ALBERT

Description: A fundamental exploratory experiment is conducted assessing the performance of a one-sided ejector with the eventual goal of noise reduction for jet engines. The hardware is comprised of an 8:1 rectangular nozzle together with an ejector box whose lower surface is flush with the lower lip of the nozzle. Secondary flow is allowed through a gap between the upper lip of the nozzle and a flap that constitutes the upper surface of the ejector. Wall static pressures and Pitot probe surveys are conducted to evaluate the performance of the ejector with variation of geometric parameters. It is found that addition of vortex generating tabs at the upper lip of the nozzle significantly increases secondary flow entrainment. The entrainment is further enhanced by a divergence of the ejector upper surface. Limited noise measurements are done. The baseline ejector (without tabs) often encounters flow resonance with accompanying tones. The tabs have the additional benefit of eliminating those tones in all cases. However, for the tabbed case, addition of the ejector produces insignificant further noise reduction. This is due to the fact that the flow remains unmixed on the lower half of the ejector. The focus of ongoing and future efforts is to achieve sufficient mixing of the flow so that the exhaust velocities are uniformly low, while keeping the ejector hardware short and lightweight.

Description: We present the case for the presence of complex organic molecules, such as amino acids and nucleobases, formed by abiotic processes on the surface and in near-subsurface regions of Pluto. Pluto's surface is tinted with a range of non-ice substances with colors ranging from light yellow to red to dark brown; the colors match those of laboratory organic residues called tholins. Tholins are broadly characterized as complex, macromolecular organic solids consisting of a network of aromatic structures connected by aliphatic bridging units (e.g., Imanaka et al.,2004; Materese et al.,2014, 2015). The synthesis of tholins in planetary atmospheres and in surface ices has been explored in numerous laboratory experiments, and both gas- and solid-phase varieties are found on Pluto. A third variety of tholins, exposed at a site of tectonic surface fracturing called Virgil Fossae, appears to have come from a reservoir in the subsurface. Eruptions of tholin-laden liquid H2O from a subsurface aqueous repository appear to have covered portions of Virgil Fossae and its surroundings with a uniquely colored deposit (D.P. Cruikshank, personal communication) that is geographically correlated with an exposure of H2O ice that includes spectroscopically detected NH3 (C.M. Dalle Ore, personal communication). The subsurface organic material could have been derived from presolar or solar nebula processes, or might have formed in situ. Photolysis and radiolysis of a mixture of ices relevant to Pluto's surface composition (N2, CH4, CO) have produced strongly colored, complex organics with a significant aromatic content having a high degree of nitrogen substitution similar to the aromatic heterocycles pyrimidine and purine (Materese et al.,2014, 2015; Cruikshank et al.,2016). Experiments with pyrimidines and purines frozen in H2O-NH3 ice resulted in the formation of numerous nucleobases, including the biologically relevant guanine, cytosine, adenine, uracil, and thymine (Materese et al.,2017). The red material associated with the H2O ice may contain nucleobases resulting from energetic processing on Pluto's surface or in the interior. Some other Kuiper Belt objects also exhibit red colors similar to those found on Pluto and may therefore carry similar inventories of complex organic materials. The widespread and ubiquitous nature of similarly complex organic materials observed in a variety of astronomical settings drives the need for additional laboratory and modeling efforts to explain the origin and evolution of organic molecules. Pluto observations reveal complex organics on a small body that remains close to its place of origin in the outermost regions of the Solar System.

Description: No abstract available

Description: Spacecraft surface charging during geomagnetically disturbed times is one of the most important causes of satellite anomalies. Predicting the surface charging environment is one prevalent task of the geospace environment models. Therefore, the Geospace Environment Modeling (GEM) Focus Group "Inner Magnetosphere Crossenergy/Population Interactions" initiated a communitywide challenge study to assess the capability of several inner magnetosphere ring current models in determining surface charging environment for the Van Allen Probes orbits during the 17 March 2013 storm event. The integrated electron flux between 10 and 50 keV is used as the metrics. Various skill scores are applied to quantitatively measure the modeling performance against observations. Results indicate that no model consistently perform the best in all of the skill scores or for both satellites. We find that from these simulations the ring current model with observational flux boundary condition and Weimer electric potential driver generally reproduces the most realistic flux level around the spacecraft. A simple and weaker VollandStern electric field is not capable of effectively transporting the same plasma at the boundary toward the Earth. On the other hand, if the ring current model solves the electric field selfconsistently and obtains similar strength and pattern in the equatorial plane as the Weimer model, the boundary condition plays another crucial role in determining the electron flux level in the inner region. When the boundary flux spectra based on magnetohydrodynamics (MHD) model/empirical model deviate from the shape or magnitude of the observed distribution function, the simulation produces poor skill scores along Van Allen Probes orbits.

Description: Outline - Introduction: X-57 CFD task overview; Motivation. Part I, Computational simulations without propulsion: Establishing CFD (Computational Fluid Dynamics) Best Practices - Grid generation - Mesh refinement study - Numerical methods - Wind tunnel validation study; Power-Off Aerodynamic Database Results. Part II, Computational simulations with propulsion: Cruise Power-On Database; High-Lift Power-On Database. Summary.

Description: A rotor blade comprises an airfoil extending radially from a root section to a tip section and axially from a leading edge to a trailing edge, the leading and trailing edges defining a curvature therebetween. The curvature determines a relative exit angle at a relative span height between the root section and the tip section, based on an incident flow velocity at the leading edge of the airfoil and a rotational velocity at the relative span height. In operation of the rotor blade, the relative exit angle determines a substantially flat exit pressure ratio profile for relative span heights from 75% to 95%, wherein the exit pressure ratio profile is constant within a tolerance of 10% of a maximum value of the exit pressure ratio profile.

Description: A simulator to artificially generate turbofan broadband signatures using the ANCF (Advanced Noise Control Fan) test article is presented. [Development of a Broadband Acoustic Emulator to Mature Propulsion Noise Reduction (CFANS-BB: Configurable Fan Artificial Noise Source- Broadband)]

Description: No abstract available

Description: No abstract available

Description: No abstract available

Description: What: Thermal moonquakes are small amplitude events that are produced by diurnal temperature changes. Why: Finding the locations of thermal moonquakes will lead to information about lunar surface processes. Where: Apollo 17 Lunar Seismic Profiling Experiment (LSPE) is able to locate thermal moonquake unlike Apollo 12-16. The primary science goal was an active source experiment to study the detailed structure of the lunar crust using 8 explosive packages (EPs). The secondary science goal was to passively listen for lunar seismic activity.

Description: No abstract available

Description: The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity landed in Gale crater to study a sequence of ~3.5 Ga old sedimentary rocks that, based on orbital visible/near-infrared reflectance spectra, contain secondary minerals that suggest deposition and/or alteration in liquid water. The sedimentary sequence that comprises the lower slopes of Mount Sharp within Gale crater may preserve a dramatic shift on early Mars from a relatively warm and wet climate to a cold and dry climate based on a transition from smectite-bearing strata to sulfate-bearing strata. The rover is equipped with cameras and geochemical and mineralogical instruments to examine the sedimentology and identify compositional changes within the stratigraphy. These observations provide information about variations in depositional and diagenetic environments over time. The Chemistry and Mineralogy (CheMin) instrument is one of two internal laboratories on Curiosity and includes a transmission X-ray diffractometer (XRD) and X-ray fluorescence (XRF) spectrometer with a Co-K source. CheMin measures loose sediment samples scooped from the surface and drilled rock powders. The XRD provides quantitative mineralogy of scooped and drilled samples to a detection limit of ~1 wt.%. Curiosity has traversed 〉20 km since landing and has primarily been exploring the site of a predominantly ancient lake environment fed by groundwater and streams emanating from the crater rim. Results from CheMin demonstrate an incredible diversity in the mineralogy of fluvio-lacustrine rocks that signify variations in source rock composition, sediment transport mechanisms, and depositional and diagenetic fluid chemistry. Abundant trioctahedral smectite and magnetite at the base of the section may have formed from low-salinity pore waters with a circumneutral pH within lake sediments. A transition to dioctahedral smectite, hematite, and Ca-sulfate going up section suggests a change to more saline and oxidative aqueous conditions within the lake waters themselves and/or within diagenetic fluids. The primary minerals detected in fluvio-lacustrine samples by CheMin also suggest diversity in the igneous source regions for the sediments, where abundant pyroxene and plagioclase in most samples suggest a basaltic protolith, but sanidine and pyroxene in one sample may have been sourced from a potassic trachyte, and tridymite and sanidine in another sample may have been transported from a rhyolitic source. Crystal chemistry of major phases in each sample have been calculated from refined unit-cell parameters, providing further constraints on aqueous alteration processes and igneous protoliths for the sediments. Perhaps one of the biggest mysteries revealed by the CheMin instrument is the high abundance of X-ray amorphous materials (15 to 73 wt.%) in all samples measured to date. X-ray amorphous materials were detected by CheMin based on the observation of broad humps in XRD patterns. How these materials formed, their composition, and why they persist near the martian surface remain a topic of debate. The sedimentology and composition of the rocks analyzed by Curiosity demonstrate that habitable environments persisted intermittently on the surface or in the subsurface of Gale crater for perhaps more than a billion years.

Description: The Habitable Exoplanet Observatory Mission (HabEx) will image and spectroscopically characterize planetary systems in the habitable zone around nearby sun-like stars. Additionally, HabEx will perform a broad range of general astrophysics science enabled by 100 to 2500 nm spectral range and 3 x 3 arc-minute FOV. Critical to achieving the HabEx science goals is a large, ultra-stable telescope. The baseline HabEx telescope is a 4-m off-axis unobscured three-mirror-anastigmatic design with diffraction limited performance at 400 nm and wavefront stability of picometers per mK. These specifications are driven by science requirements. STOP (structural thermal optical performance) analysis predicts that the baseline telescopes opto-mechanical design meets its specified performance tolerances.

Description: In recent years, several commercial companies have proposed telecommunications constellations consisting of hundreds to thousands of 100-to-300-kg class spacecraft in low Earth orbit (LEO, the region below 2000-km altitude). If deployed, such large constellations (LCs) will dramatically change the landscape of satellite operations in LEO. From the large number of spacecraft and large amount of mass involved, it is clear that the deployment, operations, and frequent de-orbit and replenishment of the proposed LCs could significantly contribute to the existing orbital debris problem. To better understand the nature of the problem, the NASA Orbital Debris Program Office (ODPO) recently completed a parametric study on LCs. The objective was to quantify the potential negative debris-generation effects from LCs to the LEO environment and provide recommendations for mitigation measures. The tool used for the LC study was the ODPOs LEO-to-GEO Environment Debris (LEGEND) numerical simulation model, which has been used for various mitigation and remediation studies in the past. For the LC study, more than 300 scenarios based on different user-specified assumptions and parameters were defined. Selected results from key scenarios are summarized in this paper.

Description: The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (henceforth AACO) is responsible for receiving and curating all of NASAs extraterrestrial samples, current and future (as per NASA Policy Directive (NPD) 7100.10E Curation of Extraterrestrial Materials). As such, the AACO coordinates sample capture, containment, and transportation to the curation facility as well as documents, preserves, prepares, and distributes all of the samples within NASAs astromaterial collections for research, education, and public outreach. Since the lunar rock and soil samples returned during the Apollo Program, NASAs first Class V Restricted Earth Return Missions, the AACO curates six other astromaterials collections. Lessons learned from each collection and respective missions (e.g. Apollo, Genesis, Stardust) as well as advancements in science and technology have informed the AACOs plan for acquiring and curating Martian samples. Given the nature of the collection, a mobile and modular facility is recommended. The two broad requirements a Mars sample facility must maintain are: 1) the ability to contain the samples to protect the public from exposure of an unknown unknown biological agent and 2) ensure the scientific integrity of the samples are maintained (while maximizing scientific outcome). Although Apollo samples were eventually deemed safe and released to the scientific community for evaluation, there is no guarantee that this will be the case for Martian samples. Therefore, the facility in which the samples will be contained and investigated must be modular and able to accommodate an array of instrumentation that could be highly variable depending on the initial scientific outcomes. Furthermore, in order to facilitate proper sample capture and containment upon landing as well as sample distribution to other laboratories with proper containment, a mobile facility is a valuable investment.

Description: Reynolds-Averaged Navier-Stokes simulations have been performed on a three-stream inverted velocity profile nozzle with and without various configurations of chevrons attached. The nozzle was mounted on a planform to imitate an engine mounted above a wing, shielding ground observers from engine noise. Several chevron designs intended to aggressively mix the jet and move noise sources upstream for shielding were examined to investigate there effects on noise and thrust. Numerical results for the baseline nozzle and one chevron configuration were compared with far-field noise and particle image velocimetry data obtained in NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory. A configuration in which chevrons alternate penetration into the primary stream and tertiary fan stream was explored using the Modern Design of Experiments approach. Short, high-penetration chevrons demonstrated a significant noise reduction for a relatively small thrust penalty.

Description: The surfaces of airless bodies, such as 101955 Bennu, are vulnerable to micrometeoroids, high-energy particles, and solar wind particles. As a result, material on the surface of these bodies experience physical and chemical changes that are collectively known as space weathering. Space weathering processes result in the production of sub-micronsized particles called submicroscopic particles. There are two types of submicroscopic particles, nanophase (〈33 nm in size) and microphase particles (〉33 nm in size). Studies of lunar samples show that nanophase particles occur within the glassy rims that surround grains and agglutinates. In contrast, microphase iron particles occur only within agglutinates. Another important difference between these two particles is that nanophase and microphase particles affect visible to near-infrared reflectance spectra differently. From lunar samples, the presence of nanophase particles in a regolith causes the regoliths reflectance spectrum to darken and redden, whereas the presence of microphase particles in a regolith causes it to only darken. In addition, the reflectance spectra of submicroscopic particle-bearing regolith exhibit weakened absorptions and spectral features. Lantz et al. (2018) found that these particles also affect spectral curvature [8]. By taking advantage of these spectral characteristics, with global spectral data, it is possible to model the nanophase and microphase particle abundances across a planetary surface resulting in the production of global space weathering maps.

Description: The chondrule regions generally regarded to be most susceptible to aqueous alteration are mesostasis and Fe-Ni metal nodules. In CMs, studies of mesostasis have successfully placed contraints into their asteroidal histories. Unlike CM mesostasis, only a few studies of CR mesostasis are currently available [e.g. 1-4]. Here we study the effects aqueous alteration can have on the texture, composition, and mineralogy of CR chondrule mesostasis from 9 Antarctic CR chondrites: EET 92062,5, EET 96259,13, GRA 95229,77, GRO 95577,61 LAP 02342,44, LAP 04516,4, LAP 04720,16 and MIL 07525,7 and MIL 090001,2, generously provided by the U.S. Antarctic Meteorite Collection. To our knowledge, this is the first detailed TEM and compositional study of differences between chondrule setting in CR mesostasis. Based on these data, we place constraints on the degree to which these CRs record aqueous alteration.

Description: The Astromaterials Curation Division at NASAs Johnson Space Center houses seven sample collections stored in separate clean rooms to avoid cross-contamination. Prior to receiving new sample collections from carbon rich asteroids, we instituted a monitoring program to characterize the microbial ecology of these labs and to understand how organisms could interact with and potentially contaminate current and future collections. Methods: Beginning in Oct. 2017 we sampled the Meteorite (ISO 7 equivalent) and Pristine Lunar (ISO 5 equivalent) labs on a monthly basis. Surface samples were collected using dry swabs. Air samples were collected using an impactor style air sampler. Cultivable organisms were identified and characterized. Aliquots of each sample were also preserved for DNA sequencing. For each sampling event recovery rate was calculated as the percentage of samples showing microbial growth1. Fungal colonies were selected for amino acid extraction and analysis via Ultra- Performance Liquid Chromatography with Fluorescence Detection and Mass Spectrometry.

Description: Exploration Mission 2 (EM-2) will be NASAs first manned flight on the Space Launch System (SLS) and Orion Spacecraft. The mission has been changed from an SLS Block 1B configuration to Block 1. This change has necessitated a reexamination of the flight profile to determine what changes must be made in order to accommodate the reduced launch vehicle performance on the Block 1. Launch availability and orbital debris risk will be traded to find the best flight profile for both SLS and Orion.

Description: The Astromaterials Research and Exploration Science Division at JSC is responsible for the curation of extraterrestrial samples from NASA's past, present and future sample return missions. These samples provide data that help scientists better understand the history and evolution of our Solar System. Our mission is to preserve, protect, and distribute samples for research by the present and future scientific community.

Description: No abstract available

Description: Data from LRO has formed a corner-stone in our understanding of many fundamental aspects of lunar geology. However, as LRO approaches its 10th year of lunar discovery, key questions about volcanic, tectonic, and interior processes and composition still re-main.

Description: NASA's Space Communications and Navigation (SCaN) program is creating an operational optical communications network to complement its current radio frequency (RF) networks. NASA is currently planning for a new optical communications relay node in geostationary (GEO) orbit to be commissioned in 2025, developed by NASA's Goddard Space Flight Center (GSFC), as evolved from Goddard's Laser Communications Relay Demonstration (LCRD) GEO relay payload that will launch in 2019. The Next Generation optical relay node will serve as an initial element in a larger optical networking constellation that will consist of Government and commercial, and international relays. NASA's nodes will aggregate traffic at data rates of up to 10 Gigabits per second (Gbps) from users on the Earth's surface and up through suborbital, LEO, MEO, GEO, cislunar and even out to Earth-Sun Lagrange (1.25 Mkm) distances. Users that require low-latency will be serviced with an onboard complementary Ka-band downlink service. The next generation network will deploy 〉 100 Gbps space-to-ground links and also optical crosslinks between nodes to allow for user traffic backhaul to minimize ground station location constraints.

Description: Oral presentation will discuss the history of the ISS, ongoing research in space, and the plans for Gateway.

Description: The goal of the Mars Science Laboratory (MSL), Curiosity Rover mission is to determine if Gale Crater, Mars ever had a habitable environment and to search for evidence of extinct microbial life. Gale Crater is ~155 km wide with a layered central mound (~5 km high). The Curiosity rover has traversed ~20 km from the crater floor up 350 m to the lower slopes of the central mound for over 2200 Martian solar days (sols). Curiosity's instruments have evaluated the geochemistry and mineralogy of regolith fines, eolian sediments, and sedimentary rocks to assess Gale Crater's aqueous alteration history. Results indicate that Gale Crater surface material have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

Description: No abstract available

Description: This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400 nm mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.

Description: Hydrogen in nominally anhydrous minerals (NAMs) in meteorites provides insight to mantle sources of indigenous water on differentiated bodies: e.g. Peslier et al. 2017 [1], including Mars [2-4]. However, all meteorite samples, including Martian shergottites, record impact events as fractures, deformation, silicate darkening, shock melt veins and pockets, etc. The effect of shock on hydrogen in NAMs is poorly constrained, and must be understood prior to using these data to infer planetary indigenous water. Here we present water contents and D/H ratios (calculated as dD, i.e. the variation of the D/H ratio relative to a standard, in this case sea water "SMOW") in pyroxene, olivine and maskelynite in the olivine-phyric shergottite Larkman Nunatak 06319 (LAR 06319) as a function of proximity to impact melt. While the results suggest impact may have a role in fractionating H isotopes, the magmatic signature of H2O in Mars can be preserved in some pyroxene.

Description: Water, in the form of structurally bound hydrogen in the crystal lattice of nominally anhydrous minerals (NAMs), strongly influences many important physical processes on terrestrial planets and planetary objects. Water enhances the rates of plastic deformation and controls the degree of partial melting in silicate rocks, which influences the generation of melt and therefore the nature of planetary volcanism. Water has also been experimentally demonstrated to influence the nature of lattice preferred orientation in deformed aggregates, and thus may be important in the interpretation of seismic anisotropy data collected from planetary bodies, such as from the current InSight mission on Mars. Therefore, much attention has been focused on characterizing the distribution and concentration of water in the planets and rocky bodies of our solar system.

Description: Exploration Mission 2 (EM-2) will be NASAs first manned flight on the Space Launch System (SLS) and Orion Spacecraft. The mission has been changed from an SLS Block 1B configuration to Block 1. This change has necessitated a reexamination of the flight profile to determine what changes must be made in order to accommodate the reduced launch vehicle performance on the Block 1. Launch availability and orbital debris risk will be traded to find the best flight profile for both SLS and Orion.

Description: The NASA Curiosity rover has encountered both ancient and modern dune deposits within Gale crater. The modern dunes are actively migrating across the surface within the Bagnold Dune field of which Curiosity conducted analysis campaigns at two different localities. Variations in mafic-felsic mineral abundances between these two sites have been related to the aeolian mineral sorting regime for basaltic environments identified on the Earth which become preferentially enriched in olivine relative to plagioclase feldspar with increasing distance from the source. This aeolian mineral sorting regime for basaltic minerals has also been inferred for Mars from orbital data. The aim of this study is to investigate whether this aeolian mafic-felsic mineral sorting trend has left a geochemical signature in the ancient dune deposits preserved within the Stimson formation. The Stimson formation unconformably overlies the Murray formation and consists of thickly laminated, cross-bedded sandstone. Stimson outcrops have a variable thickness up to 5 meters covering a total area of 17 square kilometers. A dry, aeolian origin was determined for this sandstone due to the high sphericity and roundness of the grains, uniform bimodal grain size distribution (250-710 microns), and 1-meter-thick cross-beds. Identifying the geochemical signature of mineral sorting can provide insights about the paleo-net sediment transport direction of the dunes and prevailing wind direction at the time of deposition.

Description: The Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) rover has been essential in understanding volatile-bearing phases in Gale Crater materials. SAMs evolved gas analysis mass spectrometry (EGA-MS) has detected H2O, CO2, O2, H2, SO2, H2S, HCl, NO, and other trace gases, including organic fragments, in many samples. The identity and evolution temperature of evolved gases can support CheMin instrument mineral detection and place constraints on trace volatile-bearing phases or phases difficult to characterize with X-ray diffraction (e.g., amorphous phases). For the past ~500 sols, MSL has been exploring the Vera Rubin Ridge (VRR), which exhibits a striking hematite signature in orbital remote sensing data, in order to understand the depositional and diagenetic history recorded in the rocks and how it relates to the underlying Murray Formation. Four rock samples were drilled, one from the Blunts Point Member (Duluth, DU), one from the Pettegrrove Point Member (Stoer, ST), and two from the Jura Member. The Jura Member displays differences in color, summarized as grey and red, and a key goal was to constrain the cause of this color difference and the associated implications for depositional or post-depositional conditions. To investigate, a grey (Highfield, HF) and a red (Rock Hall, RH) Jura sample were drilled. Here we will give an overview of results from SAM EGA-MS analyses of VRR materials, with some comparisons to analyses of samples of the underlying Murray.

Description: No abstract available

Description: The Astromaterials Acquisition and Curation Office at the Johnson Space Center is the past, present, and future home of all of NASAs astromaterials sample collections. The primary goals of the curation office are to maintain the long-term integrity of the samples and ensure that the samples are distributed for scientific study in a fair, timely, and responsible manner, thus maximizing the return on each sample. Part of the curation process is planning for the future. To this end, we perform fundamental research in advanced curation initiatives to better prepared for future sample return missions. Advanced Curation is tasked with developing procedures, technology, and data sets necessary for curating new sample collections, or getting new results from existing sample collections. As part of these advanced curation efforts, we have installed and are operating a Nikon XTH 320 X-ray Computed Tomography(XCT) system in the JSC curation office with four interchangeable X-ray sources, a large-area detector, and a heavy-duty stage. These instrument characteristics allow us exceptional flexibility to analyze a wide range of sample sizes, from sub-mm soil particles to rocks 〉10 cm in diameter. The penetrative nature of the XCT scans allows for astromaterials samples to be analyzed within sealed low-density containers (e.g., Teflon bags), preserving the pristinity of the samples. We have begun scanning of the Apollo and Antarctic Meteorite sample suites in order to non-destructively map out lithic clasts (and other features) within the samples. The data from these scans will be made available to scientists via the JSC curation website and the Astromaterials Curation Newsletter. We anticipate sample requests from these new lithic clasts identified in these old samples. We also anticipate that XCT analyses like these would be useful for future sample return missions, like the OSIRIS REx mission, as well as future sample return missions.

Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the large computational cost makes it impractical to support a real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube problem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computationally expensive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the established stagnation-line approach. Comparison with time-accurate simulations shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium.

Description: In magmatic systems, the availabil- ity of excess oxygen that can react with multivalent elements such as Fe and S to change their charge (oxi- dation of Fe2+ to Fe3+ or reduction of S6+ to S2-) is characterized by a parameter called the oxygen fugacity (O2). The O2 controls the availability of these ions and consequently the mineralsand the chemistry of those mineralsthat crystallize from a melt. Mineral mode and chemistry control how magmas evolve, and given that O2 varies by many orders of magnitude on different planets [2], understanding the O2 of a mag- ma is critical to relating observations about a magma to the body on which it forms. The mineral apatite was long thought to only incor- porate S6+ in a coupled substitution for P5+, but recently natural apatites with S2- were identified in lunar mare basalts that crystallized at low O2 [3]. This suggests that apatite can be used as a monitor of O2 assuming that one can 1) measure S6+/S (S6+ over total sulfur), and 2) determine some partitioning relationship be- tween apatite and melt for S6+ and S2-. The most common method for measuring S6+/S is X-ray Absorption Near-Edge Spectroscopy (XANES), but given the limited access to synchrotron facilities, it is wise to explore the potential of other methods for measuring S6+/S. One such possible method relies upon the shift in energy of the sulfur K- peak on the electron microprobe. However, apatite is subject to well-documented beam damage [4, 5], so it is neces- sary to evaluate under what conditions can reliable S6+ ethod.

Description: No abstract available

Description: Seismic data, inclusive of velocities and attenuation, can be utilized to elucidate the physical state of planetary interiors]. However, numerous micromechanical factors have been either experimentally demonstrated, or theoretically considered, to affect the propagation and dissipation of seismic energy within crystalline solids - including, but not limited to, changes in grain size, temperature, melt fraction, pressure and dislocation density. Thus, observed variations in seismic wave speeds and attenuation may be used to ultimately map variations in physical properties, such as those listed above, within planetary bodies. But, in order to complete a successful inversion of seismic data into representations of physical properties, a first requirement is to obtain a fundamental laboratory based understanding of how each of these possible factors individually influences seismic waves. Here we conduct an experimental study with the initial objective to further understand one of the most commonly invoked, yet least studied, mechanisms that could alter intrinsic seismic wave attenuation: water content (occurring as chemically-bound hydroxyl). The historical basis for determining the effect of water on seismic properties was established predominantly through analogy with large-strain creep experiments conducted on olivine under water-saturated conditions. While these deformation experiments routinely demonstrate a weakening of olivine in the presence of water, they represent a fundamentally different deformation regime in comparison to the microstrains experienced due to a passing seismic wave. Thus, in order to directly assess the effects of water on seismic properties, small-strain experiments are required. Substantially modified seismic properties in the presence of water have been observed previously at low strains and low frequencies, but only in a single exploratory study conducted under water-saturated conditions. Thus, to properly test the theoretical predictions we conducted a systematic study of the seismic properties of olivine using low-frequency torsional oscillation on aggregates containing varying concentrations of bound hydroxyl, for the first time at under saturated conditions.

Description: Impact cratering is an important geological process that occurs on every rocky body in the solar system. It alters the texture and mineralogy of rocks via shock metamorphism. The peak shock pressures experienced by a rock are traditionally evaluated using qualitative optical methods however, quantitative methods do exist. One such method was developed by Uchizono et al., who used X-ray Diffraction (XRD) to measure lattice strain () in several artificially shocked olivine grains using XRD peak broadening as a function of tan , where is the diffraction angle. They plotted the values against the known peak shock pressures experienced by the olivine grains. Using this calibration curve, the precise shock pressure experienced by a grain of olivine can be determined using its measured value. Another method was developed by McCausland et al. and Izawa et al., who used in situ XRD to measure strain-related mosaicity (SRM) of olivine in several ordinary chondrites and enstatite in enstatite chondrites, respectively. They plotted these results against the shock stage estimates for these meteorites. Using these plots, meteorites can be assigned to shock stage bins by measuring the SRM of olivine and/or enstatite. Both methods are useful for evaluating shock metamorphism, however, they have limitations. Uchizono et al.s calibration curve has been successfully applied to martian meteorites, however it can only be applied to olivine-bearing rocks. McCausland et al.s and Izawa et al.s SRM method is uncalibrated and is limited to binning meteorites by shock stage. This work aims to expand on both methods by creating calibration curves for clinopyroxene (CPX): one for , similar to Uchizono et al.s calibration curve for olivine, and one for SRM. This will extend the application of shock calibration methods to a greater variety of rock types. Preliminary results are presented herein.

Description: No abstract available

Description: No abstract available

Description: Space weathering alters the surfaces of airless planetary bodies via irradiation from the solar wind and micrometeorite impacts. These processes modify the microstructure, chemical composition, and spectral properties of surface materials, typically resulting in the reddening (increasing reflectance with increasing wavelength), darkening (reducing albedo), and attenuation of characteristic absorption features in reflectance spectra. In lunar samples, these changes in optical properties are driven by the production of reduced nanophase Fe particles (npFe). Our understanding of space weathering has largely been based on data from the Moon and, more recently, near-Earth S-type asteroids. However, the environment at Mercury is significantly different, with the surface experiencing intense solar wind irradiation and higher velocity micrometeorite impacts. Additionally, the composition of Mercurys surface varies significantly from that of the Moon, including a component with very low albedo known as low reflectance material (LRM) which is enriched with up to 4 wt.% carbon over the local mean. Our understanding of how carbon phases, including graphite, are altered as a result of these processes is limited.

Description: In a negative-polarity coronal hole, magnetic flux emergence, seen by the Solar Dynamics Observatory's {SDO) Helioseismic Magnetic lmager (HMI), begins at approximately 19:00 UT on March 3, 2016. The emerged magnetic field produced sunspots, which NOAA numbered 12514 two days later. The emerging magnetic field is largely bipolar with the opposite-polarity fluxes spreading apart overall, but there is simultaneously some convergence and cancellation of opposite-polarity flux at the polarity inversion line (PIL) inside the emerging bipole. In the first fifteen hours after emergence onset, three obvious eruptions occur, observed in the coronal EUV images from SDO's Atmospheric Imaging Assembly (AIA). The first two erupt from separate segments of the external PIL between the emerging positve-polarity flux and the extant surrounding negative-polarity flux, with the exploding magnetic field being prepared and triggered by flux cancellation at the external PIL. The emerging bipole shows obvious overall left-handed shear and/or twist in its magnetic field. The focus of th is poster is the third and largest eruption, which comes from inside the emerging bipole and blows it open to produce a CME observed by SOHO/LASCO. That eruption is preceded by flux cancellation at the emerging bipole's interior PIL, cancellation that plausibly builds a sheared and twisted flux rope above the interior PIL and finally triggers the blow-out eruption of the flux rope via photospheric-convectiondriven slow tether-cutting reconnection of the legs of the sheared core field, low above the interior PIL, as proposed by van Ballegooijen & Martens (1989) and Moore & Roumeliotis (1992). The production of this eruption is a (perhaps rare) counterexample to solar eruptions that result from external collisional shearing between opposite polarities from two distinct emerging and/or emerged bipoles (Chintzoglou et al. 2019).

Description: We present data from ground-based, vacuum-chamber tests demonstrating the ability to modulate the output of a plasma source capable of producing a low-Earth orbit (LEO) type plasma. We obtained plasma oscillations up to 2.5 kHz impingent on stationary test equipment, which corresponds to meter-level ionospheric structures in LEO. This plasma source is, therefore, suitable for developing scientific instruments that measure the LEO plasma environment, in situ, with meter-level spatial resolution. Measurements were made using a fixed-bias collector and an electrometer sampling at 40 kHz. A mechanical aperture was established at the output of the plasma source via two concentric grids. The outer grid was free to rotate in the azimuthal direction with respect to the fixed inner grid. An identical, alternating hole pattern in the two grids resulted in a variable aperture that cycles through 90 open/close cycles per revolution. The frequency of the plasma oscillations is limited by the mechanism used to spin the grids and the bearing assembly on which the grids rotate. Higher frequencies are obtainable by upgrading the drive mechanism, allowing the possibility of centimeter-level spatial resolution.

Description: Magnetic gearing is being investigated at NASA as a replacement to conventional mechanical gearing in aerospace applications. Some potential benefits of magnetic gears over mechanical gearing are torque transmission without mechanical contact, decreased transmission noise, and no required lubrication. However, in order to be a viable alternative for aerospace applications, magnetic gearing must be shown to provide high enough specific torque (torque per unit mass). NASA's second magnetic gearing prototype (PT-2) was able to achieve promising specific torque on par with low torque mechanical gearboxes. This work will briefly review the electromagnetic and structural design of PT-2, provide detailed information on fabrication and assembly, examine build errors, walk through rebuild efforts to improve operation, and conclude with remarks on build difficulties and opportunities for improvement in future prototypes.

Description: NASA Acoustic Stirling IRAD (Internal Research and Development) Thermal Recovery Energy Efficient System (TREES) Energy Conversion and Management in Aircraft. Presentation on energy conversion on aircraft. Thermal energy recovery changes aircraft thermal management from being a necessary burden on aircraft performance to a desirable asset. It improves the engine performance by recycling waste heat and ultimately rejecting all collected aircraft heat out through the engine nozzle.

Description: Turboshaft engine performance and weight models were developed to support conceptual propulsion and vehicle mission design in support of the National Aeronautics and Space Administration's (NASA) Aeronautics Mission Research Directorate's (ARMD) Revolutionary Vertical Lift Technology (RVLT) Project. These models were developed using open data sources, assuming current and advanced technology levels, and range from 650 to 7,500 shaft output horsepower (485 to 5,600 kilowatts). Documenting the methodology, assumptions, and resulting performance realizes important benefits for NASA and the aviation community. NASA concept vehicle efforts using these propulsion models can more readily shared among the government, industry and university community as common baselines to support current and future work. Assessing the benefits of advanced technologies and new configurations can be facilitated using these models, which helps guide technology investment. As the various modeling conceptual vehicle and mission analysis environments advance, these models can be used directly for broader systems analysis studies, including optimization within the propulsion model itself. To perform this effort, the turboshaft engine is briefly discussed, highlighting the specific components and their expected performance characteristics over the power range and technology levels considered. Engine configurations will also be discussed as they will vary based on power output and assumed technology level. Engine performance, such as airflow, power output and weight will be reported, noting trends that are important for system studies. The effect of advanced propulsion technologies on RVLT-concept vehicles are also reported. Finally, potential future propulsion modeling work will be proposed.

Description: A model-scale exhaust system was tested to validate low-noise concepts and noise prediction methods. The tests involved far-field acoustics, translating phased array, and particle image velocimetry; this report covers the far-field acoustic measurements. Data were acquired for a series of nozzles with different chevron designs, both uninstalled and installed on a representative aircraft planform. The impact of the various chevron treatments on the far-field noise was documented, along with the impact of the pylon and planform. For the baseline nozzle, installation produced a 2 EPNdB (Effective Perceived Noise in deciBels) reduction, as assumed in system studies. Chevrons were used to shift noise sources upstream to maximize the installation benefits and to reduce unshielded sources downstream. These resulted in reductions of 4-5 EPNdB...

Description: Turboshaft engine performance and weight models were developed to support conceptual propulsion and vehicle mission design and performance under the Revolutionary Vertical Lift Technology (RVLT) Project. These models were developed using open data sources, assuming current and advanced technology levels, and range from 650 to 7,500 shaft output horsepower (485 to 5,600 kW). Documenting the methodology, assumptions, and resulting performance realizes important benefits NASA and the aviation community. NASA concept vehicle efforts using these propulsion models can be more readily shared among the government, industry and university community as common baselines to support current and future work. Assessing the benefits of advanced technologies and new configurations can be facilitated using these models, which helps guide technology investment. As the various modeling conceptual vehicle and mission analysis environments advanced, these models can be used directly for broader systems analysis studies, including optimization within the propulsion model itself. To perform this effort, the turboshaft engine is briefly discussed, highlighting the specific components and their expected performance characteristics over the power range and technology levels considered. Engine configurations will also be discussed as they will vary based on power output and assumed technology level. Engine performance, such as airflow, power output and weight will be reported, noting trends that are important for system studies. The effect of advanced propulsion technologies on RVLT concept vehicles are also reported. Finally, potential future propulsion modeling work will be proposed.

Description: No abstract available

Description: Determining the biological impact of spaceflight through novel approaches is essential to reduce the health risks to astronauts for long-term space missions. The current established health risks due to spaceflight are only reflecting known symptomatic and physiologic responses and do not reflect early onset of other potential diseases. There are many unknown variables which still need to be identified to fully understand the health impacts due to the environmental factors in space. One method to uncover potential novel biological mechanisms responsible for health risks in astronauts is by utilizing NASA's GeneLab Data Systems (genelab.nasa.gov). GeneLab is public repository that hosts multiple omics datasets generated from space biology experiments that include experiments flown in space, simulated cosmic radiation.

Description: This paper presents the design, development, operation, and test capabilities of a proposed superconducting coil testbed to measure alternating current (AC) losses at the NASA Glenn Research Center. Superconducting AC losses are important in the design of electric stators and rotors, power transmission lines, transformers, fault current limiters, magnets, and superconducting energy storage (not batteries). The new liquid-hydrogen-based rig will allow superconducting testing across a wide range of test parameters, including injected current up to 400 A, frequency (0 to 400 Hz), magnetic field (0 to 0.6 T), phase angle between induced voltage and injected current (180 to 180), coil coolant temperature (18 to 28 K), and AC power loss (5 to 30 W). While the target application of interest is 20 K superconducting MgB2 (the only superconductor that can presently be made with low losses) stator coils for future electric machines, the rig can accommodate test articles (TAs) with straight wire, tape, cables, coils of any shape, any allowable combination of superconducting wire and fluid (e.g., yttrium barium copper oxide (YBCO) coils and liquid nitrogen), and AC or direct current (DC) testing. The new spin rig builds upon the existing Air Force spin rig through a more flexible mode of fluid control, a wider gap space (up to 10.2 cm) for TAs, and the ability to accommodate TAs over a wider range of operating temperatures (18 to 95 K) using liquid hydrogen, gaseous helium, or liquid nitrogen as the working fluid, thus supporting direct cooled machines below 77 K.

Description: No abstract available

Description: The dramatic flow of data from the Kepler and K2 missions opens the opportunity to significantly improve our knowledge of stellar interiors, surface dynamics, and structure. However, interpretation of these observations is a challenging task because it depends on tiny effects that can be studied only with advanced first-principles modeling. We present results of 3D time-dependent radiative hydrodynamic simulations of stellar outer convection zones and atmospheres taking into account chemical composition, radiative transfer, turbulence effects, and a realistic equation of state for main sequence stars. We will discuss properties of convective structure and dynamics, convective overshoot, effects of magnetic fields and rotation, as well as the potential influence of turbulent surface dynamics on high-precision RV measurements.

Description: When faced with the question of designing an asteroid deflection mission or with the decision of launching it, significant uncertainties are present in the asteroids physical properties, and its orbit solution. The success of the deflection mission relies heavily on these aspects. For example, a heavier than expected asteroid will reduce the imparted deflection DV. So will a larger porosity value by reducing the beta factor [1]. Here, we present a new capability that estimates asteroid impact risk under consideration of these uncertainties. The new method samples the uncertainty space along multiple dimensions, performs a predetermined deflection, propagates the deflected samples to the Earth, models the impact damage, and estimates the overall risk outcome. The work builds on the Probabilistic Asteroid Impact Risk (PAIR) assessment tool [2] by including orbital uncertainty and deflection capabilities. We demonstrate this risk estimation approach for threatening asteroids using the example of the fictitious impactor 2019 PDC. Such analysis provides a quantitative basis for the work of decision makers and disaster managers. It may further find application in areas such as mitigation mission planning where projected post-mitigation risk can be compared to premitigation levels as a means of cost-benefit analysis formitigation options.

Description: No abstract available

Description: Fine-grained, spinel-rich Ca-Al-rich inclusions (FGIs) in carbonaceous chondrites consist of numerous layered nodules having cores of spinel, hibonite, and/or perovskite surrounded by multiple thin layers of melilite, anorthite, diopside, and/or olivine. They are interpreted as aggregates of direct high-temperature condensates from an 16O-rich nebular gas that escaped significant melting. However, FGIs are very complex objects composed of intimate intergrowths of fine-grained refractory phases and show extremely large variations in mineralogy, modal abundance, and textures. Thus, detailed FIB/TEM analyses of FGIs are required to fully characterize their micro-to-nanometer scale textures, mineralogy, and chemical compositions and hence elucidate their formation processes and conditions in the early solar nebula. Here, we present our on-going study of pristine FGIs from the reduced CV3 chondrites Efremovka and Thiel Mountains (TIL) 07003 and 07007 that have minimal evidence for secondary parent body alteration.

Description: thermally-metamorphosed ordinary chondrite regolith breccias (Monahans 1998, hereafter simply Monahans ( 5) and Zag (H3-6)) contain fluid inclusion-bearing halite (NaCl) crystals dated to be ~4.5 billion years old. Thus, compositional data on fluid inclusions in these halites will reveal unique information regarding the origin and activity of aqueous fluids in the early solar system, and especially their interactions with organic mate- rial. Our initial analyses of solid inclusions in Monahans halite has shown the presence of olivine, high- and low- Ca pyroxene, feldspars, magnetite, sulfides, phyllosilicates, zeolites, metal, phosphates and abundant organics. We age of carbon, carbonates and organics in these residues, and low but significant amino acids concentrations in Monahans and Zag halite.

Description: The CM chondrites are generally complex impact breccias, in which lithic clasts and mineral fragments showing various degrees of aqueous alteration and possibly originating from different parent bodies are mixed together. The occurrence of CM-like clasts in other chondritic and achondritic meteorite breccias is also well-documented, however, reports on the occurrence of foreign clasts in CM chondrites are rare. In this study, we reinvestigated the white clast in the Murchison CM chondrite and demonstrate that the clast is not related to R chondrites as earlier suggested. In addition to the classification we discuss the origin and the history of its formation by studying several aspects like mineralogy, bulk chemistry, Rare Earth Elements (REE), oxygen isotopes, and the soluble organic compounds.

Description: No abstract available

Description: No abstract available

Description: For highly eccentric orbits such as that of the Magnetospheric Multiscale (MMS)mission, with apogee radius now 29.34 Earth radii, the third-body effects of Sun andMoon are the major perturbations. One key consequence is an oscillation in MMSperigee altitude, on an approximately 6 year cycle. This variation has already requiredperigee-raise maneuvers to avoid an untimely reentry. There is also a long-termevolution in the orientation of the MMS orbit, with period roughly twice as long. Thiseffect may potentially be useful for MMS science studies, as it can bring the spacecraftinto new regions of the magnetosphere.

Description: Fourteen CO3 chondrites have been recovered in the Dominion Range (DOM) dense collection area of the Transantarctic Mtns by ANSMET teams during the 2008-09, 2010-11, and 2014-15 seasons [1-3]. DOM 08006, one of the largest masses, has been studied extensively and is recognized to be a very primitive unmetamor-phosed sample of great value to planetary science [4]. Studies of pre-solar grains, organics, chondrules, inclusions, and matrix have revealed a rich scientific treasure helping to constrain the conditions in the early solar system (e.g., [4-8]). Many of the masses paired with this sample are significant, yet the pairing has been called into question due to the finding that DOM 08004 seems less primitive than DOM 08006 [5]. Because of the significant masses involved, and the great scientific value of DOM 08006, we have undertaken a detailed assessment of the pairing using field relations, macroscopic observations, petrography, and olivine compositions.

Description: The pressure gain combustion (PGC) community is currently investigating rotating detonation engine (RDE) configurations where the flow direction is predominantly radial while the detonation travels circumferentially. These configurations are sometimes referred to as disk rotating detonation engines (DRDE) due to their nominal appearance as two disks in parallel with a gap between them. Having radial flow between disks, as opposed to the conventional RDE with axial flow in an annulus, may have profound effects on both the flow field and the performance. It may also yield extraordinarily compact devices which are well suited to particular propulsion and power applications. This presentation describes a preliminary effort to model the DRDE using a modified computational fluid dynamics (CFD) code originally written for analyzing ordinary RDE's. The quasi-two-dimensional code modifications are described, and some simple test flows are analyzed to insure that the modifications are functioning as envisioned. The code is then used to examine several DRDE scenarios such as radially inward and radially outward devices to see if stable operation is possible and if so, to assess the performance in terms of pressure gain. It is found that several flow scenarios are not only stable, but show superior performance to the ordinary RDE.

Description: No abstract available

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Description: Oxygen fugacity and water content are crucial parameters for many chemical and physical properties of the Earth's mantle, for example bearing on fluid type, melting initiation, and deformation. However, the exact behaviour of Fe3+ and H during melting and metasomatism is still under debate. Here, the Fe3+/Fe ratio (Mssbauer and EMP) and water content (FTIR) of peridotite minerals are examined in mantle xenoliths from Kilbourne Hole (KH), NM, and Dish Hill (DH), CA (USA). These spinel peridotites have compositions consistent with partial melting with variable degrees of metasomatism (undetectable to cryptic to modal). Pyroxenites also allow to examine melt-rock reactions. Bulk-rock Fe2O3 content of the KH peridotites correlates with indices of melting (positive with bulk-rock Al2O3 and Cpx Yb contents, and negative with spinel Cr#) confirming that Fe3+ behaves as an incompatible element during melting. Correlations of the Fe3+/Fe ratio of minerals with these indices, however, indicates that Fe3+ is incompatible in Cpx but compatible in Opx and spinel during melting. Water contents in olivine, Cpx and Opx from most KH peridotites can be explained by partial melting and correlate negatively with the Fe3+/Fe ratio of spinel and Opx but positively with that of Cpx. This indicates partial control of Fe3+ on the incorporation of H in pyroxene, but not related to a redox equilibrium in Cpx. The higher Fe3+/Fe ratio of spinel in the metasomatized KH and DH peridotites, and in the pyroxenites confirms that oxidation characterizes modal metasomatism. Metasomatism, however, is not necessarily accompanied by water addition.

Description: Magnetic gears are currently being developed for use in a variety of industries such as wind and automotive, because of their higher reliability and lower maintenance cost than their mechanical counterparts. The bulk of magnetic gear development to date has focused on maximizing the technology's volumetric torque density. In contrast, the primary performance metrics for an aircraft's gear box are its mass and efficiency. To that end this paper presents a study of the achievable electromagnetic specific torque and efficiency of concentric magnetic gears. NASA's second magnetic gear prototype is used as the baseline for this study. Achievable electromagnetic specific torque and efficiency trends are presented with respect to higher level design variables such as gear ratio and radius.

Description: Magnetic gears are an attractive alternative to mechanical gears for electrified aircraft drive systems due to their ability to transmit torque without mechanical tooth contact. Consequently, magnetic gears enable electrified aircraft to take advantage of the benefits of gearing without introducing most of the contact-related reliability concerns associated with mechanical gearing. Magnetic gears however, have not been shown to match the specific torque (torque/mass) and efficiency of their mechanical counterparts in an aerospace application to date. In this paper, the design of a concentric magnetic gear for a personal air transport NASA reference vehicle is presented to demonstrate the feasibility of a magnetic gear for aerospace applications.

Description: Energy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how ultralow frequency (ULF) wave activity during the passage of Alfvenic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron uxes from the background. We found that the global recovery that started on 22 September 2014, which coincides with the corotating interaction region preceding a highspeed stream and the occurrence of persistent substorm activity, provides an excellent scenario to explore the contribution of ULF waves. To support our analyses, we employed ground and spacebased observational data and global magnetohydrodynamic simulations and calculated the ULF wave radial diffusion coefcients employing an empirical model. Observations show a gradual increase of electron uxes in the outer radiation belt and a concomitant enhancement of ULF activity that spreads from higher to lower Lshells. Magnetohydrodynamic simulation results agree with observed ULF wave activity in the magnetotail, which leads to both fast and Alfven modes in the magnetospheric nightside sector. The observations agree with the empirical model and are conrmed by phase space density calculations for this global recovery period.

Description: No abstract available

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Description: An experiment is conducted with hot-wire anemometry to document the exit boundary layer characteristics of two nozzle configurations at jet Mach numbers up to 0.82. Far-field noise and jet plume experimental data from these two configurations have been used in Large Eddy Simulations (LES) of jets by colleagues at other Institutions. The current experiment provides the boundary layer data which have been identified as being critical for validation of the simulations since the initial conditions can significantly affect subsequent jet evolution and its radiated noise. The data exhibit fully turbulent boundary layers for the case with a pipe attached upstream of the nozzle. The case without the pipe involves Blasius-like mean velocity profiles but a highly disturbed laminar state with large turbulence intensities in a range of subsonic Mach numbers.

Description: Electrified aircraft propulsion seeks to address ambitious goals in the commercial airline industry, including significant decreases in fuel burn, emissions, noise, and takeoff field length. In order to move these electrified propulsion concepts forward, analysis tools are needed that can model propulsion systems containing both gas turbine and power system components. This work presents the definition of an electric port, a set of electrical power systems tools, and simulation examples for the Numerical Propulsion System Simulation (NPSS) software. NPSS is the industry standard modeling and simulation package for aircraft propulsion systems, and the ability to design, size, integrate, and analyze electric power systems will enable industry efforts towards the development of electrified aircraft propulsion.

Description: The Habitable Exoplanet Observatory (HabEx) is one of four mission concepts under study for the 2020 Astrophysics Decadal Survey. Its goal is to directly image and spectroscopically characterize planetary systems in the habitable zone around nearby sun-like stars. Additionally, HabEx will perform a broad range of general astrophysics science enabled by 115 to 2500 nm spectral range and 3 x 3 arc-minute FOV. Critical to achieving the HabEx science goals is a large, ultra-stable UV/Optical/Near-IR (UVOIR) telescope. The baseline HabEx telescope is 4-meter off-axis unobscured, diffraction limited at 400 nm with wavefront stability on the order of a few 10s of picometers. The technology readiness level (TRL) to manufacture and test the HabEx baseline primary mirror is assessed to be at TRL-6 for all but two TRL-4 technologies: 1) non-destructive process to quantify CTE homogeneity of a 4-m mirror substrate with a spatial sampling of at least 100 x 100 to better than +/- 1 ppb/K; and, 2) process to quantify self-weight gravity deflection to better than 4-nm rms over a 100 x 100 spatial sampling. This paper reviews the technology needs to manufacture the HabEx primary mirror, assesses their TRL and proposes a roadmap to mature the two remaining technologies to TRL-6.

Description: An overview is given of an effort that focused on using CFD analysis to complement design and configuration definition of Lean-Direct Injection (LDI) combustion concepts for NASA's Commercial Supersonic Transport (CST) program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for second and third generation LDI configurations at CST cruise conditions. All computations were performed with a consistent approach of mesh-generation, spray modeling, ignition and kinetics modeling. Emissions (EINOx) characteristics were predicted for CST cruise conditions, and compared with emissions data from experimental measurements to evaluate the fidelity of the CFD modeling approach to predict emissions changes in response to changes in supersonic cycle conditions.

Description: Some of the challenges associated with developing electric aircraft propulsion systems include developing powertrain components that are both efficient and light-weight. In particular, electric motors must simultaneously achieve high efficiency by minimizing electrical and mechanical losses while also achieving high specific power by increasing the torque and/or speed. Normally increasing torque or speed will increase electrical and mechanical losses. The High Efficiency Megawatt Machine (HEMM) minimizes electrical losses by incorporating a superconductor to enable increased current on the rotor. And the rotor spins in a vacuum to minimize thermal and mechanical losses. Some organizations have been developing superconducting rotors for similar reasons using either cryogenic fluid transfer systems, fully immersed cryogenic cooling, and in a few cases utilized built-in cryogenic cooling on the rotor using a Brayton or Stirling system but the implementation was too large or inefficient for effective motor integration. Instead, a new approach for cryogenically cooling the superconducting rotor coil with an embedded rotating cryocooler is presented that fits completely within the rotating shaft.

Description: No abstract available

Description: This study develops a vision-based detection and classification algorithm to address the challenges of in-situ small orbital debris environment classification including debris observability and instrument requirements for small debris observation. The algorithm operates in near real time and is robust under difficult tasks in moving objects classification such as multiple moving objects, objects with various movement trajectories and speeds, very small or faint objects, and substantial background motion. The performance of the algorithm is optimized and validated using space image data available through simulated environments generated using NASA Marshall Space Flight Centers Dynamic Star Field Simulator of on-board optical sensors and cameras.

Description: By the close of the Cassini mission in 2017 the Composite Infrared Spectrometer had recorded surface brightnesstemperatures on Titan for 13 yr (almost half a Titan year). We mapped temperatures in latitude from pole to pole inseven time segments from northern mid-winter to northern summer solstice. At the beginning of the mission thewarmest temperatures were centered at 13 S where they peaked at 93.9 K. Temperatures fell off by about 4 Ktoward the north pole and 2 K toward the south pole. As the seasons progressed the warmest temperatures shiftednorthward, tracking the subsolar point, and at northern summer solstice were centered at 24 N. While moving norththe peak temperature decreased by about 1 K, reaching 92.8 K at solstice. At solstice the fall-off toward the northand south poles were 1 K and 3 K, respectively. Thus the temperature range was the same 2 K at the two poles. Ourobserved surface temperatures agree with recent general circulation model results that take account of methanehydrology and imply that hemispherical differences in Titan's topography may play a role in the north?southasymmetry on Titan.

Description: No abstract available

Description: No abstract available

Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the drastic computational cost makes it non-practical to support real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube prob- lem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computa- tionally expansive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the well-established stagnation-line approach. Comparison with the time-accurate simulation shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium, due to shock speed unsteadiness.

Description: From 2004 to 2017, the Cassini spacecraft orbited Saturn, completing 127 close ybys of its largest moon, Titan. Cassinis Composite Infrared Spectrometer (CIRS), one of 12 instruments carried on board, proled Titan in the thermal infrared (71000 m) throughout the entire 13 yr mission. CIRS observed on both targeted encounters (ybys) and more distant opportunities, collecting 8.4 million spectra from 837 individual Titan observations over 3633 hr. Observations of multiple types were made throughout the mission, building up a vast mosaic picture of Titans atmospheric state across spatial and temporal domains. This paper provides a guide to these observations, describing each type and chronicling its occurrences and global-seasonal coverage. The purpose is to provide a resource for future users of the CIRS data set, as well as those seeking to put existing CIRS publications into the overall context of the mission, and to facilitate future intercomparison of CIRS results with those of other Cassini instruments and ground-based observations.

Description: The X-57 60kW Permanent Magnet Synchronous Motor for cruise applications was modeled utilizing a two-dimensional electromagnetics simulation software called Finite Element Method Magnets (FEMM, D. Meeker). Through FEMM, the simulated induction and torque characteristics of the X-57 PMSM were obtained. These parameters and other values were compared to actual static laboratory measurements. A three-dimensional electromagnetic model of the X-57 cruise motor was created utilizing OperaFEA (Dassault Systemes SE, Velizy-Villacoublay, France). Torque, RPM, power, resistance, and inductance characteristics were examined along with establishing work to begin examining heat flow and heat dissipation for efficiency purposes.

Description: The adoption of SiC devices in high power applications enables higher switching speed, which requires lower circuit parasitic inductance to reduce the voltage overshoot. This paper presents the design of a busbar for a 500 kVA three-level active natural clamped converter. The layout of the busbar is discussed in detail based on the analysis of the multiple commutation loops, magnetic cancelling effect, and DC-link capacitor placement. The loop inductance of the designed busbar is verified with simulation, impedance measurements and converter experiment. The results can match with each other and the inductances of small and large loop are 6.5 nH and 17.5 nH respectively, which is significantly lower than the busbars of NPC type converters in other references.

Description: The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission concept to measure the gravitational-wave signature of primordial inflation through its distinctive imprint on the linear polarization of thecosmic microwave background (CMB). Its optical system couples a polarizing Fourier transform spectrometerto the sky to measure the differential signal between orthogonal linear polarization states from two co-pointedbeams on the sky. The double differential nature of the four-port measurement mitigates beam-related systematic errors common to the two-port systems used in most CMB measurements. Systematic errors coupling unpolarized temperature gradients to a false polarized signal cancel to first order for any individual detector. Thiscommon-mode cancellation is performed optically, prior to detection, and does not depend on the instrumentcalibration. Systematic errors coupling temperature to polarization cancel to second order when comparing signals from independent detectors. We describe the polarized beam patterns for PIXIE and assess the systematicerror for measurements of CMB polarization.

Description: NASA is broadly engaged in Electrified Aircraft Propulsion (EAP) efforts across air vehicle sizes and electric aircraft propulsion approaches. EAP enables a wide range of propulsion airframe integration options as well as the use of rechargeable energy storage in an aircraft. This paper is limited to a discussion of boundary layer ingestion (BLI) systems which are located on the fuselage of the aircraft and use electrical drive systems. We term that combination an "electrical propulsive fuselage". The benefits, challenges, and design parameters of an electrically driven fuselage BLI system are considered. Five existing types of fuselage BLI implementation approaches which can be implemented using either electrical or mechanical drive systems are reviewed. An overview of boundary layer types, fan response to boundary layer, and electrical system for aircraft propulsion is presented. An idea distributed electric propulsive fuselage is proposed.

Description: The Miniaturized Electron pRoton Telescope, MERiT, is a lowmass, lowpower, compact instrument using an innovative combination of particle detectors, sensor electronics, and onboard processing. MERiT is flying on the Compact Radiation belt Explorer, CeREs, a 3U CubeSat launched into a low earth orbit of 500km altitude and inclination of 85 on 16 December 2018. The primary and secondary science goals of CeREs are to investigate electron microbursts and to study solar particles. MERiT comprises a stack of solid state detectors (SSD) behind space facing avalanche photo diodes (APDs) surrounded by WAl shielding to reduce sidepenetrating particle background. The APDSSD combination enables measurement of electrons from 5 to 200 keV and 1 to 8 MeV; protons from 200400 keV and 7100 MeV in differential channels with energy resolution E/E30% for both electrons and protons. MERiT measures microbursts with a high time resolution ranging from 4 to 16 ms and solar particles with a cadence of 1 s. MERiT energy channels and cadences are software configurable via algorithms and lookup tables residing on a fieldprogrammable gate array. The lookup tables can be changed via ground commands. MERiT geometry factor is 31 sq.cmsr and optimized to measure microbursts with the instrument viewing the local zenith in orbit. MERiT enables investigation of dynamical processes of radiation belt electron energization and loss, solar electron and proton transport, and their access to the Earth's polar caps. We describe the MERiT sensor design, calibration, operational modes, data products, and science goals.

Description: C II is one of the brightest emission lines from star-forming galaxies and is an excellent tracer for star formation. Recent work measured the C II emission line amplitude for redshifts 2 〈 z 〈 3.2 by cross-correlating Planck High Frequency Instrument emission maps with tracers of overdensity from the Baryon Oscillation Spectroscopic Sky Survey, finding I(CII)=6.6(sup +5.0, sub 4.810(exp 4) Jy/sr at 95per cent confidence level. In this paper, we present a refinement of this earlier work by improving the mask weighting in each of the Planck bands and the precision in the covariance matrix. We report a detection of excess emission in the 545 GHz Planck band separate from the cosmic infrared background (CIB) present in the 353857 GHz Planck bands. This excess is consistent with redshifted C II emission, in which case we report b(CII)I(CII)=2.0(sup +1.2, sub 1.110(exp 5) Jy/sr at 95 per cent confidence level, which strongly favours many collisional excitation models of C II emission. Our detection shows strong evidence for a model with a non-zero C II parameter, though line intensity mapping observations at high spectral resolution will be needed to confirm this result.

Description: The NASA Orbital Debris Program Office (ODPO) studies all aspects of spacecraft end-of-life and orbital debris measurement, modeling, and mitigation. The reentry safety group within the ODPO uses the Object Reentry Survival Analysis Tool (ORSAT) to calculate the casualty risk due to reentry of spacecraft and other types of orbital debris. ORSAT models spacecraft as a collection of fragments that break apart from the parent object at a pre-defined breakup altitude. It then calculates the trajectory and aero-heating of these fragments to determine which fragments are completely destroyed and which survive to the ground and pose a risk to human population. Because of the historically high computational cost of these calculations, many simplifying assumptions have been made in the traditional calculation and analysis process used by the ODPO, some of which have been shown by recent research by the ODPO and others to be incorrect. Improvements to the ORSAT code and advancements in computer technology have vastly decreased the programs processing time, and have allowed the ODPO to develop a capability for large-scale parametric studies and Monte Carlo reentry simulations that can aid in both the initial spacecraft design and provide more detailed and accurate risk analysis to spacecraft operators.

Description: There is a limited amount of hypervelocity impact (HVI) data on pressurized composite overwrapped pressure vessels (COPV). In recent years, NASA has performed HVI tests to characterize impact conditions resulting in either leak or burst of the COPVs representative of spacecraft hardware. This paper reports on the results of 40 tests that have been conducted on several types of COPV configurations, pressurized by inert gas to near the vessels rated maximum expected operating pressure (MEOP). These tests were used to better understand COPV response under HVI conditions and develop ballistic limit equations (BLE) related to these tests.

Description: The statistical debris measurement campaigns conducted by the Haystack Ultrawideband Satellite Imaging Radar on behalf of the NASA Orbital Debris Program Office are used to characterize the long-term behavior of the small, low Earth orbit (LEO) orbital debris environment. Recent analyses have revealed the presence of a persistent LEO small debris cloud, which has no accompanying large component, cataloged by the U.S. Space Surveillance Network. This cloud, at an inclination of approximately 82 and below 1200 km in altitude does, however, correspond to the heavily trafficked region of space that has suffered several known, accidental collisions, e.g., Cosmos 1934 and Cosmos 2251. In this paper, we describe the observed cloud and model it using the NASA Standard Satellite Breakup Model. Key features of the cloud model, including source attribution and debris mass constraints, are presented to enable further observations and characterization.

Description: An overview is given of an effort for the use of CFD analysis to complement design and configuration definition of third generation Lean-Direct Injection combustion concepts (LDI-3) for NASAs N+3 program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for a three-cup, nineteen-element flame tube array with redesigned pilot injectors to improve spray and emissions characteristics when compared to a previous LDI-3 design. All computations were performed with a consistent approach to mesh-generation, spray modeling, ignition and kinetics modeling for a medium-power cycle condition. Computational predictions of the aerodynamics of a new pre-filming pilot injector were used to arrive at an optimized aerothermal design that meets effective area and fuel-air mixing criteria. The newly designed pilot injectors were shown to provide considerable improvements in aerodynamic stability, flame-tube pattern factor and NOx emissions, when compared to the original design.

Description: Magnetic gears are currently being explored to replace mechanical gears in various industries such as wind and automotive due to their higher reliability and lower maintenance requirements. In these applications volume minimization has been the goal of magnetic gear development. In contrast, the primary performance metrics for electrified aircraft drives are mass and efficiency. This paper presents the first ever study of design tradeoffs between electromagnetic mass and efficiency of concentric magnetic gears and the feasibility of achieving the low mass and high efficiency required for electrified aircraft applications. Higher level design variables are considered, including gear ratio, number of magnetic pole pairs, and number of magnets per pole pair.