Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts

NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ~400 km Veneneia basin by a low-velocity (<2 km/sec) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System.Comment: Icarus (Accepted) Pages: 58 Figures: 15 Tables:

Experimental investigation of the sustainable concrete production from Pyhäsalmi copper tailing in Finland

Abstract. In this study, an experimental investigation of sustainable M20 concrete production from Pyhäsalmi copper tailing was conducted. To achieve this, the physical and chemical properties of Pyhäsalmi copper tailing were investigated using X-ray florescence, specific gravity tests and sieve analysis. This was followed by partial to complete replacement of the sand content in M20 concrete with copper tailing at 0%, 20%, 40%, 60%, 80%, and 100%. The early, mid, and late ages of modified M20 concrete molds were investigated using a TONIPactII compressive machine. In addition, acid, scanning electron microscopy, water absorption and drainage tests were conducted. The results revealed that the modified concrete model with 40% sand replacement exhibited the highest compressive strength (36.93MPa). Similarly, acid tests showed that modified concrete design with 40% and 60% sand replacement possess relatively high resistance to acid corrosion as well as highest compressive strength after acid tests (28.71MPa and 26.07MPa, respectively). Water absorption and drainage tests revealed that although modified M20 concrete models with increased sand replacement possessed higher water absorption, they also possessed relatively faster drainage properties. This resulted in modified M20 models drying faster than the control specimen when submerged in water for 24 hours. Based on the study findings, the partial replacement of sand constituents (40%) in M20 concrete is recommended for sustainable concrete production. Application of the study findings could improve green environments by reducing environmental pollution associated with mine tailing disposal as well as reducing the cost of mine tailing disposal and storage in the mining industry

Standard Specifications for Road and Bridge Construction, January 1, 2021

https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1000/thumbnail.jp

Standard Specifications for Road and Bridge Construction, January 1, 2015

https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1006/thumbnail.jp

NASA Space Engineering Research Center for Utilization of Local Planetary Resources

Progress toward the goal of exploiting extraterrestrial resources for space missions is documented. Some areas of research included are as follows: Propellant and propulsion optimization; Automation of propellant processing with quantitative simulation; Ore reduction through chlorination and free radical production; Characterization of lunar ilmenite and its simulants; Carbothermal reduction of ilmenite with special reference to microgravity chemical reactor design; Gaseous carbonyl extraction and purification of ferrous metals; Overall energy management; and Information management for space processing

Exploring the Usage of Acid Mine Drainage Sludge as a Soil Amendment for Reclaimed Mine Lands

Acid mine drainage (AMD) is a form of water pollution generated when water and oxygen come into contact with sulfide minerals, forming metal ions, sulfuric acid, and sulphates in solution. AMD is characterized by its toxic metals content and low pH, both of which are an environmental concern. The treatment of AMD separates the contaminants into a high-water content sludge. This sludge is a pure waste product under current evaluation for alternative uses as well as improvements to storage and treatment processes. This thesis focused on analyzing the potential for AMD sludge to be used in recently reclaimed lands as an enhancement to initial soil development. This research was separated into two parts, The evaluation of soil development at a reclaimed site, and the evaluation of using of AMD sludge as a soil amendment. The first part of this research was the observation of soil development at a previously treated reclaimed surface mine located in Upshur County, West Virginia. The soil profile was analyzed through a qualitative soil pit analysis in accordance with USDA-NRCS sampling guidelines. Observations on the present soil conditions within the site showed no evidence of AMD within the soil profile, and it showed that the site could be suffering from separate issues with soil development due to a thin topsoil horizon consisting of 2 inches (5cm) of depth overtop a compacted overburden fill. The second part of this research was the construction and analysis of a field scale growth study. The study consisted of five mixtures of AMD sludge to topsoil at 0%, 25%, 50%, 75%, and 100% AMD by volume, each replicated three times, creating a total study of fifteen 3.28 ft by 3.28 ft (1 m by 1 m) growth plots. Plots were seeded with a grass mixture recommended and used by the West Virginia Department of Environmental Protection. Plots were analyzed by ground cover, moisture content, conductivity, and temperature. Results showed that AMD mixed soils acted similar to high organic content soils, holding from 5% to 30% more moisture within the matrix versus just topsoil. Soil conductivity, an indicator of available nutrients and salinity, showed values ranging from 0.05 to 0.35 mS/cm over topsoil values. A mixture of 25%AMD performed from 1% to 5% better in grass coverage when compared to topsoil values. Temperature had no substantial difference by soil mixture. Data shows that studies should be continued, and that AMD sludge may be added to soil matrixes without adverse growing effects

Stabilization of water treatment plant (WTP) residuals using sorbond

Disposal of water treatment plant (WTP) residuals has always been an important consideration for the water industry. Stringent water quality standards, environmental regulations, and unavailability of land for ultimate disposal affect disposal of large amounts of this residual. The search for alternate economical disposal options and beneficial use are probably the next most logical and economical step to take. This study was performed to explore the possibility of stabilization of water treatment plant (WTP) residuals using additives. Three water treatment plant (WTP) residuals from treatment plants in New Jersey were used for the analysis. The objective of this research is to, if possible, present an acceptable application such as engineering fill for this stabilized product. The investigation was divided into three phases: Study the geotechnical characteristics of the WTP residuals Review possible disposal options of WTP residuals and investigate use of WTP residuals in brickmaking Develop and test of Sorbond® stabilized WTP residuals. In the first phase of this study, the WTP residuals were characterized and the geotechnical properties evaluated. This was done to understand and differentiate between the types of WTP residuals being tested. In the second phase, attempts were made to replicate and formulate a procedure to successfully manufacture quality residual-amended bricks. WTP residuals were mixed with various additives such as fly ash, kiln dust, shale etc to manufacture bricks. This effort failed to produce promising results, as the author was unable to develop a proper manufacturing process under the laboratory setup. The residual amended brick molds from the kiln were soft and showed numerous cracks throughout the body. Thus further testing on the brick molds could not be carried out. The third phase dealt with mixing different types of Sorbond® with WTP residuals. Unconfined compressive strength, compaction tests and durability tests were conducted on the final cured samples. The results were compared with the properties of WTP residuals to illuminate the change, if any, in the properties. The results indicate that the residual-sorbond® mix showed better strength values as compared to the WTP residuals. Also the freeze-thaw and wet-dry durability characteristics of the residual-sorbond mix was greatly enhanced to qualify the product for engineering applications. A proportion of sorbond®, as low as 10% by dry weight, mixed with WTP residual can be compacted in the field provided the mix was allowed to dry for two days

Olivine or Impact Melt: Nature of the "Orange" Material on Vesta from Dawn

NASA's Dawn mission observed a great variety of colored terrains on asteroid (4) Vesta during its survey with the Framing Camera (FC). Here we present a detailed study of the orange material on Vesta, which was first observed in color ratio images obtained by the FC and presents a red spectral slope. The orange material deposits can be classified into three types, a) diffuse ejecta deposited by recent medium-size impact craters (such as Oppia), b) lobate patches with well-defined edges, and c) ejecta rays from fresh-looking impact craters. The location of the orange diffuse ejecta from Oppia corresponds to the olivine spot nicknamed "Leslie feature" first identified by Gaffey (1997) from ground-based spectral observations. The distribution of the orange material in the FC mosaic is concentrated on the equatorial region and almost exclusively outside the Rheasilvia basin. Our in-depth analysis of the composition of this material uses complementary observations from FC, the visible and infrared spectrometer (VIR), and the Gamma Ray and Neutron Detector (GRaND). Combining the interpretations from the topography, geomorphology, color and spectral parameters, and elemental abundances, the most probable analog for the orange material on Vesta is impact melt