Multi-Media Geochemical Exploration in the Critical Zone: A Case Study over the Prairie and Wolf Zn–Pb Deposits, Capricorn Orogen, Western Australia

In this study, we compared traditional lithochemical sample media (soil) with hydrochemical (groundwater), biogeochemical (plant matter of mulga and spinifex), and other near-surface sample media (ferro-manganese crust), in a case study applied to mineral exploration in weathered terrain, through the critical zone at the fault-hosted Prairie and Wolf Zn–Pb (Ag) deposits in Western Australia. We used multi-element geochemistry analyses to spatially identify geochemical anomalies in samples over known mineralization, and investigated metal dispersion processes. In all near-surface sample media, high concentrations of the metals of interest (Zn, Pb, Ag) coincided with samples proximal to the mineralization at depth. However, the lateral dispersion of these elements differed from regional (several km; groundwater) to local (several 100′s of meters; solid sample media) scales. Zinc in spinifex leaves over the Prairie and Wolf deposits exceeded the total concentrations in all other sample media, while the metal concentrations in mulga phyllodes were not as pronounced, except for Ag, which exceeded the concentrations in all other sample media. These observations indicate potential preferential metal-specific uptake by different media. Pathfinder elements in vegetation and groundwater samples also indicated the Prairie Downs fault zone at the regional (groundwater) and local (vegetation) scale, and are, therefore, potentially useful tools to trace fault systems that host structurally controlled, hydrothermal Zn–Pb mineralization.

Study on Magnetic Abrasive Finishing Process of AlSi10Mg Alloy Curved Surface Formed by Selective Laser Melting

In this paper, AlSi10Mg alloy powder is selected as the forming powder of Selective Laser Melting technology, and the AlSi10Mg alloy SLM curved surface sample is constructed by setting the internal and external layering parameters. In view of the relatively rough surface roughness of SLM technology molded parts, this paper selects the magnetic finishing technology with higher flexibility characteristics to perform surface finishing and finishing on the formed curved surface samples. Explore the feasibility of magnetic finishing technology on the finishing of SLM shaped curved parts, and test and analyze the surface roughness, surface hardness and hydrophobicity of the finishing permanent magnet tools and the curved surface samples before and after finishing. Finally, it was found that the use of a 75° trapezoidal slotted permanent magnet finishing tool to absorb spherical Al2O3 magnetic abrasives for flexible finishing of AlSi10Mg alloy SLM shaped curved surface samples can achieve better finishing results.In this paper, the orthogonal experiment method is used to optimize the finishing experiment. It is found that the finishing parameters of the spindle speed is 1800 r/min, the feed rate is 5 mm/min, the gap is 2 mm, and the abrasive consumption is 7g to form the AlSi10Mg alloy SLM. The surface roughness Ra=0.279μm can be obtained by magnetic finishing of the curved sample, and the surface morphology of the sample has been greatly improved. At the same time, it is found that the magnetic finishing technology improves the surface roughness of the AlSi10Mg alloy SLM forming surface sample, while it does not change the surface hardness of the sample, but it can significantly improve the hydrophobicity of the sample surface.

Visualization and Analysis of Data from Small-Body Missions with NASA’s Solar System Treks Portals

<p>This presentation provides an overview of portals within NASA’s Solar System Treks Project (SSTP) that specifically target small bodies within our Solar System. These, and all of the portals in the suite of Solar System Trek portals, are available at https://trek.nasa.gov.</p> <p>These portals each allow for visualization of different data products in 2D maps with various projections. They also allow users to conduct interactive 3D flyovers. The VR tool allows users to generate their own virtual reality flyovers for any user-defined paths along the bodies’ surfaces. Other tools let users measure distances, generate elevation plots, and create 3D print files for user-defined regions or the entire body.</p> <p>JAXA’s Hayabusa 2 mission recently completed a campaign of reconnaissance, sample collection, and rover deployment at the near-Earth asteroid (162173) Ryugu. JAXA is providing mission data to SSTP, which is incorporating it into the new Ryugu Trek portal (https://trek.nasa.gov/ryugu). The internationalized user interface features controls in both English and Japanese. The portal’s bookmarks feature takes users to particular areas of interest for more detailed looks at specific landforms and sites. On Ryugu, we focus on the surface sample site, impactor and sub-surface sample site, as well as landing sites and traverse paths for the HIBOU, OWL, and MASCOT rovers. We also highlight the first landforms on Ryugu to have been given official IAU names.</p> <p>While Hayabusa2 was exploring Ryugu, NASA’s OSIRIS-REx mission began conducting a detailed examination of the asteroid (101955) Bennu, another near-Earth object. At the request of NASA’s Planetary Science Division and the OSIRIS-REx mission, SSTP began implementation a new portal for the asteroid Bennu, featuring data that is being returned from OSIRIS-REx. The Bennu Trek portal (https://trek.nasa.gov/bennu) reveals Bennu’s top-like shape, a fascinating commonality with Ryugu. It also reveals details of Bennu’s intensely boulder covered terrain. Bookmarked features include Nightingale, Sandpiper, Osprey, and Kingfisher, the top four candidates for sample collection. We also highlight the first landforms on Bennu to have been given official IAU names. Each of these features were singled out as landmarks for OSIRIS-REx’s Natural Feature Tracking (NFT) navigation method that will be used to guide the spacecraft down to its surface sample collection site.</p> <p>In its investigations of Vesta and Ceres, NASA’s Dawn mission has returned spectacular data of the surfaces of these two prominent small bodies within the asteroid belt. This presentation will showcase the use of the Ceres Trek (https://trek.nasa.gov/ceres) and Vesta Trek (https://trek.nasa.gov/vesta) portals and demonstrate how they can be used to visualize and analyze particularly interesting landforms such as the pitted terrain on Vesta and relic cryovolcanoes on Ceres.</p> <p>Under development at this time is a new portal for Mars’ larger Moon, Phobos. This portal will make extensive use of data from ESA’s Mars Express. It is being designed in collaboration with JAXA to support Japan’s upcoming Martian Moons eXploration (MMX) mission. This presentation will provide a preview of a prototype for Phobos Trek.</p> <p>Other Near-Earth asteroids being considered as candidates for future portals include (433) Eros utilizing data gathered by the NEAR Shoemaker mission, and (25143) Itokawa using data from JAXA’s Hayabusa mission. Together, a growing collection of small body Trek portals would enhance capabilities for comparative planetology among this fascinating class of objects. </p> <p>All of these products are efforts in the NASA Solar System Treks Project, available at https://trek.nasa.gov. NASA's Solar System Trek online portals provide web-based suites of interactive data visualization and analysis tools to enable mission planners, planetary scientists, students, and the general public to access mapped data products from past and current missions for a growing number of planetary bodies. These portals are being used for site selection and analysis by NASA and its international partners, supporting upcoming missions. In addition to demonstrating the capabilities of selected portals in this presentation, we will solicit input from the community for ideas for future enhancements.</p> <p>The authors would like to thank the Planetary Science Division of NASA’s Science Mission Directorate, NASA’s SMD Science Engagement and Partnerships, the Advanced Explorations Systems Program of NASA’s Human Exploration Operations Directorate, and the Moon to Mars Directorate for their support and guidance in the development of the Solar System Treks.</p>

V-MOKE MAGNETOMETRY: IN PLANE MAGNETIZATION COMPONENTS SCALING

In this paper we introduce an alternative method to determine the scale factor necessary to quantitatively compare the two coplanar components of the magnetization (components in the plane of the surface of the sample) of a film using the v-MOKE technique (vectorial-MOKE). The proposed method has the advantage of not needing the reorientation ofthe electromagnet generating the magnetic field, since, depending on the dimensions and weight there of, this action can be difficult or directly impracticable. In this way, the experiment that allows for the acquisition of the two components in the plane of magnetization simultaneously, is executed without the need to modify the initial experimental arrangement (fixed assembly). As test samples, two 9 nm and 100 nm thick FePt films are used, presenting the first uniaxial anisotropy. All experiments were carried out at room temperature and using a MOKE system entirely built in the Surface Physics Group of the Instituto de Física del Litoral, allowing to simultaneously measure the two magnetization components coplanar with the surface sample (v-MOKE).

On the Very High-Resolution Radar Image Statistics of the Exponentially Correlated Rough Surface: Experimental and Numerical Studies

The aim of this study is to investigate, by means of experimental measurements and full-wave simulations, the dominant factors for the very high-resolution (VHR) radar image speckles from exponentially correlated rough surfaces. A Ka-band radar system was used to collect the return signal from such a surface sample fabricated by 3D printing and that signal was further processed into images at different resolution scales, where the image samples were obtained by horizontally turning around the surface sample. To cross-validate the results and to further discuss the VHR speckle properties, full wave simulations by full 3D Finite Difference Time Domain (FDTD) method were conducted with 1600 realizations for the speckle analysis. At the considered very high resolution, speckle statistics show divergence from the fully developed Rayleigh distribution. The factors that impact on the high-resolution speckle properties from exponentially correlated rough surface, are analyzed in views of the equivalent number of scatterers theory and scattering scales, respectively. From the data results and extended discussions, it is evident that both of the above factors matter for VHR speckle of backscattering, from the exponentially correlated rough surface as a good representative for the ground surface.

On the Very High-Resolution Radar Image Statistics of the Exponential Correlated Rough Surface: Experimental and Numerical Studies

The aim of this study is to investigate, by means of experimental measurements and full-wave simulations, the dominant factors for the very high-resolution (VHR) radar image speckles from exponential correlated rough surfaces.  A Ka-band radar system was used to collect the return signal from such a surface sample fabricated by 3D printing, and that signal was further processed into images at different resolution scales, where the image samples were obtained by horizontally turning around the surface sample.  To cross-validate the results and to further discuss the VHR speckle properties, full wave simulations by full 3D Finite Difference Time Domain (FDTD) method were conducted with 1600 realizations for the speckle analysis.  At the considered very high resolution, speckle statistics show divergence from the fully developed Rayleigh distribution.  The factors that impact on the high-resolution speckle properties from exponential correlated rough surface, are analyzed in views of the equivalent number of scatterers theory and scattering scales, respectively.  From the data results and extended discussions, it is evident that both of the above factors matter for VHR speckle of backscattering, from the exponential correlated rough surface as a good representative for the ground surface.