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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Air shower arrival directions measured at Buckland Park

The Buckland Park air shower array was operated for 3 years from 1979 to 1981 particularly for the study of anisotropies in the region of the knee of the size spectrum. The array which has been described in detail elsewhere was situated at a latitude of 35 S and had an effective size threshold of approx 3 x 10 to the 5th power particles (approx 3 x 10 to the 15th power Ev for vertical showers). A number of results from this experiment have already been published including anisotropy analyses (Gerhardy and Clay, 1983) and searches for very high energy gamma ray sources. The final distribution of measured shower arrival directions are presented here. These 1.3 x 10 to the 5th power events were selected as indicated in detail in Gerhardy and Clay (1983) and were essentially those events with well measured arrival directions. They are the same data set used in the above reference but no complete sky map has previously been presented.

Gerhardy, P. R.↗
NASA NTRS1985

The Buckland Park air shower array

The new Buckland Park Air Shower Array has been producing analyzed shower data since July 1984. The array is described and some preliminary performance figures are presented.

Clay, R. W.↗
NASA NTRS1984

The Adelaide VHF radar: Capabilities and future plans

The VHF radar at Buckland Park, South Australia commenced operation in January, 1984. The radar is located adjacent to the 2-MHz ionospheric radar. The routine method for measuring horizontal wind velocity is the space antenna technique (SA) while the Doppler technique is used to measure vertical velocities. It is possible to swing the transmitting beam in the east-west plane, allowing Doppler measurements of the EW wind component.

Briggs, B. H.↗
NASA NTRS1985

Observation of gamma-rays from LMC X-4 above 10(16) eV

Data from the University of Adelaide air shower array at Buckland Park taken over a three year period have been analyzed to search for evidence of ultra high energy gamma-ray emission from neutron star binary X-ray sources having known orbital periods. The detection of UHE gamma-rays from LMC X-4 above 10 to the 16th power eV, is reported; the first extragalactic object to be positively detected at these energies.

Protheroe, R. J.↗
NASA NTRS1990

Software requirements: Guidance and control software development specification

The software requirements for an implementation of Guidance and Control Software (GCS) are specified. The purpose of the GCS is to provide guidance and engine control to a planetary landing vehicle during its terminal descent onto a planetary surface and to communicate sensory information about that vehicle and its descent to some receiving device. The specification was developed using the structured analysis for real time system specification methodology by Hatley and Pirbhai and was based on a simulation program used to study the probability of success of the 1976 Viking Lander missions to Mars. Three versions of GCS are being generated for use in software error studies.

Withers, B. Edward↗
NASA NTRS1989

Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex. II - Seasonal trends in ozone

A photochemical model consisting of 40 species and 107 reactions is integrated along 80-day air parcel trajectories calculated in the lower stratosphere for the springtime Antarctic. For the trajectory starting at 58 deg S, which may be regarded as outside the circumpolar vortex, only a small change in O3 occurs in the model. In contrast, for the air parcel starting in the vortex at 74 deg S, the O3 concentration is reduced by 93 percent during the 80 days from the beginning of August to late October. The model results for several species are compared with measurements from the Airborne Antarctic Ozone Experiment and, in general, good agreement is obtained. In the model, the dentrification of the air parcels in polar stratospheric clouds increases the amount of chlorine present in active form. Heterogeneous reactions maintain high active chlorine which destroys O3 via the formation of the ClO dimer. Results of calculations with reduced concentrations of inorganic chlorine show considerably reduced O3 destruction rates and compare favorably with the behavior of total O3 since the late 1970s. The remaining major uncertainties in the photochemical aspects of the Antarctic ozone hole are highlighted.

Austin, J.↗
NASA NTRS1989

The Southern Hemisphere lower stratosphere during August and September 1987 - Analyses based on the United Kingdom Meteorological Office Global Model

This paper presents a series of meteorological analyses used to aid the interpretation of the in situ Airborne Antarctic Ozone Experiment (AAOE) observations obtained aboard the ER-2 and DC-8 aircraft and examines the basis and accuracy of the analytical procedure. Maps and sections of meteorological variables derived from the UK Meteorological Office Global Model are presented for ER-2 and DC-8 flight days. It is found that analyzed temperatures and winds are generally in good agreement with AAOE observations at all levels; minor discrepancies were evident only at DC-8 altitudes. Maps of potential vorticity presented on the 428-K potential temperature surface show that the vortex is essentially circumpolar, although there are periods when major distortions are apparent.

Mckenna, D. S.↗
NASA NTRS1992

On-line implementation of nonlinear parameter estimation for the Space Shuttle main engine

We investigate the performance of a nonlinear estimation scheme applied to the estimation of several parameters in a performance model of the Space Shuttle Main Engine. The nonlinear estimator is based upon the extended Kalman filter which has been augmented to provide estimates of several key performance variables. The estimated parameters are directly related to the efficiency of both the low pressure and high pressure fuel turbopumps. Decreases in the parameter estimates may be interpreted as degradations in turbine and/or pump efficiencies which can be useful measures for an online health monitoring algorithm. This paper extends previous work which has focused on off-line parameter estimation by investigating the filter's on-line potential from a computational standpoint. ln addition, we examine the robustness of the algorithm to unmodeled dynamics. The filter uses a reduced-order model of the engine that includes only fuel-side dynamics. The on-line results produced during this study are comparable to off-line results generated previously. The results show that the parameter estimates are sensitive to dynamics not included in the filter model. Off-line results using an extended Kalman filter with a full order engine model to address the robustness problems of the reduced-order model are also presented.

Buckland, Julia H.↗
NASA NTRS2018

Quantifying Methane Leak Emissions by Fused Airborne Imaging Spectroscopy with in Situ Surface Mobile and Airborne Observations of a California Producing Oil Field

Methane (CH4) emission budgets remain uncertain and are projected to grow as oil and gas production from short-lived wells increases and their subsequent transport through aging gas distribution networks. Orders-of-magnitude variations in temporal, spatial, and emission scales present a key challenge to leak detection and quantification. Also, the probability distributions for large and stochastic, leaky systems such as geological reservoirs (by natural migration-seeps) and petroleum production from those reservoirs remain largely unknown, needed to address current approach limitations. The scale of many petroleum systems favors remote sensing, but the sensitivity of such systems often precludes detection of weak emissions. Consequently, an accurate evaluation requires that the relative contribution from the emission "tails" of small leaks also be quantified, which is best carried out using high-sensitivity in situ methods. Fusion of remote sensing and in situ approaches leverages complementary capabilities to address these limitations. We show results from mobile surface (AMOG) and airborne in situ (AJAX) and thermal-infrared (TIR) hyperspectral imaging spectroscopy (Mako) data applied to a producing oil field in the California Central Valley near Bakersfield. AMOG is an automobile-based mobile lab that measures 13 trace gases, aerosol size distributions and vertical profiles, 3D winds and other meteorology, and atmospheric column measurements by solar spectroscopy at highway speeds. AJAX measures 5 trace gases and 3D winds at ~140 m/s. Mako is a broad-area TIR imaging spectrometer that can discriminate multiple gases present in each pixel acquired. In situ-derived, total field emissions were 31±16 Gg/yr CH4. This was compared with Mako-derived emissions from all plumes identified across the study site. We found that super-emitters were not the dominant emissions mode and the spatial pattern of plume locations from production infrastructure was correlated to geological structures.

Leifer, Ira↗
NASA NTRSDate not supplied

Monte Carlo simulations of neutrino and charged lepton propagation in the Earth with nuPyProp

An accurate modeling of neutrino flux attenuation and the distribution of leptons they produce in transit through the Earth is an essential component to determine neutrino flux sensitivities of underground, sub-orbital and space-based detectors. Through neutrino oscillations over cosmic distances, astrophysical neutrino sources are expected to produce nearly equal fluxes of electron, muon and tau neutrinos. Of particular interest are tau neutrinos that interact in the Earth at modest slant depths to produce leptons. Some leptons emerge from the Earth and decay in the atmosphere to produce extensive air showers. Future balloon-borne and satellite-based opticalCherenkov neutrino telescopes will be sensitive to upward air showers from tau neutrino induced lepton decays. We present nuPyProp, a python code that is part of the nuSpaceSim package. nuPyProp generates look-up tables for exit probabilities and energy distributions for (see paper for proper equation) propagation in the Earth. This flexible code runs with either stochastic or continuous electromagnetic energy losses for the lepton transit through the Earth. Current neutrino cross section models and energy loss models are included along with templates for user input of other models. Results from nuPyProp are compared with other recent simulation packages for neutrino and charged lepton propagation. Sources of modeling uncertainties are described and quantified.

Yosui Akaike↗
NASA NTRSDate not supplied

Human System Risk Changes in 2021

The Human System Risk Board (HSRB) has the overall responsibility for tracking the evolution of the top ~30 human system risks that it has identified to be associated with human spaceflight. As part of this process, the Board is charged with maintaining a consistent, integrated process to mitigate those risks, and developing evidence-based risk posture recommendations. Risks are re-evaluated in a Continuous Risk Management (CRM) process. This session will summarize the risk posture changes that have occurred in the last year and what high level research, performance, and epidemiologic data have informed those changes. Human System Risks updated in 2021 include: Dynamic Loads, Sensorimotor, EVA, Crew Egress, Behavioral Medicine, Electrical Shock, Human System Integration Architecture (HSIA), Toxic Exposure, Bone Fracture, Cardiovascular, Medical Conditions, Renal Stone, CO2 Exposure, and Pharmacology.

Mary Van Baalen↗
NASA NTRSDate not supplied

High Value Risk Targets in Human System Risk

The Human System Risk Board (HSRB) has the overall responsibility for tracking the evolution of the top ~30 human system risks that it has identified to be associated with human spaceflight. The Board is also charged with maintaining a consistent, integrated process to mitigate those risks, and developing evidence-based risk posture recommendations. Each Risk Custodian Team (RCT) identifies High Value Risk Mitigation Targets (HVRMT) that have the highest likelihood or greatest impact in reducing their risk. These typically include areas where there are major gaps in knowledge or capability; or other targets that promise to yield returns worthy of investments in time, money and other resources by stakeholders interested in reducing Human System Risk. As part of the review of each risk the Board members consider and discuss the HVRMT statements, which are then approved by the Board Chair. High Value Risk Mitigation Targets can include research activities funded by the Human Research Program, but often involve recommending standards, monitoring, or other operational goals to reduce risk. This presentation will discuss common themes and highlights of the approved HVRTs to inform IWS attendees and the wider research community.

D M Buckland↗
NASA NTRSDate not supplied

NASA’s Identified Risks of Adverse Outcomes Due to Inadequate Human Systems Integration Architecture in Human Spaceflight

The NASA Human System Risk Board (HSRB) has the overall responsibility for tracking the evolution of the top ~30 human system risks that it has identified to be associated with human spaceflight. As part of this process, the Board is charged with maintaining a consistent, integrated process to mitigate those risks, and developing evidence-based risk posture recommendations. One of the identified risks is due to inadequate human systems integration architecture (HSIA) and a driving factor of this risk is that given decreasing real-time ground support for execution of complex operations during future exploration missions, there is a possibility of adverse performance outcomes including that crew are unable to adequately respond to unanticipated critical malfunctions or detect safety critical procedural errors. The HSRB uses Directed Acyclic Graphs (DAGs) as a communication tool for describing how astronaut exposure to spaceflight hazards leads to meaningful mission-level health and performance outcomes and as the basis for understanding intermediate causal relationships between risk contributing factors and countermeasures that link hazards to outcomes. The HSIA risk DAG will be presented and described. Historically, critical malfunctions requiring Crew/MCC management occurred at a rate of 1.7 times per year for ISS averaged over the lifetime and 3-4 times per year in the burn in phase for the vehicle. These averages do not include EVA data, which greatly increases the incident rate. Prior experience from the Apollo program showed 10/11 crewed missions experienced significant anomalies where crew relied heavily on MCC expertise in real-time. These failure patterns are in line with those observed in other complex engineered systems (e.g., oil rigs, launch systems, commercial aviation, etc.) It is likely that general malfunction and error rates are > 10% for short duration missions (<30 days), based on past and current spaceflight operations data. Likelihood of adverse outcomes has the potential to increase as crew conduct work with new, complex systems and with less ground support. For Low Earth Orbit missions and Lunar missions less than 30 days, assuming minimal comm delays, disruptions and bandwidth limitations, malfunctions and errors can affect mission objectives and crew health but may be mitigated by ground support. For Lunar missions greater than 30 days and any potential Mars mission malfunctions and errors can have Loss of Crew and Loss of Mission consequences due to reduced ground support (communication delays, constraints and blackouts) for more complex operations, as well as reduced resupply and evacuation options.

Daniel M Buckland↗
NASA NTRSDate not supplied

NASA's Identified Risk of Adverse Outcomes due to Inadequate Human Systems Integration Architecture

The NASA Human System Risk Board (HSRB) is responsible for tracking the evolution of the top ~30 human system risks identified to be associated with human spaceflight. As part of this process, the Board is charged with maintaining a consistent, integrated process to evaluate those risks and developing evidence-based risk posture recommendations. Risks are ranked by likelihood and consequence. Intermediate causal relationships between risk contributing factors and countermeasures that link hazards to outcomes are described using Directed Acyclic Graphs (DAGs). The DAGs are also useful for identifying common factors and countermeasures across the top 30 risks as well as communicating how astronaut exposure to spaceflight hazards leads to meaningful mission-level health and performance outcomes. One of the top risks tracked by the HSRB is The Risk of Adverse Outcomes Due to Inadequate Human-Systems Integration Architecture (HSIA). This risk captures the possibility that due to decreasing real-time ground support during missions beyond LEO, crew will be unable to adequately respond to unanticipated critical malfunctions or detect safety-critical procedural errors. The HSIA risk is ranked red (high) for Lunar surface and Mars missions due to the probability of Loss of Crew and Loss of Mission consequences. This paper describes the evidence that supports the HSIA risk ranking and presents the central narrative of the HSIA risk DAG-- i.e., anomaly detection, diagnosis, intervention, and task performance. Characterizations of the current state of practice for each of the DAG’s central nodes and the future tools needed for successful anomaly response are provided.

human-systems integration architecture↗
NASA NTRS2022

Directed Acyclic Graph Guidance Documentation

For over a decade, the National Aeronautics and Space Administration (NASA) has tracked and configuration-managed approximately 30 risks to astronaut health and performance that occur before, during and after spaceflight. The Human System Risk Board (HSRB), a Health and Medical Technical Authority (HMTA) Board at NASA Johnson Space Center, is the entity responsible for identifying, assessing, analyzing, and monitoring the official understanding of the risk or risk posture for each of the Human System Risks and determining – based on evaluation of the available evidence – when that risk posture changes. The ultimate purpose of tracking and researching these risks is to find ways to reduce the risk that astronaut crews face during spaceflight. Historically, research, development and operations relevant to one risk have been conducted in isolation from other risks; these individual risk ‘silos’ enabled initial characterization of each specific risk. In spaceflight however, the impact of exposure to risk for astronaut crews is cumulative, and not independent of exposures or other risks, as all the adverse effects of the spaceflight environment begin at launch, continue throughout the duration of the mission and in some cases across the lifetime of the crews. In January of 2020, the HSRB at NASA embarked on a pilot project designed to assess the potential value of causal diagramming as a tool to facilitate understanding these cumulative and interdependent effects as applied within Human System Risk management. This process uses directed acyclic graphs as a means of formalizing a shared mental model of the causal flow of risk among Risk Board stakeholders. Initially this model was to improve communication among those stakeholders, but the potential value exceeds communication alone. Formalization of the process for creating these causal diagrams will enable the creation of a composite risk network that is vetted by members of the NASA community and configuration managed. The causal diagrams are formulated as directed acyclic graphs (DAGs) to function as a type of knowledge graph for reference for the board and its stakeholders. This document outlines the pilot process, the standardized approaches, and guidance for risk custodian teams when creating and updating DAGs as a part of the NASA Human System Risk Management process.

Risk↗