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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Kinetic Roughening Transition and Energetics of Tetragonal Lysozyme Crystal Growth

Interpretation of lysozyme crystal growth rates using well-established physical theories enabled the discovery of a phenomenon possibly indicative of kinetic roughening. For example, lysozyme crystals grown above a critical supersaturation sigma, (where supersaturation sigma = ln c/c(sub eq), c = the protein concentration and c(sub eq) = the solubility concentration) exhibit microscopically rough surfaces due to the continuous addition of growth units anywhere on the surface of a crystal. The rate of crystal growth, V(sub c), for the continuous growth process is determined by the continuous flux of macromolecules onto a unit area of the crystal surface, a, from a distance, xi, per unit time due to diffusion, and a probability of attachment onto the crystal surface, expressed. Based upon models applied, the energetics of lysozyme crystal growth was determined. The magnitudes of the energy barriers of crystal growth for both the (110) and (101) faces of tetragonal lysozyme crystals are compared. Finally, evidence supportive of the kinetic roughening hypothesis is presented.

Gorti, Sridhar↗
NASA NTRS2011

Low Altitude Mapping Orbit Design and Maintenance for the Dawn Discovery Mission at Vesta

NASA's Dawn discovery mission will orbit the giant asteroid Vesta beginning in the summer of 2011. Four different near polar science orbits are planned. The lowest planned orbit at Vesta is called the Low Altitude Mapping Orbit or LAMO and is by far the most challenging to design and maintain due to the strong, nonspherical gravity expected there. This paper describes the orbit selection process. The true gravity field of Vesta remains highly uncertain. The proposed orbit selection process will be applied once sufficient gravity knowledge is obtained at higher orbits. The orbit selection process is applied here to a fictitious gravity field based on a Hubble space telescope shape model for Vesta assuming uniform density. The outcome of the process described here is a variety of stable orbits. However, Initially stable orbits at the LAMO altitude are not expected to remain stable operationally due to the unpredictable impulses resulting from the Dawn spacecraft thruster firings to de-saturate its momentum wheels. As a result, orbital maintenance maneuvers will be probably be necessary. This paper also briefly describes the statistical maneuver design process that resulted in the orbit maintenance plan.

orbit stability↗
NASA NTRS1989

The winds of high luminosity late-type bright stars

The occurrence and characteristics of the Fe II line asymmetries were studied to determine the radial dependence of the wind velocity for each star. The dependence of the Fe II profiles on spectral type and luminosity class and thus the variation of the velocity fields with stellar type was also investigated. This allows the generality of the results reported for alpha Ori by Carpenter (1984b) to be judged. In addition, new atomic data was used along with observations of the C II (UV 0.01) multiplet to estimate N(sub e) in the stellar winds. Measures of relative Fe II fluxes can be used in a probability-of-escape model to determine the opacity and hydrogen column density versus height in the chromosphere of each star. Finally, analysis of the fluorescent Fe II lines (pumped by Ly alpha) near 2507 A will yield estimates of the intrinsic stellar Ly alpha flux that cannot be measured directly because of interstellar and circumstellar absorption. One important goal of the effort was to acquire high resolution spectra of the whole 2300 to 3200 A region of 13 luminous K and M stars as a data base that will be enormously valuable in planning observations with the Hubble Space Telescope High Resolution Spectrograph. It is also proposed to follow up the recent discovery of significant variations in the Fe II chromospheric emission line profiles from the M-giant Gamma Cru for the purpose of determining the underlying cause of the variations.

Stencel, Robert E.↗
NASA NTRS1990

The accumulation rate of meteorite falls at the earth's surface - The view from Roosevelt County, New Mexico

The discovery of 154 meteorite fragments within an 11-sq km area of wind-excavated basins in Roosevelt County, New Mexico, permits a new calculation of the accumulation rate of meteorite falls at the earth's surface. Thermoluminescence dating of the coversand unit comprising the prime recovery surface suggests the maximum terrestrial age of the meteorites to be about 16.0 ka. The 68 meteorite fragments subjected to petrological analyses represent a minimum of 49 individual falls. Collection bias has largely excluded carbonaceous chondrites and achondrites, requiring the accumulation rate derived from the recovered samples to be increased by a factor of 1.25. Terrestrial weathering destroying ordinary chondrites can be modeled as a first-order decay process with an estimated half-life of 3.5 + or - 1.9 ka on the semiarid American High Plains. Having accounted for the age of the recovery surface, area of field searches, pairing of finds, collection bias and weathering half-life, an accumulation rate of 940 falls/a per 10 to the 6th sq km is calculated for falls greater than 10 g total mass. This figure exceeds the best-constrained previous estimate by more than an order of magnitude. One possible reason for this disparity may be the extraordinary length of the fall record preserved in the surficial geology of Roosevelt County. The high accumulation rate determined for the past 16 ka may point to the existence of periods when the meteorite fall rate was significantly greater than at present.

Zolensky, Michael E.↗
NASA NTRS2016

NuSTAR, SWIFT, and GROND Observations of the Flairing MeV Blazar PMN J0641-0320

MeV blazars are a sub-population of the blazar family, exhibiting larger-than-average jet powers, accretion luminosities, and black hole masses. Because of their extremely hard X-ray continua, these objects are best studied in the X-ray domain. Here, we report on the discovery by the Fermi Large Area Telescope and subsequent follow-up observations with NuSTAR, Swift, and GROND of a new member of the MeV blazar family: PMN J0641-0320. Our optical spectroscopy provides confirmation that this is a flat-spectrum radio quasar located at a redshift of z = 1.196. Its very hard NuSTAR spectrum (power-law photon index of approx.1 up to approx. 80 keV) indicates that the emission is produced via inverse Compton scattering off of photons coming from outside the jet. The overall spectral energy distribution of PMN J0641-0320 is typical of powerful blazars and, using a simple one-zone leptonic emission model, we infer that the emission region is located either inside the broad line region or within the dusty torus.

galaxies: active quasars: general↗
NASA NTRS2016

Productivity Challenges for Mars Rover Operations

Achieving consistently high levels of productivity for surface exploration missions has been a challenge for Mars missions. While the rovers have made major discoveries and accomplished a large number of objectives, they often require a great deal of effort from the operations teams and achievingobjectives can take longer than anticipated. This paper describes the early stages of a multi-year project to investigate solutions for enhancing surface mission productivity. A primary focus of this early stage is to conduct in-depth studies of Mars Science Laboratory science campaigns to gain a deeper understanding of the factors that impact productivity, and to use this understanding to identify potential changes to flight software and ground operations practices to increase productivity. We present the science campaigns we have selected along with a conceptual model of how surface missions achieve objectives that is used to guide the study. We also provide some early thoughts on the technologies, and their interactions, which we believe will play an important role in addressing surface mission productivity challenges.We are in the early stages of a multi-year project to studyand address productivity challenges of future surface missions. We have identified campaigns from the MSL missionfor study which we believe will yield valuable informationabout the nature of surface mission productivity challenges.Based on preliminary analysis from the data collected weanticipate that the lessons from these case studies will helpdevelop and mature our concepts for changes to flight andground systems to address these challenges.While the focus of our work is on Mars rover missions, webelieve the concepts in the work will be applicable to a variety of in-situ explorers, including Venus, and Titan, as wellas orbital missions, such as the Europa orbiter. These missions will also benefit from the ability to adapt and respondto the latest state of the spacecraft and its environment.

Gaines, Daniel↗
NASA NTRSDate not supplied

Late Accretion of large Dark Asteroids and Their Implantation into the Outer Main Belt

Dark (geometric albedo < 0.09) asteroidsare genetically linked to carbonaceous chondrites. Most of these asteroids are located in the mid-outer main belt (2.5 < a < 4.0 AU)and thought to be remnants of the primary accretion of the first solar system planetesimals. Here we presentnew near-infrared (NIR: ~0.5-4.0 μm) reflectance spectra of dark and large (diameter > 100 km) asteroidsmeasured atNASA Infrared Telescope Facility (IRTF).We place the astronomical observations of these large dark asteroids in the context of the thermal evolution and dynamical models and provide new interpretations for the origin and evolution of these asteroids. The astronomical observations together with thermal evolution and dynamical modeling show late accretion and implantation to a confined heliocentric region (~3.0 < a < 3.4 AU)for these large dark asteroids, in agreement with the dynamical predictions. Average densities of large and dark asteroids suggest highly porous interiors and, consequently, relatively late accretion ata time of 1.5-3.5 Myr relative to the formation of calcium-aluminum-rich inclusions with maximum interior temperatures of < 900 K. This work demonstrates that thederived accretion times of large dark asteroids do not correlate in any way with their current semimajor axes. Large and dark asteroidswere likely implanted from more distant regions of the solar system during the giant planet’s dynamical instability. The discovery of dark large asteroids that are smaller than Ceres near its orbital vicinity suggests that this dwarf planet is not unique in the main belt and its surface composition is not driven by its very large size.

Driss Takir↗
NASA NTRS1988

A two-spot albedo model for the surface of Pluto

This paper summarizes the work of Marcialis (1983, 1984). A finite-element approach has been used to generate synthetic light curves of an unevenly bright, rotating sphere. Application to the Pluto-Charon system shows that two circular spots (46 and 28 deg in radius, both at south latitude 23 deg, separated by 134 deg in longitude) with albedos half that of the surrounding terrain can accurately reproduce six available photoelectric light curves between 1953 and 1982. A dark equatorial band (extending from south latitude 69 deg to anywhere between 50 and 65 deg north latitude) can be invoked to explain the secular dimming. Constraints on this equatorial band, which may alternatively be viewed as two polar caps, are such that to date its dimensions are not uniquely determined. However, polar caps with albedos near unity serve quite well to explain the 40-percent dimming of Pluto since its discovery in 1930. Hardie's 1964 photoelectric observations are presented for the first time in tabular form.

Marcialis, Robert Louis↗
NASA NTRS2014

Enhancement of Mutual Discovery, Search, and Access of Data for Users of NASA and GEOSS-Cataloged Data Systems

An ongoing NASA-funded Data Rods (time series) project has demonstrated the removal of a longstanding barrier to accessing NASA data (i.e., accessing archived time-step array data as point-time series) for selected variables of the North American and Global Land Data Assimilation Systems (NLDAS and GLDAS, respectively) and other NASA data sets. Data rods are pre-generated or generated on-the-fly (OTF), leveraging the NASA Simple Subset Wizard (SSW), a gateway to NASA data centers. Data rods Web services are accessible through the CUAHSI Hydrologic Information System (HIS) and the Goddard Earth Sciences Data and Information Services Center (GES DISC) but are not easily discoverable by users of other non-NASA data systems. An ongoing GEOSS Water Services project aims to develop a distributed, global registry of water data, map, and modeling services cataloged using the standards and procedures of the Open Geospatial Consortium and the World Meteorological Organization. Preliminary work has shown GEOSS can be leveraged to help provide access to data rods. A new NASA-funded project is extending this early work.

data access↗
NASA NTRSDate not supplied

Knowledge Discovery for Early Failure Assessment of Complex Engineered Systems Using Natural Language Processing

Emerging complex engineered systems may have unexpected safety issues due to novel operational environments, increasing autonomy, human-machine interaction, and other factors. To prevent failures in operation or testing that necessitate costly redesign, it is desirable to predict likely failure modes early in the design process. Information about past engineering failures in natural language format presents one possible solution by enabling the retrieval of information that can inform new designs. However, identifying documents containing usable information and extracting the required information can be prohibitively time-consuming when implemented at scale. In this research, an automated natural language processing (NLP) framework is proposed to discover relevant knowledge from documents containing failure-related design information. The framework is applied to NASA’s Lessons Learned Information System (LLIS),which is publicly available. Documents containing usable information are filtered using two different NLP-based models. Next, from the identified usable documents, a failure taxonomy is extracted using a partitioned hierarchical topic modeling approach. Partitions of the document describe different sections of the failure taxonomy – i.e., failure, cause of failure, and recommendations – as indicated by the structure of the original document. The extracted failure taxonomy can be leveraged in early design failure assessment methods. Moreover, the framework can be used to identify documents containing usable failure-related design information from other databases and extract relevant information from these documents.

Documentation and Information Science↗
NASA NTRSDate not supplied

Knowledge Discovery for Early Failure Assessment of Complex Engineered Systems Using Natural Language Processing

Emerging complex engineered systems may have unexpected safety issues due to novel operational environments, increasing autonomy, human-machine interaction, and other factors. To prevent failures in operation or testing that necessitate costly redesign, it is desirable to predict likely failure modes early in the design process. Information about past engineering failures in natural language format presents one possible solution by enabling the retrieval of information that can inform new designs. However, identifying documents containing usable information and extracting the required information can be prohibitively time-consuming when implemented at scale. In this research, an automated natural language processing (NLP) framework is proposed to discover relevant knowledge from documents containing failure-related design information. The framework is applied to NASA’s Lessons Learned Information System (LLIS),which is publicly available. Documents containing usable information are filtered using two different NLP-based models. Next, from the identified usable documents, a failure taxonomy is extracted using a partitioned hierarchical topic modeling approach. Partitions of the document describe different sections of the failure taxonomy – i.e., failure, cause of failure, and recommendations – as indicated by the structure of the original document. The extracted failure taxonomy can be leveraged in early design failure assessment methods. Moreover, the framework can be used to identify documents containing usable failure-related design information from other databases and extract relevant information from these documents.

Documentation and Information Science↗
NASA NTRS2021

Hunting Super-heavy Dark Matter with Ultra-high Energy Photons

At any epoch, particle physics must be open to completely unexpected discoveries, and that is reason enoughto extend the reach of searches for ultra-high energy (UHE) photons. The observation of a population ofphotons with energies𝐸 ≳100 EeVwould for example imply the existence of either a completely new physicalphenomena, or particle acceleration mechanisms heretofore never seen or imagined. But as we outline in thisLetter of Interest, there are also good arguments for super-heavy dark matter (SHDM) in a parameter rangesuch that it could be discovered via its decays to, in particular, UHE photons. Only ultra-high energy cosmic rayobservatories have capabilities to detect UHE photons. We first investigate how current and future observationscan probe and constrain SHDM models in important directions, and then outline some of the scenarios thatmotivate such searches. We also discuss connections between constraints on SHDM and on the parametervalues of cosmological models

Luis A Anchordoqui↗
NASA NTRS2021

Psyche Science Planning with the Science Opportunity Analyzer

Psyche is a NASA Discovery mission intent on solving mysteries surrounding early planetary formation. The mission spacecraft will journey to (16) Psyche: a metallic asteroid believed to be the exposed core of an early planetesimal. Despite the unique nature of the target asteroid and the mission’s novel science goals, a significant portion of the project’s science planning needs may be met through the use of legacy tools. In particular, the adoption of the Jet Propulsion Laboratory’s (JPL) Science Opportunity Analyzer (SOA) promises to satisfy mission requirements with minimal development effort. Originally developed as a multi-mission science planning tool, SOA can design and visualize observations, perform geometric flight rule checking, model physical phenomena, and much more. The software has been used by the mission since its proposal phase and is expected to continue providing valuable capabilities throughout operations.

Elkins-Tanton, Linda T.↗
NASA NTRS2011

Status of NASA In-Space Propulsion Technologies and Their Infusion Potential

Since 2001, the In-Space Propulsion Technology (ISPT) program has been developing in-space propulsion technologies that will enable or enhance NASA robotic science missions. These in-space propulsion technologies have broad applicability to future competed Discovery and New Frontiers mission solicitations, and are potentially enabling for future NASA flagship and sample return missions currently being considered. This paper provides status of the technology development of several in-space propulsion technologies that are ready for infusion into future missions. The technologies that are ready for flight infusion are: 1) the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance; 2) NASA s Evolutionary Xenon Thruster (NEXT) ion propulsion system, a 0.6-7 kW throttle-able gridded ion system; and 3) Aerocapture technology development with investments in a family of thermal protection system (TPS) materials and structures; guidance, navigation, and control (GN&C) models of blunt-body rigid aeroshells; and aerothermal effect models. Two component technologies that will be ready for flight infusion in FY12/13 are 1) Advanced Xenon Flow Control System, and 2) ultra-lightweight propellant tank technology advancements and their infusion potential will be also discussed. The paper will also describe the ISPT project s future focus on propulsion for sample return missions: 1) Mars Ascent Vehicles (MAV); 2) multi-mission technologies for Earth Entry Vehicles (MMEEV) needed for sample return missions from many different destinations; and 3) electric propulsion for sample return and low cost missions. These technologies are more vehicle-focused, and present a different set of technology infusion challenges. Systems/Mission Analysis focused on developing tools and assessing the application of propulsion technologies to a wide variety of mission concepts.

Anderson, David↗
NASA NTRS2011

In-Space Propulsion Engine Architecture Based on Sublimation of Planetary Resources: From Exploration Robots to NED Mitigation

Volatile solids occur naturally on most planetary bodies including the Moon, Mars, asteroids and comets. Examples of recent discoveries include water ice, frozen carbon dioxide and hydrocarbons. The ability to utilize readily available resources for in-space propulsion and for powering surface systems during a planetary mission will help minimize the overall cost and extend the op.erational life of a mission. The utilization of volatile solids to achieve these goals is attractive for its simplicity. We have investigated the potential of subliming in situ volatiles and silicate minerals to power propulsion engines for a wide range of in-space applications where environmental conditions are favorable. This paper addresses the' practicality of using planetary solid volatiles as a power source for propulsion and surface systems by presenting results of modeling involving thermodynamic and physical mechanics calculations, and laboratory testing to measure the thrust obtained from ,a volatile solid engine (VSE). Applications of a VSE for planetary exploration are discussed as a means for propulsion and for mechanical actuators and surface mobility platforms.

Sibille, Laurent↗
NASA NTRS1994

The discovery of Ni V in the photospheres of the hot DA white dwarfs RE 2214-492 and G191-B2B

We have co-added six recently obtained International Ultraviolet Explorer (IUE) echelle spectra of the hot DA white dwarf RE 2214-492 and 10 existing archive spectra of the well-known hot DA, G191-B2B. We find that both stars contain numerous weak features due to Ni V. Nickel is thus the second iron-group element to be found in the spectra of the very hottest DA white dwarfs. In addition to Ni V, we also observe Al III in both stars and present evidence for the possible presence of Ni IV and Fe IV in RE 2214-492. The presence of Ni and Al, together with previously reported elements, will contribute significantly to both the EUV opacity and to the apparent complexity of the UV spectra of these stars. Using Non-Local Thermodynamic Equilibrium (NLTE) model atmospheres we estimate the Ni abundances in RE 2214-492 the G191-B2B to be log(Ni/H) = -5.5 +/- 0.3 and -6.0 +/- 0.3, respectively.

Holberg, J. B.↗
NASA NTRS2015

Metal-Poor, Strongly Star-Forming Galaxies in the DEEP2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

We report on the discovery of 28 redshift (z) approximately equal to 0.8 metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [O (sub III)] lambda 4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A primary goal for identifying these rare galaxies is to examine whether the fundamental metallicity relation (FMR) between stellar mass, gas metallicity, and star formation rate (SFR) holds for low stellar mass and high SFR galaxies. The FMR suggests that higher SFR galaxies have lower metallicity (at fixed stellar mass). To test this trend, we combine spectroscopic measurements of metallicity and dust-corrected SFR with stellar mass estimates from modeling the optical photometry. We find that these galaxies are 1.05 plus or minus 0.61 dex above the redshift (z) approximately 1 stellar mass-SFR relation and 0.23 plus or minus 0.23 dex below the local mass-metallicity relation. Relative to the FMR, the latter offset is reduced to 0.01 dex, but significant dispersion remains dex with 0.16 dex due to measurement uncertainties). This dispersion suggests that gas accretion, star formation, and chemical enrichment have not reached equilibrium in these galaxies. This is evident by their short stellar mass doubling timescale of approximately equal to 100 (sup plus 310) (sub minus 75) million years which suggests stochastic star formation. Combining our sample with other redshift (z) of approximately 1 metal-poor galaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar mass) that is significant at 94.4 percent confidence. We interpret this positive correlation as recent star formation that has enriched the gas but has not had time to drive the metal-enriched gas out with feedback mechanisms.

Metal-Poor↗
NASA NTRS1996

Studies of plasma flow past Jupiter's satellite Io

We have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus. The interaction of Io with the plasma surrounding it has been a subject of interest for almost 30 years, dating from the discovery by Bigg (1964) that radio emissions from the Jovian magnetosphere are controlled by Io's position. Since that time, both ground-based and spacecraft observations have shown that Io is a unique satellite that influences the Jovian magnetosphere in important ways. In particular, material from Io is a major source of plasma for the magnetosphere, and the energy that this plasma harnesses from Jupiter's co-rotating magnetic field is an important power source for the magnetosphere. It is apparent that the local interaction of the torus plasma with Io plays a key role in the formation, composition, and energetics of the Io torus; the interaction is also highly nonlinear. We have modeled this interaction using time-dependent three-dimensional magnetohydrodynamic (MHD) simulations. During this past year, we have used NASA support to develop a new MHD code to study the interaction. As part of the Galileo spacecraft's recent successful insertion into orbit around Jupiter, the spacecraft passed within 900 km of Io's surface. Our calculations have focused on using Galileo particles and fields data to examine a question that was not resolved by the Voyager observations: Does Io have an intrinsic magnetic field? In this progress summary, we describe our efforts on this problem to date.

Linker, Jon↗