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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 235 records · Page 13
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NASA NTRS2020

Climate change reshapes the drivers of false spring risk across European trees

(1) Temperate forests are shaped by late spring freezes after budburst—false springs—which may shift with climate change. Research to date has generated conflicting results, potentially because few studies focus on the multiple underlying drivers of false spring risk. (2) Here, we assessed the effects of mean spring temperature, distance from the coast, elevation and the North Atlantic Oscillation (NAO) using PEP725 leafout data for six tree species across 11648 sites in Europe, to determine which were the strongest predictors of false spring risk and how these predictors shifted with climate change. (3) All predictors influenced false spring risk before recent warming, but their effects have shifted in both magnitude and direction with warming. These shifts have potentially magnified the variation in false spring risk among species with an increase in risk for early‐leafout species (i.e., Aesculus hippocastanum , Alnus glutinosa , Betula pendula ) versus a decline or no change in risk among late‐leafout species (i.e., Fagus sylvatica , Fraxinus excelsior , Quercus robur ). (4) Our results show how climate change has reshaped the drivers of false spring risk, complicating forecasts of future false springs, and potentially reshaping plant community dynamics given uneven shifts in risk across species.

false spring↗
NASA NTRS2022

Systemic Risk

Systemic risk is the name given to impacts that spread within and across systems and sectors (e.g. ecosystems, health, infrastructure and the food sector) via the movements of people, goods, capital and information within and across boundaries (e.g. regions, countries and continents). The spread of these impacts can lead to potentially existential consequences and system collapse across a range of time horizons. Globalization contributes to systemic risk affecting people worldwide. The impacts of climate change or COVID-19 show how the challenges of addressing systemic risk go beyond conventional risk management and governance. Critical system interdependencies, amplified by underlying vulnerabilities, highlight that there is a growing need to better understand cascading impacts, systemic risks and the possible political (governance) and societal responses. This includes improving our understanding of the root causes of systemic risk, both biophysical and socio-economic, and related information needs. Addressing contemporary challenges in terms of systemic risk requires integrating different systems perspectives and fostering system thinking, while implementing key intergovernmental agendas, such as the Paris Agreement, the Sendai Framework for Disaster Risk Reduction and the Sustainable Development Goals.

systemic risk↗
NASA NTRS1996

Risk as a Resource: A New Paradigm

In the new NASA, risk management must be developed as a skill to a far greater degree than has existed in the past. Past approaches have produced great successes but at great cost and lengthy schedules. In the future, risk and its component contributors must be re-evaluated. There are three contexts of risk that will be addressed in this paper: risk as a resource, which expands and shifts traditional risk considerations; marginal cost of risk, which addresses the cumulative and time related effects of risk reduction; and an alternative definition or new meaning of success and how it relates to work.

risk management risk success mission risk↗
NASA NTRS1988

Risk analysis of earth return options for the Mars rover/sample return mission

Four options for return of a Mars surface sample to Earth were studied to estimate the risk of mission failure and the risk of a sample container breach that might result in the release of Martian life forms, should such exist, in the Earth's biosphere. The probabilities calculated refer only to the time period from the last midcourse correction burn to possession of the sample on Earth. Two extreme views characterize this subject. In one view, there is no life on Mars, therefore there is no significant risk and no serious effort is required to deal with back contamination. In the other view, public safety overrides any desire to return Martian samples, and any risk of damaging contamination greater than zero is unacceptable. Zero risk requires great expense to achieve and may prevent the mission as currently envisioned from taking place. The major conclusion is that risk of sample container breach can be reduced to a very low number within the framework of the mission as now envisioned, but significant expense and effort, above that currently planned is needed. There are benefits to the public that warrant some risk. Martian life, if it exists, will be a major discovery. If it does not, there is no risk.

Source record↗
NASA NTRS2000

Summary of Results from the Risk Management Program for the Mars Microrover Flight Experiment

On 4 July 1997, the Mars Pathfinder landed on the surface of Mars carrying the first planetary rover, known as the Sojourner. Formally known as the Microrover Flight Experiment (MFEX), the Sojourner was a low cost, high-risk technology demonstration, in which new risk management techniques were tried. This paper summarizes the activities and results of the effort to conduct a low-cost, yet meaningful risk management program for the MFEX. The specific activities focused on cost, performance, schedule, and operations risks. Just as the systems engineering process was iterative and produced successive refinements of requirements, designs, etc., so was the risk management process. Qualitative risk assessments were performed first to gain some insights for refining the microrover design and operations concept. These then evolved into more quantitative analyses. Risk management lessons from the manager's perspective is presented for other low-cost, high-risk space missions.

Shishko, Robert↗
NASA NTRS2003

Reducing the Risk of Human Space Missions with INTEGRITY

The INTEGRITY Program will design and operate a test bed facility to help prepare for future beyond-LEO missions. The purpose of INTEGRITY is to enable future missions by developing, testing, and demonstrating advanced human space systems. INTEGRITY will also implement and validate advanced management techniques including risk analysis and mitigation. One important way INTEGRITY will help enable future missions is by reducing their risk. A risk analysis of human space missions is important in defining the steps that INTEGRITY should take to mitigate risk. This paper describes how a Probabilistic Risk Assessment (PRA) of human space missions will help support the planning and development of INTEGRITY to maximize its benefits to future missions. PRA is a systematic methodology to decompose the system into subsystems and components, to quantify the failure risk as a function of the design elements and their corresponding probability of failure. PRA provides a quantitative estimate of the probability of failure of the system, including an assessment and display of the degree of uncertainty surrounding the probability. PRA provides a basis for understanding the impacts of decisions that affect safety, reliability, performance, and cost. Risks with both high probability and high impact are identified as top priority. The PRA of human missions beyond Earth orbit will help indicate how the risk of future human space missions can be reduced by integrating and testing systems in INTEGRITY.

Jones, Harry W.↗
NASA NTRS2008

The Integrated Medical Model: Statistical Forecasting of Risks to Crew Health and Mission Success

The Integrated Medical Model (IMM) helps capture and use organizational knowledge across the space medicine, training, operations, engineering, and research domains. The IMM uses this domain knowledge in the context of a mission and crew profile to forecast crew health and mission success risks. The IMM is most helpful in comparing the risk of two or more mission profiles, not as a tool for predicting absolute risk. The process of building the IMM adheres to Probability Risk Assessment (PRA) techniques described in NASA Procedural Requirement (NPR) 8705.5, and uses current evidence-based information to establish a defensible position for making decisions that help ensure crew health and mission success. The IMM quantitatively describes the following input parameters: 1) medical conditions and likelihood, 2) mission duration, 3) vehicle environment, 4) crew attributes (e.g. age, sex), 5) crew activities (e.g. EVA's, Lunar excursions), 6) diagnosis and treatment protocols (e.g. medical equipment, consumables pharmaceuticals), and 7) Crew Medical Officer (CMO) training effectiveness. It is worth reiterating that the IMM uses the data sets above as inputs. Many other risk management efforts stop at determining only likelihood. The IMM is unique in that it models not only likelihood, but risk mitigations, as well as subsequent clinical outcomes based on those mitigations. Once the mathematical relationships among the above parameters are established, the IMM uses a Monte Carlo simulation technique (a random sampling of the inputs as described by their statistical distribution) to determine the probable outcomes. Because the IMM is a stochastic model (i.e. the input parameters are represented by various statistical distributions depending on the data type), when the mission is simulated 10-50,000 times with a given set of medical capabilities (risk mitigations), a prediction of the most probable outcomes can be generated. For each mission, the IMM tracks which conditions occurred and decrements the pharmaceuticals and supplies required to diagnose and treat these medical conditions. If supplies are depleted, then the medical condition goes untreated, and crew and mission risk increase. The IMM currently models approximately 30 medical conditions. By the end of FY2008, the IMM will be modeling over 100 medical conditions, approximately 60 of which have been recorded to have occurred during short and long space missions.

Fitts, M. A.↗
NASA NTRS2009

Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis

This document, Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis, is intended to provide guidelines for the collection and evaluation of risk and reliability-related data. It is aimed at scientists and engineers familiar with risk and reliability methods and provides a hands-on approach to the investigation and application of a variety of risk and reliability data assessment methods, tools, and techniques. This document provides both: A broad perspective on data analysis collection and evaluation issues. A narrow focus on the methods to implement a comprehensive information repository. The topics addressed herein cover the fundamentals of how data and information are to be used in risk and reliability analysis models and their potential role in decision making. Understanding these topics is essential to attaining a risk informed decision making environment that is being sought by NASA requirements and procedures such as 8000.4 (Agency Risk Management Procedural Requirements), NPR 8705.05 (Probabilistic Risk Assessment Procedures for NASA Programs and Projects), and the System Safety requirements of NPR 8715.3 (NASA General Safety Program Requirements).

Dezfuli, Homayoon↗
NASA NTRS2009

Human Research Program Human Health Countermeasures Element Sensorimotor Risk Standing Review Panel (SRP) Final Report

The Sensorimotor Risk Standing Review Panel (SRP) met at the NASA Johnson Space Center on October 4-6, 2009 to discuss the areas of future research targeted by the Human Health Countermeasures (HHC) Element of the Human Research Program (HRP). Using evidence-based knowledge as a background for risks, NASA had identified gaps in knowledge to address those risks. Ongoing and proposed tasks were presented to address the gaps. The charge to the Sensorimotor Risk SRP was to review the gaps, evaluate whether the tasks addressed these gaps and to make recommendations to NASA s HRP Science Management Office regarding the SRP's review. The SRP was requested to evaluate the practicality of the proposed efforts in light of the realistic demands placed on the HRP. In short, all tasks presented in the Integrated Research Plan (IRP) should address specific risks related to the challenges faced by the astronauts as a result of prolonged exposure to microgravity. All tasks proposed to fill the gaps in knowledge should provide applied, translational data necessary to address the specific risks. Several presentations were made to the SRP during the site visit and the SRP spent sufficient time to address the panel charge, either as a group or in separate sessions. The SRP made a final debriefing to the HRP Program Scientist. Taking the evidence and the risk as givens, the SRP reached the following conclusions: 1) the panel is very supportive of and endorses the present activities of the Sensorimotor Risk; and the panel is likewise supportive of the gaps and associated tasks in the IRP; 2) overall, the tasks addressed the gaps in the IRP; 3) there were some gaps and tasks that merit further enhancement and some new gaps/tasks that the SRP recommends.

Peterson, Barry↗
NASA NTRS2009

Human Research Program Human Health Countermeasures Element Bone and Muscle Risk Standing Review Panel (SRP)

The Bone and Muscle Risk Standing Review Panel (SRP) met at the NASA Johnson Space Center (JSC) on October 4-6, 2009 to discuss the areas of current and future research targeted by the Human Health Countermeasures (HHC) Element of the Human Research Program (HRP). Using evidence-based knowledge as a background for identified risks to astronaut health and performance, NASA had identified gaps in knowledge to address those risks. Ongoing and proposed tasks were presented to address the gaps. The charge to the Bone and Muscle Risk SRP was to review the gaps, evaluate whether the tasks addressed these gaps and to make recommendations to NASA s HRP Science Management Office regarding the Panel's review. The Bone and Muscle Risk SRP consisted of scientists who are experts in muscle, bone, or both and could evaluate the existing evidence with sufficient knowledge of the potential effects of long duration exposure to microgravity. More important, although expertise in basic science is important, the SRP was requested to evaluate the practicality of the proposed efforts in light of the realistic demands placed on the HRP. In short, all tasks presented in the Integrated Research Plan (IRP) should address specific questions related to the challenges faced by the astronauts as a result of prolonged exposure to microgravity. All tasks proposed to fill the gaps in knowledge should provide applied, translational data necessary to answer the specific questions. Several presentations were made to the SRP during the site visit and the SRP spent sufficient time to address the panel charge, either as a group or in separate sessions for the Bone and Muscle Risk subgroups. The SRP made a final debriefing to the HRP Program Scientist, Dr. John B. Charles, on October 6, 2009. Taking the evidence and identified risks as givens, the SRP concluded that 1) integration of information should lead to a more comprehensive approach to identifying the gaps, 2) not all tasks addressed the gaps as stated in the IRP, 3) better access should be given to the SRP to existing data to include in its review, and 4) there were some missing gaps and tasks. As a result the SRP recommended 1) combining certain gaps, which in some cases were addressed with identical tasks, 2) additional gaps and tasks to address some of the gaps, 3) deleting some gaps and tasks to better focus the efforts of NASA s HRP in prioritizing their efforts, and 4) prioritizing gaps to address significant issues needing resolution in the short term while maintaining an awareness of long-term goals. The SRP commended the efforts by the HHC Element to integrate knowledge gaps and design tasks to address the higher order questions. This integration did not apply to the Bone and Muscle Risk alone, but the musculoskeletal system as its functions integrate with issues in

Glowacki, Julie↗
NASA NTRS2010

Risk-Informed Safety Assurance and Probabilistic Assessment of Mission-Critical Software-Intensive Systems

This report validates and documents the detailed features and practical application of the framework for software intensive digital systems risk assessment and risk-informed safety assurance presented in the NASA PRA Procedures Guide for Managers and Practitioner. This framework, called herein the "Context-based Software Risk Model" (CSRM), enables the assessment of the contribution of software and software-intensive digital systems to overall system risk, in a manner which is entirely compatible and integrated with the format of a "standard" Probabilistic Risk Assessment (PRA), as currently documented and applied for NASA missions and applications. The CSRM also provides a risk-informed path and criteria for conducting organized and systematic digital system and software testing so that, within this risk-informed paradigm, the achievement of a quantitatively defined level of safety and mission success assurance may be targeted and demonstrated. The framework is based on the concept of context-dependent software risk scenarios and on the modeling of such scenarios via the use of traditional PRA techniques - i.e., event trees and fault trees - in combination with more advanced modeling devices such as the Dynamic Flowgraph Methodology (DFM) or other dynamic logic-modeling representations. The scenarios can be synthesized and quantified in a conditional logic and probabilistic formulation. The application of the CSRM method documented in this report refers to the MiniAERCam system designed and developed by the NASA Johnson Space Center.

Guarro, Sergio B.↗
NASA NTRS2010

Risk-Informed Decision Making: Application to Technology Development Alternative Selection

NASA NPR 8000.4A, Agency Risk Management Procedural Requirements, defines risk management in terms of two complementary processes: Risk-informed Decision Making (RIDM) and Continuous Risk Management (CRM). The RIDM process is used to inform decision making by emphasizing proper use of risk analysis to make decisions that impact all mission execution domains (e.g., safety, technical, cost, and schedule) for program/projects and mission support organizations. The RIDM process supports the selection of an alternative prior to program commitment. The CRM process is used to manage risk associated with the implementation of the selected alternative. The two processes work together to foster proactive risk management at NASA. The Office of Safety and Mission Assurance at NASA Headquarters has developed a technical handbook to provide guidance for implementing the RIDM process in the context of NASA risk management and systems engineering. This paper summarizes the key concepts and procedures of the RIDM process as presented in the handbook, and also illustrates how the RIDM process can be applied to the selection of technology investments as NASA's new technology development programs are initiated.

Dezfuli, Homayoon↗
NASA NTRS2010

Assessing the Fire Risk for a Historic Hangar

NASA Ames Research Center (ARC) is evaluating options of reuse of its historic Hangar 1. As a part of this evaluation, a qualitative fire risk assessment study was performed to evaluate the potential threat of combustion of the historic hangar. The study focused on the fire risk trade-off of either installing or not installing a Special Hazard Fire Suppression System in the Hangar 1 deck areas. The assessment methodology was useful in discussing the important issues among various groups within the Center. Once the methodology was deemed acceptable, the results were assessed. The results showed that the risk remained in the same risk category, whether Hangar 1 does or does not have a Special Hazard Fire Suppression System. Note that the methodology assessed the risk to Hangar 1 and not the risk to an aircraft in the hangar. If one had a high value aircraft, the aircraft risk analysis could potentially show a different result. The assessed risk results were then communicated to management and other stakeholders.

Datta, Koushik↗
NASA NTRS2010

From Process to Product: Your Risk Process at Work

The Space Life Sciences Directorate (SLSD) and Human Research Program (HRP) at the NASA/Johnson Space Center work together to address and manage the human health and performance risks associated with human space flight. This includes all human system requirements before, during, and after space flight, providing for research, and managing the risk of adverse long-term health outcomes for the crew. We previously described the framework and processes developed for identifying and managing these human system risks. The focus of this panel is to demonstrate how the implementation of the framework and associated processes has provided guidance in the management and communication of human system risks. The risks of early onset osteoporosis, CO2 exposure, and intracranial hypertension in particular have all benefitted from the processes developed for human system risk management. Moreover, we are continuing to develop capabilities, particularly in the area of information architecture, which will also be described. We are working to create a system whereby all risks and associated actions can be tracked and related to one another electronically. Such a system will enhance the management and communication capabilities for the human system risks, thereby increasing the benefit to researchers and flight surgeons.

Kundrot, Craig E.↗
NASA NTRS2011

Shuttle Risk Progression by Flight

Understanding the early mission risk and progression of risk as a vehicle gains insights through flight is important: . a) To the Shuttle Program to understand the impact of re-designs and operational changes on risk. . b) To new programs to understand reliability growth and first flight risk. . Estimation of Shuttle Risk Progression by flight: . a) Uses Shuttle Probabilistic Risk Assessment (SPRA) and current knowledge to calculate early vehicle risk. . b) Shows impact of major Shuttle upgrades. . c) Can be used to understand first flight risk for new programs.

Hamlin, Teri↗
NASA NTRS2011

Cancer Risk Map for the Surface of Mars

We discuss calculations of the median and 95th percentile cancer risks on the surface of Mars for different solar conditions. The NASA Space Radiation Cancer Risk 2010 model is used to estimate gender and age specific cancer incidence and mortality risks for astronauts exploring Mars. Organ specific fluence spectra and doses for large solar particle events (SPE) and galactic cosmic rays (GCR) at various levels of solar activity are simulated using the HZETRN/QMSFRG computer code, and the 2010 version of the Badhwar and O Neill GCR model. The NASA JSC propensity model of SPE fluence and occurrence is used to consider upper bounds on SPE fluence for increasing mission lengths. In the transport of particles through the Mars atmosphere, a vertical distribution of Mars atmospheric thickness is calculated from the temperature and pressure data of Mars Global Surveyor, and the directional cosine distribution is implemented to describe the spherically distributed atmospheric distance along the slant path at each elevation on Mars. The resultant directional shielding by Mars atmosphere at each elevation is coupled with vehicle and body shielding for organ dose estimates. Astronaut cancer risks are mapped on the global topography of Mars, which was measured by the Mars Orbiter Laser Altimeter. Variation of cancer risk on the surface of Mars is due to a 16-km elevation range, and the large difference is obtained between the Tharsis Montes (Ascraeus, Pavonis, and Arsia) and the Hellas impact basin. Cancer incidence risks are found to be about 2-fold higher than mortality risks with a disproportionate increase in skin and thyroid cancers for all astronauts and breast cancer risk for female astronauts. The number of safe days on Mars to be below radiation limits at the 95th percent confidence level is reported for several Mission design scenarios.

Kim, Myung-Hee Y.↗
NASA NTRS2012

Calysto: Risk Management for Commercial Manned Spaceflight

The Calysto: Risk Management for Commercial Manned Spaceflight study analyzes risk management in large enterprises and how to effectively communicate risks across organizations. The Calysto Risk Management tool developed by NASA's Kennedy Space Center's SharePoint team is used and referenced throughout the study. Calysto is a web-base tool built on Microsoft's SharePoint platform. The risk management process at NASA is examined and incorporated in the study. Using risk management standards from industry and specific organizations at the Kennedy Space Center, three methods of communicating and elevating risk are examined. Each method describes details of the effectiveness and plausibility of using the method in the Calysto Risk Management Tool. At the end of the study suggestions are made for future renditions of Calysto.

Dillaman, Gary↗
NASA NTRS2007

Measurement Decision Risk - The Importance of Definitions

One of the more misunderstood areas of metrology is the Test Uncertainty Ratio (TUR) and its cousin, the Test Accuracy Ratio (TAR). There have been many definitions over the years, but why are these definitions important to a discussion on measurement decision risk? The importance lies in the clarity of communication. Problems can immediately arise in the application (or misapplication) of the definition of these terms. In other words, while it is important to understand the definitions, it is more important to understand concepts behind the definitions and to be precise in how they are applied. The objective of any measurement is a decision. Measurement Decision Risk is a way to look at the quality of a measurement and although it is not a new concept, it has generated a lot of attention since its addition as a requirement in the new U.S. National Standard, ANSI/NCSL Z540.3-2006. In addition to Measurement Decision Risk as the prime method of managing measurement risk, Z540.3 has also added, as a fall-back, an explicit definition for TUR. The impact these changes might have on calibration service providers if these requirements are levied on them has become the topic of much discussion and in some cases concern. This paper looks at the concepts behind the definitions and how they relate to Measurement Decision Risk. Using common examples, this paper will also provide a comparison of various elements of risk related to measurement science using the concepts of TAR, TUR, accuracy ratios, and Consumer Risk (False Accept Risk). The goal is to provide a better understanding of their relevance to the measurement decision process.

Mimbs, Scott M.↗