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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

The Heliogyro Reloaded

The heliogyro is a high-performance, spinning solar sail architecture that uses long - order of kilometers - reflective membrane strips to produce thrust from solar radiation pressure. The heliogyro s membrane blades spin about a central hub and are stiffened by centrifugal forces only, making the design exceedingly light weight. Blades are also stowed and deployed from rolls; eliminating deployment and packaging problems associated with handling extremely large, and delicate, membrane sheets used with most traditional square-rigged or spinning disk solar sail designs. The heliogyro solar sail concept was first advanced in the 1960s by MacNeal. A 15 km diameter version was later extensively studied in the 1970s by JPL for an ambitious Comet Halley rendezvous mission, but ultimately not selected due to the need for a risk-reduction flight demonstration. Demonstrating system-level feasibility of a large, spinning heliogyro solar sail on the ground is impossible; however, recent advances in microsatellite bus technologies, coupled with the successful flight demonstration of reflectance control technologies on the JAXA IKAROS solar sail, now make an affordable, small-scale heliogyro technology flight demonstration potentially feasible. In this paper, we will present an overview of the history of the heliogyro solar sail concept, with particular attention paid to the MIT 200-meter-diameter heliogyro study of 1989, followed by a description of our updated, low-cost, heliogyro flight demonstration concept. Our preliminary heliogyro concept (HELIOS) should be capable of demonstrating an order-of-magnitude characteristic acceleration performance improvement over existing solar sail demonstrators (HELIOS target: 0.5 to 1.0 mm/s2 at 1.0 AU); placing the heliogyro technology in the range required to enable a variety of science and human exploration relevant support missions.

Wilkie, William K.↗
DOE OSTI2022

The Diurnal Dynamics of Gross Primary Productivity Using Observations From the Advanced Baseline Imager on the Geostationary Operational Environmental Satellite‐R Series at an Oak Savanna Ecosystem

Gross primary productivity (GPP) is the largest flux in the global carbon cycle and satellite-based GPP estimates have long been used to study the trends and interannual variability of GPP. With recent updates to geostationary satellites, we can now explore the diurnal variability of GPP at a comparable spatial resolution to polar-orbiting satellites and at temporal frequencies comparable to eddy covariance (EC) tower sites. We used observations from the Advanced Baseline Imager on the Geostationary Operational Environmental Satellite-R series (GOES-R) to test the ability of subdaily satellite data to capture the shifts in the diurnal course of GPP at an oak savanna EC site in California, USA that is subject to seasonal soil moisture declines. We compared three methods to estimate GPP: (a) a light-use efficiency model, (b) a linear relationship between the product of near-infrared reflectance of vegetation and photosynthetically active radiation (LIN-NIR v P) and EC tower GPP, and (c) a light response curve (LRC-NIR v P) between NIR v P and EC GPP. The LRC-NIR v P achieved the lowest mean absolute error for winter (2 µmol CO 2 m –2 s –1 ), spring (2.51 µmol CO 2 m –2 s –1 ), summer (1.43 µmol CO 2 m –2 s –1 ), and fall (1.35 µmol CO 2 m –2 s –1 ). The ecosystem experienced the largest shift in daily peak GPP in relation to the peak of incoming solar radiation toward the morning hours during the dry summers. The LRC-NIRvP and the light-use efficiency model were in agreement with these patterns of a shift in peak daily GPP toward the morning hours during summer. Our results can help develop diurnal estimates of GPP from geostationary satellites that are sensitive to fluctuating environmental conditions during the day.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Solar receivers and methods for capturing solar energy

Thermal receivers, systems, and methods are disclosed that efficiently capture concentrated solar energy into a plurality of heat absorption bodies for conversion into thermal energy. In an embodiment, the thermal receivers, systems, and methods enable simultaneous electricity conversion and thermal energy capture. The receiver design enables a high penetration of concentrated sunlight deep into the thermal receiver to increase light trapping and reduce thermal losses. The thermal receiver is integrated with a photovoltaic (PV) receiver platform that converts some of the incident light to electricity while passing the remaining light to the thermal receiver. In another embodiment, other thermal receivers, systems, and methods are disclosed that efficiently capture concentrated solar energy into a sheet of falling particles. In an embodiment, the thermal receivers, systems, and methods enable simultaneous electricity conversion and thermal energy capture.

Ho, Clifford K.↗
DOE OSTI2025

Sequential Infiltration Synthesis (SIS) of In 2 O 3 -Based Porous Photoelectrodes for Molecular Sensitization

High-surface-area photoelectrodes are highly desirable for solar energy conversion applications, particularly in systems where surface-bound molecular chromophores are responsible for light absorption. To this end, porous Indium-Zinc-Oxide (IZO) frameworks are fabricated via Sequential Infiltration Synthesis (SIS) into poly(methyl methacrylate) (PMMA) films followed by air annealing. A more complete understanding of the multimetal infiltration process conditions and postannealing temperature allows for precise control of zinc (Zn) incorporation to afford porous, conductive, transparent, and amorphous photoelectrodes. Uniform incorporation of both indium (In) and Zn is found to require extended diethylzinc (DEZ) exposures to compensate for remarkably slow precursor diffusion in the presence of indium oxyhydroxide nuclei. SIS-fabricated IZO photoelectrodes are structurally robust, electrochemically active, and exhibit dye adsorption that suggest practical surface area enhancements greater than 100×. In conclusion, these attributes establish SIS as a rapid, scalable, and reproducible route to photoelectrodes for solar energy conversion and hybrid interface characterization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1983

Solar flare X-ray spectra from the P78-1 spacecraft

Results from the high resolution solar X-ray spectrometer experiments on the P78-1 spacecraft are discussed. These results concern physical quantities such as electron temperature and density, turbulence, mass motions, and state of ionization equilibrium, characteristic of the thermal soft X-ray emitting flare plasma, and the time behavior of these quantities during flares. In addition, a brief description of the instruments is given, the plasma diagnostics used in interpreting the spectra are summarized, and the origin of the thermal soft X-ray emitting plasma is discussed in light of the P78-1 results, earlier data, and numerical simulations of magnetic flux tubes heated to solar flare temperatures.

Doschek, G. A.↗
NASA NTRS1977

Solar polar coronal hole - A mathematical simulation

The northern polar region of the sun was studied during July 1973 by Munro and Jackson through use of the white-light coronagraph and the X-ray photographs produced by the Skylab mission. They described the northern polar hole as nearly axisymmetric and gave the geometry and density distribution under this approximation. The present work gives quasi-radial approximation to the full magnetohydrodynamic equations for axisymmetric, polytropic solar wind flow to simulate this polar hole, with the benefit that model temperature and magnetic field intensities and distributions in this particular polar hole can be deduced. It is concluded that from 2 out to 5 solar radii the temperature varies only slightly with radius, but is larger near the center of the polar hole than at the edge. It is also found that the magnetic field intensity at 2 solar radii could be about 1 gauss at the center of the hole, decreasing toward the edge of the hole. If this is extrapolated to the surface, a field as high as 20 gauss is suggested.

Suess, S. T.↗
DOE OSTI2020

Stable CdTe Photoanodes with Energetics Matching Those of a Coating Intermediate Band

Here, a TiO 2 coating was grown on a CdTe absorber by atomic layer deposition for stabilization against its photocorrosion during photoelectrochemical water splitting. Under simulated sunlight (AM 1.5G, 100 mW cm –2 ), this multilayer CdS/CdTe/TiO 2 /Ni/NiO x photoanode produced a light-limited photocurrent density of 24.5 ± 0.5 mA cm –2 and a photovoltage of 780 ± 20 mV. This record energy-conversion performance was comparable to those of baseline CdS/CdTe solar cells and was achieved only after the development of proper CdTe surface treatments prior to coating the stabilization layer. The TiO 2 coating, with its in-gap charge-transport intermediate band, facilitates hole transport as light exits the CdTe/TiO 2 interface. With proper interfacial chemistry, the electrochemical potential energy of the coating intermediate band matched that of the CdTe valence band. Moreover, the stabilized CdS/CdTe/TiO 2 /Ni/NiO x photoanodes showed 100 h stability for water oxidation under light-on/light-off cycles. This study provides insightful guidance for designing stabilization contacts for efficient and stable light-driven water oxidation.

14 SOLAR ENERGY↗
NASA NTRS1986

Astronomy on a manned Mars mission

Three extra-solar-system astronomical experiments onboard a manned Mars mission are proposed. First, a modest, 50 cm aperture optical-ultraviolet-infrared telescope (or pair used as an interferometer) coupled with the Mars-Sun baseline would increase the number (by a factor of 3.4) and a volume of stars with accurately measured distances via stellar parallax and, therefore, greatly improve upon the cosmic distance scale; the darker sky at Mars would also provide nearly a full astronomical magnitude deeper images of distant and low brightness objects (limited by zodiacal light). Second, a gamma-ray burst detector coupled with similar detectors in other parts of the solar system will be used to reduce the position error boxes and to study the nature of these energetic sources. Third, the long baselines on a Mars mission radio interferometer will provide a view of the radio universe at unprescedented resolution, 4 x 10 to the minus 9th arcsec at 1 mm wavelength, which can potentially resolve the engine in nearby active galaxies. Each of these experiments is relatively inexpensive, taking advantage of the human presence for operation and maintenance, and the long Earth to Mars baseline.

Burns, Jack O.↗
NASA NTRS2008

Stereo and Solar Cycle 24

The twin STEREO spacecrafi, launched in October 2006, are in heliocentric orbits near 4 AU with one spacecraft (Ahead) leading Earth in its orbit around the Sun and the other (Behind) trailing Earth. As viewed from the Sun, the STEREO spacecraft are continually separating from one another at about 45 degrees per year with Earth biseding the angle. At present, th@spaser=raft are a bit more than 45 degrees apart, thus they are able to each 'vie@ ground the limb's of the Sun by about 23 degrees, corresponding to about 1.75 days of solar rotation. Both spameraft contain an identical set of instruments including an extreme ultraviolet imager, two white light coronagraphs, tws all-sky imagers, a wide selection of energetic particle detectors, a magnetometer and a radio burst tracker. A snapshot of the real time data is continually broadcast to NOW-managed ground stations and this small stream of data is immediately sent to the STEREO Science Center and converted into useful space weather data within 5 minutes of ground receipt. The resulting images, particle, magnetometer and radio astronomy plots are available at ~ ~ j ~ g ~ ~ ~ i t , : gAs~ timqe~ co~n~ting ue~s ijnto~ ~ ~ ~ ~ . ~ g ~ solar cycle 24, the separation angle becomes 90 degrees in early 2009 and 180 degrees in early 201 1 as the activity heads toward maximum. By the time of solar maximum, STEREO will provide for the first time a view of the entire Sun with the mronagraphs and e*reme ultraviolet instruments. This view wilt allow us to follow the evolution of active regions continuously and also detect new active regions long before they pose a space weather threat to Earth. The in situ instruments will be able to provide about 7 days advanced notice of co-rotating structures in the solar wind. During this same intewal near solar maximum, the wide-angle imagers on STEREB will both be ;able to view EarlCP-dirsted CMEs in their plane-oPsky. When combined with Eat-lhorbiting assets available at that time, it seems solar cycle 24 will mark a great increase in our ability to understand and predict space weather.

Kaise,r Michael L.↗
NASA NTRS1992

Influence of mass moment of inertia on normal modes of preloaded solar array mast

Earth-orbiting spacecraft often contain solar arrays or antennas supported by a preloaded mast. Because of weight and cost considerations, the structures supporting the spacecraft appendages are extremely light and flexible; therefore, it is vital to investigate the influence of all physical and structural parameters that may influence the dynamic behavior of the overall structure. The study primarily focuses on the mast for the space station solar arrays, but the formulations and the techniques developed in this study apply to any large and flexible mast in zero gravity. Furthermore, to determine the influence on the circular frequencies, the mass moment of inertia of the mast was incorporated into the governing equation of motion for bending. A finite element technique (MSC/NASTRAN) was used to verify the formulation. Results indicate that when the mast is relatively flexible and long, the mass moment inertia influences the circular frequencies.

Armand, Sasan C.↗
DOE OSTI2024

Photosynthetic biohybrid systems for solar fuels catalysis

Photosynthetic reaction center (RC) proteins are finely tuned molecular systems optimized for solar energy conversion. RCs effectively capture and convert sunlight with near unity quantum efficiency utilizing light-induced directional electron transfer through a series of molecular cofactors embedded within the protein core to generate a long-lived charge separated state with a useable electrochemical potential. Of current interest are new strategies that couple RC chemistry to the direct synthesis of energy-rich compounds. This Feature Article highlights recent work from our lab on RC and RC-inspired hybrid systems that capture the Sun's energy and convert it to chemical energy in the form of H2, a carbon-neutral energy source derived from water. Further, biohybrids made from the Photosystem I (PSI) RC are among the best photocatalytic H2-producing protein hybrids to date. Targeted self-assembly strategies that couple abiotic catalysts to PSI translate to catalyst incorporation at intrinsic PSI sites within thylakoid membranes to achieve complete solar water-splitting systems. RC-inspired biohybrids interface synthetic photosensitizers and molecular catalysts with small proteins to create photocatalytic systems and enable the spectroscopic discernment of the structural features and electron transfer processes that underpin solar-driven proton reduction. In total, these studies showcase the incredible scientific opportunities photosynthetic biohybrid research provides for harnessing the optimal qualities of both artificial and natural photosynthetic systems and developing materials that capture, convert, and store solar energy as a fuel.

14 SOLAR ENERGY↗
NASA NTRS2005

MODEL CORRELATION STUDY OF A RETRACTABLE BOOM FOR A SOLAR SAIL SPACECRAFT

To realize design concepts, predict dynamic behavior and develop appropriate control strategies for high performance operation of a solar-sail spacecraft, we developed a simple analytical model that represents dynamic behavior of spacecraft with various sizes. Since motion of the vehicle is dominated by retractable booms that support the structure, our study concentrates on developing and validating a dynamic model of a long retractable boom. Extensive tests with various configurations were conducted for the 30 Meter, light-weight, retractable, lattice boom at NASA MSFC that is structurally and dynamically similar to those of a solar-sail spacecraft currently under construction. Experimental data were then compared with the corresponding response of the analytical model. Though mixed results were obtained, the analytical model emulates several key characteristics of the boom. The paper concludes with a detailed discussion of issues observed during the study.

Adetona, O.↗
NASA NTRS1991

NASA advanced aeronautics design solar powered remotely piloted vehicle

Environmental problems such as the depletion of the ozone layer and air pollution demand a change in traditional means of propulsion that is sensitive to the ecology. Solar powered propulsion is a favorable alternative that is both ecologically harmless as well as cost effective. Integration of solar energy into designs ranging from futuristic vehicles to heating is beneficial to society. The design and construction of a Multi-Purpose Remotely Piloted Vehicle (MPRPV) seeks to verify the feasibility of utilizing solar propulsion as a primary fuel source. This task has been a year long effort by a group of ten students, divided into five teams, each dealing with different aspects of the design. The aircraft was designed to take-off, climb to the design altitude, fly in a sustained figure-eight flight path, and cruise for approximately one hour. This mission requires flight at Reynolds numbers between 150,000 and 200,000 and demands special considerations in the aerodynamic design in order to achieve flight in this regime. Optimal performance requires a light weight configuration with both structural integrity and maximum power availability. The structure design and choice of solar cells for the propulsion was governed by the weight, efficiency, and cost considerations. The final design is a MPRPV weighting 35 N which cruises 7 m/s at the design altitude of 50 m. The configuration includes a wing composed of balsa and foam NACA 6409 airfoil sections and carbon fiber spars, a tail of similar construction, and a truss structure fuselage. The propulsion system consists of 98 10 percent efficient solar cells donated by Mobil Solar, a NiCad battery for energy storage, and a folding propeller regulated by a lightweight and efficient control system. The airfoils and propeller chosen for the design were research and tested during the design process.

Elario, David S.↗
NASA NTRS1979

Magnetohydrodynamic models of coronal transients in the meridional plane. II - Simulation of the coronal transient of 1973 August 21

A two-dimensional planar MHD model of solar atmospheric transient events is used to simulate the flare-associated events of August 21, 1973. This event, observed in H-alpha, He II 304 A, soft X-ray, and coronal white light, provided sufficient information (especially in the latter diagnostic) for an assessment to be made of the model's ability to simulate major features of an actual solar event. It was found that a thermodynamic input pulse based on data provided by the NASA Marshall Space Flight Center-Aerospace Corporation X-ray telescope (S-056) on Skylab was sufficient to produce the global geometry, shock and contact-surface velocities, excess mass contours, and energy budget which were, for the most part, observed by the High Altitude Observatory white-light coronagraph (S-052) on Skylab in the form of a forerunner and coronal transient.

Dryer, M.↗
DOE OSTI2024

Field-Effect Passivation by Desired Charge Injection into SiNx Passivation in Crystalline-Silicon Solar Cells

Effective surface passivation is a necessity for high efficiency crystalline silicon solar cells. The field effect passivation of p-type surfaces is typically accomplished using aluminum oxide (Al 2 O 3 ) which contains a high density of negative fixed charges. The accumulation layer formed by the negative charges prevents surface recombination loss of photo-generated carriers by repelling minority carriers (electrons) from the surface with interface state recombination centers. However, the Al 2 O 3 surface passivation technology has two key concerns of cost and safety associated with the precursor material tri-methyl-aluminum (TMA).

14 SOLAR ENERGY↗
NASA NTRS2021

Statistical Error Analysis on White-Light Filter Ratio Experiments to Measure Electron Parameters

The Filter ratio technique to remotely measure electron temperature and speed using four color filters in visible light and a polarization camera was described in detail in four articles by Reginald et al., Solar physics, (2018, 2019a, 2019b, 2020). In these four articles we quantified the systematic error associated with using models of symmetric corona to interpret results from asymmetric corona. We also showed the criteria applied to select the bandwidths of filters, and the pros and cons of replacing the traditional linear polarizer with a polarization camera to measure pB. What started in 1990s as ground experiments conducted during total solar eclipses that lasted for a few minutes lead to a balloon borne experiment lasting eight hours in 2019 and will blossom into a space experiment on the International Space Station in 2023. Due to constraints on the bandwidths of the four filters, a successful mission requires quantification of the statistical error using Monte Carlo simulation to generate two feasibility profiles, which are unique to the design parameters of the coronagraph, to comprehend the feasibility to measure temperature and speed within the desired temporal and spatial resolutions. For the statistical error analysis, we use modeled K and F corona profiles, representative theoretical diffraction, scattering, and vignetting profiles, assumed efficiencies for lenses, mirrors, and polarizers, assumed detector properties on quantum efficiency, full well depth, dark noise, and read noise, and assumed instrument properties on aperture diameter, solid angle, and pixel resolution. We hope future white-light coronagraphs will exhibit capabilities to measure electron density, temperature, and speed.

Nelson Reginald↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of near Sheomaker s NIS Global Dataaset at 433 Eros; Evaluation of Preparation and Measuring Techniques for Interplanetary Dust Particles for the MIDAS Experiment on Rosetta; Chiron: a Proposed Remote Sensing Prompt Gamma Ray Activation Analysis Instrument for a Nuclear Powered Prometheus Mission;From Present Surveying to Future Prospecting of the Asteroid Belt; Asteroid Physical Properties Probe Microgravity Testing of a Surface Sampling System for Sample Return from Small Solar System Bodies;and Penetrator Coring Apparatus for Cometary Surfaces.

Source record↗
NASA NTRS1979

Thermal design concept for a high resolution UV spectrometer

The thermal design concept described has been developed for the High Resolution UV Spectrometer/Polarimeter to be flown on the Solar Maximum Mission. Based on experience gained from a similar Orbiting Solar Observatory mission payload, it has been recognized that initial protection of the optical elements, contamination control, reduction of scattered light, tight bulk temperature, and gradient constraints are key elements that must be accommodated in any thermal control concept for this class of instrument. Salient features of the design include: (1) a telescope door providing contamination protection of an aplanatic Gregorian telescope; (2) a rastering system for the secondary mirror; (3) a unique solar heat absorbing device; (4) heat pipes and special radiators; (5) heaters for active temperature control and optics contamination protection; and (6) high precision platinum resistance thermometers. Viability of the design concept has been established by extensive thermal analysis and some subsystem testing. A summary of analytical and test results is included.

Caruso, P.↗