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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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84 records · Page 5
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NASA NTRS2019

Urban Area Unmanned Aerial Systems Sensor Capabilities for Ensuring Ground Hazards Safety

Unmanned aerial systems (UASs) in urban areas can pose significant safety risks to dynamic ground objects (DGOs) such as people, pets, and bikes; especially for off-nominal emergency traverses and landings. This paper will examine a framework for evaluating the UAS safety benefits which can be achieved by classifying DGO hazards, modeling their behavior, and assigning collision costs. DGOs are assumed to be any ground objects which are either moving or capable of moving. Safety benefits will be assessed by analyzing metrics computed from UAS and DGO trajectories which take into account intent and uncertainties. This paper will establish the theoretical relationships mapping these trajectories and DGO classifications to safety levels. Sensor capabilities will be mapped to DGO trajectory uncertainties, so that safety can be directly estimated from the sensor specifications for a given UAS trajectory.

Bouyssounouse, Xavier↗
NASA NTRS2019

Assessing precipitation, evapotranspiration, and NDVI as controls of US Great Plains plant production

Productivity throughout the North American Great Plains grasslands is generally considered to be water limited, with the strength of this limitation increasing as precipitation decreases. We hypothesize that cumulative actual evapotranspiration water loss (AET) from April to July is the precipitation-related variable most correlated to aboveground net primary production (ANPP) in the U.S. Great Plains (GP). We tested this by evaluating the relationship of ANPP to AET, precipitation, and plant transpiration (Tr). We used multi-year ANPP data from five sites ranging from semiarid grasslands in Colorado and Wyoming to mesic grasslands in Nebraska and Kansas, mean annual NRCS ANPP, and satellite-derived normalized difference vegetation index (NDVI) data. Results from the five sites showed that cumulative April-to-July AET, precipitation, and Tr were well correlated (R2: 0.54–0.70) to annual changes in ANPP for all but the wettest site. AET and Tr were better correlated to annual changes in ANPP compared to precipitation for the drier sites, and precipitation in August and September had little impact on productivity in drier sites. April-to-July cumulative precipitation was best correlated (R2 = 0.63) with interannual variability in ANPP in the most mesic site, while AET and Tr were poorly correlated with ANPP at this site. Cumulative growing season (May-to-September) NDVI (iNDVI) was strongly correlated with annual ANPP at the five sites (R2 = 0.90). Using iNDVI as a surrogate for ANPP, we found that county-level cumulative April–July AET was more strongly correlated to ANPP than precipitation for more than 80% of the GP counties, with precipitation tending to perform better in the eastern more mesic portion of the GP. Including the ratio of AET to potential evapotranspiration (PET) improved the correlation of AET to both iNDVI and mean county-level NRCS ANPP. Accounting for how different precipitation-related variables control ANPP (AET in drier portion, precipitation in wetter portion) provides opportunity to develop spatially explicit forecasting of ANPP across the GP for enhancing decision-making by land managers and use of grassland ANPP for biofuels.

Maosi Chen↗
NASA NTRSDate not supplied

Characteristics of Mineralogy and Space Weathering Observed on the Grains in the Fine Fraction Samples Returned From the C-type Asteroid Ryugu.

Samples returned from near-Earth C-type asteroid Ryugu by the JAXA Hayabusa2 spacecraft have been investigated from June, 2021. Our Min-Pet Fine ("sand") sub-team have investigated mineralogy and petrology and space weathering of grains in the fine fraction of the samples. Space weathering is alteration induced mainly by solar wind irradiation and micrometeoroid impact. Here, we report mineralogy and microstructural and chemical features related to space weathering of Ryugu grains.

Takaaki Noguchi↗
NASA NTRSDate not supplied

Mineralogy and space weathering found in the fine-grained samples returned from the C-type asteroid Ryugu

The JAXA Hayabusa2 spacecraft returned samples from near-Earth C-type asteroid Ryugu. Our Hayabusa2-initial-analysisMin-Pet Fine (“Sand”) team has investigated mineralogy and petrology and space weathering of grains in the fine-grained fraction of the samples. Space weathering is alteration induced mainly by solar wind irradiation and micrometeoroid impact. Here, we report the mineralogy, microstructural, and chemical features related to space weathering of the Ryugu grains.

Takaaki Noguchi↗
NASA NTRSDate not supplied

Characterization of Modern Spacecraft Materials under Space-simulated Environment

External spacecraft materials play an important role in satellite protection from the harsh space environment. Research has shown that the physical, chemical, and optical properties of matter change continuously as a result of exposure to solar radiation and aggressive chemical species produced in Earth’s upper atmosphere. Thorough knowledge of the material properties evolution throughout a planned mission lifetime helps to improve the reliability of spacecraft. Moreover, the establishment of correlation factors between true space exposure and accelerated space weather experiments at ground facilities enables accurate prediction of on-orbit material performance based on laboratory-based testing. The presented work aims to evaluate the radiation effects of low Earth orbit (LEO) environment, namely, exposure to the high-energy electrons, atomic oxygen (AO), and vacuum ultraviolet (VUV), of several modern spacecraft materials. The studied materials represent the “flight duplicates” of samples that will be launched as a part of the Materials International Space Station Experiment Flight Facility (MISSE-FF) mission in 2022. MISSE-FF flight sample collection comprises different classes of polymers, including polyimides from the Kapton family, manufactured by E.I du Pont de Nemours and Co., Polyethylene terephthalate (PET) materials, liquid crystal polymers, PI/Polyhedral Oligomeric Silsesquioxanes (POSS), and carbon and glass fiber reinforced polymers. A sequential exposure approach was undertaken to allow monitoring of degradation induced by each environmental component (electrons, AO, and VUV) separately. Surface morphology, optical, and charge transport properties of selected materials were characterized using different techniques, namely, atomic force and scanning electron microscopy, ultraviolet visible (UV/Vis) transmission, reflectance, Bidirectional Reflectance Distribution Function (BRDF), and surface potential decay measurements.

Elena Plis↗
NASA NTRSDate not supplied

Maipo River Valley Agriculture: Determining Crop Coefficients Using Remote Sensing for the Maipo River Valley Basin in Chile

Agriculture is the primary use of water in the Maipo River basin of Central Chile, accounting for ~ 75% of the total demand. Assessment of irrigation needs for agricultural production has commonly relied on reference crop coefficients (Kc) derived from geographic and climatic conditions that differ from those of Chile. In partnership with the Centro de Información de Recursos Naturales (CIREN), this work focused on calculating site-specific crop coefficients tailored to crop production in the water-stressed Maipo River Valley. Two distinct approaches were implemented, each relying on remotely-sensed Earth observation datasets from NASA over consecutive growing seasons from 2019 to 2022. The first method estimated Kc values based on their linear relationship with the Normalized Difference Vegetation Index (NDVI) obtained from either Terra Moderate Resolution Imaging Spectroradiometer (MODIS) or Landsat 8 Operational Land Imager (OLI) surface reflectance. The second technique leveraged information from the ISS Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) by computing the ratio between actual crop evapotranspiration (ET) and potential evapotranspiration (PET). Both procedures showed promising results that can build on one another. The former approach best captured vegetation signals of annual crops while the latter appeared suited for perennials. Overall, this study provides a strong basis and novel way to accurately estimate Kc using remote sensing, with the potential for improved irrigation management and reduction in water consumption.

Benjamin Goffin↗
NASA NTRSDate not supplied

Helmet-Mounted Display Technology for Eva Training in NASA's Neutral Buoyancy Lab

Currently, during extravehicular activity (EVA) on the International Space Station (ISS), astronauts are in constant communication with mission control; however, this paradigm will significantly change during future NASA exploration missions due to limited and time-delayed communications. As exploration missions will thereby require an increase in crew autonomy, it is hypothesized that heads-up display (HUD) technology can supplement communications with mission control. Before introducing novel display technology to EVA operations, it must first be demonstrated and evaluated in an EVA training environment. The UC Davis Center for Spaceflight Research, in collaboration with NASA Johnson Space Center’s Human Physiology, Performance, Protection, and Operations (H-3PO) Lab has developed a low-cost and rapid development helmet-mounted display (HMD) for EVA training at NASA’s Neutral Buoyancy Lab (NBL). The first two phases of HMD testing (Phase I and II) at the NBL focused on technology and capability development and demonstration. Crew member feedback was obtained that evaluated aspects of HMD including its user satisfaction, visibility, readability, and usefulness. Overall, feedback indicated HMD was readable, un-obtrusive, and the available display modes had potential to be useful and enhance EVA training. HMD display modes currently available include: real-time biofeedback (metabolic rate), phase elapsed time (PET), ability to set timers, task procedural aids (e.g. Pistol Grip Tool settings) and custom messages. The goal for Phase III, which is currently underway, is to evaluate the effects that access to bioinformatics through HMD has on astronaut training and performance at the NBL. For this phase of testing, crewmembers will be asked to perform a go/no-go task while wearing HMD throughout the NBL run to characterize crew member state of situational awareness with respect to HMD. This information could be used to inform how best to display relatively important or supplemental, but not critical, data in the future.

Heads up display↗
NASA NTRSDate not supplied

Thermodynamic Modeling of the Vapor in Equilibrium With Apollo 17 Basalts.

Lunar mare basalts sampled during the Apollo 17 mission provide insight to the chemical evolution of mare basalt magmas and their associated vapor as these samples erupted and cooled rapidly at the lunar surface. We focus on minerals present on vesicle and vug surfaces in Apollo 17 basalts, such as 71036, which was opened as part of the Apollo Next Generation Sample Analysis (ANGSA) program. The mineral assemblage observed includes native Fe, SiO2, and a Mg-P mineral, possibly merrillite [1, 2]. The pet-rographic context of these phases suggests that they may have been deposited directly from the vapor phase after eruption. Here we use thermodynamic modeling to assess the plausibility of the vapor-phase deposition hypothesis.

D. L. Thompson↗
NASA NTRSDate not supplied

Overview of the MISSE-16 Mission and Preliminary Characterization of Novel Space Weathered Materials

The Materials International Space Station Experiment (MISSE) project is a series of experiments that began in 2001, involving the deployment of external experiment platforms on the International Space Station (ISS). Since then, more than 4,000 materials were tested yielding valuable data and insights into the performance of materials and coatings in the harsh space environment, as well as providing a platform for testing and validating new materials and technologies. The results of the MISSE experiments have contributed to the development of more durable and reliable spacecraft and equipment, as well as improving our understanding of the space environment and its effects on human space exploration. To gain deeper insights into the changes in material properties of both novel and heritage spacecraft materials over the course of a mission, we proposed to enhance the MISSE hardware. This was achieved by integrating a high-resolution camera that can capture both RGB and IR color data, along with an updated illumination scheme. The identical sets of selected materials were mounted on the Zenith, Ram, and Wake faces of the ISS to expose them to predominant vacuum ultraviolet (VUV), atomic oxygen, and high-energy electron conditions. In addition, we exposed flight duplicates of these materials to a simulated space environment, which included sequential exposure to the same irradiation species on the ground. This allowed us to study the effects of space exposure on the materials in a controlled manner and to compare their behavior in both real and simulated space environments. The MISSE-FF flight sample collection comprised different classes of polymers, including polyimides from the Kapton family, manufactured by E.I du Pont de Nemours and Co., Polyethylene terephthalate (PET) materials, liquid crystal polymers, PI/Polyhedral Oligomeric Silsesquioxanes (POSS), and carbon and glass fiber reinforced polymers. The experimental cadence during the MISSE-16 mission (~6 months) included daily images of each sample for the first week, weekly for the next 2 months, and monthly the remaining duration of the mission. This paper will focus on the flight duplicate as well as the postflight optical characterization of novel and heritage materials currently under observation on the MISSE-FF.

Jainisha R Shah↗
NASA NTRSDate not supplied

Atomic Oxygen Impacts on Materials International Space Station Experiment (MISSE)-16 flight Samples

A variety of materials consisting of polyimides, polyethylene terephthalates (PETs), fiber reinforced polymers, and polyhedral oligomeric silsesquioxanes (POSS) were on the exterior of the International Space Station (ISS) as part of Materials International Space Station Experiment (MISSE)-16. Samples on the side of the ISS pointing in the direction of the spacecraft’s motion (the ram direction) were observed for effects due to atomic oxygen (AO). The erosion yield of select materials from MISSE-16 is reported, as well as their variation in surface roughness due to AO erosion. Trade names and trademarks are used in this paper for identification only. Their usage does not constitute an official endorsement, either expressed or implied, by the National Aeronautics and Space Administration.

Samuel A Westrick↗
NASA NTRS2020

Novel High Barrier Films for Packaging Food and Medicine

Long manned missions require food packaging to maintain food safety, nutrition, and acceptability for the length of 3-5 years1,2 while the shelf life assigned by NASA for current provisions is 18-24 months1. The focus of this design project was to make a polymer film specifically to function as a high oxygen barrier to later be included in an improved multi-layer packaging system of other specialized polymers with capabilities to allow for a 5-year shelf-life. To qualify as a high oxygen barrier film and to be a successful design for the future packaging, the resulting film is required to have an oxygen transmission rate (OTR) less than 0.06 cc/ m2/24 hr/atm, the standard for the current packaging3. This new film was designed to have a decreased permeability by increasing the “tortuous path” a gas molecule travels to permeate through a film. The increase in the “tortuous path” of a gas molecule is accomplished by introducing a 2D material additive. The additive chosen for this project was hexagonal boron nitride (h-BN) which exfoliates into boron nitride nanosheets (BNNs). Nylon 6 was chosen as the candidate for the matrix. This project is required to determine the best methods to synthesize the sample film and then to test the OTR of the film to determine if this design was successful. This project examined methods for pulverizing polymer resin pellets, h-BN exfoliation, and film fabrication using a hot press. This report includes the exfoliation and analysis of h-BN, procedural preparations for films, and a modeling study of estimated OTR of the h-BN/Nylon. The work in this report did not yield a high barrier composite film because of the laboratory closure in response to COVID -19 guidance but provides a concise method of the additive preparation and film synthesis. This gives a good starting point for future research in high barrier films by 2D additive composites.

Polymer, Nylon, PET, boron nitride, nanocomposite↗