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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

LEO effects on candidate solar cell cover materials

The Long Duration Exposure Facility (LDEF) test samples discussed within are part of the Solar Array Materials Passive (SAMPLE) LDEF experiment, which included contributions from NASA and Jet Propulsion Lab (JPL). Only the JPL portion is described in this paper. The JPL test plate contains 30 individual thin silicon solar cell/cover samples. It was the intent of the experiment to evaluate the stability and protective capability of various cover materials such as conventional fused silica and potential alternative materials such as Teflon, silicone RTV's, glass resins, polyimides, and a copolymer encapsulate. Examination of the recovered experiment shows extensive physical changes have occurred. Approximately 150 micrometeoroid/debris impact were noted, some directly on the solar cells. Of particular interest are the results of ultraviolet and atomic oxygen interactions with the various cover materials. Initial results show that the fused silica cover is the most stable and protective, with performance of other materials varying widely. Electrical measurements of the cell/cover samples are presented as part of the evaluation of cover materials to protect cells in low earth orbit environments.

Stella, Paul M.↗
NASA NTRS1978

Measurements of material properties for solar cells

Measurements on two candidate materials for space flight are reported. The observed optical transmittance of aluminum films vapor deposited on fused quartz showed anomalously high transmittance thru 400 A and 600 A and showed an effective skin depth of 110 A in the latter part of the 1000 A thickness. KAPTON films are shown by their optical transmission spectra to have an energy gap for electron excitation of approximately 2.5 eV, which value depends on the thickness as manufactured. The resistance of KAPTON film to ionizing radiation is described by their optical spectra and their electron spin resonance spectra.

Castle, J. G., Jr.↗
NASA NTRS2003

The Genesis Mission: An Overview

One of the scientists studying the formation of planets is Don Burnett, principal investigator of the Genesis mission. He designed a NASA project to collect a sample of solar material that may help scientists answer important and puzzling questions. In August 2002, NASA launched the Genesis spacecraft. The spacecraft is not a time machine; it cannot go back to the time of formation of the solar system. What it will do is the next best thing. The Genesis spacecraft will journey toward the sun. It will go to a place outside the Earth's magnetic field where the Earth and sun gravities are balanced. While in orbit, the spacecraft will bathe in solar wind that is flung out from the sun. Solar wind particles are similar to material from which the planets formed, and are atoms, ions, or high-energy particles.

Source record↗
NASA NTRS1988

Planetary optical and infrared imaging

The purpose of this investigation is to obtain and analyze high spatial resolution charge coupled device (CCD) coronagraphic images of extra-solar planetary material and solar system objects. These data will provide information on the distribution of planetary and proto-planetary material around nearby stars leading to a better understanding of the origin and evolution of the solar system. Imaging within our solar system will provide information on the current cloud configurations on the outer planets, search for new objects around the outer planets, and provide direct support for Voyager, Galileo, and CRAF by imaging material around asteroids and clouds on Neptune. Over the last year this program acquired multispectral and polarization images of the disk of material around the nearby star Beta Pictoris. This material is believed to be associated with the formation of planets and provides a first look at a planetary system much younger than our own. Preliminary color and polarization data suggest that the material is very low albedo and similar to dark outer solar system carbon rich material. A coronagraphic search for other systems is underway and has already examined over 100 nearby stars. Coronagraphic imaging provided the first clear look at the rings of Uranus and albedo limits for the ring arcs around Neptune.

Terrile, R. J.↗
NASA NTRS1980

Measurement of loss angle, volume resistivity and surface resistivity of insulating materials used on solar cells

The complete measuring and test system developed to measure the quality and the stability of insulating materials used on solar cell arrays for space application is described. The test set up and measurements are primarily aimed at the measurement and analysis of the degradation of the electrical insulating properties of material used on solar cells. Degradation characteristics of the material subject to thermal cycling, space plasma and very high electrical fields individually and in combination can be investigated.

Doreswamy, C. V.↗
NASA NTRS1984

Electrical research on solar cells and photovoltaic materials

The flat-plate solar cell array program which increases the service lifetime of the photovoltaic modules used for terrestrial energy applications is discussed. The current-voltage response characteristics of the solar cells encapsulated in the modules degrade with service time and this degradation places a limitation on the useful lifetime of the modules. The most desirable flat-plate array system involves solar cells consisting of highly polarizable materials with similar electrochemical potentials where the cells are encapsulated in polymers in which ionic concentrations and mobilities are negligibly small. Another possible mechanism limiting the service lifetime of the photovoltaic modules is the gradual loss of the electrical insulation characteristics of the polymer pottant due to water absorption or due to polymer degradation from light or heat effects. The mechanical properties of various polymer pottant materials and of electrochemical corrosion mechanisms in solar cell material are as follows: (1) electrical and ionic resistivity; (2) water absorption kinetics and water solubility limits; and (3) corrosion characterization of various metallization systems used in solar cell construction.

Orehotsky, J.↗
NASA NTRS1977

Real time outdoor exposure testing of solar cell modules and component materials

Plastic samples, solar cell modules, and sub-modules were exposed at test sites in Florida, Arizona, Puerto Rico, and Cleveland, Ohio, in order to determine materials suitable for use in solar cell modules with a proposed 20-year lifetime. Various environments were encountered including subtropical, subtropical with a sea air atmosphere, desert, rain forest, normal urban, and urban-polluted. The samples were exposed for periods up to six months. Materials found not suitable were polyurethane, polyester, Kapton, Mylar, and UV-stabilized Lexan. Suitable materials were acrylic, FEP-A, and glass. The results of exposure of polyvinylidene fluoride were dependent on the specific formulation, but several types appear suitable. RTV silicone rubber (clear) appears to pick up and hold dirt both as a free film and as a potting medium for modules. The results indicate that dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

Anagnostou, E.↗
NASA NTRS1972

Solar energy, its conversion and utilization

The work being carried out at the University of Florida Solar Energy and Energy Conversion Laboratory in converting solar energy, our only income, into other needed and useful forms of energy is described. A treatment such as this demonstrates, in proper perspective, how solar energy can benefit mankind with its many problems of shortages and pollution. Descriptions were given of the conversion processes, equipment, and performance. The testing of materials, solar water heating, space heating, cooking and baking, solar distillation, refrigeration and air-conditioning, work with the solar furnace, conversion to mechanical power, hot air engines, solar-heated sewage digestion, conversion to electricity, and other devices will be discussed.

Farber, E. A.↗
NASA NTRS1986

Oxidation-resistant reflective surfaces for solar dynamic power generation in near Earth orbit

Reflective surfaces for space station power generation systems are required to withstand the atomic oxygen-dominated environment of near Earth orbit. Thin films of platinum and rhodium, which are corrosion resistant reflective metals, have been deposited by ion beam sputter deposition onto various substrate materials. Solar reflectances were then measured as a function of time of exposure to a RF-generated air plasma. Similarly, various protective coating materials, including MgF2, SiO2, Al2O3, and Si3N4, were deposited onto silver-coated substrates and then exposed to the plasma. Analysis of the films both before and after exposure by both ESCA and Auger spectroscopy was also performed. The results indicate that Pt and Rh do not suffer any loss in reflectance over the duration of the tests. Also, each of the coating materials survived the plasma environment. The ESCA and Auger analyses are discussed as well.

Gulino, D. A.↗
NASA NTRS1982

Laser processing

Progress in the Progress ceramic materials is reported. Experiments and models for sintering and microstructure evolution are described. Models and data for understanding the kinetics of grain boundary motion and of pore coarsening and new materials for fuel cells and batteries; are developed. New experimental techniques using lasers for forming fine, monosized powders and for forming stable and metastable structures from liquids, and solar materials research are also developed. Colloidal science and ceramics processing are explored; and research programs on the presintering science necessary for controlled green microstructures are outlined.

Source record↗
DOE OSTI2024

High-temperature 205 Tl decay clarifies 205 Pb dating in early Solar System

Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth. Among such nuclei whose decay signatures are found in the oldest meteorites, 205 Pb is a powerful example, as it is produced exclusively by slow neutron captures (the s process), with most being synthesized in asymptotic giant branch (AGB) stars. However, making accurate abundance predictions for 205 Pb has so far been impossible because the weak decay rates of 205 Pb and 205 Tl are very uncertain at stellar temperatures. To constrain these decay rates, we measured for the first time the bound-state β - decay of fully ionized 205 Tl 81+ , an exotic decay mode that only occurs in highly charged ions. The measured half-life is 4.7 times longer than the previous theoretical estimate and our 10% experimental uncertainty has eliminated the main nuclear-physics limitation. With new, experimentally backed decay rates, we used AGB stellar models to calculate 205 Pb yields. Propagating those yields with basic galactic chemical evolution (GCE) and comparing with the 205 Pb/ 204 Pb ratio from meteorites, we determined the isolation time of solar material inside its parent molecular cloud. We find positive isolation times that are consistent with the other s-process short-lived radioactive nuclei found in the early Solar System. Our results reaffirm the site of the Sun’s birth as a long-lived, giant molecular cloud and support the use of the 205 Pb– 205 Tl decay system as a chronometer in the early Solar System.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1980

New mounting improves solar-cell efficiency

Method boosts output by about 20 percent by trapping and redirecting solar radiation without increasing module depth. Mounted solar-cell array is covered with internally reflecting plate. Plate is attached to each cell by transparent adhesive, and space between cells is covered with layer of diffusely reflecting material. Solar energy falling on space between cells is diffused and reflected internally by plate until it is reflected onto solar cell.

Shepard, N. F., Jr.↗
NASA NTRS1989

Compatibility of molten salts with advanced solar dynamic receiver materials

Metal-coated graphite fibers are being considered as a thermal conductivity enhancement filler material for molten salts in solar dynamic thermal energy storage systems. The successful metal coating chosen for this application must exhibit acceptable wettability and must be compatible with the molten salt environment. Contact angle values between molten lithium fluoride and several metal, metal fluoride, and metal oxide substrates have been determined at 892 C using a modification of the Wilhelmy plate technique. Reproducible contact angles with repeated exposure to the molten LiF indicated compatibility.

Jaworske, D. A.↗
NASA NTRS2014

Mass Spectum Imaging of Organics Injected into Stardust Aerogel by Cometary Impacts

Comets have largely escaped the hydrothermal processing that has affected the chemistry and mineralogy of even the most primitive meteorites. Consequently, they are expected to better preserve nebular and interstellar organic materials. Organic matter constitutes roughly 20-30% by weight of vol-atile and refractory cometary materials [1,2]. Yet organic matter identified in Stardust aerogel samples is only a minor component [3-5]. The dearth of intact organic matter, fine-grained and pre-solar materials led to suggestions that comet 81P/Wild-2 is com-posed largely of altered materials, and is more similar to meteorites than the primitive view of comets [6]. However, fine-grained materials are particularly susceptible to alteration and destruction during the hypervelocity impact. While hypervelocity capture can cause thermal pyrolysis of organic phases, some of the impacting organic component appears to have been explosively dispersed into surrounding aerogel [7]. We used a two-step laser mass spectrometer to map the distribution of organic matter within and sur-rounding a bulbous Stardust track to constrain the dispersion of organic matter during the impact.

Clemett, S. J.↗
NASA NTRS1991

Planetary optical and infrared imaging

The purpose is to obtain and analyze high spatial resolution CCD coronagraphic images of extra-solar planetary material and solar system objects. These data will provide information on the distribution of planetary and proto-planetary material around nearby stars leading to a better understanding of the origin and evolution of the solar system.

Terrile, Richard J.↗
NASA NTRS1987

Oxidation-resistant reflective surfaces for solar dynamic power generation in near earth orbit

Reflective surfaces for Space Station power generation systems are required to withstand the atomic oxygen-dominated environment of near earth orbit. Thin films of platinum and rhodium, which are corrosion resistant reflective metals, have been deposited by ion beam sputter deposition onto various substrate materials. Solar reflectances were then measured as a function of time of exposure to a RF-generated air plasma.

Gulino, Daniel A.↗
NASA NTRS1979

Low-cost encapsulation materials for terrestrial solar cell modules

The paper presents the findings of material surveys intended to identify low cost materials which could be functional as encapsulants (by 1986) for terrestrial solar cell modules. Economic analyses have indicated that in order to meet the low cost goal of $2.70 per sq m, some or all of the following material technologies must be developed or advanced: (1) UV screening outer covers; (2) elastomeric acrylics; (3) weatherproofing and waterproofing of structural wood and paper products; (4) transparent UV stabilizers for the UV-sensitive transparent pottants; and (5) cost-effective utilization of silicone and fluorocarbon materials.

Cuddihy, E. F.↗