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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Theoretical infrared spectra of SN 1987A

A simple model for the ejecta of SN 1987A is used to show that the expected fluxes in infared fine structure lines from nickel, cobalt, iron, argon, sulfur, silicon, and neon are likely to be detectable for several years following the supernova explosion. Energy sources due to radioactive decay and a central pulsar are considered separately. Most of the mass of heavy elements resides in the inner, pure metal shells of the ejecta, so that the infrared lines will probe the temperature, ejecta masses, and dynamics of this region and not the overlying, hydrogen-rich envelope.

Colgan, Sean W. J.↗
NASA NTRS1988

An unusual outflow around IRAS 16293-2422

The dense dusty molecular cloud core associated with the unusual protostellar source IRAS 16293-1422 (IRAS 1629A) was observed in the J = 2-1 transition of (C-12)O and (C-13)O. These observations indicate that IRAS 1629A is a source of an unusual high-velocity molecular outflow with four separate emission lobes. The morphology and velocity structure of the lobes may suggest the presence of a dual jet or double bipolar outflow system originating from the vicinity of IRAS 1269A. These observations resolve the outflowing gas into numerous high-velocity clumps which are either being continuously accelerated from low to high velocity along the entire length of the flow or are undergoing free-flow expansion.

Walker, Christopher K.↗
NASA NTRS1994

The first BATSE gamma-ray burst catalog

The Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory detected 260 cosmic gamma-ray bursts during the period 19 Apr 1991 to 5 Mar 1992. This paper presents the occurrence times, locations, peak count rates, peak fluxes, fluences, durations, and plots of time histories for these bursts. The angular distribution is consistent with isotropy. The intensity distribution shows a deficit in the number of weak bursts, which is not consistent with a homogeneous distribution of burst sources in Euclidean space. The duration distribution shows evidence for a separate class of bursts with durations less than about 2 seconds.

Fishman, Gerald J.↗
NASA NTRS2011

NASA's Radiation Belt Storm Probe Mission

NASA's Radiation Belt Storm Probe (RBSP) mission, comprising two identically-instrumented spacecraft, is scheduled for launch in May 2012. In addition to identifying and quantifying the processes responsible for energizing, transporting, and removing energetic particles from the Earth's Van Allen radiation, the mission will determine the characteristics of the ring current and its effect upon the magnetosphere as a whole. The distances separating the two RBSP spacecraft will vary as they move along their 1000 km altitude x 5.8 RE geocentric orbits in order to enable the spacecraft to separate spatial from temporal effects, measure gradients that help identify particle sources, and determine the spatial extent of a wide array of phenomena. This talk explores the scientific objectives of the mission and the manner by which the mission has been tailored to achieve them.

Sibeck, David G.↗
NASA NTRS2015

A Linearized Prognostic Cloud Scheme in NASAs Goddard Earth Observing System Data Assimilation Tools

A linearized prognostic cloud scheme has been developed to accompany the linearized convection scheme recently implemented in NASA's Goddard Earth Observing System data assimilation tools. The linearization, developed from the nonlinear cloud scheme, treats cloud variables prognostically so they are subject to linearized advection, diffusion, generation, and evaporation. Four linearized cloud variables are modeled, the ice and water phases of clouds generated by large-scale condensation and, separately, by detraining convection. For each species the scheme models their sources, sublimation, evaporation, and autoconversion. Large-scale, anvil and convective species of precipitation are modeled and evaporated. The cloud scheme exhibits linearity and realistic perturbation growth, except around the generation of clouds through large-scale condensation. Discontinuities and steep gradients are widely used here and severe problems occur in the calculation of cloud fraction. For data assimilation applications this poor behavior is controlled by replacing this part of the scheme with a perturbation model. For observation impacts, where efficiency is less of a concern, a filtering is developed that examines the Jacobian. The replacement scheme is only invoked if Jacobian elements or eigenvalues violate a series of tuned constants. The linearized prognostic cloud scheme is tested by comparing the linear and nonlinear perturbation trajectories for 6-, 12-, and 24-h forecast times. The tangent linear model performs well and perturbations of clouds are well captured for the lead times of interest.

Precipitation↗
NASA NTRS2016

Localized and Areally Extensive Alterations in Marathon Valley, Endeavour Crater Rim, Mars

Mars Exploration Rover Opportunity is exploring the rim of 22 km diameter, Noachian-aged Endeavour crater. Marathon Valley cuts through the central region of the western rim providing a window into the local lower rim stratigraphic record. Spectra from the Compact Reconnaissance Imaging Spectrometer for Mars show evidence for the occurrence of Fe-Mg smectite in this valley, indicating areally extensive and distinct lithologic units and/or styles of aqueous alteration. The Alpha Particle X-ray Spectrometer has determined the compositions of 59 outcrop targets on untreated, brushed and abraded surfaces. Rocks in the Marathon Valley region are soft breccias composed of mm- to cm-sized darker clasts set in a lighter-toned, finegrained matrix. They are basaltic in non-volatile-element composition and compositionally similar to breccias investigated elsewhere on the rim. Alteration styles recorded in the rocks include: (1) Enrichments in Si, Al, Ti and Cr in more reddish-colored rock, consistent with leaching of more soluble cations and/or precipitation of Si +/- Al, Ti, Cr from fluids. Coprecipitation of Ge-rich phases with Si occurred in the western area only; high water:rock is indicated. Pancam multispectral observations indicate higher nanophase ferric oxide contents, but the rocks have lower Fe contents. The highly localized nature of the red zones indicate they cannot be the source of the widespread smectite signature observed from orbit. (2) Outcrops separated by approximately 65 m show common compositional changes between brushed and abraded (approximately 1 mm deep) targets: increases in S and Mg; decreases in Al, Cl and Ca. These changes are likely due to relatively recent, surface-related alteration of valley rocks and formation of surface coatings under low water:rock. (3) One target, from the center of a region of strong CRISM smectite signature, shows modest differences in composition (higher Si, K; lower Mn) compared to most Marathon Valley rocks, while another target approximately 40 cm away on the same outcrop does not; a change towards smectite bulk compositions is not observed. The smectite signature likely resulted from alteration under low water:rock such that primary minerals were partially altered to phyllosilicates, but wholesale leaching of cations by fluids did not occur.

Mittlefehldt, David W.↗
NASA NTRSDate not supplied

Microbial Factories for Solar System Exploration

As humans venture deeper into space for longer duration missions, resupply missions become far more difficult and costly. To address this, alternative methods of in situ biomanufacturing can be developed to provide a reliable source of required nutrients. BioNutrients is an ongoing project including three separate flight experiments that aims to provide on-demand nutrient production through 5-year shelf stable microbial factories for astronauts on long-duration missions. The BioNutrients-3 (BN-3) flight experiment aims to demonstrate on-orbit food safety, user-friendly production pack design, and multi-compound production capability. This current study seeks to support the multiple compound production element of BN-3 by investigating the production of multiple compounds via multiple pathways in one organism. An experiment has been designed to modify an existing strain of Saccharomyces boulardii designed by the BioNutrients team to efficiently produce β-carotene to also efficiently produce a second nutrient, riboflavin. This experiment entails the random shuffling and recombination of gene elements including promoters and terminators of various strengths to identify optimal combinations for the upregulation of the riboflavin production pathway. Implementation of this experiment would provide insight into the efficiency of the multiple pathways production method and pave the way for additional fine tuning of the riboflavin production pathway and additional nutrient production pathways in S. boulardii.

Biomanufacturing↗
NASA NTRS2023

Computational Study of Vortex-Induced Separation for a 5-Bladed Rotor

This work computationally investigated the rotor blade vortex-induced separation recently observed during an aerodynamic rotor test campaign in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel. Two separate approaches (i.e., airfoil modification and blade tip modification) were studied to mitigate the vortex-induced separation. Low-fidelity tools based on blade element momentum theory were shown to mispredict the rotor inflow and were also shown to not capture the vortex-induced separation caused by perpendicular blade-vortex interaction. This misprediction was exploited to isolate the aerodynamic thrust deficit caused by the vortex-induced separation (i.e., 20%) from the thrust deficit due to inflow variation (i.e., 31%). High-fidelity tools were shown to reasonably predict aerodynamic forces within 13% and flow separation when compared to experimental results. The modified airfoil variant of the baseline rotor effectively mitigated the vortex-induced separation while the blade tip modified variant still showed separation, though the size and strength of the vortex was reduced. Acoustic predictions were underpredicted by 10 dB from preliminary measurements taken in the untreated wind tunnel. Broadband noise contributions from different rotor blade sections showed that self-noise due to flow separation and other turbulent boundary layer mechanisms was the dominant noise source for all three rotor cases, followed by blade-wake interaction noise caused by perpendicular blade-vortex interactions.

aerodynamics↗
NASA NTRS2012

Ultraminiature broadband light source with spiral shaped filament

An ultraminiature light source using a double-spiral shaped tungsten filament includes end contact portions which are separated to allow for radial and length-wise unwinding of the spiral. The double-spiral filament is spaced relatively far apart at the end portions thereof so that contact between portions of the filament upon expansion is avoided. The light source is made by fabricating a double-spiral ultraminiature tungsten filament from tungsten foil and housing the filament in a ceramic package having a reflective bottom and a well wherein the filament is suspended. A vacuum furnace brazing process attaches the filament to contacts of the ceramic package. Finally, a cover with a transparent window is attached onto the top of the ceramic package by solder reflow in a second vacuum furnace process to form a complete hermetically sealed package.

Tuma, Margaret L.↗
NASA NTRS1996

On the High-Frequency Asymptotic Evaluation of the Potentials of Elemental Sources on an Anisotropic Impedance Cylinder

In an effort to formulate the high-frequency coupling between antennas located on airframes composed of multilayer imperfectly conducting materials a general model was sought which would embody the electromagnetic properties of the layers and would apply over a broader range of separations of the antennas. Such a model is described here. This work is a generalization of the work of Pearson [1986, 1987a] concerning the high-frequency asymptotic representation of the fields of elemental sources diffracted by a multilayer cylinder. In that work the source and field points were located off the cylinder surface, and they were sufficiently separated to permit the effective use of the residue series representation of the spectral integrals involved. Here the source and field points are located on the cylinder surface and are permitted to be sufficiently close as to render the residue series poorly convergent. To obtain a more effective representation in this situation, the cylinder is modeled by an anisotropic impedance cylinder, and the resulting spectral integrals are evaluated by reduction to forms amenable to multiple applications of techniques described in the literature in connection with treatment of axially uniform sources in this context.

Pogorzelski, Ronald J.↗
NASA NTRS1999

Pilot Performance on New ATM Operations: Maintaining In-Trail Separation and Arrival Sequencing

Cockpit Display of Traffic Information (CDTI) may enable new Air Traffic Management (ATM) operations. However, CDTI is not the only source of traffic information in the cockpit; ATM procedures may provide information, implicitly and explicitly, about other aircraft. An experiment investigated pilot ability to perform two new ATM operations - maintaining in-trail separation from another aircraft and sequencing into an arrival stream. In the experiment, pilots were provided different amounts of information from displays and procedures. The results are described.

Pritchett, Amy R.↗
NASA NTRS2011

Relative Effects of Trajectory Prediction Errors on the AAC Autoresolver

Trajectory prediction is fundamental to automated separation assurance. Every missed alert, false alert and loss of separation can be traced to one or more errors in trajectory prediction. These errors are a product of many different sources including wind prediction errors, inferred pilot intent errors, surveillance errors, navigation errors and aircraft weight estimation errors. This study analyzes the impact of six different types of errors on the performance of an automated separation assurance system composed of a geometric conflict detection algorithm and the Advanced Airspace Concept Autoresolver resolution algorithm. Results show that, of the error sources considered in this study, top-of-descent errors were the leading contributor to missed alerts and failed resolution maneuvers. Descent-speed errors were another significant contributor, as were cruise-speed errors in certain situations. The results further suggest that increasing horizontal detection and resolution standards are not effective strategies for mitigating these types of error sources.

Lauderdale, Todd↗
NASA NTRSDate not supplied

Use of Beacon Satellites for Efficient Uplink Transmission for Free-Space Quantum Entanglement Distribution

Efficient transmission of optical beams from ground to space is important for free-space entanglement distribution in a dual-uplink architecture in which photons from entanglement sources at two ground locations interact in an optical Bell-state measurement implemented on a satellite. Efficient transmission requires large transmitting apertures to minimize diffraction losses and high-performance adaptive optics to overcome the effects of atmospheric turbulence. Achieving good atmospheric compensation for beams transmitted to satellites is challenging because the need to point ahead of the satellite introduces anisoplanatism error that limits the effectiveness of the adaptive optics. An attractive approach for solving the point-ahead problem is to position a separate small satellite at the point-ahead location to provide a beacon source for the adaptive optics. This paper presents analysis of the requirements for the beacon source(s) for a dual-uplink entanglement-distribution demonstration. A relative performance metric is defined and evaluated for multiple beacon configurations, from a single, fixed beacon serving both ground sites to a dedicated beacon for each site continually adjusted to be at the correct point-ahead distance from the target satellite.

quantum↗
NASA NTRS1977

Infrared studies of H II regions and dust clouds near K3-50

Ground-based infrared observations of the K3-50 region are reported at wavelengths between 2 and 34 microns as well as at 1 mm. The main results are that (1) the visible nebular K3-50 is displaced from its infrared and radio counterparts; (2) component Cl (the OH source ON-3) appears very faint at wavelengths not exceeding 20 microns and is therefore probably obscured by several hundred magnitudes of visual extinction; (3) both K3-50 and component C are associated with separate condensations of molecular hydrogen, each of about 3000 solar masses; and (4) there are no strong sources in this region at 20 microns other than those associated with H II condensations.

Wynn-Williams, C. G.↗
NASA NTRS1987

Simultaneous measurements of energetic ion (50 keV and above) and electron (220 keV and above) activity upstream of earth's bow shock and inside the plasma sheet - Magnetospheric source for the November 3 and December 3, 1977 upstream events

Simultaneous observations of energetic ions and electrons by the IMP 7 and 8 spacecraft are used here to separate temporal variations from spatial variations during the upstream ion events observed on December 3, 1977 and November 2-3, 1977, in order to determine the source of these particles. Analysis of the observations and comparison with theory shows that: (1) for each of the observed upstream enhancements, energetic ions and electrons were simultaneously present inside the plasma sheet; (2) the low-energy ion intensity profile inside the plasma sheet was relatively flat, while at higher energies there was considrable variability; (3) relativistic electron bursts were seen inside the plasma sheet and also upstream of the shock but at substantially reduced intensities; (4) the ion energy spectrum for the December 3 event, extended to energies of about 2 MeV, was identical in form with the plasma sheet and upstream of the shock; (5) ion anisotropies exhibited typically large dawn-dusk or dusk-dawn gradients and large field-aligned streaming away from the bow shock.

Sarris, E. T.↗
NASA NTRS2003

High Precision Laser Range Sensor

The present invention is an improved distance measuring interferometer that includes high speed phase modulators and additional phase meters to generate and analyze multiple heterodyne signal pairs with distinct frequencies. Modulation sidebands with large frequency separation are generated by the high speed electro-optic phase modulators, requiring only a single frequency stable laser source and eliminating the need for a fist laser to be tuned or stabilized relative to a second laser. The combination of signals produced by the modulated sidebands is separated and processed to give the target distance. The resulting metrology apparatus enables a sensor with submicron accuracy or better over a multi- kilometer ambiguity range.

Dubovitsky, Serge↗
DOE OSTI2025

18-membered macrocycle appended on resin for selective rare earth element extraction and separation

The rare earth elements are critically important for a wide range of modern technologies. However, obtaining them selectively and efficiently from natural sources and recycled materials is challenging and often requires harsh or wasteful conditions. Here we show that a macrocyclic chelator appended to a solid resin can overcome this challenge by acting as a robust platform for both the extraction and separation of these elements. This resin preferably captures the large rare earth elements in mixtures of these ions, giving rise to higher extraction efficiencies for them over the smaller ions. We further demonstrate that this resin can be used to separate rare earth elements. As a proof-of-principle validation, this resin was demonstrated to selectively extract rare earth elements in the presence of many different types of competing metal ions in a bioleachate solution obtained from autoslag waste, leading to their enrichment.

Coordination chemistry↗