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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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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.
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.
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.
The objectives were to develop the flat-plate photovoltaic (PV) array technologies required for large-scale terrestrial use late in the 1980s and in the 1990s; advance crystalline silicon PV technologies; develop the technologies required to convert thin-film PV research results into viable module and array technology; and to stimulate transfer of knowledge of advanced PV materials, solar cells, modules, and arrays to the PV community. Progress reached on attaining these goals, along with future recommendations are discussed.
The OSIRIS-REx spacecraft returned regolith from asteroid Bennu to Earth September 24, 2023 [1]. As part of initial science allocations and sample analysis plan [2], JSC science team members received aggregate material from within the TAGSAM head (OREX-803017-0) to characterize. Here we report the results of analyses that have been carried out to determine mineralogic composition, surface features, and overall lithologic diversity in Bennu particles. These initial observations will inform additional analyses that will address the nature of pre-biotic and pre-solar material, formation location of Bennu, geologic history of the asteroid, and its impact/collisional/re-accretion history [3].
Radiation damage effects on power efficiency of solar cell composite assemblies
Recent results in the development of high-efficiency, low-bandgap GaInAsP solar cells epitaxially grown and lattice matched on InP substrates are presented. Such cells are intended to be used as optimum bottom cell components in tandem solar cells. Assuming that a GaAs-based top cell is used, computer simulation of the potential bottom cell performance as a function of the cell bandgap and incident spectrum indicates that two particular alloys are desirable: Ga0.47In0.53As (Eg = 0.75 eV) for space applications and Ga0.25In0.75As0.54P0.46 (Eg = 0.95 eV) for terrestrial applications. In each of these materials, solar cells with new record-level efficiencies have been fabricated. The efficiency boost available to tandem configurations from these low-bandgap cells is discussed.
An acid-resistant residue prepared from Greenland cryoconite has been investigated to determine whether the micrometeorite component within the cryoconite contains pre-solar material analogous to that found in primitive chondritic meteorites. The residue has been analyzed for carbon content and stable isotopic comparison, by electron probe micro-analysis (EPMA) for major element chemistry and then by a combination of X-ray diffraction (XRD) and transmission electron microscopy (TEM) to elucidate the structure of any constituent mineral phases. The cryoconite sample, which was collected ca. 25 km inland of the ice margin at the latitude of Sondre Stromfjord on the west coast of Greenland, was processed following procedures used on bulk meteorite samples for the isolation of pre-solar dust components.
GaAlAs/GaAs heteroface solar cells used in space offer advantages of higher operating temperatures and recovery from radiation damage using thermal annealing. Elevated temperature experiments were conducted to evaluate the electrical stability of cells with different contact materials. These experiments indicate that for operation of GaAs heteroface solar cells at elevated temperatures, front contact metals must be carefully chosen. The short circuit current varied by only about 3% for cells with Pd/Ag contacts that were heated to 240 C for a total of 500 hours. However, a total decrease in the open circuit voltage of about 20% was observed for these cells. After heating cells to 400 C, large changes in open circuit voltage were observed for cells with Pd/Ag, Pd/Au, Pd, Ag, and Ti contacts; however, preliminary results indicate more stable open circuit voltages for cells with Au, Cr, Zn, and Cr/Au contacts.
Coronal jets are transient thin bursts of magnetically channeled solar material from the surface into the corona. They are brightest at their base, with a bright point (jet bright point, JBP) at an edge of the base. Early studies (Shibata et al. 1992) suggested that jets result from magnetic flux emergence: a small bipole emerges into unipolar ambient field, driving the jet and forming the JBP via interchange reconnection. More recent studies, using higher-cadence, higher-resolution, and broader wavelength coverage than before, show that prominent coronal jets are usually driven by a minifialment eruption (Sterling et al. 2015), and that, rather than flux emergence, flux cancelation usually prepares and triggers the eruption (Panesar et al. 2016). Here, we analyzed eight emerging flux regions to determine whether the emerging flux directly drove any coronal jets. We used EUV images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) (in 304, 171, 211, 193, and 94 Å channels), and magnetograms from SDO/Helioseismic & Magnetic Imager (HMI). All eight regions produced jet-like features that were weak in intensity (“faint jets’’), by which we mean they were so faint that we likely would not have identified them as jets had we initially searched for jets in AIA movies alone (as in, e.g., Panesar et al. 2016, Moore et al. 2013) without knowing whether the base was an emerging bipole. In seven of the eight regions, all jets (faint or prominent) erupted from locations where one leg of the emerging bipole was evidently canceling with an ambient opposite-polarity flux clump. The eighth case, the one that had the fastest flux emergence, possibly made faint jets by the flux-emergence mechanism, but these too might instead have resulted from flux cancelation.
Understanding semiconductor surface properties and manipulating them chemically are critical for improving their performance in optoelectronic devices. Hybrid halide perovskites have emerged as an exciting class of highly efficient solar materials; however, their device performance could be limited by undesirable surface properties that impede carrier transport and induce recombination. Here we show that surface functionalization of methylammonium lead iodide (MAPbI 3 ) perovskite with phenethylammonium iodide (PEAI), a commonly employed spacer cation in two-dimensional perovskites, can enhance carrier diffusion in the near-surface regions and reduce defect density by more than one order of magnitude. Using transient transmission and reflection microscopy, we selectively imaged the transport of the carriers near the (001) surface and the bulk carriers in single-crystal MAPbI 3 microplates. The surface functionalization increases the diffusion coefficient of the carriers in a 40-nm subsurface region from ~ 0.6 cm 2 s -1 to ~ 1 cm 2 s -1 , similar to the value for bulk carriers. These results suggest the PEA ligands are effective in suppressing surface defect and phonon scattering and shed light on the mechanisms for enhancing photophysical properties and improving solar cell efficiency.
Materials optimization for organic solar cells (OSCs) is a highly active field, with many approaches using empirical experimental synthesis, computational brute force to screen a subset of chemical space, or generative machine learning methods that often require significant training sets. While these methods may find high-performing materials, they can be inefficient and time-consuming. Genetic algorithms (GAs) are an alternative approach, allowing for the “virtual synthesis” of molecules and a prediction of their “fitness” for some property, with new candidates suggested based on good characteristics of previously generated molecules. In this work, a GA is used to discover high-performing unfused non-fullerene acceptors (NFAs) based on an empirical prediction of power conversion efficiency (PCE) and provides design rules for future work. The electron-withdrawing/donating strength, as well as the sequence and symmetry, of those units are examined. The utilization of a GA over a brute-force approach resulted in speedups up to 1.8 × 10 12 . New types of units, not frequently seen in OSCs, are suggested, and in total 5426 NFAs are discovered with the GA. Of these, 1087 NFAs are predicted to have a PCE greater than 18%, which is roughly the current record efficiency. While the symmetry of the sequence showed no correlation with PCE, analysis of the sequence arrangement revealed that higher performance can be achieved with a donor core and acceptor end groups. Future NFA designs should consider this strategy as an alternative to the current A-D-A'-D-A architecture.
The dendritic web process is a technique for growing thin silicon ribbon from liquid silicon. The material is suitable for solar cell fabrication and, in fact, cells fabricated on web material are equivalent in performance to cells fabricated on Czochralski-grown material. A recently concluded study has delineated the thermal requirements for silicon web crucibles, and a detailed conceptual design has been developed for a laboratory growth apparatus.
Lunar geology evidence is examined for clues to the origin and evolution of the moon and earth. Seven evolutionary episodes, the last covering three billion years to the present day, are constructed for the moon. Parallel episodes in the earth's evolution are masked by the dynamic continuing evolution of the earth over a 4.5 billion year span, in contrast to the moon's quiescence and inability to retain fluids. Comparisons are drawn between the geochemistry and tectonics of the lunar basaltic maria and the earth's ocean basins. Lunar maria rocks differ strikingly in chemical composition from meteoritic matter and solar material. Inundation of frontside lunar maria basins by vast oceans of dark basalt mark the last of the major internally generated evolutionary episodes, and is attributed to consequences of meltdown of the lunar mantle and crust by radioisotope decay from below. Data are drawn primarily from Apollo missions 11-17, supplemented by other sources.
The electrostatically controlled membrane mirror (ECMM) is a way to achieve large, very light reflectors for radar, radio astronomy, radiometry, and optical devices. The concept is that of using electrostatic forces to tension a thin conducting membrane and to maintain it in a precision antenna shape. The ECMM is an adaptive structure which maintains surface quality despite errors in construction, irregularities of materials, solar heating, and onboard disturbances. The combination of high gain and low mass makes the ECMM ideally suited for space applications.
The concept of using electrostatic forces to tension a thin, conducting membrane and maintain it in a precision antenna shape is discussed. This electrostatically controlled membrane mirror is an adpative structure which maintains surface quality despite errors in construction, irregularities of materials, solar heating, and on board disturbances.
A survey of Brazilian meteorites is presented, along with basic premises of meteoritics, including classification, naming, and analytic procedures. Meteorites are noted to be of interest as representative samples of ancient rocks, perhaps half as old as the universe, as sometimes originating from outside the solar system, containing early solar material, and containing evidence of cosmic ray interactions or collisions. The characteristics which make up the achondrite and chondrite group are reviewed, and a listing of the primary characteristics of known Brazilian meteorites is provided.
The relative charge abundance of galactic cosmic-ray nuclei is measured between 600 and 1000 MeV per nucleon over a range of Z from 2 to 28. The abundances observed at earth are extrapolated to the cosmic-ray source, yielding accurate source abundances for 15 elements. These abundances, together with recently measured isotopic abundance ratios, are compared with the average abundances observed in another sample of accelerated material - solar cosmic rays. Appreciable differences are found in the composition for the elements He, C, N, and Ne. The galactic and solar cosmic-ray abundances are also compared with a variety of compilations of unaccelerated matter.