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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Proximity Within Interphase Chromosome Contributes to the Breakpoint Distribution in Radiation-Induced Intrachromosomal Exchanges

Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome3 in human mammary epithelial cells after exposures to either low-or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome exchange event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-induced chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome exchanges involving breaks on the p-arm and in the centromere region of chromosome3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-induced chromosome aberrations. Further investigations suggest that the 3D chromosome folding is cell type and culture condition dependent.

Zhang, Ye↗
NASA NTRS2015

Development of a Near Real-Time Hail Damage Swath Identification Algorithm for Vegetation

Every year in the Midwest and Great Plains, widespread greenness forms in conjunction with the latter part of the spring-summer growing season. This prevalent greenness forms as a result of the high concentration of agricultural areas having their crops reach their maturity before the fall harvest. This time of year also coincides with an enhanced hail frequency for the Great Plains (Cintineo et al. 2012). These severe thunderstorms can bring damaging winds and large hail that can result in damage to the surface vegetation. The spatial extent of the damage can relatively small concentrated area or be a vast swath of damage that is visible from space. These large areas of damage have been well documented over the years. In the late 1960s aerial photography was used to evaluate crop damage caused by hail. As satellite remote sensing technology has evolved, the identification of these hail damage streaks has increased. Satellites have made it possible to view these streaks in additional spectrums. Parker et al. (2005) documented two streaks using the Moderate Resolution Imaging Spectroradiometer (MODIS) that occurred in South Dakota. He noted the potential impact that these streaks had on the surface temperature and associated surface fluxes that are impacted by a change in temperature. Gallo et al. (2012) examined at the correlation between radar signatures and ground observations from storms that produced a hail damage swath in Central Iowa also using MODIS. Finally, Molthan et al. (2013) identified hail damage streaks through MODIS, Landsat-7, and SPOT observations of different resolutions for the development of a potential near-real time applications. The manual analysis of hail damage streaks in satellite imagery is both tedious and time consuming, and may be inconsistent from event to event. This study focuses on development of an objective and automatic algorithm to detect these areas of damage in a more efficient and timely manner. This study utilizes the MODIS sensor aboard the NASA Aqua satellite. Aqua was chosen due to an afternoon orbit over the United States when land surface temperatures are relatively warm and improve the contrast between damaged and undamaged areas. This orbit is also similar to the orbit of the Suomi-National Polar-orbiting Partnership (NPP) satellite. The Suomi NPP satellite hosts the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument, which is the next generation of a MODIS-like sensor in polar orbit.

MODIS VIIRS↗
NASA NTRS2015

Constraints on Cumulus Parameterization from Simulations of Observed MJO Events

Two recent activities offer an opportunity to test general circulation model (GCM) convection and its interaction with large-scale dynamics for observed Madden-Julian oscillation (MJO) events. This study evaluates the sensitivity of the Goddard Institute for Space Studies (GISS) GCM to entrainment, rain evaporation, downdrafts, and cold pools. Single Column Model versions that restrict weakly entraining convection produce the most realistic dependence of convection depth on column water vapor (CWV) during the Atmospheric Radiation Measurement MJO Investigation Experiment at Gan Island. Differences among models are primarily at intermediate CWV where the transition from shallow to deeper convection occurs. GCM 20-day hindcasts during the Year of Tropical Convection that best capture the shallow–deep transition also produce strong MJOs, with significant predictability compared to Tropical Rainfall Measuring Mission data. The dry anomaly east of the disturbance on hindcast day 1 is a good predictor of MJO onset and evolution. Initial CWV there is near the shallow–deep transition point, implicating premature onset of deep convection as a predictor of a poor MJO simulation. Convection weakly moistens the dry region in good MJO simulations in the first week; weakening of large-scale subsidence over this time may also affect MJO onset. Longwave radiation anomalies are weakest in the worst model version, consistent with previous analyses of cloud/moisture greenhouse enhancement as the primary MJO energy source. The authors’ results suggest that both cloud-/moisture-radiative interactions and convection–moisture sensitivity are required to produce a successful MJO simulation.

Madden-Julian Oscillation↗
NASA NTRS2016

Datalist: A Value Added Service to Enable Easy Data Selection

Imagine a user wanting to study hurricane events. This could involve searching and downloading multiple data variables from multiple data sets. The currently available services from the Goddard Earth Sciences Data and Information Services Center (GES DISC) only allow the user to select one data set at a time. The GES DISC started a Data List initiative, in order to enable users to easily select multiple data variables. A Data List is a collection of predefined or user-defined data variables from one or more archived data sets. Target users of Data Lists include science teams, individual science researchers, application users, and educational users. Data Lists are more than just data. Data Lists effectively provide users with a sophisticated integrated data and services package, including metadata, citation, documentation, visualization, and data-specific services, all available from one-stop shopping. Data Lists are created based on the software architecture of the GES DISC Unified User Interface (UUI). The Data List service is completely data-driven, and a Data List is treated just as any other data set. The predefined Data Lists, created by the experienced GES DISC science support team, should save a significant amount of time that users would otherwise have to spend.

Datalist↗
NASA NTRS2017

Thermal Radiation Anomalies Associated with Major Earthquakes

Recent developments of remote sensing methods for Earth satellite data analysis contribute to our understanding of earthquake related thermal anomalies. It was realized that the thermal heat fluxes over areas of earthquake preparation is a result of air ionization by radon (and other gases) and consequent water vapor condensation on newly formed ions. Latent heat (LH) is released as a result of this process and leads to the formation of local thermal radiation anomalies (TRA) known as OLR (outgoing Longwave radiation, Ouzounov et al, 2007). We compare the LH energy, obtained by integrating surface latent heat flux (SLHF) over the area and time with released energies associated with these events. Extended studies of the TRA using the data from the most recent major earthquakes allowed establishing the main morphological features. It was also established that the TRA are the part of more complex chain of the short-term pre-earthquake generation, which is explained within the framework of a lithosphere-atmosphere coupling processes.

Ouzounov, Dimitar↗
NASA NTRS2017

Simulation-Based Height of Burst Map for Asteroid Airburst Damage Prediction

Entry and breakup models predict that airburst in the Earth's atmosphere is likely for asteroids up to approximately 200 meters in diameter. Objects of this size can deposit over 250 megatons of energy into the atmosphere. Fast-running ground damage prediction codes for such events rely heavily upon methods developed from nuclear weapons research to estimate the damage potential for an airburst at altitude. (Collins, 2005; Mathias, 2017; Hills and Goda, 1993). In particular, these tools rely upon the powerful yield scaling laws developed for point-source blasts that are used in conjunction with a Height of Burst (HOB) map to predict ground damage for an airburst of a specific energy at a given altitude. While this approach works extremely well for yields as large as tens of megatons, it becomes less accurate as yields increase to the hundreds of megatons potentially released by larger airburst events. This study revisits the assumptions underlying this approach and shows how atmospheric buoyancy becomes important as yield increases beyond a few megatons. We then use large-scale three-dimensional simulations to construct numerically generated height of burst maps that are appropriate at the higher energy levels associated with the entry of asteroids with diameters of hundreds of meters. These numerically generated HOB maps can then be incorporated into engineering methods for damage prediction, significantly improving their accuracy for asteroids with diameters greater than 80-100 m.

Burst Map↗
NASA NTRS2018

Estimation of Heatshield Mass Loss for Mars 2020 Entry Vehicle

The Mars2020 entry vehicle is currently being developed by NASA to safely land its next rover on the Martian surface in 2021. During entry, the vehicle will be protected from aerothermal environments using a PICA (Phenolic Impregnated Carbon Ablator)-tiled heatshield. PICA loses mass through surface recession and in-depth pyrolysis as it is heated. Pre-flight knowledge of heatshield mass loss is required for vehicle balancing during critical mission events. This study attempts to predict the total mass loss experienced by the Mars2020's heatshield during its entry. A grid was created over the half of the heatshield which generated 108 points across a total of 9 spokes. Aero-thermal environments were provided from CFD (Computational Fluid Dynamics) calculations that considered a baselined trajectory. The TPS (Thermal Protection System) stack was a build-up of composite, aluminum, composite, an HT-424 bond, followed by PICA. The FIAT (Fully Implicit Ablation, Thermal-response) 1-D analysis utilized this TPS stack and the CFD environments and was run at each grid point giving mass flux information from the point of atmospheric entry until parachute deployment. The mass flux due to recession and pyrolysis gas was summed and integrated first through time and then across the half heatshield using a polar integration tool. The mass loss results were mirrored to the other half of the heatshield to calculate total mass loss throughout the entry phase of flight. This total mass loss value and its distribution was used by entry vehicle designers to account for CG (Center of Gravity) offset during parachute descent when the heatshield is no longer losing significant mass.

PICA↗
NASA NTRS2020

Recurring Causes of Human Spaceflight Mishaps during Flight Tests and Early Operations

n analysis of recurring causes underlying human spaceflight mishaps that occurred during flight tests and early operations was performed. Eight mishaps from the Apollo, Soyuz, Skylab, Space Shuttle, and Constellation Programs (i.e., the Ares-1X test flight) and commercial suborbital systems were included in the study. Detailed event analyses were performed for the historical mishaps and aggregate data analyses conducted to identify recurring issues. The nine most frequent issues were inadequate technical controls or risk management practices, incomplete procedures, system design and development issues, inadequate inspection or secondary verification requirements, failures of organizations to learn from previous incidents, inadequate schedule controls, inadequate task analyses or design processes, flaws in the design of organizations, and issues with organizational safety cultures.

Timothy S Barth↗
NASA NTRSDate not supplied

Recurring Causes of Human Spaceflight Mishaps During Flight Tests and Early Operations

An analysis of recurring causes underlying human spaceflight mishaps that occurred during flight tests and early operations was performed. Eight mishaps from the Apollo, Soyuz, Skylab, Space Shuttle, and Constellation Programs (i.e., the Ares-1X test flight) and early commercial suborbital operations were included in the study. Detailed event analyses were performed for the historical mishaps and aggregate data analyses conducted to identify recurring issues. The nine most frequent issues were inadequate technical controls or risk management practices, incomplete procedures, system design and development issues, inadequate inspection or secondary verification requirements, failures of organizations to learn from previous incidents, inadequate schedule controls, inadequate task analyses or design processes, flaws in the design of organizations, and issues with organizational safety cultures.

Human Spaceflight↗
NASA NTRSDate not supplied

Electrostatic Regolith Interaction Experiment (ERIE) Electrometer Instrument Development

The Electrostatic Regolith Interaction Experiment (ERIE) is a joint venture between the University of Central Florida (UCF) Center for Microgravity Research (CMR) and the NASA Kennedy Space Center (KSC) Electrostatics and Surface Physics Laboratory (ESPL) seeking to examine charged dust grain behavior in a microgravity environment. Two separate systems have been combined for this suborbital flight experiment: the COLLisions Into Dust Experiment (COLLIDE) developed by the UCF CMR and the Wheel Electrostatic Spectrometer (WES) developed by the NASA KSC ESPL. This combination will advance the understanding of the natural and induced charged grain behavior on the Moon, asteroids, and other low gravity bodies comprised of charged dust particles. COLLIDE retains granular material under vacuum in a shallow tray behind a metal door, which then opens and releases the particles into a larger open volume when microgravity is achieved. The experiment is observed with a high-speed camera, such that the motions of these particles can then be tracked so the kinematics of each grain may be analyzed. The original application for this apparatus was to study cratering events into granular beds, but electrostatic repulsion was detected in the early frames of the video data returned from completed experiments, so a re-flight with a focus on these events was proposed. Agitation of the grains during launch combined with the frictional charge transfer between the grains and the door as it slides open provides an opportunity to use this setup to observe material tribocharging and charged particle behaviors in microgravity. In this updated version, the charged particles released into the chamber will traverse through an electric field produced by high voltage parallel plates and their resulting trajectories will be determined by their net charges. WES was originally developed to characterize the triboelectric properties of the Martian regolith through the contact of a rover wheel with the surface as it rotates. Improvements were made upon this legacy system to develop a sensor suite that will be installed within the COLLIDE door to measure charge transferred between the granular material and insulating disks protruding through the door. These insulator disks span the triboelectric series so, as they slide across the particulate matter when the door opens, each will accumulate a charge consistent with its relative position to the grains within the series. This charge on each insulator is distributed between two capacitances in series with an electrometer amplifier returning an analog voltage proportional to the charge accumulated. Calibration of this system has been performed using applications of known charge to the inputs and characterization of the frictional charge transfer between various regolith simulants and the sensor insulators is currently being examined in the lab.

Electrostatics↗
NASA NTRS2020

Uncertainty Quantification of Global Net Methane Emissions From Terrestrial Ecosystems Using a Mechanistically Based Biogeochemistry Model

Quantification of methane (CH4) emissions from wetlands and its sinks from uplands is still fraught with large uncertainties. Here, a methane biogeochemistry model was revised, parameterized, and verified for various wetland ecosystems across the globe. The model was then extrapolated to the global scale to quantify the uncertainty induced from four different types of uncertainty sources including parameterization, wetland type distribution, wetland area distribution, and meteorological input. We found that global wetland emissions are 212 ± 62 and 212 ± 32 Tg CH4 year−1 (1Tg = 1012 g) due to uncertain parameters and wetland type distribution, respectively, during 2000–2012. Using two wetland distribution data sets and three sets of climate data, the model simulations indicated that the global wetland emissions range from 186 to 212 CH4 year−1 for the same period. The parameters were the most significant uncertainty source. After combining the global methane consumption in the range of −34 to −46 Tg CH4 year−1, we estimated that the global net land methane emissions are 149–176 Tg CH4 year−1 due to uncertain wetland distribution and meteorological input. Spatially, the northeast United States and Amazon were two hotspots of methane emission, while consumption hotspots were in the Eastern United States and eastern China. During 1950–2016, both wetland emissions and upland consumption increased during El Niño events and decreased during La Niña events. This study highlights the need for more in situ methane flux data, more accurate wetland type, and area distribution information to better constrain the model uncertainty.

wetland methane emission↗
NASA NTRS2020

Evaluation of a Method to Retrieve Temperature and Wind Velocity Profiles of the Venusian Nightside Mesosphere from Mid-Infrared CO2 Absorption Line Observed by Heterodyne Spectroscopy

We evaluated a method for retrieving vertical temperature and Doppler wind velocity profiles of the Venusian nightside mesosphere from the CO2 absorption line resolved by mid-infrared heterodyne spectroscopy. The achievable sensitive altitude and retrieval accuracy were derived with multiple model spectra generated from various temperature and wind velocity profiles with several noise levels. The temperature profiles were retrieved at altitudes of 70–100 km with a vertical resolution of 5 km and a retrieval accuracy of ±15 K. The wind velocity was also retrieved at an altitude of approximately 85 km with a vertical resolution of 10 km and a retrieval accuracy of ± 25–50 m/s. In addition, we studied an event and applied our method to spectra obtained by the HIPWAC instrument attached to the NASA/IRTF 3-m telescope on May 19–22, 2012. Retrieved wind velocities in a latitude of 33° S at 3:00 LT were interpreted as subsolar-to-antisolar (SS-AS) flows at altitudes of 84 ±6 km and 94 ±7 km, and they were stronger than expected. This result suggested that the transition between the retrograde super rotational zonal (RSZ) wind and SS-AS flow may occur at altitudes below 90 km which previously was predicted to be the transition region. This work provides a basis for our analysis of further observations obtained by a mid-infrared heterodyne spectrometer MILAHI attached to the Tohoku University 60-cm telescope at Haleakalā, Hawaii.

Venus↗
NASA NTRSDate not supplied

Using Degradation Modeling to Identify Fragile Operational Conditions in Human- and Component-driven Resilience Assessment

Studying failure events shows that many high-impact events result from the complex interactions between precipitating failure events and degraded operational conditions. Often, when a system is put in operations, unforeseen practical realities (e.g., maintenance and/or workforce availability) lead the system to be operated in configurations outside its envisioned nominal range. However, design-time failure models often assume that the failure events are initiated in an idealized, nominal state of system operation, resulting in an incomplete assessment of future risk. To solve this, this paper develops a framework to consider degraded operational performance in scenario-based resilience models which uses a corresponding model of performance degradation to determine the values of deteriorated model parameters in the resilience model. This framework is demonstrated on a remotely-piloted rover to determine the (individual and combined) effect of drive-train wear and operator fatigue on the resilience of the rover to drive-train faults. This demonstration showed the substantial impact that degradation has on resilience, highlighting the need to account for degradation in resilience models–specifically, unconsidered degradation can lead to overestimates of resilience (and thus underestimates of safety margin) and because resilience can degrade prior to visible unreliability, which can lead to an operational environment with a high propensity for high-impact unforeseen failure events.

resilience↗
NASA NTRSDate not supplied

Reversion to the mean of the Solar Wind Input to the Magnetosphere

Earth’s magnetosphere responds to solar wind input over time scales ranging from minutes to days. On minute times scales, researchers seek to identify discontinuities in the solar wind that may trigger transient magnetospheric phenomena such as flux transfer events or substorm onsets. On hour time scales, researchers seek to determine the solar wind phenomena that drive the growth phase of geomagnetic substorms and the storage of magnetic flux within the magnetotail. On longer time scales, researchers seek to determine the solar wind features than propel geomagnetic storms through their initial, main, and recovery phases. Researchers must, perforce, rely upon spacecraft located near the L1 libration point for observations of the solar wind input into the magnetosphere over periods ranging from hours to days. Some of the hazards of doing this are well known. Features seen far upstream at locations away from the Sun-Earth line may never arrive at Earth due to structure in the solar wind transverse to the Sun-Earth line. Alternatively, they may arrive at unexpected times due to errors in calculating their orientation and velocity. Other hazards when predicting the magnetospheric response to varying solar wind conditions are less well understood. When observations of large solar wind drivers at spacecraft far upstream and off the Sun-Earth line are used to select events for study, the ‘reversion to the mean’ effect associated with spatial structure and errors in arrival timing for solar wind features at Earth demands that the magnetosphere will actually be subjected to and respond to solar wind drivers with much lower strengths. Consequently, the magnetospheric response must saturate for the highest solar wind drivers.

David Sibeck↗
NASA NTRSDate not supplied

Using Degradation Modeling to Identify Fragile Operational Conditions in Human- and Component-driven Resilience Assessment

Studying failure events shows that many high-impact events result from the complex interactions between precipitating failure events and degraded operational conditions. Often, when a system is put in operations, unforeseen practical realities (e.g., maintenance and/or workforce availability) lead the system to be operated in configurations outside its envisioned nominal range. However, design-time failure models often assume that the failure events are initiated in an idealized, nominal state of system operation, resulting in an incomplete assessment of future risk. To solve this, this paper develops a framework to consider degraded operational performance in scenario-based resilience models which uses a corresponding model of performance degradation to determine the values of deteriorated model parameters in the resilience model. This framework is demonstrated on a remotely-piloted rover to determine the (individual and combined) effect of drive-train wear and operator fatigue on the resilience of the rover to drive-train faults. This demonstration showed the substantial impact that degradation has on resilience, highlighting the need to account for degradation in resilience models--specifically, unconsidered degradation can lead to overestimates of resilience (and thus underestimates of safety margin) and because resilience can degrade prior to visible unreliability, which can lead to an operational environment with a high propensity for high-impact unforeseen failure events.

Daniel Hulse↗
NASA NTRSDate not supplied

Resources at GES DISC for Agriculture Studies

● Introduction to GES DISC (Distributed Active Archive Center- DAAC) ○ Data Holding for Agriculture study ● Resources for Agricultural studies at GES DISC ○ Data Access ○ Data Services and Tools ○ Learning resources : ■ Studying seasonality ■ Studying extreme events: Floods, Flash Floods, Heat Waves, Drought ■ Data Recipe (How-To) ● Demo and hands-on

Zhong Liu↗