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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Survival of infectious microorganisms in space cabin environments

Aerosol survival and virulence of S. aureus and P. aeruginosa cultures isolated during exposure to simulated space cabin environment was studied using the microthread captured aerosol technique. The aerosol survival of P. aeruginosa isolates did not differ significantly from that of the original culture from which the isolates were obtained. The mean death rate of the isolates was 1.03%/min and that of the controls 1.10%/min. Similarly exposure to the 5 psi environment did not affect the virulence of P. aeruginosa. Both strains of S. aureus (IITRI and NASA) after exposure to 5 psi environment showed some degree of adaptation to this environmental stress. The aerosol death rates of the isolated organisms were 5 to 10-fold lower than of the original cultures. At the same time the virulence of the isolates was approximately 5-fold higher than that of the original culture.

Vana, S. C.↗
NASA NTRS1977

Effects of acceleration on thermoregulatory responses of unanesthetized rats

An experimental study was carried out to examine the thermoregulatory responses of rats to step changes in ambient temperature during centrifugation. Attention is focused on the analysis of problems as to whether the ability of rats to regulate body temperature during one hour of cold exposure is altered by increasing the acceleration field to 2G, whether prior environmental conditioning can affect the temperature response to the combined stressors of acceleration and cold, and whether the orientation of the animal in the acceleration field modifies the temperature response. The finding that the decline in colonic temperature is accompanied by parallel changes in hypothalamic and spinal cord temperatures indicates that the decreasing heat production with increasing heat loss is an atypical thermoregulatory response of these animals to cooling. Mechanical forces acting on the brain may underline the temperature decrease when inverting the animal during acceleration.

Fuller, C. A.↗
NASA NTRS1987

Time-temperature-stress capabilities of composite materials for advanced supersonic technology application

Advanced composites will play a key role in the development of the technology for the design and fabrication of future supersonic vehicles. However, incorporating the material into vehicle usage is contingent on accelerating the demonstration of service capacity and design technology. Because of the added material complexity and lack of extensive data, laboratory replication of the flight service will provide the most rapid method to document the airworthiness of advanced composite systems. Consequently, a laboratory program was conducted to determine the time-temperature-stress capabilities of several high temperature composites. Tests included were thermal aging, environmental aging, fatigue, creep, fracture, tensile, and real-time flight simulation exposure. The program had two phases. The first included all the material property determinations and aging and simulation exposures up through 10,000 hours. The second continued these tests up to 50,000 cumulative hours. This report presents the results of the Phase 1 baseline and 10,000-hr aging and flight simulation studies, the Phase 2 50,000-hr aging studies, and the Phase 2 flight simulation tests, some of which extended to almost 40,000 hours.

Kerr, James R.↗
NASA NTRS1989

Photovoltaic array environmental protection program

During the photovoltaic array environmental protection program, a coating material, application technique, and design approach intended to protect flexible solar array blankets during a nominal fifteen-year operating lifetime were developed. Numerous thin-film coatings for protecting the Kapton polyimide material used in the construction of the Space Station Freedom flexible solar array blanket were evaluated. The critical solar array design features and protection measures are discussed with special emphasis on the effects of solar array fabrication and flexible printed circuit manufacturing processes on coating durability. The results of the mechanical and environmental test evaluation, including oxygen plasma, neutral oxygen beam, and UV/charged-particle combined exposure, are discussed. These results led to the selection of a silicon dioxide thin-film coating to protect the solar array blanket from the low-earth-orbit atomic oxygen environment.

Bilger, Kevin M.↗
NASA NTRS1992

Creep fatigue life prediction for engine hot section materials (isotropic)

This Final Report covers the activities completed under the optional program of the NASA HOST Contract, NAS3-23288. The initial effort of the optional program was report-in NASA CR189221, which consisted of high temperature strain controlled fatigue tests to study the effects of thermomechanical fatigue, multiaxial loading, reactive environments, and imposed stresses. The baseline alloy used in the tests included B1900+Hf (with or without coating) and wrought INCO 718. Tests conducted on B1900+Hf included environmental tests using various atmospheres (75 psig oxygen, purified argon, or block exposures) and specimen tests of wrought INCO 718 included tensile, creep, stress rupture, TMF, multiaxial, and mean stress tests. Results of these testings were used to calibrate a CDA model for INCO 718 alloy and to develop modifications or corrections to the CDA model to handle additional failure mechanisms. The Socie parameter was found to provide the best correlation for INCO multiaxial loading. Microstructural evaluations consisting of optical, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) techniques, and surface replication techniques to determine crack initiation lives provided data which were used to develop life prediction models.

Nelson, R. S.↗
NASA NTRS1991

Medical care delivery in the US space program

The stated goal of this meeting is to examine the use of telemedicine in disaster management, public health, and remote health care. NASA has a vested interest in providing health care to crews in remote environments. NASA has unique requirements for telemedicine support, in that our flight crews conduct their job in the most remote of all work environments. Compounding the degree of remoteness are other environmental concerns, including confinement, lack of atmosphere, spaceflight physiological deconditioning, and radiation exposure, to name a few. In-flight medical care is a key component in the overall support for missions, which also includes extensive medical screening during selection, preventive medical programs for astronauts, and in-flight medical monitoring and consultation. This latter element constitutes the telemedicine aspect of crew health care. The level of in-flight resources dedicated to medical care is determined by the perceived risk of a given mission, which in turn is related to mission duration, planned crew activities, and length of time required for return to definitive medical care facilities.

Stewart, Donald F.↗
NASA NTRS1993

What LDEF means for development and testing of materials

The Long Duration Exposure Facility (LDEF) served as the ultimate laboratory to provide combined space environmental effects on materials. The LDEF structure and its 57 experiments contained an estimated 12,000 to 14,000 specimens of materials and materials processes. It not only provided information about the resistance of these materials to the space environment but gives us direction into future needs for spacecraft materials development and testing. This paper provides an overview of the materials effects observed on the satellite and suggests recommendations for the future work in space-qualified materials development and space environmental simulation.

Whitaker, Ann F.↗
NASA NTRS1999

Solar Cycle Variation and Application to the Space Radiation Environment

The interplanetary plasma and fields are affected by the degree of disturbance that is related to the number and types of sunspots in the solar surface. Sunspot observations were improved with the introduction of the telescope in the seventeenth century, allowing observations which cover many centuries. A single quantity (sunspot number) was defined by Wolf in 1848 that is now known to be well correlated with many space observable quantities and is used herein to represent variations caused in the space radiation environment. The resultant environmental models are intended for future aircraft and space-travel-related exposure estimates.

Wilson, John W.↗
NASA NTRS2014

Oxidative Stress Responses to Simulated Spaceflight in Mineralized and Marrow Compartments of Bone and Associated Vasculature

Long-term spaceflight causes profound changes to the musculoskeletal system attributable to unloading and fluid shifts in microgravity. Future space explorations beyond the earth’s magnetosphere will expose astronauts to space radiation, which may cause additional skeletal deficits that are not yet fully understood. Our long-term goals are twofold: to define the mechanisms and risk of bone loss in the spaceflight environment and to facilitate the development of effective countermeasures if necessary. Our central hypothesis is that oxidative stress plays a key role in progressive bone loss and vascular dysfunction caused by spaceflight. In animal’s models, overproduction of free radicals is associated with increased bone resorption, lower bone formation, and decrements in bone mineral density and structure which can ultimately lead to skeletal fragility. Evidence in support of a possible causative role for oxidative stress in spaceflight-induced bone loss derive from knockout and transgenic mouse studies and the use of pharmacological interventions with known anti-oxidant properties. In our studies to simulate spaceflight, 16-wk old, male C56Bl/6J mice were assigned to one of four groups: hind limb unloading to simulate weightlessness (HU), normally loaded Controls (‘NL’) (sham irradiated, no hind limb unloading), irradiated at NASA Space Radiation Laboratory ‘IR’ with 1-2Gy of (600MeV/n) alone, or in combination with protons (0.5Gy Protons/0.5Gy 56Fe), (IR) or both hind limb unloaded and irradiated, ‘HU+IR’. Mice were exposed to radiation 3 days after initiating HU and tissues harvested were 1-14 days after initiating treatments for analyses. Results from our laboratories, which employ various biochemical, gene expression, functional, and transgenic animal model methods, implicate dynamic regulation of redox-related pathways by spaceflight-related environmental factors. As one example, we found that combined HU and radiation exposure caused oxidative damage in skeletal tissues (lipid peroxidation) of wildtype mice, whereas bone from transgenic mice that overexpress human catalase in mitochondria were protected. Interestingly, marrow cells grown under culture conditions that select for endothelial progenitor cells (EPC), showed that HU but not IR reduced EPC cell migration; in contrast HU and IR each inhibited growth of marrow-derived osteoblast progenitors. Taken together, these results indicate that unloading and ionizing elicit distinct effects on progenitor and mature cells of vascular and skeletal tissue, and that oxidative damage may contribute to skeletal and vascular deficits that may emerge during extended space travel.

Globus, R. K.↗
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

Effects of Long Duration Space Flight on Low Frequency Hearing

Pure tone hearing threshold data has been collected on astronauts since the early days of spaceflight. Between 1981 and 2001 (STS-1 thru 108) it was found that of the 608 shuttle astronauts, 17% returned home with a significant hearing threshold shift, and of that 6% had permanent changes in the high frequencies. Believed to be due to prolonged noise exposure on the space crafts. (Hart, 2006) As NASA aimed for longer duration missions the uncertainty about the effects of month-long noise exposure needed to be addressed. To avoid constraining crewmembers to constant earplug usage, and satisfying budget demands, a focused effort on overcoming the issues began. Noise monitoring systems were introduced onto the International Space Station (ISS) and astronauts were given education on the noise environment aboard the ISS, the hazards of noise induced hearing loss, hearing conservation principles, and countermeasure strategies (earplugs, noise cancellation headsets). As well as being trained on a new countermeasure effort that had been in trial testing on prior shuttle missions (STS-6 thru 8), On-Orbit Hearing Assessment (OOHA). (Hart, 2006) OOHA was implemented to routinely monitor the hearing thresholds of crewmembers who are on orbit for longer than 30 days. Flight Surgeons on ground monitor these test for significant hearing changes while aboard. Between 2000 and 2021 the ISS OOHA system (EarQ) recorded changes in the low frequency hearing thresholds. Low frequency hearing changes are not typically caused by noise exposure, and it was initially believed that these changes were due to environmental noise interference. In 2021 an ISS software upgrade (KUDUwave) allowed for a more comprehensive hearing assessment. The new testing system allowed for additional tests that helped describe the type of hearing loss being experienced and determine the influence of ambient noise or other environmental factors. OOHA Data indicates a low frequency hearing shift in 40% of all tests and 60% of all crewmembers. Since 2021, OOHA results (using the KUDUwave) suggest that these shifts are sensorineural and are not the result of ambient noise. While hearing shifts are seen at both 250 and 500 Hz, metrics tracking these shifts have only used 500 Hz data. The lack of 250 Hz has prevented accurate reporting of low frequency hearing shift recovery. The aim of this study is to capture 250 Hz data and accurately present low frequency hearing loss recovery.

hearing↗
DOE OSTI2020

GPR Robotic Assisted Non-Destructive Evaluation of Concrete Structures - 20196

Reinforced concrete structures are always under exposure of internal or external deteriorations due to many factors such as environmental, nuclear radiation or even construction deficiencies. The use of nondestructive test is one of the reliable methods to inspect structural members. In this case, GPR has a good capability to detect inside deteriorations of concrete structures. However, in many cases it is hard to inspect structural members by hand due to safety issues or inaccessibility. Thus, an alternative way to reduce such risks is to employ robot to carry nondestructive equipment. In this research, twelve reinforced concrete RC beams (8 x 16 x 96, width, height and length) are cast in the lab. Three RC beams have no defect and nine others various defects such as corrosion, de-bonded bars, void, delamination and honeycombing. The one-point load is applied at the center of the RC beam. The loading level is carried out at three levels: 50%, 75% and 100% of maximum load and total load-displacement diagram are performed. The load is held at each level and the robotic GPR is used to scan the side of RC beams. Then, RADAN software is employed to find out any defects at different loading conditions and visualize the crack propagation. The RADAN results show that the pattern of crack propagation for corrosion and debonding are same. Also, the load-displacement results present that inside defect cause reduction of load-capacity of RC beam. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Effectiveness of street trees in reducing air temperature and outdoor heat exposure in Las Vegas

Urban greening and especially tree planting strategies are being widely planned and implemented to mitigate urban overheating and thermal stress in many urban areas. However, the effectiveness of these strategies depends on multiple factors, including urban morphology, environmental conditions, and tree characteristics. This study investigates the effects of street tree planting strategies on air temperature and outdoor heat exposure in Las Vegas by combining an urbanized mesoscale climate model coupled to a multi-layer street tree model (Weather Research and Forecasting-BEP-Tree; Δ x = 900 m) with a microscale pedestrian heat exposure model (Temperatures of Urban Facets for Pedestrian; Δ x = 1 m). A series of simulations are conducted for July and August 2022. Large city-wide increases of a drought tolerant tree species cool air temperature mainly during the nighttime (up to 1.5 °C), with daytime effects being limited due to leaves shedding sensible instead of latent heat as stomata close in response to high vapor pressure deficits. Increased evaporative cooling is achieved with a different tree species (double at night, and reaching 0.4 °C during the day), but water requirements increase threefold. Despite their relatively small effect on air temperature during the day, trees provide significant shade by intercepting solar radiation, reducing mean radiant temperature (up to 16 °C) and enhancing outdoor thermal comfort, a major benefit of street trees in hot arid climates. The nighttime cooling of trees and the daytime reduction of radiant loading show potential to reduce the heat-related health impacts. Our results highlight the need to evaluate the effects of street trees on a case-by-case basis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Systemic immunological responses are dependent on sex and ovarian hormone presence following acute inhaled woodsmoke exposure

Background: Rural regions of the western United States have experienced a noticeable surge in both the frequency and severity of acute wildfire events, which brings significant challenges to both public safety and environmental conservation efforts, with impacts felt globally. Identifying factors contributing to immune dysfunction, including endocrinological phenotypes, is essential to understanding how hormones may influence toxicological susceptibility. Methods: This exploratory study utilized male and female C57BL/6 mice as in vivo models to investigate distinct responses to acute woodsmoke (WS) exposure with a focus on sex-based differences. In a second set of investigations, two groups were established within the female mouse cohort. In one group, mice experienced ovariectomy (OVX) to simulate an ovarian hormone-deficient state similar to surgical menopause, while the other group received Sham surgery as controls, to investigate the mechanistic role of ovarian hormone presence in driving immune dysregulation following acute WS exposure. Each experimental cohort followed a consecutive 2-day protocol with daily 4-h exposure intervals under two conditions: control HEPA-filtered air (FA) and acute WS to simulate an acute wildfire episode. Results: Metals analysis of WS particulate matter (PM) revealed significantly increased levels of 63 Cu, 182 W, 208 Pb, and 238 U, compared to filtered air (FA) controls, providing insights into the specific metal components most impacted by the changing dynamics of wildfire occurrences in the region. Male and female mice exhibited diverse patterns in lung mRNA cytokine expression following WS exposure, with males showing downregulation and females displaying upregulation, notably for IL-1β, TNF-α, CXCL-1, CCL-5, TGF-β, and IL-6. After acute WS exposure, there were notable differences in the responses of macrophages, neutrophils, and bronchoalveolar lavage (BAL) cytokines IL-10, IL-6, IL-1β, and TNF-α. Significant diverse alterations were observed in BAL cytokines, specifically IL-1β, IL-10, IL-6, and TNF-α, as well as in the populations of immune cells, such as macrophages and polymorphonuclear leukocytes, in both Sham and OVX mice, following acute WS exposure. These findings elucidated the profound influence of hormonal changes on inflammatory outcomes, delineating substantial sex-related differences in immune activation and revealing altered immune responses in OVX mice due to ovarian hormone deficiency. In addition, the flow cytometry analysis highlighted the complex interaction between OVX surgery, acute WS exposure, and their collective impact on immune cell populations within the hematopoietic bone marrow niche. Conclusions: In summary, both male and female mice, alongside females subjected to OVX and those who had sham surgery, exhibit significant variations in the expression of proinflammatory cytokines, chemokines, lung mRNA gene expression, and related functional networks linked to signaling pathways. These differences potentially act as mediators of sex-specific and hormonal influences in the systemic inflammatory response to acute WS exposure during a wildfire event. Understanding the regulatory roles of genes expressed differentially under environmental stressors holds considerable implications, aiding in identifying sex-specific therapeutic targets for addressing acute lung inflammation and injury.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

PM 2.5 Is Insufficient to Explain Personal PAH Exposure

To understand how chemical exposure can impact health, researchers need tools that capture the complexities of personal chemical exposure. In practice, fine particulate matter (PM 2.5 ) air quality index (AQI) data from outdoor stationary monitors and Hazard Mapping System (HMS) smoke density data from satellites are often used as proxies for personal chemical exposure, but do not capture total chemical exposure. Silicone wristbands can quantify more individualized exposure data than stationary air monitors or smoke satellites. However, it is not understood how these proxy measurements compare to chemical data measured from wristbands. In this study, participants wore daily wristbands, carried a phone that recorded locations, and answered daily questionnaires for a 7-day period in multiple seasons. We gathered publicly available daily PM 2.5 AQI data and HMS data. We analyzed wristbands for 94 organic chemicals, including 53 polycyclic aromatic hydrocarbons. Wristband chemical detections and concentrations, behavioral variables (e.g., time spent indoors), and environmental conditions (e.g., PM 2.5 AQI) significantly differed between seasons. Machine learning models were fit to predict personal chemical exposure using PM 2.5 AQI only, HMS only, and a multivariate feature set including PM 2.5 AQI, HMS, and other environmental and behavioral information. On average, the multivariate models increased predictive accuracy by approximately 70% compared to either the AQI model or the HMS model for all chemicals modeled. This study provides evidence that PM 2.5 AQI data alone or HMS data alone is insufficient to explain personal chemical exposures. Our results identify additional key predictors of personal chemical exposure.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS2008

Reversible Chemochromic Hydrogen Detectors

The Florida Solar Energy Center (FSEC), affiliated with the University of Central Florida, has invented a reversible pigment that changes from light beige to blue when exposed to hydrogen and back to light beige when exposed to atmospheric oxygen. In laboratory and environmental studies, the FSEC pigment in its tape form failed to change color adequately when exposed to hydrogen after one day of exposure at Kennedy Space Center's Beach Corrosion Test Facility. The reversible hydrogen-detecting tape also lost its ability to change color after being placed in an environmental chamber at 45 C for one day. The first attempts at extruding the reversible pigment into various polymers were unsuccessful because of the pigment's poor thermal stability. The goal of this project was to formulate a pigment with improved thermal and environmental stability for extrusion into a variety of appropriate polymer matrices. The formulation of the reversible hydrogen-detecting pigment was modified by removing one reagent and chemically modifying the hydrogen sensitive ingredient. This was intended to improve the hydrophobicity of the pigment and alter the thermal degradation mechanism.

Source record↗
NASA NTRS2021

Dynamic Ensemble Prediction of Cognitive Performance in Space

Astronauts are exposed to a unique set of stressors in spaceflight. Microgravity, isolation, confinement, and environmental and operational hazards: all of these can impact sleep, vigilant attention, and alertness, which are critical to mission success. In this paper, we seek to understand the most important predictors of alertness over the course of a space mission, using self-reported, cognitive, and environmental data collected from 24 astronauts on 6-month missions to the International Space Station (ISS). Alertness was repeatedly and objectively assessed on the ISS with a brief 3-minute Psychomotor Vigilance Test (PVT) that is highly sensitive to sleep deprivation. To relate PVT performance to time-varying and sparsely-measured environmental, operational, and psychological covariates, we propose a n ensemble prediction model comprising of linear mixed effects regression, random forest, and functional concurrent regression models. An extensive cross-validation procedure reveals that this ensemble outperforms any one of its components alone. We also discover that a participant’s past performance, reported fatigue and stress, and temperature and radiation exposure were among the most important variables associated with alertness. This method is broadly applicable to environmental studies where the main goal is accurate, individualized prediction involving a mixture of person-level traits and irregularly measured time series.

Danni Tu↗
NASA NTRS1977

Effects of space radiation on thin polymers and nonmetallics

Advanced materials for various spacecraft systems in the 1980s and 1990s have been evaluated in situ after exposure to space radiation. Emphasis has been placed on materials having little or no previous base of environmental effects data. Applications ranging from earth orbit to near-sun have been covered. High temperature polymers and composites have been included. Silica composites may offer improved reflectance stability compared with metallized fluorocarbons. Directional reflectance properties of FEP are a function of charged particle energy and flux as well as total exposure fluence and material characteristics. Data obtained on polyimides and polyxylylenes under high temperature radiation exposure conditions will be discussed in the context of near-sun solar sailing and rendezvousing.

Fogdall, L. B.↗