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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 307 records · Page 17

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NASA NTRS2004

Prototype Training Materials for Acceptance Criteria of Maintenance ASAP Events Occurring Within Social Context

The aviation maintenance community is at a crossroads with respect to implementing the Aviation Safety Action Program (ASAP). While there is considerable interest, several key issues have emerged that cast doubt on how to assure a successful implementation, including buy-in from all levels of the company and training for key participants. There are two objectives for the present report. The first is to provide an examination of limits (or more properly, examples) of the degree of acceptability of more problematic events for risk-based decisions within the current ASAP guidelines. The second objective is to apply these limits of community standards to a set of further refined ASAP training scenarios.

ASAP (AVIATION SAFETY ACTION PROGRAM)↗

NASA NTRS2019

Pilot Evaluation of Proposed Go-Around Criteria for Transport Category Aircraft

The primary objective of this study was to capture pilot feedback and decision-making with regard to proposed, hypothetical, go-around criteria that were developed based on previous research. A secondary objective of the study was to assess crew members' awareness of the aircraft state on approach. An experiment was conducted using Boeing 737-800 and Airbus A330-200 level D full-flight simulators, in which pilots flew multiple approaches which were on the borderline of the proposed go-around criteria at 300 ft. Pilots were instructed that they could either execute a go-around or land the airplane on each run, forcing a decision for the borderline cases at 300 ft. Pilots were instructed to go around if the aircraft was outside of the go-around criteria at 300 ft or if either pilot was uncomfortable with the approach. The results revealed that: 1) the most important factors which drove go-around decision-making during the experiment were airspeed and localizer deviation, 2) the objective data suggested that the 300-ft gate is viable, although many pilots were still uncomfortable with that gate height; perhaps more emphasis on checking stability at 1,000 ft and 500 ft would make more pilots comfortable with the 300-ft go-around gate, 3) allowing for momentary deviations should be considered, and 4) the acceptability of the criteria is highly dependent on given pilot's risk tolerance. Overall, the proposed criteria performed well, and most pilots would find the criteria acceptable with some minor adjustments.

go-arounds↗

NASA NTRS2016

A Structured, Model-Based Systems Engineering Methodology for Operations System Design

Two widely accepted techniques for lowering the cost and risk of developing systems are (1) the use of a defined systems engineering (SE) process or methodology and (2) the reuse of existing (previously built) system components. The first technique is represented, for example, in materials published by NASA (e.g., NASA Systems Engineering Handbook) or by professional societies such as INCOSE (International Council on Systems Engineering). Well-formed SE techniques provide value by establishing the proper scope of the system (e.g., requirements), and by identifying and resolving problems relatively early in project lifecycles, when fixes are less expensive. The second technique (reuse) is applied most commonly to hardware and software; it seeks to avoid replicating design and implementation costs while also reducing risk by placing proven capabilities into operational use. In this paper, we outline a methodology combining these two techniques and extending reuse beyond hardware and software to foundational aspects of a Mission Operation System’s (MOS) design. We describe the system design artifacts that result (e.g., requirements, design documentation), as well as the reusable patterns and elements of the design, and their interrelationships. This approach is enabled by model-based systems engineering (MBSE) techniques and tools and is currently available in SysML form as a plug-in to MagicDraw. Additionally, usage of a rigorous MBSE approach allows for training materials and tutorials to be packaged within the overall model itself. The results of such an approach include decreased cost and risk during the design phase, improved ability of the MOS development team to investigate trade spaces and identify impacts to important flight-ground trade studies. Such results extend into decreased costs and risk in later phases due to improved design, decreased need for late fixes or development of "glue-ware" or scripts to fill unanticipated gaps in functionality, and improved ability to identify and plan testing and other validation activities. Finally, lower operational costs can be expected, both due to improved quality of the MOS, increased ease of maintaining updated knowledge of system configuration, and the fact that training and procedural materials are also updated at the same time as accepted system changes.

Bindschadler, Duane L.↗

NASA NTRS1988

Risk to civilization: A planetary science perspective

One of the most profound changes in our perspective of the solar system resulting from the first quarter century of planetary exploration by spacecraft is the recognition that planets, including Earth, were bombarded by cosmic projectiles for 4.5 aeons and continue to be bombarded today. Although the planetary cratering rate is much lower now than it was during the first 0.5 aeons, sizeable Earth-approaching asteroids and comets continue to hit the Earth at a rate that poses a finite risk to civilization. The evolution of this planetary perspective on impact cratering is gradual over the last two decades. It took explorations of Mars and Mercury by early Mariner spacecraft and of the outer solar system by the Voyagers to reveal the significance of asteroidal and cometary impacts in shaping the morphologies and even chemical compositions of the planets. An unsettling implication of the new perspective is addressed: the risk to human civilization. Serious scientific attention was given to this issue in July 1981 at a NASA-sponsored Spacewatch Workshop in Snowmass, Colorado. The basic conclusion of the 1981 NASA sponsored workshop still stands: the risk that civilization might be destroyed by impact with an as-yet-undiscovered asteroid or comet exceeds risk levels that are sometimes deemed unacceptable by modern societies in other contexts. Yet these impact risks have gone almost undiscussed and undebated. The tentative quantitative assessment by some members of the 1981 workshop was that each year, civilization is threatened with destruction with a probability of about 1 in 100,000. The enormous spread in risk levels deemed by the public to be at the threshold of acceptability derives from a host of psychological factors that were widely discussed in the risk assessment literature. Slovic shows that public fears of hazards are greatest for hazards that are uncontrollable, involuntary, fatal, dreadful, globally catastrophic, and which have consequences that seem inequitable, especially if they affect future generations.

Chapman, Clark R.↗

NASA NTRS2025

Assessment of Model Outcomes Between the Integrated Medical Model (IMM) and the Medical Extensible Dynamic Probabilistic Risk Assessment Tool (MEDPRAT)

The Medical Extensible Dynamic Probabilistic Risk Assessment Tool (MEDPRAT) is a computational model that provides human health and medical risk predictions for crewed spaceflight missions. MEDPRAT utilizes discrete event modeling and dynamic probabilistic simulation to predict critical mission outcomes (total medical events, crew health index, quality time lost, loss of crew life, removal to definitive care), condition occurrences, and resource consumption. Input parameters for MEDPRAT include crew attributes (e.g., sex), types of mission activities (e.g., whether and where crew members perform an extravehicular activity (EVA)), available resources, treatment information, and probability distributions for medical conditions. As an evolution of the Integrated Medical Model (IMM), MEDPRAT provides enhanced capabilities and higher fidelity, and incorporates more appropriate assumptions for long-duration spaceflight. IMM is the currently accepted standard for quantifying spaceflight mission medical risk in NASA operations that uses a probabilistic risk assessment (PRA) approach. MEDPRAT builds on the same logical foundation as IMM but implements the model architecture through highly optimized Monte Carlo sampling methods. An analysis is performed comparing the outputs from IMM with those from MEDPRAT V1.0 and V2.0 for the same reference missions in order to quantify similarities and differences in the model outcomes. The juxtaposition between IMM and MEDPRAT V1.0 and 2.0 shown in this report demonstrates that these two models generate very similar results; where differences in outcomes are shown, these are in accordance with the underlying assumptions and differences in the model architectures. This validation effort further establishes the credibility and reliability of the MEDPRAT software.

Matthew T Prelich↗

NASA NTRS1986

An optimization model for the US Air-Traffic System

A systematic approach for monitoring U.S. air traffic was developed in the context of system-wide planning and control. Towards this end, a network optimization model with nonlinear objectives was chosen as the central element in the planning/control system. The network representation was selected because: (1) it provides a comprehensive structure for depicting essential aspects of the air traffic system, (2) it can be solved efficiently for large scale problems, and (3) the design can be easily communicated to non-technical users through computer graphics. Briefly, the network planning models consider the flow of traffic through a graph as the basic structure. Nodes depict locations and time periods for either individual planes or for aggregated groups of airplanes. Arcs define variables as actual airplanes flying through space or as delays across time periods. As such, a special case of the network can be used to model the so called flow control problem. Due to the large number of interacting variables and the difficulty in subdividing the problem into relatively independent subproblems, an integrated model was designed which will depict the entire high level (above 29000 feet) jet route system for the 48 contiguous states in the U.S. As a first step in demonstrating the concept's feasibility a nonlinear risk/cost model was developed for the Indianapolis Airspace. The nonlinear network program --NLPNETG-- was employed in solving the resulting test cases. This optimization program uses the Truncated-Newton method (quadratic approximation) for determining the search direction at each iteration in the nonlinear algorithm. It was shown that aircraft could be re-routed in an optimal fashion whenever traffic congestion increased beyond an acceptable level, as measured by the nonlinear risk function.

Mulvey, J. M.↗

NASA NTRS1992

Health-risk based approach to setting drinking water standards for long-term space missions

In order to develop plausible and appropriate drinking water contaminant standards for longer-term NASA space missions, such as those planned for the Space Exploration Initiative, a human health risk characterization was performed using toxicological and exposure values typical of space operations and crew. This risk characterization showed that the greatest acute waterborne health concern was from microbial infection leading to incapacitating gastrointestinal illness. Ingestion exposure pathways for toxic materials yielded de minimus acute health risks unlikely to affect SEI space missions. Risks of chronic health problems were within acceptable public health limits. Our analysis indicates that current Space Station Freedom maximum contamination levels may be unnecessarily strict. We propose alternative environmental contaminant values consistent with both acceptable short and long-term crew health safety.

Macler, Bruce A.↗

NASA NTRS1993

Automated Estimation Of Software-Development Costs

COSTMODL is automated software development-estimation tool. Yields significant reduction in risk of cost overruns and failed projects. Accepts description of software product developed and computes estimates of effort required to produce it, calendar schedule required, and distribution of effort and staffing as function of defined set of development life-cycle phases. Written for IBM PC(R)-compatible computers.

Roush, George B.↗

NASA NTRS1999

Departure Energies, Trip Times and Entry Speeds for Human Mars Missions

The study examines how the mission design variables departure energy, entry speed, and trip time vary for round-trip conjunction-class Mars missions. These three parameters must be balanced in order to produce a mission that is acceptable in terms of mass, cost, and risk. For the analysis, a simple, massless- planet trajectory program was employed. The premise of this work is that if the trans-Mars and trans-Earth injection stages are designed for the most stringent opportunity in the energy cycle, then there is extra energy capability in the "easier" opportunities which can be used to decrease the planetary entry speed, or shorten the trip time. Both of these effects are desirable for a human exploration program.

Munk, Michelle M.↗

NASA NTRS2000

Empirical Approaches to Motor Stability Problems

Combustion stability remains a technical issue in some solid rocket motor development programs because techniques to characterize propellant and motor during a development program either do not exist or are inadequate. Moreover, the situation will remain uncertain until one or more stability related diagnostics that are routine, inexpensive, introduce no risk, and 'industrial strength' are qualified and accepted by the Department of Defense (DoD) and commercial customers. This paper describes an empirical diagnostic technique--passive motor diagnostics--with this potential and illustrates some of its characteristics. This methodology will provide customers with a level of confidence, after early development firing, that does not exist today.

Hessler, R. O.↗

NASA NTRS2001

High-Purity Aluminum Magnet Technology for Advanced Space Transportation Systems

Basic research on advanced plasma-based propulsion systems is routinely focused on plasmadynamics, performance, and efficiency aspects while relegating the development of critical enabling technologies, such as flight-weight magnets, to follow-on development work. Unfortunately, the low technology readiness levels (TRLs) associated with critical enabling technologies tend to be perceived as an indicator of high technical risk, and this, in turn, hampers the acceptance of advanced system architectures for flight development. Consequently, there is growing recognition that applied research on the critical enabling technologies needs to be conducted hand in hand with basic research activities. The development of flight-weight magnet technology, for example, is one area of applied research having broad crosscutting applications to a number of advanced propulsion system architectures. Therefore, NASA Marshall Space Flight Center, Louisiana State University (LSU), and the National High Magnetic Field Laboratory (NHMFL) have initiated an applied research project aimed at advancing the TRL of flight-weight magnets. This Technical Publication reports on the group's initial effort to demonstrate the feasibility of cryogenic high-purity aluminum magnet technology and describes the design, construction, and testing of a 6-in-diameter by 12-in-long aluminum solenoid magnet. The coil was constructed in the machine shop of the Department of Physics and Astronomy at LSU and testing was conducted in NHMFL facilities at Florida State University and at Los Alamos National Laboratory. The solenoid magnet was first wound, reinforced, potted in high thermal conductivity epoxy, and bench tested in the LSU laboratories. A cryogenic container for operation at 77 K was also constructed and mated to the solenoid. The coil was then taken to NHMFL facilities in Tallahassee, FL. where its magnetoresistance was measured in a 77 K environment under steady magnetic fields as high as 10 T. In addition, the temperature dependence of the coil's resistance was measured from 77 to 300 K. Following this series of tests, the coil was transported to NHMFL facilities in Los Alamos, NM, and pulsed to 2 T using an existing capacitor bank pulse generator. The coil was completely successful in producing the desired field without damage to the windings.

Goodrich, R. G.↗

NASA NTRS1999

Departure Energies, Trip Times and Entry Speeds for Human Mars Missions

The study examines how the mission design variables departure energy, entry speed, and trip time vary for round-trip conjunction-class Mars missions. These three parameters must be balanced in order to produce a mission that is acceptable in terms of mass, cost, and risk. For the analysis, a simple, massless-planet trajectory program was employed. The premise of this work is that if the trans-Mars and trans-Earth injection stages are designed for the most stringent opportunity in the energy cycle, then there is extra energy capability in the "easier" opportunities which can be used to decrease the planetary entry speed, or shorten the trip time. Both of these effects are desirable for a human exploration program.

Munk, Michelle M.↗

NASA NTRSDate not supplied

Assessment of Model Outcomes between MEDPRAT and the IMM

- The Integrated Medical Model (IMM) is the accepted standard for quantifying spaceflight mission medical risk in NASA operations. - While MEDPRAT implemented a new, efficient architecture and new capability, it's basic functionality mimics that of the IMM. - How does the outcome for the same reference missions and input data compare between IMM and MEDPRAT V1 and MEDPRAT V2?

Clara Gasiewski↗

NASA NTRS2023

Requirements Engineering Scorecard and the Next-Generation Space Suit

The objective for a NASA contractor, the performing organization in this case study, is to provide engineering services to develop and deliver the next generation space suit to NASA, the customer in this case study. A case study with qualitative and quantitative analyses regarding a new process and approach to requirements engineering is described, with the intent that if utilized, these tools may have contributed to improvements across the project in terms of meeting cost, scope, budget and quality while appropriately accounting for risk management. The procedure entails a research method in which the current state of the project, current state of the art, and the identified systems engineering challenges are evaluated. Iterative models are tempered through development by continual improvements by engineering evaluation of engineers on the project. The current results have produced a prototype of a requirements engineering scorecard with implementations of FMEA and quantitative analysis to (i) identify root cause of underdeveloped requirements and (ii) project management impacts with regards to project risk. Forward work includes customer, performing organization, acceptance against applicable INCOSE community accepted practices.

INCOSE↗

NASA NTRS2016

Estimating Orion Heat Shield Failure Due To Ablator Cracking During The EFT-1 Mission

The Orion EFT-1 heatshield suffered from two major certification challenges: First, the mechanical properties used in design were not evident in the flight hardware and second, the flight article itself cracked during fabrication. The combination of these events motivated the Orion Program to pursue an engineering-level Probabilistic Risk Assessment (PRA) as part of heatshield certification rationale. The PRA provided loss of Mission (LOM) likelihoods considering the probability of a crack occurring during the mission and the likelihood of subsequent structure over-temperature. The methods and input data for the PRA are presented along with a discussion of the test data used to anchor the results. The Orion program accepted an EFT-1 Loss of Vehicle (LOV) risk of 1-in-160,000 due to in-mission Avcoat cracking based on the results of this analysis. Conservatisms in the result, along with future considerations for Exploration Missions (EM) are also addressed.

Avcoat↗

NASA NTRS2000

A Nuclear Interaction Model for Understanding Results of Single Event Testing with High Energy Protons

An internuclear cascade and evaporation model has been adapted to estimate the LET spectrum generated during testing with 200 MeV protons. The model-generated heavy ion LET spectrum is compared to the heavy ion LET spectrum seen on orbit. This comparison is the basis for predicting single event failure rates from heavy ions using results from a single proton test. Of equal importance, this spectra comparison also establishes an estimate of the risk of encountering a failure mode on orbit that was not detected during proton testing. Verification of the general results of the model is presented based on experiments, individual part test results, and flight data. Acceptance of this model and its estimate of remaining risk opens the hardware verification philosophy to the consideration of radiation testing with high energy protons at the board and box level instead of the more standard method of individual part testing with low energy heavy ions.

Culpepper, William X.↗

NASA NTRS1993

The Application of Integrated Knowledge-based Systems for the Biomedical Risk Assessment Intelligent Network (BRAIN)

One of NASA's goals for long duration space flight is to maintain acceptable levels of crew health, safety, and performance. One way of meeting this goal is through the Biomedical Risk Assessment Intelligent Network (BRAIN), an integrated network of both human and computer elements. The BRAIN will function as an advisor to flight surgeons by assessing the risk of in-flight biomedical problems and recommending appropriate countermeasures. This paper describes the joint effort among various NASA elements to develop BRAIN and an Infectious Disease Risk Assessment (IDRA) prototype. The implementation of this effort addresses the technological aspects of the following: (1) knowledge acquisition; (2) integration of IDRA components; (3) use of expert systems to automate the biomedical prediction process; (4) development of a user-friendly interface; and (5) integration of the IDRA prototype and Exercise Countermeasures Intelligent System (ExerCISys). Because the C Language, CLIPS (the C Language Integrated Production System), and the X-Window System were portable and easily integrated, they were chosen as the tools for the initial IDRA prototype. The feasibility was tested by developing an IDRA prototype that predicts the individual risk of influenza. The application of knowledge-based systems to risk assessment is of great market value to the medical technology industry.

Loftin, Karin C.↗

NASA NTRS2015

Process Control for Precipitation Prevention in Space Water Recovery Systems

The ability to recover and purify water through physiochemical processes is crucial for realizing long‐term human space missions, including both planetary habitation and space travel. Because of their robust nature, rotary distillation systems have been actively pursued by NASA as one of the technologies for water recovery from wastewater primarily comprised of human urine. A specific area of interest is the prevention of the formation of solids that could clog fluid lines and damage rotating equipment. To mitigate the formation of solids, operational constraints are in place that limits such that the concentration of key precipitating ions in the wastewater brine are below the theoretical threshold. This control in effected by limiting the amount of water recovered such that the risk of reaching the precipitation threshold is within acceptable limits. The water recovery limit is based on an empirically derived worst case wastewater composition. During the batch process, water recovery is estimated by monitoring the throughput of the system. NASA Johnson Space Center is working on means of enhancing the process controls to increase water recovery. Options include more precise prediction of the precipitation threshold. To this end, JSC is developing a means of more accurately measuring the constituent of the brine and/or wastewater. Another means would be to more accurately monitor the throughput of the system. In spring of 2015, testing will be performed to test strategies for optimizing water recovery without increasing the risk of solids formation in the brine.

Sargusingh, Miriam↗