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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Characterization and Compensation of the Atmosphere for the Inversion of AVIRIS Calibrated Radiance to Apparent Surface Reflectance

Calibrated radiance spectra measured remotely, record the integrated effects of the solar source, the atmosphere, and the surface. To pursue scientific research and applications, based on the molecular absorptions and constituent scattering properties of the surface, the solar source and atmosphere must be characterized and compensated in the spectra. This paper describes a set of radiative transfer spectral fitting algorithms to characterize the absorbing and scattering constituents of the atmosphere from calibrated AVIRIS spectra.

atmosphere↗
NASA NTRS2021

Empirical Model of 10 – 130 MeV Solar Energetic Particle Spectra at 1 AU Based on Coronal Mass Ejection Speed and Direction

We present a new empirical model to predict solar energetic particle (SEP) event integrated and peak intensity spectra between 10 and 130 MeV at 1 AU, based on multi-point spacecraft measurements from the Solar TErrestrial RElations Observatory (STEREO), the Geostationary Operational Environmental Satellites (GOES), and the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment. The analyzed data sample includes 32 SEP events occurring between 2010 and 2014, with a statistically significant proton signal at energies in excess of a few tens of MeV, unambiguously recorded at three spacecraft locations. The spatial distributions of SEP intensities are reconstructed by assuming an energy-dependent 2D Gaussian functional form, and accounting for the correlation between the intensity and the speed of the parent coronal mass ejection (CME), and the magnetic-field-line connection angle. The CME measurements used are from the Space Weather Database Of Notifications, Knowledge, Information (DONKI). The model performance, including its extrapolations to lower/higher energies, is tested by comparing with the spectra of 20 SEP events not used to derive the model parameters. Despite the simplicity of the model, the observed and predicted event-integrated and peak intensities at Earth and at the STEREO spacecraft for these events show remarkable agreement, both in the spectral shapes and their absolute values.

Alessandro Bruno↗
NASA NTRS2015

Thin, Flexible IMM Solar Array

NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

Walmsley, Nicholas↗
NASA NTRS2001

Integrated Power Source Grant

Traditional spacecraft power systems incorporate a solar array energy source, an energy storage element (battery), and battery charge control and bus voltage regulation electronics to provide continuous electrical power for spacecraft systems and instruments. Dedicated power conditioning components provide limited fault isolation between systems and instruments, while a centralized power-switching unit provides spacecraft load control. Battery undervoltage conditions are detected by the spacecraft processor, which removes fault conditions and non-critical loads before permanent battery damage can occur. Cost effective operation of a micro-sat constellation requires a fault tolerant spacecraft architecture that minimizes on-orbit operational costs by permitting autonomous reconfiguration in response to unexpected fault conditions. A new micro-sat power system architecture that enhances spacecraft fault tolerance and improves power system survivability by continuously managing the battery charge and discharge processes on a cell-by-cell basis has been developed. This architecture is based on the Integrated Power Source (US patent 5644207), which integrates dual junction solar cells, Lithium Ion battery cells, and processor based charge control electronics into a structural panel that can be deployed or used to form a portion of the outer shell of a micro-spacecraft. The first generation Integrated Power Source is configured as a one inch thick panel in which prismatic Lithium Ion battery cells are arranged in a 3x7 matrix (26VDC) and a 3x1 matrix (3.7VDC) to provide the required output voltages and load currents. A multi-layer structure holds the battery cells, as well as the thermal insulators that are necessary to protect the Lithium Ion battery cells from the extreme temperatures of the solar cell layer. Independent thermal radiators, located on the back of the panel, are dedicated to the solar cell array, the electronics, and the battery cell array. In deployed panel applications, these radiators maintain the battery cells in an appropriate operational temperature range.

Source record↗
NASA NTRS1999

Comparison of the SPE Model with Proton and Heavy Ion Data

Proton data from the GOES 6 and 7 satellites and heavy ion data from the IMP-8 satellite have been compared to the expected results of Nymmik's new model for solar particle event fluences. This model calculates the energy spectra of Ions for protons through nickel for solar particle events, based upon the observed proton integral fluence above 30 MeV. Based upon 27 observed proton events of solar cycle 22, and three large historical events, with integral fluences above 30 MeV of greater than 106 particles/cm2, a reasonable agreement with model predictions is seen for more than half of the events. However, several events show a marked departure from the model predictions, leading to the conclusion that there may exist more than a single class of event, or that it may be necessary to include additional parameters within the model, such as solar disk position of the source flare, or height of disturbance in the solar corona. Data for heavy Ions, (oxygen and iron), were limited to a total of six solar particle events, of which only two occurred in solar cycle 22. The agreement between data and the model predictions appeared to be quite good, however this agreement was sensitively dependent upon the value taken for the proton fluence above 30 MeV.

Cleghorn, Timothy F.↗
NASA NTRS2019

Solar Power System and Radioisotope Thermoelectric Generation Technologies at Jupiter-Saturn-Uranus Environments: New Insights and Paradigms

Power system selection for outer planet destinations, such as Jupiter, Saturn, and Uranus and beyond, is complex, involving and dependent on many interdisciplinary factors such as power system mass, specific power, cost, mechanical and electrical integration, and natural radiation environment. Low solar irradiance at Jupiter, Saturn, and Uranus systems (i.e., 50, 15, and 4 W/m2 , respectively) makes solar power systems challenging in mechanical / electrical integration and accommodating radiation environments. More costly radioisotope thermoelectric generator (RTG) systems can help proposed missions overcome radiation environment and spacecraft control challenges at Jupiter, Saturn, and Uranus. NASA’s Jet Propulsion Laboratory (JPL) has recently made significant strides in demonstrating high-efficiency, radiation-hard solar cell technologies for low-irradiance, low-temperature (LILT) applications, and high-efficiency thermoelectric (TE) materials and modules for higher-specific-power RTGs. Stateof-art multi-junction solar cells now routinely demonstrate high efficiencies of 30-34% at LILT (9.5AU and -165°C), making solar arrays a viable option for many near-term Saturn mission concepts. Emerging technologies like LILToptimized solar cells have recently demonstrated even higher efficiencies of 37% at 9.5AU and -165°C and 30% lower mass than the state-of-art, offering the prospect of ~3W/kg array-level, end-of-life specific powers under Saturn conditions. Having already demonstrated the tremendous utility of RTGs on Mars and in deep-space missions (e.g., Galileo at Jupiter, New Horizons at Pluto), NASA is now developing and demonstrating new TE materials and modules (e.g., skutterudites, La3-x Te4, and Zintls) for increasing RTG specific power (up to >8.5 W/kg), which strongly impacts an RTG’s mass, fuel utilization, and modularity in the power system trade domain. New accomplishments in both areas highlight the renewed requisite for updated comparisons and trade-offs in power output, specific power and mass, cost, mechanical and electrical integration, new technology timelines, and natural radiation impacts between new LILT-optimized photovoltaic technologies and next-generation RTG technologies. This work discusses and demonstrates how new LILT-based technologies are now allowing one to consider and design solar power systems for Saturn orbit and beyond, and are changing the potential cost-mass trade-offs between emerging solar power technologies and newly-envisioned RTG technologies. Key updated system mass and cost trade-offs between high-performance LILT solar technologies and new RTG technologies are presented, reinforcing and refining power selection criteria supporting possible future NASA deep-space science and exploration missions to Mars, the Jupiter system (Europa, Ganymede), the Saturn system (Titan, Enceladus), Uranus, and beyond. Key trade-offs in other above-mentioned interdisciplinary factors between these two power technologies are also discussed.

Bairstow, Brian K.↗
NASA NTRS1980

Solar space heating for the Visitors Center, Stephens College, Columbia, Missouri

The solar energy system located at the Visitors' Center on the Stephens College Campus, Columbia, Missouri is discussed. The system is installed in a four-story, 15,000 square foot building. The solar energy system is an integral design of the building and utilizes 176 hydronic flat plate collectors which use a 50 percent water ethylene blycol solution and water-to-water heat exchanger. Solar heated water is stored in a 5,000 gallon water storage tank located in the basement equipment room. A natural gas fired hot water boiler supplies hot water when the solar energy heat supply fails to meet the demand. The designed solar contribution is 71 percent of the heating load.

Source record↗
NASA NTRS2000

Mapping Agricultural Crops with AVIRIS Spectra in Washington State

Spectroscopy is used in the laboratory to measure the molecular components and concentrations of plant constituents to answer questions about the plant type, status, and health. Imaging spectrometers measure the upwelling spectral radiance above the Earth's surface as images. Ideally, imaging spectrometer data sets should be used to understand plant type, plant status, and health of plants in an agricultural setting. An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data set was acquired over agricultural fields near Wallula, Washington on July 23rd, 1997. AVIRIS measures upwelling radiance spectra through 224 spectral channels with contiguous 10-nm sampling from 400 to 2500 run in the solar-reflected spectrum. The spectra are measured as images of 11 by up to 800 km with 20-m spatial resolution. The spectral images measured by AVIRIS represent the integrated signal resulting from: the solar irradiance; two way transmittance and scattering of the atmosphere; the absorptions and scattering of surface materials; as well as the spectral, radiometric and spatial response functions of AVIRIS. This paper presents initial research to derive properties of the agricultural fields near Wallula from the calibrated spectral images measured by AVIRIS near the top of the atmosphere.

Green, Robert O.↗
NASA NTRS1998

Mapping Agricultural Crops with AVIRIS Spectra in Washington State

Spectroscopy is used in the laboratory to measure the molecular components and concentrations of plant constituents to answer questions about the plant type, status, and health. Imaging spectrometers measure the upwelling spectral radiance above the Earth's surface as images. Ideally, imaging spectrometer data sets should be used to understand plant type, plant status, and health of plants in an agricultural setting. An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data set was acquired over agricultural fields near Wallula, Washington on July 23rd, 1997. AVIRIS measures upwelling radiance spectra through 224 spectral channels with contiguous 10-nm sampling from 400 to 2500 nm in the solar-reflected spectrum. The spectra are measured as images of 11 by up to 800 km with 20-m spatial resolution. The spectral images measured by AVIRIS represent the integrated signal resulting from: the solar irradiance; two way transmittance and scattering of the atmosphere; the absorptions and scattering of surface materials; as well as the spectral, radiometric and spatial response functions of AVIRIS. This paper presents initial research to derive properties of the agricultural fields near Wallula from the calibrated spectral images measured by AVIRIS near the top of the atmosphere.

Green, Robert↗
NASA NTRS1974

Properties criteria for components and materials used in lightweight solar arrays

The present work describes the characteristics and design criteria for components and materials used in lightweight substrate solar arrays. This includes descriptions of wraparound-electrode solar cells, cell covers, and cell interconnects. Cell cover systems briefly discussed are fused silica, cerium stabilized glass, microsheet, FEP (tape, heat laminated, and spray on), and ESB 7070 glass integral covers. The majority of solar arrays orbited have used either silver, Kovar, copper, or molybdenum as interconnect metals. Data are presented comparing the Young's modulus E, ultimate tensile strength, coefficient of expansion, thermal conductivity, and percent elongation of these and other interconnect candidate materials. Guidelines for the use of end tab wraparound cells are listed.

Lott, D. R.↗
NASA NTRS1977

Simplified methods for calculating photodissociation rates

Simplified methods for calculating the transmission of solar UV radiation and the dissociation coefficients of various molecules are compared. A significant difference sometimes appears in calculations of the individual band, but the total transmission and the total dissociation coefficients integrated over the entire SR (solar radiation) band region agree well between the methods. The ambiguities in the solar flux data affect the calculated dissociation coefficients more strongly than does the method. A simpler method is developed for the purpose of reducing the computation time and computer memory size necessary for storing coefficients of the equations. The new method can reduce the computation time by a factor of more than 3 and the memory size by a factor of more than 50 compared with the Hudson-Mahle method, and yet the result agrees within 10 percent (in most cases much less) with the original Hudson-Mahle results, except for H2O and CO2. A revised method is necessary for these two molecules, whose absorption cross sections change very rapidly over the SR band spectral range.

Shimazaki, T.↗
NASA NTRS1979

Proceedings of the 13th Project integration meeting

Progress made by the Low Cost Solar Array Project during the period April through August 1979 is presented. Reports are given on project analysis and integration; technology development in silicon material, large area sheet silicon, and encapsulation; production process and equipment development; engineering and operations, and a discussion of the steps taken to integrate these efforts. A report on, and copies of viewgraphs presented at the Project Integration Meeting held August 22-23, 1979 are presented.

Mcdonald, R. R.↗
NASA NTRS1973

High voltage solar cell power generating system for regulated solar array development

A laboratory solar power system regulated by on-panel switches has been delivered for operating high power (3 kw), high voltage (15,000 volt) loads (communication tubes, ion thrusters). The modular system consists of 26 solar arrays, each with an integral light source and cooling system. A typical array contains 2560 series-connected cells. Each light source consists of twenty 500 watt tungsten iodide lamps providing plus or minus 5 per cent uniformity at one solar constant. An array temperature of less than 40 C is achieved using an infrared filter, a water cooled plate, a vacuum hold-down system, and air flushing.

Levy, E., Jr.↗
NASA NTRS1974

High voltage solar cell power generating system

A laboratory solar power system regulated by on-panel switches has been delivered for operating high power (3 kW), high voltage (15,000 volt) loads (communication tubes, ion thrusters). The modular system consists of 26 solar arrays, each with an integral light source and cooling system. A typical array contains 2,560 series-connected cells. Each light source consists of twenty 500-watt tungsten iodide lamps providing plus or minus 5 percent uniformity at one solar constant. An array temperature of less than 40 C is achieved using an infrared filter, a water-cooled plate, a vacuum hold-down system, and air flushing.

Levy, E., Jr.↗
NASA NTRS1974

A low cost ""Air Mass 2'' solar simulator

Tungsten halogen projection lamps have integral ellipsoidal reflector, and hexagonal shaped plastic Fresnel lenses. Reflector is dichroic coated to reduce infrared content of reflected radiation. Array of lamps and lenses produces uniform collimated beam having near AM2 spectrum and intensity that can be used for testing flat plate solar collectors.

Yass, K.↗
NASA NTRS1976

SAMIS - A simulation of the solar array manufacturing industry

SAMIS is a continuing activity of the Project Analysis and Integration Task of the Low-cost Silicon Solar Array Project (LSSA). It provides a standardized procedure for producing reliable estimates of the cost of manufacturing solar arrays or their components. These estimates are based on descriptions of the manufacturing processes which are being studied and developed by LSSA subcontractors and will be used to assess the commercial viability of those processes and to set research priorities.

Chamberlain, R. G.↗
NASA NTRS1980

Solar cell system having alternating current output

A monolithic multijunction solar cell was modified by fabricating an integrated circuit inverter on the back of the cell to produce a device capable of generating an alternating current output. In another embodiment, integrated curcuit power conditioning electronics was incorporated in a module containing a solar cell power supply.

Evans, J. C., Jr.↗
NASA NTRS1973

Solar flare alpha particles

Interplanetary disturbances frequently change the instantaneous values of the low energy solar flare alpha-to-proton flux ratios. The fluxes of alpha particles were integrated over the duration of seven large solar events occurring between May 28, 1967, and November 6, 1969, in order to investigate the total alpha particles fluxes observed at 1 AU resulting from the flares. The spectra of the event integrated alphas are always softer than the spectra of the event integrated protons. As a consequence, the event-integrated alpha-to-proton ratios decrease slightly with increasing energy per nucleon. The He-4/H-1 ratios averaged over the seven events are found to vary as 0.026 (E/nucl) sup -0.2 in the range 1 to 10 MeV/nucleon. The value of the ratio at 1 MeV/nucleon is less than the helium-to-hydrogen abundance determined from spectroscopic studies of prominences and the chromosphere, and is less than the average solar wind helium-to-hydrogen abundance.

Lanzerotti, L. J.↗