Can Fractional Crystallization of a Lunar Magma Ocean Produce the Lunar Crust.

images[7]New techniques enable the study of Apollo samples and lunar meteorites in unprecedented detail, and recent orbital spectral data reveal more about the lunar farside than ever before, raising new questions about the supposed simplicity of lunar geology. Nevertheless, crystallization of a global-scale magma ocean remains the best model to account for known lunar lithologies. Crystallization of a lunar magma ocean (LMO) is modeled to proceed by two end-member processes – fractional crystallization from (mostly) the bottom up, or initial equilibrium crystallization as the magma is vigorously convecting and crystals remain entrained, followed by crystal settling and a final period of fractional crystallization (1). Physical models of magma viscosity and convection at this scale suggest that both processes are possible. We have been carrying out high-fidelity experimental simulations of LMO crystallization using two bulk compositions that can be regarded as end-members in the likely relevant range: Taylor Whole Moon (TWM) (2) and Lunar Primitive Upper Mantle (LPUM) (3). TWM is enriched in refractory elements by 1.5 times relative to Earth, whereas LPUM is similar to the terrestrial primitive upper mantle, with adjustments made for the depletion of volatile alkalis observed on the Moon. Here we extend our earlier equilibrium-crystallization experiments (4) with runs simulating full fractional crystallization.
Personal Author D. S. Draper J. F. Rapp For more info go to: or call NTIS 800-553-6847 Mon – Fri 8am to 5pm est.

Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles

images[3]Demand for electric vehicles is increasing, and lithium-ion (Li-ion) batteries with increased ranges will be critical to increasing electric vehicle marketability and reducing greenhouse gas emissions. While Li-ion batteries are expected to play a key role in the electric drive transportation industry, there are opportunities for improvements in the batteries life-cycles that will reduce possible impacts to the environment and public health in a few specific areas, as their use increases. This study, carried out through a partnership led by EPA, with the U.S. Department of Energy (DOE), the Li-ion battery industry, and academics, was the first life-cycle assessment (LCA) to bring together and use life-cycle inventory data directly provided by Li-ion battery suppliers, manufacturers, and recyclers. Its purpose was to identify the materials or processes within a Li-ion batterys life cycle (from materials extraction and processing, manufacturing, use, and end-of-life) that most contribute to impacts on public health and the environment. It also sought to evaluate the potential impacts of a nanotechnology innovation (i.e., a carbon nanotube anode) that could improve battery performance.
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Generalized Framework and Algorithms for Illustrative Visualization of Time-Varying Data on Unstructured Meshes

images[1]Photo- and physically-realistic techniques are often insufficient for visualization of simulation results, especially for three-dimensional and timevarying datasets. Substantial research efforts have been dedicated to the development of nonphoto-realistic and illustration-inspired visualization techniques for compact and intuitive presentation of such complex datasets. While these efforts have yielded valuable visualization results, a great deal of work has been reproduced in studies as individual research groups often develop purpose-built platforms. Additionally, interoperability between illustrative visualization software is limited because of specialized processing and rendering architectures employed in different studies. This report proposes a generalized framework for illustrative visualization and implements it in MarmotViz, a ParaView plug-in, enabling its use on a variety of computing platforms with various data file formats and mesh geometries. This report gives detailed descriptions of the region-of-interest identification and feature-tracking algorithms incorporated into this tool. Implementations of multiple illustrative effect algorithms are presented to demonstrate the use and flexibility of this framework. By providing a framework and useful underlying functionality, the MarmotViz tool can act as a springboard for future research in the field of illustrative visualization. Personal Author A. Joshi A. S. Rattner D. P. Guillen S. Garimella
Personal Author A. Joshi A. S. Rattner D. P. Guillen S. Garimella

Response of Lower Atmospheric Ozone to ENSO in Aura Measurements and a Chemistry-Climate Simulation

images[7]The El Nino-Southern Oscillation (ENSO) is the dominant mode of tropical variability on interannual time scales. ENSO appears to extend its influence into the chemical composition of the tropical troposphere. Recent work has revealed an ENSO-induced wave-1 anomaly in observed tropical tropospheric column ozone. This results in a dipole over the western and eastern tropical Pacific, whereby differencing the two regions produces an ozone anomaly with an extremely high correlation to the Nino 3.4 Index. We have successfully reproduced this feature using the Goddard Earth Observing System Version 5 (GEOS-5) general circulation model coupled to a comprehensive stratospheric and tropospheric chemical mechanism forced with observed sea surface temperatures over the past 25 years. An examination of the modeled ozone field reveals the vertical contributions of tropospheric ozone to the column over the western and eastern Pacific region. We will show composition sensitivity in observations from NASA’s Aura satellite Microwave Limb Sounder (MLS) and the Tropospheric Emissions Spectrometer (TES) and a simulation to provide insight into the vertical structure of these ENSO-induced ozone changes. The ozone changes due to the Quasi-Biennial Oscillation (QBO) in the extra-polar upper troposphere and lower stratosphere in MLS measurements will also be discussed.
Personal Author A. R. Douglass D. W. Waugh J. E. Nielsen J. M. Rodriquez J. R. Ziemke L. D. Oman
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Entry, Descent, and Landing for Human Mars Missions.

imagesCA18WE00One of the most challenging aspects of a human mission to Mars is landing safely on the Martian surface. Mars has such low atmospheric density that decelerating large masses (tens of metric tons) requires methods that have not yet been demonstrated, and are not yet planned in future Mars missions. To identify the most promising options for Mars entry, descent, and landing, and to plan development of the needed technologies, NASA’s Human Architecture Team (HAT) has refined candidate methods for emplacing needed elements of the human Mars exploration architecture (such as ascent vehicles and habitats) on the Mars surface. This paper explains the detailed, optimized simulations that have been developed to define the mass needed at Mars arrival to accomplish the entry, descent, and landing functions. Based on previous work, technology options for hypersonic deceleration include rigid, mid-L/D (lift-to-drag ratio) aeroshells, and inflatable aerodynamic decelerators (IADs). The hypersonic IADs, or HIADs, are about 20% less massive than the rigid vehicles, but both have their technology development challenges. For the supersonic regime, supersonic retropropulsion (SRP) is an attractive option, since a propulsive stage must be carried for terminal descent and can be ignited at higher speeds. The use of SRP eliminates the need for an additional deceleration system, but SRP is at a low Technology Readiness Level (TRL) in that the interacting plumes are not well-characterized, and their effect on vehicle stability has not been studied, to date. These architecture-level assessments have been used to define the key performance parameters and a technology development strategy for achieving the challenging mission of landing large payloads on Mars.

Personal Author A. M. DwyerCianciolo M. M. Munk

Launch and Assembly Reliability Analysis for Mars Human Space Exploration Missions

imagesCA18WE00NASA’s long-range goal is focused upon human exploration of Mars. Missions to Mars will require campaigns of multiple launches to assemble Mars Transfer Vehicles in Earth orbit. Launch campaigns are subject to delays, launch vehicles can fail to place their payloads into the required orbit, and spacecraft may fail during the assembly process or while loitering prior to the Trans-Mars Injection (TMI) burn. Additionally, missions to Mars have constrained departure windows lasting approximately sixty days that repeat approximately every two years. Ensuring high reliability of launching and assembling all required elements in time to support the TMI window will be a key enabler to mission success. This paper describes an integrated methodology for analyzing and improving the reliability of the launch and assembly campaign phase. A discrete event simulation involves several pertinent risk factors including, but not limited to: manufacturing completion; transportation; ground processing; launch countdown; ascent; rendezvous and docking, assembly, and orbital operations leading up to TMI. The model accommodates varying numbers of launches, including the potential for spare launches. Having a spare launch capability provides significant improvement to mission success. For more

info please go to: 

Personal Author C. Stromgren G. R. Cates K. E. Goodliff W. M. Cirillo