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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Perspective on the local interstellar medium

Theoretical local-interstellar-medium (LISM) models designed to explain the observed soft-X-ray background (SXRB) are reviewed. Consideration is given to the LISM in the immediate solar vicinity (the Local Fluff, extending 3-10 pc), the local bubble (a large irregularly shaped cavity filled with very-low-density gas at 10 to the 6th K and surrounded by denser material), the three-dimensional structure of the SXRB emitting region, the thermal nature of the SXRB, and the implications of process time scales for LISM theories. A number of possible mechanisms are discussed in the context of a model in which the LISM hot gas is a remnant from the creation of the local bubble about 20 Myr ago and/or the product of supernova reheating as recently as 150 kyr ago.

Cox, D. P.↗
NASA NTRS2019

Taking Climate Model Evaluation to the Next Level

Earth system models are complex and represent a large number of processes, resulting in a persistent spread across climate projections for a given future scenario. Owing to different model performances against observations and the lack of independence among models, there is now evidence that giving equal weight to each available model projection is suboptimal. This Perspective discusses newly developed tools that facilitate a more rapid and comprehensive evaluation of model simulations with observations, process-based emergent constraints that are a promising way to focus evaluation on the observations most relevant to climate projections, and advanced methods for model weighting. These approaches are needed to distil the most credible information on regional climate changes, impacts, and risks for stakeholders and policy-makers.

Eyring, Veronika↗
NASA NTRS2012

Next Generation Life Support Project Status

Next Generation Life Support (NGLS) is one of several technology development projects sponsored by NASA s Game Changing Development Program. The NGLS Project is developing life support technologies (including water recovery and space suit life support technologies) needed for humans to live and work productively in space. NGLS has three project tasks: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, and Alternative Water Processor (AWP). The RCA swing bed and VOR tasks are directed at key technology needs for the Portable Life Support System (PLSS) for an Advanced Extravehicular Mobility Unit, with focus on test article development and integrated testing in an Advanced PLSS in cooperation with the Advanced Extra Vehicular Activity (EVA) Project. An RCA swing-bed provides integrated carbon dioxide removal and humidity control that can be regenerated in real time during an EVA. The VOR technology will significantly increase the number of pressure settings available to the space suit. Current space suit pressure regulators are limited to only two settings whereas the adjustability of the advanced regulator will be nearly continuous. The AWP effort, based on natural biological processes and membrane-based secondary treatment, will result in the development of a system capable of recycling wastewater from sources expected in future exploration missions, including hygiene and laundry water. This paper will provide a status of technology development activities and future plans.

Barta, Daniel J.↗
DOE OSTI2022

Mortality among Tennessee Eastman Corporation (TEC) uranium processing workers, 1943–2019

Background: There are few occupational studies of women exposed to ionizing radiation. During World War II, the Tennessee Eastman Corporation (TEC) operated an electromagnetic field separation facility of 1152 calutrons to obtain enriched uranium (235U) used for the Hiroshima atomic bomb. Thousands of women were involved in these operations. Materials and methods: We report a new study was conducted of 13,951 women and 12,699 men employed at TEC between 1943 and 1947 for at least 90 days. Comprehensive dose reconstruction techniques were used to estimate lung doses from the inhalation of uranium dust based on airborne measurements. Vital status through 2018/2019 was obtained from the National Death Index, Social Security Death Index, Tennessee death records and online public record databases. Analyses included standardized mortality ratios (SMRs) and Cox proportional hazards models. Results: Most workers were hourly (77.7%), white (95.6%), born before 1920 (58.3%), worked in dusty environments (57.0%), and had died (94.9%). Vital status was confirmed for 97.4% of the workers. Women were younger than men when first employed: mean ages 25.0 years and 33.0 years, respectively. The estimated mean absorbed dose to the lung was 32.7 mGy (max 1048 mGy) for women and 18.9 mGy (max 501 mGy) for men. The mean dose to thoracic lymph nodes (TLNs) was 127 mGy. Statistically significant SMRs were observed for lung cancer (SMR 1.25; 95% CI 1.19, 1.31; n = 1654), nonmalignant respiratory diseases (NMRDs) (1.23; 95% CI 1.19, 1.28; n = 2585), and cerebrovascular disease (CeVD) (1.13; 95% CI 1.08, 1.18; n = 1945). For lung cancer, the excess relative rate (ERR) at 100 mGy (95% CI) was 0.01 (–0.10, 0.12; n = 652) among women, and –0.15 (–0.38, 0.07; n = 1002) among men based on a preferred model for men with lung doses <300 mGy. NMRD and non-Hodgkin lymphoma were not associated with estimated absorbed dose to the lung or TLN. Conclusions: There was little evidence that radiation increased the risk of lung cancer, suggesting that inhalation of uranium dust and the associated high-LET alpha particle exposure to lung tissue experienced over a few years is less effective in causing lung cancer than other types of exposures. There was no statistically significant difference in the lung cancer risk estimates between men and women. The elevation of certain causes of death such as CeVD is unexplained and will require additional scrutiny of workplace or lifestyle factors given that radiation is an unlikely contributor since only the lung and lymph nodes received appreciable dose.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS1974

Thermal preparation of foods in space-vehicle environments

Convection is the primary heat transfer mechanism for most foods heated in an earth-based environment. In contrast, in the low-gravity environment of space flight, the primary heat transfer mechanism is conduction (or radiation in the absence of a conducting medium). Conduction heating is significantly slower and less efficient than convection heating. This fact poses a problem for food heating during space flight. A numerical model has been developed to evaluate this problem. This model simulates the food-heating process for Skylab. The model includes the effect of a thermally controlled on/off heat flux. Parametric studies using this model establish how the required heating time is affected by: the thermal diffusivity of the nutrient materials, the power level of the heater, the initial food temperatures, and the food container dimensions.

Bannerot, R. B.↗
DOE OSTI2022

Technoeconomic Analysis of High-Value, Crystalline Silicon Photovoltaic Module Recycling Processes

Recycling is an important circular economy strategy, and for photovoltaics (PV), the one that has received the greatest research attention. Recycling of PV modules is required in Europe; everywhere else it competes in the market of end-of-life options, where cost is a primary decision factor. The vast majority of PV modules sold globally are crystalline-silicon (c-Si); most of the rest of the market are cadmium telluride thin film modules whose primary manufacturer runs its own commercial-scale recycling program. While many different c-Si recycling approaches and technologies have been proposed, they generally lack accompanying cost estimates or enough process information to model costs. Herein we develop detailed estimates of seven categories of capital and operating costs along with estimates of revenue from recovered materials for each step in two proposed recycling processes for c-Si PV modules. Using these results, we develop a hypothetical third recycling process merging process steps from the original two, estimate surcharges required to achieve minimum sustainable prices for each recycling process, as well as consider how economies of scale could reduce costs. Increasing the purity of and identifying higher-value markets for recovered materials are approaches to reducing costs and increasing recycling rates in voluntary markets.

crystalline silicon↗
DOE OSTI2025

The Two Arctic Wintertime Boundary Layer States: Disentangling the Role of Cloud and Wind Regimes in Reanalysis and Observations During MOSAiC

The wintertime central Arctic atmosphere comprises a radiatively clear and a radiatively opaque state, which are linked to synoptic forcing and mixed-phase clouds. Weather and climate models often lack process representations surrounding these states, but prior work mostly treated the problem as an aggregate of synoptic conditions, resulting in partially overlapping biases. Here, we disaggregate the Arctic states and confront ERA5 reanalysis with observations from the MOSAiC campaign over the central Arctic sea ice during winter 2019/2020. Low-level winds and liquid water path (LWP) are combined to derive different synoptic classes. Results show that the clear state is primarily formed by weak/moderate winds and the absence of liquid-bearing clouds, while strong winds and enhanced LWP primarily form the radiatively opaque state. ERA5 struggles to reproduce these basic statistics, shows too weak sensitivity of thermal radiation to synoptic forcing, and overestimates thermal radiation for similar LWP amounts. The latter is caused by a warm bias, which has a pronounced inversion structure and is largest in clear and calm conditions. Under strong synoptic forcing, the warm bias is constant with height and discrepancies in mixed-phase cloud altitude appear. Separating synoptic conditions is regarded as useful for process-oriented evaluation of the Arctic troposphere in models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Nuclear level density and γ -ray strength function of Ni 67 and the impact on the i process

Proton- γ coincidences from ( d , p ) reactions between a Ni 66 beam and a deuterated polyethylene target have been analyzed with the inverse-Oslo method to find the nuclear level density (NLD) and γ -ray strength function ( γ SF ) of Ni 67 . The Ni 66 ( n , γ ) capture cross section has been calculated using the Hauser-Feshbach model in using the measured NLD and γ SF as constraints. The results confirm that the Ni 66 ( n , γ ) reaction acts as a bottleneck when relying on one-zone nucleosynthesis calculations. However, the impact of this reaction is strongly dampened in multizone models of low-metallicity AGB stars experiencing i -process nucleosynthesis. Published by the American Physical Society 2025

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2002

A Closed-Loop Hardware Simulation of Decentralized Satellite Formation Control

In recent years, there has been significant interest in the use of formation flying spacecraft for a variety of earth and space science missions. Formation flying may provide smaller and cheaper satellites that, working together, have more capability than larger and more expensive satellites. Several decentralized architectures have been proposed for autonomous establishment and maintenance of satellite formations. In such architectures, each satellite cooperatively maintains the shape of the formation without a central supervisor, and processing only local measurement information. The Global Positioning System (GPS) sensors are ideally suited to provide such local position and velocity measurements to the individual satellites. An investigation of the feasibility of a decentralized approach to satellite formation flying was originally presented by Carpenter. He extended a decentralized linear-quadratic-Gaussian (LQG) framework proposed by Speyer in a fashion similar to an extended Kalman filter (EKE) which processed GPS position fix solutions. The new decentralized LQG architecture was demonstrated in a numerical simulation for a realistic scenario that is similar to missions that have been proposed by NASA and the U.S. Air Force. Another decentralized architecture was proposed by Park et al. using carrier differential-phase GPS (CDGPS). Recently, Busse et al demonstrated the decentralized CDGPS architecture in a hardware-in-the-loop simulation on the Formation Flying TestBed (FFTB) at Goddard Space Flight Center (GSFC), which features two Spirent Cox 16 channel GPS signal generator. Although representing a step forward by utilizing GPS signal simulators for a spacecraft formation flying simulation, only an open-loop performance, in which no maneuvers were executed based on the real-time state estimates, was considered. In this research, hardware experimentation has been extended to include closed-loop integrated guidance and navigation of multiple spacecraft formations using GPS receivers and real-time vehicle telemetry. A hardware closed-loop simulation has been performed using the decentralized LQG architecture proposed by Carpenter in the GPS test facility at the Center for Space Research (CSR). This is the first presentation using this type of hardware for demonstration of closed-loop spacecraft formation flying.

Ebimuma, Takuji↗
NASA NTRS1977

Integration of land-use data and soil survey data

Approaches are discussed for increasing the utility of remotely sensed interpretations through the use of a computer-assisted process which provides capabilities for merging several types of data of varying formats. The resulting maps and summary data are used for planning and zoning in a rapidly developing area (34,000 ha) adjacent to the Black Hills in South Dakota. Attention is given to the data source, data digitization, and aspects of data handling and analysis.

Cox, T. L.↗
NASA NTRS1999

The Role of Calcium in the Response of Osteoblasts to Mechanical Stimulation

A major biomedical concern in the exploration and development of space is the rapid loss of bone associated with extended periods of spaceflight. Mineral content, bone formation, matrix protein production and total body calcium are all reduced during long-term periods of weightlessness. These effects of weightlessness appears to be due to decreases in the anabolic function of osteoblasts and osteocytes rather than changes in the resorptive activity of osteoclasts. Conversely, subjecting the skeleton to exogenous mechanical loading increases matrix protein synthesis and bone formation rate, a process which also appears mediated through osteogenic cells. Osteoblasts have been shown to respond to a number of types of mechanical stimulation. However recently we have demonstrated that osteoblasts respond to fluid shear, but not physiologic levels of mechanical strain, with increases in expression of the matrix protein, osteopontin. We have also shown similar responses in other markers for the anabolic response in bone. The expression of the early response gene, c-fos, and the inducible-isoform of the prostaglandin synthetic enzyme, cyclooygenase-2 (COX-2), both increase rapidly in response to fluid shear, but not strain. How osteoblasts and osteocytes perceive mechanical stimuli and convert this stimulus into a biochemical event within the cell is still unknown. However, examination of the cellular events following mechanical stimulation indicate that two of the earliest responses are a rapid increase in intracellular calcium ([Ca(2+)](sub i)) and a reorganization of the actin cytoskeleton. The increase in [Ca(2+)](sub i) is dependent on the presence of extracellular Ca(2+), suggesting the activation of membrane Ca(2+) channel. We have previously characterized a mechanosensitive, cation-selective channel (MSCC) in osteoblast-like clonal cells, which we postulate is important in this early response to mechanical loading. Using an antisense oligodeoxynucleotide strategy, we have tentatively identified this channel as an isoform of the alc subunit of the dihydropyridine-sensitive, voltage sensitive Ca(2+) channel (VSCC). However, a major component in this mechanically induced rise in [Ca(2+)](sub i) is the release of Ca(2+) from intracellular stores. The actin cytoskeleton also rapidly responds to fluid shear with an increase in stress fiber formation and a realignment of the cell parallel to the direction of flow. To ascertain whether these two observations are related and how they effect shear-induced gene expression, we examined the role of Ca(2+) channels and intracellular Ca(2+) release on cytoskeletal reorganization and the resultant increases in the expression and production of c-fos and COX-2 in response to fluid shear.

Duncan, R. L.↗
NASA NTRS1994

Improved solution accuracy for TDRSS-based TOPEX/Poseidon orbit determination

Orbit determination results are obtained by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) using a batch-least-squares estimator available in the Goddard Trajectory Determination System (GTDS) and an extended Kalman filter estimation system to process Tracking and Data Relay Satellite (TDRS) System (TDRSS) measurements. GTDS is the operational orbit determination system used by the FDD in support of the Ocean Topography Experiment (TOPEX)/Poseidon spacecraft navigation and health and safety operations. The extended Kalman filter was implemented in an orbit determination analysis prototype system, closely related to the Real-Time Orbit Determination System/Enhanced (RTOD/E) system. In addition, the Precision Orbit Determination (POD) team within the GSFC Space Geodesy Branch generated an independent set of high-accuracy trajectories to support the TOPEX/Poseidon scientific data. These latter solutions use the geodynamics (GEODYN) orbit determination system with laser ranging and Doppler Orbitography and Radiopositioning integrated by satellite (DORIS) tracking measurements. The TOPEX/Poseidon trajectories were estimated for November 7 through November 11, 1992, the timeframe under study. Independent assessments were made of the consistencies of solutions produced by the batch and sequential methods. The batch-least-squares solutions were assessed based on the solution residuals, while the sequential solutions were assessed based on primarily the estimated covariances. The batch-least-squares and sequential orbit solutions were compared with the definitive POD orbit solutions. The solution differences were generally less than 2 meters for the batch-least-squares and less than 13 meters for the sequential estimation solutions. After the sequential estimation solutions were processed with a smoother algorithm, position differences with POD orbit solutions of less than 7 meters were obtained. The differences among the POD, GTDS, and filter/smoother solutions can be traced to differences in modeling and tracking data types, which are being analyzed in detail.

Doll, C. E.↗
NASA NTRS2003

Time-Variable Gravity Signal due to Extratropic Pacific Water Mass Redistribution

Using the satellite-laser-ranging (SLR) data, Cox and Chao [2002] reported the detection of a large post-1998 anomaly (in the form of a positive jump) in the time series of Earth s lowest-degree gravity harmonic 52, or the dynamic oblateness. Among several groups now examining the mass redistribution in the global geophysical fluids in search of the cause(s), we report here a temporally coinciding anomalies found in the extratropic north + south Pacific basins. Clearly seen in the leading EOFPC mode for extratropic Pacific, these anomalies occurred in sea-surface height, sea-surface temperature, and temperature- and salinity-depth profiles. We based our analysis on two different data sources: TOPEX/Poseidon altimetry, and the ECCO ocean general circulation model output assimilating T/P data. The magnitude of these changes, when converted to equivalent J2 change, appears to be a few times too small to explain the observed J2 directly. These findings, and the fact that the anomalies occurred following the strong 1997-98 El Nino, suggest strong geophysical connection of the interannual-to-decadal variation of 52 with the Pacific Decadal Oscillation (PDO) and the ultimate global-change processes that cause PDO. More work is underway, and additional independent data sources are examined, paying close attention to the fact that the J2 anomaly has been reversing back to normal since 2001. These include: (1) cryospheric contributions (melting of glaciers and ice sheets); (2) land hydrological contributions; (3) polar sea influences ( e g , via deep flow); (4) fluid flow in Earth's core; (5) time-variable gravity signals from SLR in higher harmonic degree/order, including J3,J4, (2,1), and (2,2) coefficients, considering their lower signal-to-noise ratios; (6) Earth rotation data in terms of length-of-day and polar motion.

Chao, B. F.↗
DOE OSTI2023

Tracking of Marangoni driven motion during laser powder bed fusion

Laser Powder Bed Fusion (LPBF) can be used to create Functionally Graded Materials (FGMs) by selectively distributing property augmenting particles throughout the build matrix. With this method parts can be created with nonhomogeneous properties tuned to spatially varied, pre-determined design constraints. To unlock this capability, the fluid motion that occurs in the molten liquid phase must be thoroughly understood. More importantly, the actual tracking of motion during the LPBF process is needed. Further, a numerical model of heat transfer and fluid flow in LPBF process was created. Using results from the model the motion of particles starting at many different locations was tracked. The average change in position for these particles based on starting location was calculated. The effects of non-dimensional parameters on melt pool size were examined. These results were validated experimentally and compared to what is available in the literature.

42 ENGINEERING↗
DOE OSTI2021

Solar wind contributions to Earth’s oceans

The isotopic composition of water in Earth’s oceans is challenging to recreate using a plausible mixture of known extraterrestrial sources such as asteroids—an additional isotopically light reservoir is required. The Sun’s solar wind could provide an answer to balance Earth’s water budget. Here, we used atom probe tomography to directly observe an average ~1 mol% enrichment in water and hydroxyls in the solar-wind-irradiated rim of an olivine grain from the S-type asteroid Itokawa. We also experimentally confirm that H + irradiation of silicate mineral surfaces produces water molecules. These results suggest that the Itokawa regolith could contain ~20 l m -3 of solar-wind-derived water and that such water reservoirs are probably ubiquitous on airless worlds throughout our Galaxy. The production of this isotopically light water reservoir by solar wind implantation into fine-grained silicates may have been a particularly important process in the early Solar System, potentially providing a means to recreate Earth’s current water isotope ratios.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Chemical Recycling of Thiol Epoxy Thermosets via Light-Driven C–C Bond Cleavage

Epoxy thermosets are high-volume materials that play a central role in a wide range of engineering applications; however, technologies to recycle these polymers remain rare. Here, we present a catalytic, light-driven method that enables chemical recycling of industrially relevant thiol epoxy thermosets to their original monomer at ambient temperature. This strategy relies on the proton-coupled electron transfer (PCET) activation of hydroxy groups within the polymer network to generate key alkoxy radicals that promote the fragmentation of the polymer through C–C bond β-scission. The method fully depolymerizes insoluble thiol epoxy thermosets into well-defined mixtures of small-molecule products, which can collectively be converted into the original monomer via a one-step dealkylation process. Notably, this process is selective and efficient even in the presence of other commodity plastics and additives commonly found in commercial applications. Finally, these results constitute an important step toward making epoxy thermosets recyclable and more generally exemplify the potential of PCET to offer a more sustainable end-of-life for a diverse array of commercial plastics.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Segmentation of remotely sensed data using parallel region growing

The improved spatial resolution of the new earth resources satellites will increase the need for effective utilization of spatial information in machine processing of remotely sensed data. One promising technique is scene segmentation by region growing. Region growing can use spatial information in two ways: only spatially adjacent regions merge together, and merging criteria can be based on region-wide spatial features. A simple region growing approach is described in which the similarity criterion is based on region mean and variance (a simple spatial feature). An effective way to implement region growing for remote sensing is as an iterative parallel process on a large parallel processor. A straightforward parallel pixel-based implementation of the algorithm is explored and its efficiency is compared with sequential pixel-based, sequential region-based, and parallel region-based implementations. Experimental results from on aircraft scanner data set are presented, as is a discussioon of proposed improvements to the segmentation algorithm.

Tilton, J. C.↗