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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Colloidal superionic conductors

Nanoparticles with highly asymmetric sizes and charges that self-assemble into crystals via electrostatics may exhibit behaviors reminiscent of those of metals or superionic materials. Here, we use coarse-grained molecular simulations with underdamped Langevin dynamics to explore how a binary charged colloidal crystal reacts to an external electric field. As the field strength increases, we find transitions from insulator (ionic state), to superionic (conductive state), to laning, to complete melting (liquid state). In the superionic state, the resistivity decreases with increasing temperature, which is contrary to metals, yet the increment decreases as the electric field becomes stronger. Additionally, we verify that the dissipation of the system and the fluctuation of charge currents obey recently developed thermodynamic uncertainty relation. Our results describe charge transport mechanisms in colloidal superionic conductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2001

Relationship between Jovian Hectometric Attenuation Lanes And Io Volcanic Activity

Within the Galileo plasma wave instrument data a narrow (in frequency) attenuation band is seen in the hectometric (HOM) emission that varies in frequency with system III longitude. This attenuation lane is believed to be the result of near-grazing incidence or coherent scattering of radio emission near the outer edge of the Io torus, i.e., when the ray path is nearly tangent to an L shell containing the Io flux tube. Such a process should, therefore, be enhanced when the Io volcanic activity is increased and the Io flux tube has enhanced density. We have performed a systematic study of the existing Galileo radio emission data in an effort to determine the phenomenology and frequency of occurrence of the attenuation lanes and the association, if any, with published volcanic activity of Io. Our results indicate that the attenuation lanes are present almost all of the time but are enhanced on occasion. The best examples of attenuation lanes occur when Galileo is within approximately 65 R(sub J) of Jupiter and thus are probably more apparent because of the increased signal-to-noise ratio of the radio receivers. The lack of continuous monitoring of Io activity and the lack of known activity on the anti-Earthward side of Io are problematic and make detailed correlation with radio emission very difficult at this time. Nevertheless, if the data are displayed for periods when the spacecraft is within 65 R(sub J) (i.e., for each perijove pass), then the highest-contrast lanes occur on most passes when the Io volcanic activity is also high for that pass. These results support our current understanding of attenuation lane formation and suggest that future efforts can be made to better understand the interaction of HOM emission with the Io flux tube.

Menietti, J. D.↗
NASA NTRS1986

Terrain types and local-scale stratigraphy of grooved terrain on ganymede

Grooved terrain is subdivided on the basis of pervasive morphology into: (1) groove lanes - elongate parallel groove bands, (2) grooved polygons - polygonal domains of parallel grooves, (3) reticulate terrain - polygonal domains of orthogonal grooves, and (4) complex grooved terrain - polygons with several complexly cross-cutting groove sets. Detailed geologic mapping of select areas, employing previously established conventions for determining relative age relations, reveals a general three-stage sequence of grooved terrain emplacement: first, dissection of the lithosphere by throughgoing grooves, and pervasive deformation of intervening blocks; second, extensive flooding and continued deformation of the intervening blocks; third, repeated superposition of groove lanes concentrated at sites of initial throughgoing grooves. This sequence is corroborated by crater-density measurements. Dominant orientations of groove sets are parallel to relict zones of weakness that probably were reactivated during grooved terrain formation. Groove lane morphology and development consistent with that predicted for passive rifts suggests a major role of global expansion in grooved terrain formation.

Murchie, Scott L.↗
NASA NTRS2003

Fine-grained Goethite as a Precursor for Martian Gray Hematite

Several isolated deposits of gray, crystalline hematite on Mars were discovered using data returned from the Thermal Emission Spectrometer (TES) instrument aboard the Mars Global Surveyor spacecraft. Christensen et al. provided five testable hypotheses regarding the formation of crystalline hematite on Mars: 1) low-temperature precipitation of Fe oxides/hydroxides from standing, oxygenated, Fe-rich water, followed by subsequent alteration to gray hematite, 2) low-temperature leaching of iron-bearing silicates and other materials leaving a Fe-rich residue laterite-style weathering) which is subsequently altered to gray hematite, 3) direct precipitation of gray hematite from Fe-rich circulating fluids of hydrothermal or other origin, 4) formation of gray hematitic surface coatings during weathering, and 5) thermal oxidation of magnetite-rich lavas. Since this initial work, several authors have examined the hematite deposits to determine their formation mechanism. Lane et al. cited the absence of a 390/ cm absorption in the martian hematite spectrum as evidence for platy hematite grains. Their model for the formation of the deposits includes deposition of any of a variety of iron oxides or oxyhydroxides by aqueous or hydrothermal fluids, burial and metamorphosis to gray platy hematite grains, and exhumation in recent times. Based on a detailed geomorphic examination of the Sinus Meridiani region, Hynek et al. conclude that the most likely method of hematite formation was either emplacement by a hydrothermal fluid or oxidation of a magnetite-rich pyroclastic deposit. Similarly, Arvidson et al., favor a model involving the alteration of pyroclastic deposits by aqueous or hydrothermal fluids. Finally, based on geochemical modeling and an examination of Aram Chaos, Catling and Moore favor emplacement by hydrothermal fluids with a minimum temperature of 100 C. Comparison of the average martian hematite spectrum measured by TES to hematite emissivity spectra for a variety of naturally occurring hematites shows small but potentially important differences. In particular, band shapes, positions and relative band emissivities of hematite spectra vary over the range of samples. These differences imply that the natural variability of thermal infrared hematite spectra has not been fully characterized, especially with respect to the reaction pathway and crystal structure.

T D Glotch↗
DOE OSTI2025

Skyrmion-skyrmionium phase separation and laning transitions via spin-orbit torque currents

Many driven binary systems can exhibit laning transitions when the two species have different mobilities, such as colloidal particles with opposite charges in electric fields. Another example is pedestrian or active-matter systems, where particles moving in opposite directions form a phase-separated state that enhances the overall mobility. In this work, we use atomistic simulations to demonstrate that mixtures of skyrmions and skyrmioniums also exhibit pattern formation and laning transitions. Skyrmions move more slowly and at a finite skyrmion Hall angle compared to skyrmioniums, which move faster and without a skyrmion Hall effect. At low drives, the system forms a partially jammed phase where the skyrmioniums are dragged by the surrounding skyrmions, resulting in a finite angle of motion for the skyrmioniums. At higher drives, the system transitions into a laned state, but unlike colloidal systems, the lanes in the skyrmion-skyrmionium mixture are tilted relative to the driving direction due to the intrinsic skyrmion Hall angle. In the laned state, the skyrmionium angle of motion is reversed when it aligns with the tilted lane structure. At even higher drives, the skyrmioniums collapse into skyrmions. Below a critical skyrmion density, both textures can move independently with few collisions, but above this density, the laning state disappears entirely, and the system transitions to a skyrmion-only state. We map out the velocity and Hall responses of the different textures and identify three distinct phases: partially jammed, laned, and skyrmion-only moving crystal states. In conclusion, we compare our results to recent observations of tilted laning phases in pedestrian flows, where chiral symmetry breaking in the particle interactions leads to similar behavior.

36 MATERIALS SCIENCE↗
NASA NTRS1993

NGC 4314. II - Hubble Space Telescope I-band surface photometry of the nuclear region

We present an HST I-band Planetary Camera image of the nuclear region of NGC 4314, an anemic barred galaxy with recent star formation confined to a nuclear ring. These data resolve the nuclear ring into multiple sites of new star formation and resolve associated dust lanes into discrete clouds. Deconvolution results in at least 0.13 arcsec resolution, as demonstrated by the de Vaucouleurs r exp 1/4 law. Contrasted with similar studies of M87 and NGC 7457, we find no photometric evidence for an extreme concentration of stars in the center of NGC 4314. We identify an oval distortion of length 8 arcsec in the nuclear region, using ellipse-fitting routines and the unsharp masked frame. This nuclear bar has newer stars near its ends. We catalog 14 star clusters associated with H II regions in the nuclear ring. As an additional demonstration of the resolution achieved, the integral size distribution of these clusters is described by an exponential relationship which prevails down to 0.14 arcsec.

Benedict, G. F.↗
NASA NTRS1993

Cenozoic crustal rotations in the Mojave Desert from paleomagnetic studies around Barstow, California

Paleomagnetic data from the Mojave Desert around Barstow, California, suggest 55 to 75 deg of clockwise rotation of this area in earliest Miocene time, followed by 23 deg of counterclockwise rotation in the Early Miocene, and no rotation after 18 Ma. Earliest Miocene clockwise rotation of the Barstow area is suggested by data from nine sites in the Oligocene-Miocene Lane Mountain Quartz Latite and Jackhammer Formation and may be related to oroclinal bending of the southern Sierra Nevada batholith. Data from 13 sites in the Early Miocene Pickhandle Formation indicate counterclockwise rotation, which coincides with Early Miocene E-NE - W-SW extension and detachment faulting in the Mojave Desert. These results suggest that Miocene extension in the Mojave Desert is related to similarly oriented extension in the Colorado River extensional corridor. Early Miocene to Pliocene rocks of the Andesite and Dacite of the Calico Mountains, Barstow Formation, Andesite of Murphy's Well, and Black Mountain Basalt show no evidence for significant rotation of the Barstow area after 18 Ma. Most other paleomagnetic data from elsewhere in the Mojave are consistent with a lack of significant post-18 Ma rotations, suggesting that post-10 Ma right-lateral faulting there has produced relatively little crustal rotation.

Valentine, Michael J.↗
NASA NTRS2000

Circumnuclear Regions In Barred Spiral Galaxies: Near-Infrared Imaging - 1

We present sub-arcsecond resolution ground-based near-infrared images of the central regions of a sample of twelve barred galaxies with circumnuclear star formation activity, which is organized in ring-like regions typically one kiloparsec in diameter. We also present Hubble Space Telescope near-infrared images of ten of our sample galaxies, and compare them with our ground-based data. Although our sample galaxies were selected for the presence of circumnuclear star formation activity, our broad-band near-infrared images are heterogeneous, showing a substantial amount of small-scale structure in some galaxies, and practically none in others. We argue that, where it exists, this structure is caused by young stars, which also cause the characteristic bumps or changes in slope in the radial profiles of ellipticity, major axis position angle, surface brightness and colour at the radius of the circumnuclear ring in most of our sample galaxies. In 7 out of 10 HST images, star formation in the nuclear ring is clearly visible as a large number of small emitting regions, organised into spiral arm fragments, which are accompanied by dust lanes. NIR colour index maps show much more clearly the location of dust lanes and, in certain cases, regions of star formation than single broad-band images. Circumnuclear spiral structure thus outlined appears to be common in barred spiral galaxies with circumnuclear star formation.

Perez-Ramirez, D.↗
NASA NTRS1981

A high-resolution study of the gas flow in barred spirals

The considered investigation is concerned with conditions in that type of spiral galaxy which is known as a 'barred spiral'. The lack of star formation and the smoothness of the dark dust lanes may indicate that the bar region is pervaded by a more homogeneous interstellar medium with a lower viscosity than that characteristic of the outer regions. The effects of such a reduced viscosity are investigated on the basis of high-resolution time-dependent gasdynamical equations. Calculations modeling the gas flow in a given bar potential are presented. The calculations were performed on grids with various mesh sizes and consequently had different resolutions and numerical viscosities. A reduction in the numerical diffusion and viscosity was accompanied by changes in the flow pattern, including the appearance of a strong shock in the bar region and the occurrence of postshock outflow.

Van Albada, G. D.↗
NASA NTRS1989

Development of a stereo 3-D pictorial primary flight display

Computer-generated displays are becoming increasingly popular in aerospace applications. The use of stereo 3-D technology provides an opportunity to present depth perceptions which otherwise might be lacking. In addition, the third dimension could also be used as an additional dimension along which information can be encoded. Historically, the stereo 3-D displays have been used in entertainment, in experimental facilities, and in the handling of hazardous waste. In the last example, the source of the stereo images generally has been remotely controlled television camera pairs. The development of a stereo 3-D pictorial primary flight display used in a flight simulation environment is described. The applicability of stereo 3-D displays for aerospace crew stations to meet the anticipated needs for 2000 to 2020 time frame is investigated. Although, the actual equipment that could be used in an aerospace vehicle is not currently available, the lab research is necessary to determine where stereo 3-D enhances the display of information and how the displays should be formatted.

Nataupsky, Mark↗
NASA NTRS1993

A (12)CO J = 2-1 map of the disk of Centaurus A: Evidence for large scale heating in the dust lane

Centaurus A (NGC 5128) is a nearby (3 Mpc) elliptical galaxy with a prominent dust lane, extensive radio lobes, and a compact radio continuum source, suggestive of nuclear activity. As a consequence of its peculiar morphology, this merger candidate has been the subject of much attention, particularly at optical wavelengths. Unfortunately the high and patchy extinction in the disk, aggravated by the warped structure of the dust lane, has severely hindered investigations into the properties of the interstellar medium, particularly with regard to the extent of star formation. Here we present a map of the (12)CO J = 2-1 line throughout the dust lane which, when combined with a previously measured (12)CO J = 1-0 map and data on molecular absorption lines observed against the compact non-thermal continuum source, offers insight into the excitation conditions of the molecular gas.

Wild, W.↗
DOE OSTI2026

Automatic Lane-Level Road Network Extraction from Aerial Imagery for Transportation Digital Twins

Accurate road networks are essential for credible traffic microsimulation and transportation digital twins, yet high-definition maps are often difficult to obtain due to limited availability, high cost, or proprietary restrictions. Some build networks from crowdsourced data, such as OpenStreetMap, but these sources often contain geometric and semantic inconsistencies. Others create networks manually, a process that is labor-intensive and difficult to scale. To address these limitations, this work presents an end-to-end pipeline that automatically extracts georeferenced, lane-level road networks from publicly available high-resolution satellite imagery and converts them into simulation-ready assets. The developed end-to-end pipeline has three primary modules: (1) A computer-vision-based module first detects directed lane geometries and intersection layouts. (2) A heuristic-based topology construction module then identifies approach and exit legs and establishes conflict-free lane-to-lane connections. (3) Finally, an automatic simulation-building module converts the extracted network into standard formats, e.g., OpenDRIVE, and generates routable SUMO networks. The framework supports both complete network construction from scratch and local-scale refinement of existing networks through lane-count correction, transition recovery, and geometric regularization. The proposed pipeline provides a practical pathway to generate traffic simulation networks from satellite imagery, significantly reducing manual reconstruction effort and enabling scalable, continuously updated transportation digital twins.

Guo, Hetian [University of Georgia, Athens] (ORCID↗
NASA NTRS1984

Spiral structure and star formation. I - Formation mechanisms and mean free paths

The wide variety of optical appearances observed in spiral galaxies has encouraged the growth of two theoretical approaches to explain the spiral patterns exhibited by such young objects as OB associations, giant H II regions, and dark dust lanes. These approaches are related to the density wave theory of spiral structure and 'stochastic, self-propagating star formation'. Levinson and Roberts (1981) tried to reconcile these two theoretical approaches, and considered a disk filled with discrete gas clouds. The present investigation is concerned with refinements and extensions of the model of Levinson and Roberts. Attention is given to gravitational forces and dynamical propagation, cloud-cloud collisions, supernova interactions, computational models, a theory concerning the interactions of the gas cloud and stellar association systems, the time evolution of the gas cloud-stellar association systems, and aspects of collisionally triggered star formation.

Roberts, W. W., Jr.↗
NASA NTRS2004

Analysis of Formation Flying in Eccentric Orbits Using Linearized Equations of Relative Motion

Geometrical methods for formation flying design based on the analytical solution to Hill's equations have been previously developed and used to specify desired relative motions in near circular orbits. By generating relationships between the vehicles that are intuitive, these approaches offer valuable insight into the relative motion and allow for the rapid design of satellite configurations to achieve mission specific requirements, such as vehicle separation at perigee or apogee, minimum separation, or a specific geometrical shape. Furthermore, the results obtained using geometrical approaches can be used to better constrain numerical optimization methods; allowing those methods to converge to optimal satellite configurations faster. This paper presents a set of geometrical relationships for formations in eccentric orbits, where Hill.s equations are not valid, and shows how these relationships can be used to investigate formation designs and how they evolve with time.

Lane, Christopher↗
NASA NTRS1984

Aeolian processes on Venus

Many of the questions regarding aeolian processes on Venus and the subsequent implications for surface history involve understanding the physics of particle motion in the venusian environment. The surface environment of Venus is simulated as closely as practicable using the Venus Wind Tunnel and to determine threshold wind speeds, particle flux, particle velocities, and the characteristics of various aeolian bedforms. Despite the relatively low wind speeds on Venus, the flux of windblown material on Venus is potentially high. A high fraction of material is transported as surface creep by rolling, estimates yield rates up to 100 kg per cm lane width per year depending upon the availability of material and wind frequency, suggesting that the formation of lowland plains by aeolian processes and the burial of various landforms such as impact craters could occur on short geological time-scales. Wind tunnel simulations demonstrate that aeolian processes may be very effective in modifying the surface through erosion and deposited and may have an important influence on the composition of the atmosphere.

Greeley, R.↗
NASA NTRS2019

A Dissection of Spatially Resolved AGN Feedback across the Electromagnetic Spectrum

We present optical SuperNova Integral Field Spectrograph integral field spectroscopy, Hubble Space Telescope optical imaging, Chandra X-ray imaging, and Very Large Array radio interferometry of the merging galaxy 2MASX J04234080+0408017, which hosts a Seyfert 2 active galactic nucleus (AGN) at z = 0.046. Our observations reveal that radiatively driven, ionized gas outflows are successful to distances >10 kpc due to the low mass of the host system, encompassing the entirety of the observed optical emission. We also find that at large radii, where observed velocities cannot be reproduced by radiative driving models, high-velocity kinematics are likely due to mechanical driving from AGN winds impacting high-density host material. This impacting deposits sufficient energy to shock the host material, producing thermal X-ray emission and cosmic rays, which in turn promote the formation of in situ radio structure in a pseudo-jet morphology along the high-density lanes.

Travis Fischer↗
NASA NTRS1990

The CO-12 and CO-13 J=2-1 and J=1-0 observations of hot and cold galaxies

Researchers observed the nuclear regions of the galaxies NGC 2146 and IC 342 in CO-12 and CO-13 J=1-0 and J=2-1 lines using the Five College Radio Astronomy Observatory (FCRAO) 14m telescope. NGC 2146 is a peculiar Sab spiral galaxy. Its complex optical morphology and strong nuclear radio continuum emission suggest that it is experiencing a phase of violent activity and could have a polar ring which may have resulted from an interaction. IC 342 is a nearby luminous Scd spiral galaxy. Strong CO, infrared and radio continuum emission from the nuclear region of IC 342 indicate enhanced star-forming activity, and interferometric CO-12 J=1-0 observations reveal a bar-like structure centered on the nucleus, along the dark lane in the NS direction. These two galaxies are selected based on their different dust temperatures and star formation efficiencies (SFE) as derived from the Infrared Astronomy Satellite (IRAS) S sub 60 mu/S sub 100 mu flux density ratio and L sub IR/M(H2), respectively, with a relatively high SFE and dust temperature of 45 K in NGC 2146 and a relatively low SFE and dust temperature of 35 K in IC 342. The data from the different CO-12 and CO-13 lines are used to study the physical conditions in the molecular clouds in the galaxies. Researchers also consider the radiative transfer to determine whether a warm and optically thin gas component exists in these galaxies, as has been suggested in the case of M82 (Knapp et al. 1980), and whether the warm gas is related to the dust properties. Since optically thin CO-12 gas is rarely detected in our own Galaxy (except in outflow sources), to confirm its existence in external galaxies is very important in understanding the molecular content of external galaxies and its relationship to star formation activity. The present CO-12 J=2-1 and CO-13 J=2-1 and J=1-0 data for NGC 2146 are the first detections of this galaxy to our knowledge. The CO-12 J=1-0 distribution in NGC 2146 has been measured as part of the FCRAO Extragalactic Survey. For the well-studied IC 342, the data are compared with 30m observations and other available data. Researchers present the observed results.

Xie, Shuding↗