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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 703 records · Page 39

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NASA NTRS1990

ECLSS Integration Analysis: Advanced ECLSS Subsystem and Instrumentation Technology Study for the Space Exploration Initiative

In his July 1989 space policy speech, President Bush proposed a long range continuing commitment to space exploration and development. Included in his goals were the establishment of permanent lunar and Mars habitats and the development of extended duration space transportation. In both cases, a major issue is the availability of qualified sensor technologies for use in real-time monitoring and control of integrated physical/chemical/biological (p/c/b) Environmental Control and Life Support Systems (ECLSS). The purpose of this study is to determine the most promising instrumentation technologies for future ECLSS applications. The study approach is as follows: 1. Precursor ECLSS Subsystem Technology Trade Study - A database of existing and advanced Atmosphere Revitalization (AR) and Water Recovery and Management (WRM) ECLSS subsystem technologies was created. A trade study was performed to recommend AR and WRM subsystem technologies for future lunar and Mars mission scenarios. The purpose of this trade study was to begin defining future ECLSS instrumentation requirements as a precursor to determining the instrumentation technologies that will be applicable to future ECLS systems. 2. Instrumentation Survey - An instrumentation database of Chemical, Microbial, Conductivity, Humidity, Flowrate, Pressure, and Temperature sensors was created. Each page of the sensor database report contains information for one type of sensor, including a description of the operating principles, specifications, and the reference(s) from which the information was obtained. This section includes a cursory look at the history of instrumentation on U.S. spacecraft. 3. Results and Recommendations - Instrumentation technologies were recommended for further research and optimization based on a consideration of both of the above sections. A sensor or monitor technology was recommended based on its applicability to future ECLS systems, as defined by the ECLSS Trade Study (1), and on whether its characteristics were considered favorable relative to similar instrumentation technologies (competitors), as determined from the Instrumentation Survey (2). The instrumentation technologies recommended by this study show considerable potential for development and promise significant returns if research efforts are invested.

Source record↗

NASA NTRS1982

Integral dependent spin couplings in CI calculations

Although the number of ways to combine Slater determinants to form spin eigenfunctions increases rapidly with the number of open shells, most of these spin couplings will make only a small contribution to a given state, provided the spin coupling is chosen judiciously. The technique of limiting calculations to the interacting subspace pioneered by Bunge (1970) was employed by Munch and Davidson (1975) to the vanadium atom. The use of an interacting space looses its advantage in more complex cases. However, the problem can always be reduced to only one interacting spin coupling by making the coefficients integral dependent. The present investigation is concerned with the performance of integral dependent interacting couplings, taking into account the results of three test calculations.

Iberle, K.↗

NASA NTRS2015

On the Reconstruction of Palaeo-Ice Sheets: Recent Advances and Future Challenges

Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding mechanisms of global climate change and associated sea-level fluctuations in the past, present and future. The significance of palaeo-ice sheets is further underlined by the broad range of disciplines concerned with reconstructing their behaviour, many of which have undergone a rapid expansion since the 1980s. In particular, there has been a major increase in the size and qualitative diversity of empirical data used to reconstruct and date ice sheets, and major improvements in our ability to simulate their dynamics in numerical ice sheet models. These developments have made it increasingly necessary to forge interdisciplinary links between sub-disciplines and to link numerical modelling with observations and dating of proxy records. The aim of this paper is to evaluate recent developments in the methods used to reconstruct ice sheets and outline some key challenges that remain, with an emphasis on how future work might integrate terrestrial and marine evidence together with numerical modelling. Our focus is on pan-ice sheet reconstructions of the last deglaciation, but regional case studies are used to illustrate methodological achievements, challenges and opportunities. Whilst various disciplines have made important progress in our understanding of ice-sheet dynamics, it is clear that data-model integration remains under-used, and that uncertainties remain poorly quantified in both empirically-based and numerical ice-sheet reconstructions. The representation of past climate will continue to be the largest source of uncertainty for numerical modelling. As such, palaeo-observations are critical to constrain and validate modelling. State-of-the-art numerical models will continue to improve both in model resolution and in the breadth of inclusion of relevant processes, thereby enabling more accurate and more direct comparison with the increasing range of palaeo-observations. Thus, the capability is developing to use all relevant palaeo-records to more strongly constrain deglacial (and to a lesser extent pre-LGM) ice sheet evolution. In working towards that goal, the accurate representation of uncertainties is required for both constraint data and model outputs. Close cooperation between modelling and data-gathering communities is essential to ensure this capability is realised and continues to progress.

Ice sheet reconstruction↗

NASA NTRS2007

Bridging the Gap between Earth Science and Students: An Integrated Approach using NASA Earth Science Climate Data

Under the auspices of the Department of Education's No Child Left Behind (NCLB) Act, beginning in 2007 students will be tested in the science area. There are many techniques that educators can employ to teach students science. The use of authentic materials or in this case authentic data can be an engaging alternative to more traditional methods. An Earth science classroom is a great place for the integration of authentic data and science concepts. The National Aeronautics and Space Administration (NASA) has a wealth of high quality Earth science data available to the general public. For instance, the Atmospheric Science Data Center (ASDC) at NASA s Langley Research Center houses over 800 Earth science data sets related to Earth's radiation budget, clouds, aerosols and tropospheric chemistry. These data sets were produced to increase academic understanding of the natural and anthropogenic factors that influence global climate; however, a major hurdle in using authentic data is the size of the data and data documentation. To facilitate the use of these data sets for educational purposes, the Mentoring and inquirY using NASA Data on Atmospheric and Earth science for Teachers and Amateurs (MY NASA DATA) project has been established to systematically support educational activities at all levels of formal and informal education. The MY NASA DATA project accomplishes this by reducing these large data holdings to microsets that are easily accessible and explored by K-12 educators and students though the project's Web page. MY NASA DATA seeks to ease the difficulty in understanding the jargon-heavy language of Earth science. This manuscript will show how MY NASA DATA provides resources for NCLB implementation in the science area through an overview of the Web site, the different microsets available, the lesson plans and computer tools, and an overview of educational support mechanisms.

Alston, Erica J.↗

NASA NTRS2024

Making Rocket Fuel from Moon Rocks: Silicon-Liquid Oxygen (SiLOX) as a Hybrid Propellant

The research team at KSC explored the controlled passivation and burning of Lunar soil constituents in an oxygen combustion vessel for use as an in-space resource. Technologies such as carbothermal reduction (CaRD) and molten regolith electrolysis (MRE) are being developed to remove the oxygen for use and leave constituents in an enriched state. This leaves behind reduced compounds that can react with oxygen for heat generation. The team at KSC looked to explore the feasibility of controlling such reactions in a pure oxygen environment for potential technology integrations. Our proof-of-concept demonstrations have given promise to many potential applications for the controlled burning or combustion of nano- and porous silicon for silicon based, Lunar economy applications. The team at KSC was able to control the burn rate and total energy released effectively via pre-treatment of the nano-silicon in a muffle furnace at varying temperatures at one-hour durations. We created a new capability at KSC with the supporting safety documentation and procedural writeup. Our work highlights the need for greater investigation to understand the regenerative properties of the proposed porous silicon discs, and its viability of a thermal and electrical energy source. This work has demonstrated the proof-of-concept that elemental silicon is able to be combusted with gaseous and liquid oxygen in a controlled manner. This report provides such evidence as well as theoretical calculations and assumptions made for technologies that would be useful in Lunar surface operations with in-situ resources. The concepts are based on the assumption that oxygen extraction technologies from Lunar regolith processing will result in enriched silicon that may be adapted for the presented use cases. Additionally, the energy storage concept is able to be adapted for terrestrial use and integrated into already existing infrastructure.

Kenneth Engeling↗

NASA NTRS1979

Manufacturing methods of a composite cell case for a Ni-Cd battery

Graphite epoxy material for a nickel cadmium battery cell case has been evaluated and determined to perform in the simulated environment of the battery. The basic manufacturing method requires refinement to demonstrate production feasibility. The various facets of production scale-up, i.e., process and tooling development together with material and process control, have been integrated into a comprehensive manufacturing process that assures production reproducibility and product uniformity. Test results substantiate that a battery cell case produced from graphite epoxy pre-impregnated material utilizing internal pressure bag fabrication method is feasible.

Bauer, J. L.↗

NASA NTRS1947

Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream

A theoretical study, based on the linearized equations of motion for small disturbance, is made of the air forces on wings of general plan forms moving forward at a constant supersonic speed. The boundary problem is set up for both the harmonically oscillating and the steady conditions. Two types of boundary conditions are distinguished, which are designated "purely supersonic" and "mixed supersonic." the method is illustrated by applications to a number of examples for both the steady and the oscillating conditions. The purely supersonic case involves independence of action of the upper and lower surfaces of the airfoil and present analysis is mainly concerned with this case. A discussion is first given of the fundamental or elementary solution corresponding to a moving source. The solutions for the velocity potential are then synthesized by means of integration of the fundamental solution for the moving source. The method is illustrated by applications to a number of examples for both the steady and the oscillating cases and for various plan forms, including swept wings and rectangular and triangular plan forms. The special results of a number of authors are shown to be included in the analysis.

Garrick, I E↗

NASA NTRS2018

A Hybrid Method of Assurance Cases and Testing for Improved Confidence in Autonomous Space Systems

Autonomous systems react intelligently to their environments, making them capable of handling many possible conditions, but challenging to test. We are investigating a new test development method that aims to maximize the confidence to be achieved by combining Assurance Cases with High Throughput Testing (HTT). Assurance Cases, developed for safety-critical systems, are a rigorous argument that the system satisfies a property (e.g., the Mars rover will not tip over during a traverse). They integrate testing, analysis, and environmental and operational assumptions, from which the set of conditions that testing must cover is determined. In our method, information from the Assurance Case is used to determine the test coverage needed, and then input to HTT to generate the minimal test suites needed to provide that coverage.

Huntsberger, Terry↗

NASA NTRS2017

New Mathematical Functions for Vacuum System Analysis

A new bivariate function has been found that provides solutions of integrals having the form u (sup minus eta) e (sup u) du which arise when developing predictions for the behavior of pressure within a rigid volume under high vacuum conditions in the presence of venting as well as sources characterized by power law transient decay over the range [0,1] for eta and for u greater than or equal to 0. A few properties of the new function are explored in this work. For instance the eta equals 1/2 case reproduces the Dawson function. In addition, a slight variation of the solution technique reproduces the exponential integral for eta equals 1. The technique used to generate these functions leads to an approach for solving a more general class of nonlinear ordinary differential equations, with the potential for identifying other new functions that solve other integrals.

Dawson Function↗

NASA NTRS1972

Some contamination problems in the European TD satellite

Materials were selected for the European TD satellite with a view to avoiding contamination of its stellar ultraviolet telescopes. Materiels were selected using the micro-VCM technique, and some typical cases of materials evaluation are described. The cleanliness of the satellite was monitored during integration and test phases, and in particular during long duration thermal vacuum tests.

Dauphin, J.↗

NASA NTRS1976

Diurnal variation of the Jovian ionosphere

The time-dependent structure of the Jovian ionosphere is examined. Diurnal variation of appreciable magnitude is revealed in the lower ionosphere. The upper ionosphere remains more or less intact at nighttime, as in the case of the earth's ionosphere. There is considerable difference in the height-integrated electrical conductivities on the day and night sides.

Tan, A.↗

NASA NTRS1976

Thermal microwave emission from half-space random media

Brightness temperatures resulting from microwave thermal emission from a half-space random medium are calculated. The random medium has a nonuniform temperature profile and is characterized by correlation functions that possess both vertical and lateral variations. Radiative transfer equations are derived. They are solved with an iterative integral equation approach for small scattering albedo and with a numerical approach for general cases. New results are illustrated, discussed, and compared with various special cases. Phenomena caused by resonant scattering, which is absent under Rayleigh approximations, are revealed. Scattering in the lateral direction contributes to the decrease of the equivalent reflectivity and the increase of the brightness temperature.

Tsang, L.↗

NASA NTRS1979

Miniature Ku-Band down converter

Hybrid circuit serves as receiver front end for 13.75- to 14.0-GHz communications and radar systems. Complete microwave integrated circuit (MIC) assembly is packaged in small hermetically welded, nitrogen-filled aluminum case. Simplicity and size proves useful for lower-frequency wideband applications.

Norbury, D. A.↗

NASA NTRS1977

Probe corrected far-field reconstruction from measurements on a cylinder: A novel formulation and efficient algorithm

A novel and numerically efficient method of far field evaluation from measurements taken on a cylinder is based on the representation of both the antenna and the probe fields as superpositions of plane waves. A system of two integral equations are established whose unknown functions are the azimuthal and elevation components of the antenna pattern and whose known terms are the set of measurement data taken with two different probes - the second probe in most practical instances being simply the same probe with a different geometrical orientation. The equations express the known data - for each angular position of the antenna under measurement - as the integrals of the products of the corresponding components of the unknown antenna and known probe patterns multiplied by a phase term. The convolutional nature of the integral equations makes their solutions straight-forward. If, as is virtually always the case, the probe is small or of moderate size so that the axis of rotation of the antenna mount is in the far field of the probe, the intervention of asymptotic techniques makes the solution numerically very efficient. The agreement of calculated and experimental patterns is excellent.

Borgiotti, G. V.↗

NASA NTRS1978

Investigation of ODE integrators using interactive graphics

In the present paper, two FORTRAN programs are described which use an interactive graphic terminal to generate accuracy and stability plots for a given multistep integrator of ordinary differential equations (ODE). One program treats the fixed-stepsize linear case with complex variable solutions, and generates plots to show accuracy and error response to step driving function of a numerical solution. It also generates the linear stability region. The other program generates an analog with an accuracy plot. Both systems are capable of computing method coefficients from a simple specification of the method. Example plots are given.

Brown, R. L.↗

NASA NTRS1980

Acid rain: Microphysical model

A microphysical model was used to simulate the case of a ground cloud without dilution by entrainment and without precipitation. The numerical integration techniques of the model are presented. The droplet size spectra versus time and the droplet molalities for each value of time are discussed.

Dingle, A. N.↗

NASA NTRS1981

Thermal modeling of cometary nuclei

A model of the sublimation of volatile ices from a cometary nucleus is presented which includes the effects of (1) diurnal heating and cooling, (2) rotation period and pole orientation, (3) the thermal properties of the ice and subsurface layers, and (4) the contributions from coma opacity, scattering and thermal emission where the properties of the coma are derived from the integrated rate of volatile production by the nucleus. In applying the model to the case of the 1986 apparition of Halley's comet, it is found that the generation of a cometary dust coma increases the total energy reaching the Halley nucleus due to the greater geometrical cross-section of the coma as compared with the bare nucleus. The calculated coma opacity of Halley is about 0.2 at 1 AU from the sun and 1.2 at perihelion. Possible consequences of the results obtained for the generation of nongravitational forces, volatile production rates for comets and cometary lifetimes against sublimation are discussed.

Weissman, P. R.↗

NASA NTRS1984

Theoretical approach to labyrinth seal forces - cross-coupled stiffness of a straight-through labyrinth seal

Two kinds of three dimensional flows in a labyrinth seal, a jet flow and a core flow, are considered and theoretical equations are set up concerning the motion of each flow. The pressure distribution within the labyrinth is calculated, when the rotor shaft makes a small displacement from the center line of the casing, keeping parallel with it. The theoretical values of cross coupled stiffness obtained by integrating the pressure under different labyrinth geometries and operating conditions through these formulas are compared with the experimental data.

Kameoka, T.↗