SEARCH · Engineering Papers

Results for “Phase evolution”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53

All sources NASA NTRS DOE OSTI

NASA NTRS1995

Analytical pyrolysis experiments of Titan aerosol analogues in preparation for the Cassini Huygens mission

Comparative pyrolysis mass spectrometric data of Titan aerosol analogs, called 'tholins', are presented. The Titan tholins were produced in the laboratory at Cornell by irradiation of simulated Titan atmospheres with high energy electrons in plasma discharge. Mass-spectrometry measurements were performed at FOM of the solid phase of various tholins by Curie-point pyrolysis Gas-Chromatography/Mass-Spectrometry (GCMS) and by temperature resolved in-source Pyrolysis Mass-Spectrometry to reveal the composition and evolution temperature of the dissociation products. The results presented here are used to further define the ACP (Aerosol Collector Pyrolyser)-GCMS experiment and provide a basis for modelling of aerosol composition on Titan and for the iterpretation of Titan atmosphere data from the Huygens probe in the future.

Ehrenfreund, P.↗

NASA NTRS2000

The Collapse of Vapor Bubbles in a Spatially Non-Uniform Flow

Pressure gradients act differently on liquid particles and suspended bubbles and are, therefore, capable of inducing a relative motion between the phases even when no relative velocity initially exists. As a consequence of the enhanced heat transfer in the presence of convection, this fact may have a major impact on the evolution of a vapor bubble. The effect is particularly strong in the case of a collapsing bubble for which, due to the conservation of the system's impulse, the induced relative velocity tends to be magnified when the bubble volume shrinks. A practical application could be, for instance, the enhancement of the condensation rate of bubbles downstream of a heated region, thereby reducing the quality of a flowing liquid-vapor mixture. A simple model of the process, in which the bubble is assumed to be spherical and the flow potential, is developed in the paper.

Hao, Y.↗

NASA NTRS2003

Changes in the X-ray Emission from the Magnetar Candidate 1E 2259+586 during its 2002 Outburst

An outburst of more thm 80 individual bursts, similar to those see^ from Soft Gamma Repeaters (SGRs), was detected from the Anomalous X-ray Pulsar (AXP) 1E 2259+586 in 2002 June. Coincident with this burst activity were gross changes in the pulsed flux, persistent flux, energy spectrum, pulse profile and spin down of the underlying X-ray source. We present Rossa X-ray Tirnsng Explorer and X-ray Multi-Mirror Mission observations of 1E 2259+586 that show the evolution of the aforementioned source parameters during and following this episode and identify recovery time scales for each. Specifically, we observe an X-ray flux increase (pulsed and phase-averaged) by more than an order of magnitude having two distinct components. The first component is linked to the burst activity and decays within approx. 2 days during which the energy spectrum is considerably harder than during the quiescent state of the source. The second component decays over the year following the glitch according to a power law in time with an exponent -0.22+/-0.01. The pulsed fraction decreased initially to approx. 15% RMS, but recovered rapidly to the pre-outburst level of approx. 2 3 % within the first three days.

Woods, P. M.↗

NASA NTRS2005

NASA Tech Briefs, October 2005

Topics covered include: Insect-Inspired Optical-Flow Navigation Sensors; Chemical Sensors Based on Optical Ring Resonators; A Broad-Band Phase-Contrast Wave-Front Sensor; Progress in Insect-Inspired Optical Navigation Sensors; Portable Airborne Laser System Measures Forest-Canopy Height; Deployable Wide-Aperture Array Antennas; Faster Evolution of More Multifunctional Logic Circuits; Video-Camera-Based Position-Measuring System; N-Type delta Doping of High-Purity Silicon Imaging Arrays; Avionics System Architecture Tool; Updated Chemical Kinetics and Sensitivity Analysis Code; Predicting Flutter and Forced Response in Turbomachinery; Upgrades of Two Computer Codes for Analysis of Turbomachinery; Program Facilitates CMMI Appraisals; Grid Visualization Tool; Program Computes Sound Pressures at Rocket Launches; Solar-System Ephemeris Toolbox; Data-Acquisition Software for PSP/TSP Wind-Tunnel Cameras; Corrosion-Prevention Capabilities of a Water-Borne, Silicone-Based, Primerless Coating; Sol-Gel Process for Making Pt-Ru Fuel-Cell Catalysts; Making Activated Carbon for Storing Gas; System Regulates the Water Contents of Fuel-Cell Streams; Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig; Modifications of Fabrication of Vibratory Microgyroscopes; Chamber for Growing and Observing Fungi; Electroporation System for Sterilizing Water; Thermoelectric Air/Soil Energy-Harvesting Device; Flexible Metal-Fabric Radiators; Actuated Hybrid Mirror Telescope; Optical Design of an Optical Communications Terminal; Algorithm for Identifying Erroneous Rain-Gauge Readings; Condition Assessment and End-of-Life Prediction System for Electric Machines and Their Loads; Lightweight Thermal Insulation for a Liquid-Oxygen Tank; Stellar Gyroscope for Determining Attitude of a Spacecraft; and Lifting Mechanism for the Mars Explorer Rover.

Source record↗

NASA NTRS2017

The Importance of Lake Overflow Floods for Early Martian Landscape Evolution: Insights From Licus Vallis

Open-basin lake outlet valleys are incised when water breaches the basin-confining topography and overflows. Outlet valleys record this flooding event and provide insight into how the lake and surrounding terrain evolved over time. Here we present a study of the paleolake outlet Licus Vallis, a >350 km long, >2 km wide, >100 m deep valley that heads at the outlet breach of an approx.30 km diameter impact crater. Multiple geomorphic features of this valley system suggest it records a more complex evolution than formation from a single lake overflow flood. This provides unique insight into the paleohydrology of lakes on early Mars, as we can make inferences beyond the most recent phase of activity..

Goudge, T. A.↗

NASA NTRS2017

Hydrogen Balmer Line Broadening in Solar and Stellar Flares

The broadening of the hydrogen lines during flares is thought to result from increased charge (electron, proton) density in the flare chromosphere. However, disagreements between theory and modeling prescriptions have precluded an accurate diagnostic of the degree of ionization and compression resulting from flare heating in the chromosphere. To resolve this issue, we have incorporated the unified theory of electric pressure broadening of the hydrogen lines into the non-LTE radiative-transfer code RH. This broadening prescription produces a much more realistic spectrum of the quiescent, A0 star Vega compared to the analytic approximations used as a damping parameter in the Voigt profiles. We test recent radiative-hydrodynamic (RHD) simulations of the atmospheric response to high nonthermal electron beam fluxes with the new broadening prescription and find that the Balmer lines are overbroadened at the densest times in the simulations. Adding many simultaneously heated and cooling model loops as a 'multithread' model improves the agreement with the observations. We revisit the three component phenomenological flare model of the YZ CMi Megaflare using recent and new RHD models. The evolution of the broadening, line flux ratios, and continuum flux ratios are well-reproduced by a multithread model with high-flux nonthermal electron beam heating, an extended decay phase model, and a 'hot spot' atmosphere heated by an ultra relativistic electron beam with reasonable filling factors: approximately 0.1%, 1%, and 0.1% of the visible stellar hemisphere, respectively. The new modeling motivates future work to understand the origin of the extended gradual phase emission.

Kowalski, Adam F.↗

NASA NTRS2019

The Geochemistry of Aubrites: Investigating Reduced Parent Bodies

The aubrites (~30 known meteorites) are a unique group of differentiated meteorites that formed on asteroids with oxygen fugacities (ƒO2) from ~2 to ~6 log units below the iron-wüstite buffer [1–2]. At these highly reduced conditions, elements deviate from the geochemical behavior exhibited at terrestrial ƒO2, forming FeO-poor silicates, Si-bearing metals, and exotic sulfides [3]. Here we examine the 3D mineralogy and the geochemistry of fourteen aubrites, including mineral major element compositions, bulk-rock compositions, and oxygen isotopic compositions to understand their formation and evolution at extreme ƒO2 conditions. While previous studies have described the petrology and 2D modal abundances of aubrites, this work investigates the 3D modal mineralogies of silicate, metal, and sulfide phases in aubrite samples, which are then com-pared to the available 2D data. We utilize X-ray computed tomography (XCT) to non-destructively analyze the distribution and abundances of mineral phases in aubrites and locate composite clasts of sulfide grains for future analysis.

Wilbur, Z. E.↗

NASA NTRS2022

CME Evolution in the Structured Heliosphere and Effects at Earth and Mars During Solar Minimum

The activity of the Sun alternates between a solar minimum and a solar maximum, the former corresponding to a period of “quieter” status of the heliosphere. During solar minimum, it is in principle more straightforward to follow eruptive events and solar wind structures from their birth at the Sun throughout their interplanetary journey. In this paper, we report analysis of the origin, evolution, and heliospheric impact of a series of solar transient events that took place during the second half of August 2018, that is, in the midst of the late declining phase of Solar Cycle 24. In particular, we focus on two successive coronal mass ejections (CMEs) and a following high-speed stream (HSS) on their way toward Earth and Mars. We find that the first CME impacted both planets, whilst the second caused a strong magnetic storm at Earth and went on to miss Mars, which nevertheless experienced space weather effects from the stream interacting region preceding the HSS. Analysis of remote-sensing and in-situ data supported by heliospheric modeling suggests that CME–HSS interaction resulted in the second CME rotating and deflecting in interplanetary space, highlighting that accurately reproducing the ambient solar wind is crucial even during “simpler” solar minimum periods. Lastly, we discuss the upstream solar wind conditions and transient structures responsible for driving space weather effects at Earth and Mars.

Space weather↗

NASA NTRS1999

Boundary Conditions for the Paleoenvironment: Chemical and Physical Processes in Dense Interstellar Clouds: Summary of Research

The basic theme of this program was the study of molecular complexity and evolution for the biogenic elements and compounds in interstellar clouds and in primitive solar system objects. Research included the detection and study of new interstellar and cometary molecules and investigation of reaction pathways for astrochemistry from a comparison of theory and observed molecular abundances. The latter includes studies of cold, dark clouds in which ion-molecule chemistry should predominate, searches for the effects of interchange of material between the gas and solid phases in interstellar clouds, unbiased spectral surveys of particular sources, and systematic investigation of the interlinked chemistry and physics of dense interstellar clouds. In addition, the study of comets has allowed a comparison between the chemistry of such minimally thermally processed objects and that of interstellar clouds, shedding light on the evolution of the biogenic elements during the process of solar system formation. One PhD dissertation on this research was completed by a graduate student at the University of Massachusetts. An additional 4 graduate students at the University of Massachusetts and 5 graduate students from other institutions participated in research supported by this grant, with 6 of these thus far receiving PhD degrees from the University of Massachusetts or their home institutions. Four postdoctoral research associates at the University of Massachusetts also participated in research supported by this grant, receiving valuable training.

Irvine, William M.↗

NASA NTRS1990

Gas dynamics, accretion, and evolution of Algols: Initial results for three representative systems

IUE (International Ultraviolet Explorer) observations were made around the orbits of three Algol-type binaries: R Arae, U Cephei and Algol. These stars were selected to represent, respectively, the rapid, moderate and slow phases of mass transfer and mass loss in Algols. The data was obtained to derive maps of gas flow and mass loss, to study accretion processes and kinetic heating, and to investigate the importance of magnetic fields in these systems. Continuous observations were made from GSFC and VILSPA over 4 1/3 consecutive days during 10 to 14 Sep. 1989. A total of 100 spectra are obtained. This is the first time that Algol systems are observed continuously over their orbits with IUE. Initial results from this program are discussed.

Gimenez, A.↗

NASA NTRS2011

Space Shuttle Ascent Flight Design Process: Evolution and Lessons Learned

The Space Shuttle Ascent Flight Design team is responsible for defining a launch to orbit trajectory profile that satisfies all programmatic mission objectives and defines the ground and onboard reconfiguration requirements for this high-speed and demanding flight phase. This design, verification and reconfiguration process ensures that all applicable mission scenarios are enveloped within integrated vehicle and spacecraft certification constraints and criteria, and includes the design of the nominal ascent profile and trajectory profiles for both uphill and ground-to-ground aborts. The team also develops a wide array of associated training, avionics flight software verification, onboard crew and operations facility products. These key ground and onboard products provide the ultimate users and operators the necessary insight and situational awareness for trajectory dynamics, performance and event sequences, abort mode boundaries and moding, flight performance and impact predictions for launch vehicle stages for use in range safety, and flight software performance. These products also provide the necessary insight to or reconfiguration of communications and tracking systems, launch collision avoidance requirements, and day of launch crew targeting and onboard guidance, navigation and flight control updates that incorporate the final vehicle configuration and environment conditions for the mission. Over the course of the Space Shuttle Program, ascent trajectory design and mission planning has evolved in order to improve program flexibility and reduce cost, while maintaining outstanding data quality. Along the way, the team has implemented innovative solutions and technologies in order to overcome significant challenges. A number of these solutions may have applicability to future human spaceflight programs.

Picka, Bret A.↗

NASA NTRS2018

The Evolution of Payload Data Capabilities on the Commercial Visiting Vehicles that Service the International Space Station

In 2008, NASA awarded the first contracts to U.S. commercial companies to deliver cargo and supplies to the International Space Station (ISS). These contracts, called the first phase of Commercial Resupply Services (CRS1), were awarded to Space Exploration Technologies (SpaceX) and Orbital Sciences. Under the CRS1 contracts, commercial visiting vehicles not only provide a couple tons of cargo to the ISS each mission, but they also provide the ability for payloads to be transferred to the ISS in an active, powered state. Prior to the start of the CRS1 program, most vehicles that serviced the ISS transported science experiments as passive cargo. Therefore, the CRS1 program through offering frequent flight opportunities with powered payload transport capability ushered in a new era in which NASA and payload developers could reimagine operational concepts for payloads during the transit phase to and from the ISS. To take advantage of this powered payload transport capability, NASA first added requirements under the CRS1 program for the commercial vehicles to provide telemetry monitoring services for pressurized payloads to give payload developers situational awareness during the transport phase. Since then, payload developer use-cases for visiting vehicle data services during free-flight have evolved with each new commercial visiting vehicle contract to cover a variety of payload monitoring and control abilities. Additional commercial contracts include the Commercial Crew Transportation Capability (CCtCap) contracts that were awarded to SpaceX and Boeing, and the second phase of Commercial Resupply Services (CRS2) contracts that were awarded to SpaceX, Orbital ATK (formerly Orbital Sciences), and Sierra Nevada Corporation. Commercial crew flights will commence in 2018, and the first flight under the CRS2 program is currently planned for 2019.

Wiggins, Lindsay M.↗

NASA NTRS1991

Tidal evolution of planetary satellites

Early in the history of the Solar System, Europa and Ganymede may have evolved through a 3:1 mean-motion commensurability, which would have been encountered prior to the establishment of the current Laplace resonance involving Io, Europa, and Ganymede. If Europa and Ganymede passed through the 3:1 mean-motion commensurability, the orbital eccentricities of both satellites may have increased to large values during a phase of chaotic behavior, after which the satellites would have escaped from the resonance. In spite of the relatively large J sub 2 of Jupiter, Europa, and Ganymede are sufficiently massive and distant from the planet that resonances at the 3:1 mean-motion commensurability interact strongly, leading to chaotic behavior via the same kinds of dynamical mechanisms present at resonances among the Uranian satellites. As a result of the large eccentricity increases possible during the evolution of Europa and Ganymede through the 3:1 mean-motion commensurability, tidal heating may have melted water ice in the mantles of both satellites, and stresses on the lithosphere of both satellites due to tidal deformation may have been sufficient to cause extensive fracturing, making resurfacing possible. This may account for the post-heavy bombardment geological activity on both Europa and Ganymede. In addition, the effects of resonance passage on Ganymede may provide an explanation of the Ganymede-Callisto dichotomy by providing Ganymede with an intense source of internal heat and lithospheric stress not present in Callisto. Further possibilities of this evolution are presented.

Tittemore, William C.↗

NASA NTRS2015

Essentials for Team Based Rehearsals and the Differences Between Earth Orbiting and Deep Space Missions

The mission readiness environment is where spacecraft and ground systems converge to form the entire as built flight system for the final phase of operationally-themed testing. For most space missions, this phase starts between nine to twelve months prior to the planned launch. In the mission readiness environment, the goal is to perform sufficient testing to exercise the flight teams and systems through all mission phases in order to demonstrate that all elements are ready to support. As part of the maturation process, a mission rehearsal program is introduced to focus on team processes within the final flight system, in a more realistic operational environment. The overall goal for a mission rehearsal program is to: 1) ensure all flight system elements are able to meet mission objectives as a cohesive team; 2) reduce the risk in space based operations due to deficiencies in people, processes, procedures, or systems; and 3) instill confidence in the teams that will execute these first time flight activities. A good rehearsal program ensures critical events are exercised, discovers team or flight system nuances whose impact were previously unknown, and provides a real-time environment in which to interact with the various teams and systems. For flight team members, the rehearsal program provides experience and training in the event of planned (or unplanned) flight contingencies. To preserve the essence for team based rehearsals, this paper will explore the important elements necessary for a successful rehearsal program, document differences driven by Earth Orbiting (Aqua, Aura, Suomi-National Polar-orbiting Partnership (NPP)) and Deep Space missions (New Horizons, Mars Atmosphere and Volatile EvolutioN (MAVEN)) and discuss common challenges to both mission types. In addition, large scale program considerations and enhancements or additional steps for developing a rehearsal program will also be considered. For NASA missions, the mission rehearsal phase is a key milestone for predicting and ensuring on-orbit success.

Gomez-Rosa, Carlos↗

NASA NTRS2012

Vesta Mineralogy after Dawn Global Observations

The Dawn mission has completed its mapping phases at Vesta and millions of spectra have been acquired by the Visible and InfraRed Mapping Spectrometer, VIR(1). VIR characterizes and maps the mineral distribution on Vesta -strengthening the Vesta HED linkage- and provides new insights into Vesta s formation and evolution(2,3). VIR spectra are dominated by pyroxene absorptions near 0.9 and 2.0 m and large thermal emission beyond 3.5 m. Although almost all surface materials exhibit howardite-like spectra, some large regions can be interpreted to be richer in eucritic (basaltic) material and others richer in diogenititic (Mg-orthopyroxenitic) material. The Rheasilvia basin contains Mg-pyroxene-rich terrains for example. Vesta' s surface shows considerable diversity at local scales. Many bright and dark areas(3,4) are associated with various geological features and show remarkably different morphology. Moreover, VIR detected statistically significant, but weak, variations at 2.8 m that have been interpreted as indicating the presence of OH-bearing phases on the surface(5). The OH distribution is uneven with large regions lacking this absorption feature. Associations of 2.8 m band with morphological structures indicate complex process responsible for OH. Vesta exhibits large spectral variations that often correlate with geological structures, indicating a complex geological and evolutionary history, more similar to that of the terrestrial planets than to other asteroids visited by spacecrafts.

ChristinaDeSanctis, Maria↗

NASA NTRS2020

Propanal, an Interstellar Aldehyde - First Infrared Band Strengths and Other Properties of the Amorphous and Crystalline Forms

Chemical evolution in molecular clouds in the interstellar medium is well established, with the identification of over 200 molecules and molecular ions. Among the classes of interstellar organic compounds found are the aldehydes. However, laboratory work on the aldehydes has scarcely kept pace with astronomical discoveries as little quantitative solid-phase infrared (IR) data has been published on any of the aldehydes, and the same is true for important properties such as density, refractive indices, and vapor pressures. In this paper we examine the IR spectra of solid propanal (HC(O)CH2CH3, propionaldehyde), along with several physical properties, for both the amorphous and crystalline forms of the compound. The quantitative measurements we report, such as infrared intensities and optical constants, will be useful in laboratory investigations of the formation and evolution of propanal-containing ices, will serve as benchmark data for theoretical investigations, and will inform observational studies.

Yukiko Yagi Yarnall↗

NASA NTRS1988

Morphological evolution of growing crystals - A Monte Carlo simulation

The combined effects of nutrient diffusion and surface kinetics on the crystal morphology were investigated using a Monte Carlo model to simulate the evolving morphology of a crystal growing from a two-component gaseous nutrient phase. The model combines nutrient diffusion, based on a modified diffusion-limited aggregation process, with anisotropic surface-attachment kinetics and surface diffusion. A variety of conditions, ranging from kinetic-controlled to diffusion-controlled growth, were examined. Successive transitions from compact faceted (dominant surface kinetics) to open dendritic morphologies (dominant volume diffusion) were obtained.

Xiao, Rong-Fu↗

NASA NTRS1995

Evolution of Coronal MHD Shocks into Interplanetary MHD Shocks

The energetic particle environment near the Sun, particularly during solar activity, is of major importance to the planning of a solar probe. It is not known if intensive fluxes are generated solely in the impulsive phase of flares or whether they are augmented by, or contained within, the coronal mass ejections and shock waves spatially preceding them. A solar wind model with various ejecta is studied.

sun coronal shocks interplanetary shocks solar pro↗