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Inexpensive, conventional solar-cell module uses focusing principle of electric lamp in reverse to produce electric power from sunlight. Standard outdoor light enclosure provides low-cost housing which concentrates sunlight in solar cell. Unit is capable of producing approximately 1 watt of electric power.
The electrostatic charging of the Space Shuttle Orbiter during the operation of the Solar Array Module Plasma Interaction Experiment (SAMPIE) was modeled using the NASA Charging Analyzer Program/ low Earth orbit (NASCAP/LEO) computer code. The SAMPIE experiment consists of an array of various solar cells representing the present technologies. The objectives of the experiment are to investigate the arcing and current collection characteristics of these cells when biased to high potentials in a LEO plasma. NASCAP/LEO is a 3-D code designed to simulate the electrostatic charging of a spacecraft exposed to a plasma at LEO or ground test conditions. At its most extreme configuration, with the largest array segment of the SAMPIE experiment biased + 600 V with respect to the orbiter and facing the ram direction, the computer simulations predict that the orbiter's potential will be approximately -20 V with respect to the plasma.
Liquid diffusion masks and liquid applied dopants to replace the CVD Silox masking and gaseous diffusion operations specified for forming junctions in the Westinghouse baseline process sequence for producing solar cells from dendritic web silicon were investigated. The baseline diffusion masking and drive processes were compared with those involving direct liquid applications to the dendritic web silicon strips. Attempts were made to control the number of variables by subjecting dendritic web strips cut from a single web crystal to both types of operations. Data generated reinforced earlier conclusions that efficiency levels at least as high as those achieved with the baseline back junction formation process can be achieved using liquid diffusion masks and liquid dopants. The deliveries of dendritic web sheet material and solar cells specified by the current contract were made as scheduled.
Data obtained from the fourteen solar cell modules on the NTS-2 satellite are presented together with a record of panel temperature and sun inclination. The following flight data are discussed: (1) state of the art solar cell configurations which embody improvements in solar cell efficiency through new silicon surface and bulk technology, (2) improved coverslip materials and coverslip bonding techniques, (3) short and long term effects of ultraviolet rejection filters vs. no filters on the cells, (4) degradation on a developmental type of liquid epitaxy gallium-aluminum-arsenide solar cell, and (5) space radiation effects.
Liquid diffusion masks and liquid dopants to replace the more expensive CVD SiO2 mask and gaseous diffusion processes were investigated. Silicon pellets were prepared in the silicon shot tower; and solar cells were fabricated using web grown where the pellets were used as a replenishment material. Verification runs were made using the boron dopant and liquid diffusion mask materials. The average of cells produced in these runs was 13%. The relationship of sheet resistivity, temperature, gas flows, and gas composition for the diffusion of the P-8 liquid phosphorus solution was investigated. Solar cells processed from web grown from Si shot material were evaluated, and results qualified the use of the material produced in the shot tower for web furnace feed stock.
The 154d periodicity was found in the cosmic ray intensity (RE) vs Flares, and some other peaks of coherency in the RC vs aa sub I, that when interpreted as aliased values, might correspond to recurring interplanetary magnetic field structures and solar wind streams. It cannot be excluded, however, that some of the correspondence with aa are of terrestrial origin. This study cannot be considered exhaustive due to the fact that other solar variables, such as polar hole size, are possibly correlated to cosmic ray intensities. However, the number of observations is small so that the interpretation of the results is very difficult.
The Interstellar Boundary Explorer (IBEX) has revealed the existence of the energetic neutral atom (ENA) ribbon, a narrow and nearly circular band of enhanced flux that enables probing plasma and magnetic field conditions outside the heliopause (HP). In this study, we investigate the global structure and temporal variation of the IBEX ribbon using 14 yr of IBEX-Hi ENA observations. We derive geometric parameters of the ribbon: center location, angular radius, eccentricity, and major axis orientation. We find that the ribbon exhibits systematic variations tied to the solar cycle. The ribbon center shows a solar cycle–modulated latitudinal motion at low energies. The angular radius increases with ENA energy and displays a pronounced enlargement between 2013 and 2018, coinciding with changes in high-latitude fast solar wind from polar coronal holes. The eccentricity remains consistently around 0.3 with some temporal evolution, while the major axis rotates gradually over time, becoming increasingly perpendicular to the ecliptic meridional plane. A notable hemispheric asymmetry has emerged over time: the ribbon in the northern hemisphere remains remarkably stable in position, whereas the southern ribbon exhibits temporal migration. By combining these results with solar wind observations, global heliosphere, and ribbon modeling, we suggest that this asymmetry is explained by a coupled effect of magnetic field draping and the latitude-dependent timing of fast solar wind from polar coronal holes. These results establish the most detailed long-term geometric characterization of the IBEX ribbon to date and provide observational support for models of secondary ENA production and magnetic field draping outside the HP.
Changes in solar radius and luminosity are discussed as a function of age. Surface and satellite observations showing departures from mean solar irradiance on a time scale of a few days are summarized. The most prominent depressions in these data appear to be correlated with sunspot number, indicating that the activity modulation of solar luminosity may be larger than expected. High activity is correlated with low luminosity, but during the Maunder minimum the mini ice age (presumably low luminosity) was accompanied by a near absence of solar activity. Pulsations driven by sources deep within the Sun are thought to be an unlikely cause of luminosity changes, but causes may be sought in the unstable convective zone. Experiments designed to measure the solar radius are mentioned, along with modelling efforts.
Hipot (high voltage potential) and module frame continuity tests of solar energy conversion modules intended for deployment into large arrays are discussed. The purpose of the tests is to reveal potentially hazardous voltage conditions in installed modules, and leakage currents that may result in loss of power or cause ground fault system problems, i.e., current leakage potential and leakage voltage distribution. The tests show a combined failure rate of 36% (69% when environmental testing is included). These failure rates are believed easily corrected by greater care in fabrication.
The orientation effects of six Space Station Freedom Electrical Power System (EPS) components are evaluated for three environmental interactions: aerodynamic drag, atomic oxygen erosion, and orbital debris impact. Designers can directly apply these orientation factors to estimate the magnitude of the examined environment and the environmental effects for the EPS component of interest. The six EPS components are the solar array, photovoltaic module radiator, integrated equipment assembly, solar dynamic concentrator, solar dynamic radiator, and beta gimbal.
Whether the Sun has significantly influenced the climate during the last century has been under extensive debates for almost two decades. Since the solar irradiance varies very little in a solar cycle, it is puzzling that some geophysical parameters show proportionally large variations which appear to be responding to the solar cycles. For example, variation in low altitude clouds is shown correlated with solar cycle, and the onset of Forbush decrease is shown correlated with the reduction of the vorticity area index. A possible sun-climate connection is that galactic cosmic rays modulated by solar activities influence cloud formation. In this paper, we apply wavelet transform to satellite and surface data to examine this hypothesis. Data analyzed include the time series for solar irradiance, sunspots, UV index, temperature, cloud coverage, and neutron counter measurements. The interactions among the elements in the Earth System under the external and internal forcings give out very complex signals.The periodicity of the forcings or signals could range widely. Since wavelet transforms can analyze multi-scale phenomena that are both localized in frequency and time, it is a very useful technique for detecting, understanding and monitoring climate changes.
Concepts for integral glass sheet encapsulation of terrestrial solar cell modules using techniques based upon electrostatic bonding are being developed. It is possible for the glass to provide hermetic encapsulation, the structural support, and a vehicle for integral interconnection of the solar cells. Anticipated capabilities, present status, and cost projections for large scale terrestrial utilization are discussed.
The solar cell module process development activities in the areas of surface preparation are presented. The process step development was carried out on texture etching including the evolution of a conceptual process model for the texturing process; plasma etching; and diffusion studies that focused on doped polymer diffusion sources. Cell processing was carried out to test process steps and a simplified diode solar cell process was developed. Cell processing was also run to fabricate square cells to populate sample minimodules. Module fabrication featured the demonstration of a porcelainized steel glass structure that should exceed the 20 year life goal of the low cost silicon array program. High efficiency cell development was carried out in the development of the tandem junction cell and a modification of the TJC called the front surface field cell. Cell efficiencies in excess of 16 percent at AM1 have been attained with only modest fill factors. The transistor-like model was proposed that fits the cell performance and provides a guideline for future improvements in cell performance.
Electric power generation for the Space Station Freedom will be provided by four photovoltaic (PV) power modules using silicon solar cells during phase I operation. Each PV power module requires two solar arrays with 32,800 solar cells generating 18.75 kW of dc power for a total of 75 kW. A portion of this power will be stored in nickel-hydrogen batteries for use during eclipse, and the balance will be processed and converted to 20 kHz ac power for distribution to end users through the power management and distribution system. The design incorporates an optimized thermal control system, pointing and tracking provision with the application of gimbals, and the use of orbital replacement units to achieve modularization. The design status of the PV power module, as derived from major trade studies, is discussed at hardware levels ranging from component to system. Details of the design are presented where appropriate.
Electric power generation for Space Station Freedom will be provided by four photovoltaic (PV) power modules using silicon solar cells during Phase 1 operation. Each PV power module requires two solar arrays with 32,800 solar cells generating 18.75 kW of dc power for a total of 75 kW. A portion of this power will be stored in nickel-hydrogen batteries for use during eclipse, and the balance will be processed and converted to 20 kHz ac power for distribution to end users through the power management and distribution system. The design incorporates an optimized thermal control system, pointing and tracking provision with the application of gimbals, and the use of orbital replacement units (ORU's) to achieve modularization. Design status of the PV power module, as derived from major trade studies, is discussed at hardware levels ranging from component to system. Details of the design are presented where appropriate.
Thermal cycling tests of bent solar cell interconnection tabs on OAO module
The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 yr of operation by the Pierre Auger Observatory surface detectors in Malargüe, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability.
The Advanced Composite Solar Sail System (ACS3) will be the first practical solar sail for the National Aeronautics and Space Administration. [1] ACS3 will also be the first spaceflight demonstration of NASA compact deployable composite boom technology.[2] The primary mission objective of ACS3 will be to deploy and characterize an 80-m2 composite boom structure solar sail technology in low Earth orbit. Extended mission goals will be to demonstrate controlled solar sailing flight via a series of orbit raising and lowering maneuvers. Target mission orbit is a 1000 km x 1000 km midnight-noon sun-synchronous orbit. Launch of ACS3 is scheduled for July 2023 with sail deployment in September 2023. Mission duration is expected to be six to nine months. The ACS3 solar sail vehicle is a 12U Cubesat consisting of a bus module, containing flight and solar sail control avionics, and a solar sail module, containing the composite booms and metallized polymer solar sail membranes of the solar sail structure stowed within a boom deployer mechanism. A four-camera instrument suite for 360-degree imaging of the ACS3 solar sail during and after deployment is also housed within the bus module. The ACS3 80-m2 solar sail design is a sub-scale version of an intermediate-size 500-m2 solar sail using NASA deployable composite boom technology. The sail consists of four metallized 2-m thick polyethylene naphthalate (PEN) 20-m2 triangular quadrants supported by four 7-m long lenticular cross-section composite booms. Booms are flattened and co-coiled for stowage within a tape-spool driven deployer mechanism. Total mass of the ACS3 space vehicle including solar sail is 16 kg. An overview of the ACS3 mission and mission systems will be provided in this presentation. This overview will include descriptions of the solar sail structures and materials technology used with ACS3, and discussion of the scalability and extensibility of the ACS3 solar sail to future larger-scale solar sailing mission requirements. An update on progress towards the launch of ACS3 in July 2023 will also be provided. References [1] https://www.nasa.gov/directorates/spacetech/small_spacecraft/ACS3 [2] https://www.nasa.gov/directorates/spacetech/game_changing_development/projects/dcb