturais de campo, associados com análises de imagens de sensoriamento remoto, revelam WNW-ESE como a principal direção de deformação além de camadas invertidas preferencialmente concentradas no setor noroeste do colar, o que sugere um impacto oblíquo de sul para norte. Feições de deformação por choque incluem shatter cones, feather features (FF), planar fractures (PF) e planar deformation features (PDF) formadas ao longo da direção (0001), indicando pressão de choque <10 GPa. Esse conjunto de feições foi encontrado principalmente nas brechas polimíticas e shatter cones da depressão central e comprova a origem por impacto meteorítico da estrutura de SdC. Finalmente, resultados obtidos pela modelagem numérica da formação de SdC indicam que ela foi formada por um bólido com diâmetro de 1,4 km, viajando a 12 km/s, resultando na formação de uma cratera com ~15 km de diâmetro que liberou energia da ordem de 2,74x1020 J, considerando um nível atual de erosão de aproximadamente 500 metrosAbstract: The sedimentary Parnaíba basin encompasses in its domains several circular structures, some of which have their origin attributed to meteoritic impacts without, however, diagnostic evidence. This thesis presents a study of the geophysical signatures of the São Miguel do Tapuio (SMT), Santa Marta (SM), Riachão (Ria) and Serra da Cangalha (SdC) structures using low-resolution geophysical data, in order to compare them with other similar meteorite impact structures. It also employs high-resolution aerogeophysical and ground geophysical data for the SdC and Ria structures, and detailed geological data from SdC. These are two circular features ~13 km (SdC) and ~4 km (Ria) in diameter, and which are located in the state of Tocantins and Maranhão, respectively. The results provided by geophysical methods show that SMT exhibits a high gravity and variable magnetic signature, which are not compatible with the patterns of similar sized impact structures; SM has a negative magnetic anomaly and positive gravity anomaly, which is compatible with other impact structures; Ria exhibits high magnetic and gravity in the central region, and a circular gamma-ray anomaly with high levels of K, Th and U in the center. Despite the fact that the gravity signature of Ria is not clearly comparable with that of other impact craters, the magnetic signature is similar to that of other craters. SdC shows a gravity anomaly of ~1 mGal and there is magnetic evidence that the basement rocks sit at ~1.9 km depth, decreasing to about 500 to 1000 meters depth in the central region of the structure. Gamma-ray data show high values of K, Th and U over the central uplift and high Th and U in the region near the outermost limit of the crater. Morpho-structural analysis indicates that SdC contains a central uplift ~ 5.8 km in diameter with a prominent collar ~ 3 km wide in its inner zone. Structural data associated with remote sensing images show WNW-ESE as the main direction of deformation as well as overturned layers preferentially concentrated in the northwestern sector of the collar, which suggest an oblique impact from south to north. Shock deformation features include shatter cones, feather features (FF), planar fractures (PF), and planar deformation features (PDF) formed along (0001), indicating the shock pressure experienced by the rocks of the central uplift to have been <10 GPa. These features have been found in polymict breccias and shatter coned samples from the central depression and provide definite evidence that SdC was formed by meteorite impact. Finally, numerical modeling indicates that a meteorite some 1.4 km in diameter and impacting at a velocity of 12 km/s could have formed the originally ~15 km diameter crater, releasing energy of 2.74x1020 J, assuming a current erosion level of approximately 500 metersDoutoradoGeologia e Recursos NaturaisDoutor em Ciência

Space station systems: A bibliography with indexes (supplement 10)

This bibliography lists 1,422 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1989 and December 31, 1989. Its purpose is to provide helpful information to researchers, designers and managers engaged in Space Station technology development and mission design. Coverage includes documents that define major systems and subsystems related to structures and dynamic control, electronics and power supplies, propulsion, and payload integration. In addition, orbital construction methods, servicing and support requirements, procedures and operations, and missions for the current and future Space Station are included

Reaching for the Stars : Studies in the History of Swedish Stellar and Nebular Astronomy, 1860–1940

This study considers astrophysics, stellar and nebular astronomy in Sweden. Emphasis is on the role of scientific technologies and practice, and the emergence of a modern observational astronomy, supplanting classical astronomy as the most vital field of Swedish astronomy. The introduction of photography and spectroscopy is discussed, mainly focused on Nils Dunér. The mechanical nature of the photographic observations was seen as something that entailed objectivity. Photography changed the way astronomers worked; the observations were industrialised. The stellar statistics of C.V.L. Charlier led to models of the distribution of stars in space; Charlier’s statistical astronomy was also connected with an increased interest for statistical methods in other parts of early twentieth-century Swedish culture. Knut Lundmark’s work was mainly on the distances to nebulæ. Lundmark also tried to catalogue the increased numbers of nebulæ observed in a general catalogue. A group centred on Bertil Lindblad worked on developing spectroscopical criteria for determining stellar distances. Lindblad and his group constructed a new observatory at Saltsjöbaden that was geared towards their research interests. Four professorial appointments are studied, where arguments about the relative merits of the fields of astronomy surfaced. The changing patterns of international contacts are also discussed, as are a number of astronomy-related scientists in other fields, publications on the history of astronomy and popular science

OGO program summary

An overview of the OGO program is presented. Brief descriptions of the six OGO spacecraft, and the experiments on each are included