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At least 235 records · Page 13

Autonomous Assessment and Predictive Capabilities for Low-Altitude Urban Flight Operations

The integration of unmanned aerial vehicles in the national airspace will introduce new vehicle types, technologies, and operational paradigms for which safety must be maintained and hazards mitigated. One approach is to attempt to design for possible hazards and unsafe incidents that can occur at different phases of flight (pre-flight, in-flight, and post-flight) and during ground operations. Another is to mitigate safety incidents by implementing changes to policies, procedures, regulations, and design to cover personnel, equipment, and aircraft during operations. These and other techniques, not described herein, are typically conservative or adhoc in that they reduce the likelihood of risk after safety incidents have occurred. In this work, the goal is to develop a more predictive capability to monitor and mitigate risk and hazards to safety “in-time” enough for decisions to be made. In line with NASA’s Aeronautics Mission Directorate Strategic Thrust 5 [1] (In-Time System-Wide Safety Assurance), the System-Wide Safety (SWS) project under which this work falls, is developing and demonstrating innovative and safety-oriented solutions that enable modernization and aviation transformation. To that effect, this work will detail data-driven efforts on the SWS project to develop a number of safety-critical services for in-time monitoring and mitigation of hazards to low-altitude flight operations. First, hazards to these operations are identified based on previous work by NASA [2,3] and others in the aerospace industry. These hazards include (i) unsafe proximity to other vehicles, property, and people on the ground, (ii) critical system failures such as communication signal/GPS loss, unexpected propulsion system degradation, engine/power failure, and (iii) operational/environmental issues such as severe weather and gusty winds. For these hazards, safety metrics, which can be quantified and assessed are defined, models to monitor and predict them are developed, and flight test data is generated to develop, validate, and test these models, considering the complex interplay of the different hazards that define them [4-6]. In addition, the uncertainty in the non-deterministic effects that cannot be modeled nor predicted and unknown unknowns that arise after design/testing and during operations must be handled in rigorous manner. As a result, for each of the developed safety metrics, their dependencies on one another are characterized and a framework for handling the uncertainties inherent in the modeling, algorithms, and measurements required for prediction is also developed [7]. To that effect, this presentation will describe the safety metrics and services already developed and underway under the System-Wide Safety project that utilize data-driven techniques for the identification of anomalies, precursors, and trends (APTs) to monitor and mitigate hazards to safety, in-time, for urban flight operations in low-altitude airspace.

Okolo, Wendy A.↗

Accidental ignition in propellant processing

Sources of ignition during solid propellant processing are discussed in terms of the operations performed and the resultant hazard to facilities and personnel. The most serious ignition hazard in composite solid propellant processing occurs during the mixing operation where the sources for Ignition are greatest and the result of an ignition most catastrophic because of the state of subdivision of flammable material and its confinement.

H M Shuey↗

Certification methodology applied to the NASA experimental radar system

The objective of the research is to apply selected FAA certification techniques to the NASA experimental wind shear radar system. Although there is no intent to certify the NASA system, the procedures developed may prove useful to manufacturers that plan to undergo the certification process. The certification methodology for forward-looking wind shear detection radars will require estimation of system performance in several FAA-specified microburst/clutter scenarios as well as the estimation of probabilities of missed and false hazard alerts under general operational conditions. Because of the near-impossibility of obtaining these results experimentally, analytical and simulation approaches must be used. Hazard detection algorithms were developed that derived predictive estimates of aircraft hazard from basic radar measurements of weather reflectivity and radial wind velocity. These algorithms were designed to prevent false alarms due to ground clutter while providing accurate predictions of hazard to the aircraft due to weather. A method of calculation of the probability of missed and false hazard alerts has been developed that takes into account the effect of the various algorithms used in the system and provides estimates of the probability of missed and false alerts per microburst encounter under weather conditions found at Denver, Kansas City, and Orlando. Simulation techniques have been developed that permit the proper merging of radar ground clutter data (obtained from flight tests) with simulated microburst data (obtained from microburst models) to estimate system performance using the microburst/clutter scenarios defined by the FAA.

Britt, Charles L.↗

Industrial and biomedical use of aerospace personal cooling garments

Liquid-cooled garments (LCG) have been developed which utilize liquid-cooled modules rather than the network of tygon tubing typical of Apollo LCG's. The ultra-thin, heat-sealed, polyurethane modules are situated over the body to cover 50 percent of the body surface area with special emphasis on the 'working' muscles and the head-neck area. These garments are being designed specifically for industrial and biomedical uses, such as: a head-neck cooling system which is being tested for race-car drivers, tractor drivers, truck drivers, or a head-neck cooling system tested for the reduction of the scalp hair loss which normally accompanies cancer treatments. A combined head-neck and thorax unit is being developed for use during mine distaster rescue operations, and for other hazardous hot applications. Finally applications for head-neck and partitional cooling are anticipated for military pilots, tank drivers, and heavy equipment operations.

Williams, B. A.↗

Cassini's Grand Finale: A Mission Planning Retrospective

On September 15, 2017, Cassini plunged deep into Saturn, down to where the atmosphere was sufficiently dense to destroy the spacecraft, making it part of Saturn forever. In the five months leading up to its destruction, Cassini flew between Saturn and its rings 22 times, collecting data from the never before-explored region of the Kronian system. These orbits, the Grand Finale of Cassini, were the culmination of years of planning by the Cassini flight team. This paper looks back upon the mission planning effort in particular, comparing the baseline operational scenarios and contingency plans to the as flown Grand Finale. The bulk of the Grand Finale mission planning effort was focused on the environmental hazards present in the region between Saturn and its rings: the dust and the atmosphere. Dust hazard and atmospheric transit contingency plans were in place to help ensure spacecraft health and maximize science data return. The dust hazard plan gave the operations team the option to turn the spacecraft to a safe attitude during ring-plane crossings had the dust environment proved more threatening than anticipated. The atmospheric transit plan would have made use of an orbital trim maneuver in order to raise or lower periapsis depending on the density of the atmosphere. The proximal environment did have its surprises, though they were good surprises. The dust was significantly less hazardous than predicted. So much so that elements of the contingency plan were leveraged in order to remove a dust hazard protection from the baseline plan, rather than add one to it. While the atmosphere was substantially denser than predicted, it was not dense enough to warrant a periapsis-raise maneuver and actually meant that better in-situ data was gathered. Ultimately, from a mission planning perspective, the Grand Finale went better than expected.

Sturm II, Erick J.↗

PAAV Concept Document

The Pathfinding for Airspace with Autonomous Vehicles (PAAV) Concept Document, version 1.0, lays out the key challenges and potential solutions for the use of uncrewed aircraft (UA) technology for future regional air cargo operations. The challenges and solutions described in this document were informed by communications with the UA industry community (e.g., RTCA, the Federal Aviation Administration, and regional air cargo business operators), as well as the PAAV team’s research activities during the last two years including four tabletop exercises, a human-in-the-loop simulation study, a numerical simulation study, a functional allocation study, and flight data analysis (Appendix A). This document first describes the expected operational context of PAAV (Section 2), such as the flight mission, baseline UAS components, nominal operations, m:N operations (i.e., "m" remote pilots per "N" aircraft), and off-nominal operations. This context sets the scope for the PAAV concept development work. PAAV concept development assumes that UA operations will be increasingly autonomous. Thus, near- and far-term assumptions are defined (Section 3). PAAV identified seven key challenges for UA operations (Section 4): - Flight route planning - Separation and flow management - Traffic pattern integration - Contingency management - Taxi, takeoff, and landing - m:N operations - Communications operations The following 13 potential solutions to these challenges are then described (Section 5): - Scalable communications architecture - Data link - Designated UAS corridors - Crew planning for m:N operations - Flight route optimization - Traffic load-level control - Trajectory solutions with data link - Automated hazard avoidance for m:N operations - Traffic pattern integration (TPI) tool - Standard lost command and control (C2) link (LC2L) procedures - Automated hazard avoidance under LC2L - Auto-taxi, auto-takeoff, and auto-land - Ground control station (GCS) user interface for m:N operations The document attempts to link each of these solutions to one or more of the challenge areas. Novel solutions involving numerous automation technologies are needed to mitigate traffic and airspace management challenges, especially for realizing m:N operations and ensuring safety under LC2L conditions. The purpose of this document is to help understand alternatives and tradeoffs among potential solutions and provide a foundation for a cohesive PAAV concept that will be described and refined in subsequent concept versions.

Unmanned aircraft, uncrewed aircraft, regional air↗

Study of alternate methods of disposal of propellants and gases at KSC

A comprehensive study was conducted at KSC launch support facilities to determine the nature and extent of potential hazards from propellant and gas releases to the environment. The results of the study, alternate methods for reducing or eliminating the hazards, and recommendations pertaining to these alternatives are presented. The operational modes of the propellant or hazardous gas systems considered include: system charging, system standby, system operation, and post-test operations. The results are outlined on an area-by-area basis.

Moore, W. I.↗

Safety in earth orbit study. Volume 4: Space shuttle orbiter: Safety requirements and guidelines on-orbit phase

Safety requirements and guidelines are listed for the space shuttle orbiter and for its interface with other vehicles. The requirements and guidelines are specific to the hazards and emergencies in earth orbit. The requirements and guidelines for the orbiter are those with respect to vehicle design, safety devices, warning devices, operational procedures, and residual hazards. The requirements and guidelines for interface with the space station, upper stage vehicles, and sortie payloads are imposed on these vehicles to ensure the safety of the shuttle orbiter. The rationale for the safety requirements and guidelines is also discussed.

Source record↗

Exploring Concepts of Operations for On-Demand Passenger Air Transportation

In recent years, a surge of interest in "flying cars" for city commutes has led to rapid development of new technologies to help make them and similar on-demand mobility platforms a reality. To this end, this paper provides analyses of the stakeholders involved, their proposed operational concepts, and the hazards and regulations that must be addressed. Three system architectures emerged from the analyses, ranging from conventional air taxi to revolutionary fully autonomous aircraft operations, each with vehicle safety functions allocated differently between humans and machines. Advancements for enabling technologies such as distributed electric propulsion and artificial intelligence have had major investments and initial experimental success, but may be some years away from being deployed for on-demand passenger air transportation at scale.

Nneji, Victoria Chibuogu↗

The Integrated Hazard Analysis Integrator

Hazard analysis addresses hazards that arise in the design, development, manufacturing, construction, facilities, transportation, operations and disposal activities associated with hardware, software, maintenance, operations and environments. An integrated hazard is an event or condition that is caused by or controlled by multiple systems, elements, or subsystems. Integrated hazard analysis (IHA) is especially daunting and ambitious for large, complex systems such as NASA s Constellation program which incorporates program, systems and element components that impact others (International Space Station, public, International Partners, etc.). An appropriate IHA should identify all hazards, causes, controls and verifications used to mitigate the risk of catastrophic loss of crew, vehicle and/or mission. Unfortunately, in the current age of increased technology dependence, there is the tendency to sometimes overlook the necessary and sufficient qualifications of the integrator, that is, the person/team that identifies the parts, analyzes the architectural structure, aligns the analysis with the program plan and then communicates/coordinates with large and small components, each contributing necessary hardware, software and/or information to prevent catastrophic loss. As viewed from both Challenger and Columbia accidents, lack of appropriate communication, management errors and lack of resources dedicated to safety were cited as major contributors to these fatalities. From the accident reports, it would appear that the organizational impact of managers, integrators and safety personnel contributes more significantly to mission success and mission failure than purely technological components. If this is so, then organizations who sincerely desire mission success must put as much effort in selecting managers and integrators as they do when designing the hardware, writing the software code and analyzing competitive proposals. This paper will discuss the necessary and sufficient requirements of one of the significant contributors to mission success, the IHA integrator. Discussions will be provided to describe both the mindset required as well as deleterious assumptions/behaviors to avoid when integrating within a large scale system.

Morris, A. Terry↗

Use of Traffic Intent Information by Autonomous Aircraft in Constrained Operations

This paper presents findings of a research study designed to provide insight into the issue of intent information exchange in constrained en-route air-traffic operations and its effect on pilot decision-making and flight performance. The piloted simulation was conducted in the Air Traffic Operations Laboratory at the NASA Langley Research Center. Two operational modes for autonomous flight management were compared under conditions of low and high operational complexity (traffic and airspace hazard density). The tactical mode was characterized primarily by the use of traffic state data for conflict detection and resolution and a manual approach to meeting operational constraints. The strategic mode involved the combined use of traffic state and intent information, provided the pilot an additional level of alerting, and allowed an automated approach to meeting operational constraints. Operational constraints applied in the experiment included separation assurance, schedule adherence, airspace hazard avoidance, flight efficiency, and passenger comfort. The strategic operational mode was found to be effective in reducing unnecessary maneuvering in conflict situations where the intruder's intended maneuvers would resolve the conflict. Conditions of high operational complexity and vertical maneuvering resulted in increased proliferation of conflicts, but both operational modes exhibited characteristics of stability based on observed conflict proliferation rates of less than 30 percent. Scenario case studies illustrated the need for maneuver flight restrictions to prevent the creation of new conflicts through maneuvering and the need for an improved user interface design that appropriately focuses the pilot's attention on conflict prevention information. Pilot real-time assessment of maximum workload indicated minimal sensitivity to operational complexity, providing further evidence that pilot workload is not the limiting factor for feasibility of an en-route distributed traffic management system, even under highly constrained conditions.

Wing, David J.↗

Neural operators for stochastic modeling of nonlinear structural system response to natural hazards

Traditionally, neural networks have been employed to learn the mapping between finite-dimensional Euclidean spaces. However, recent research has opened up new horizons, focusing on the utilization of deep neural networks to learn operators capable of mapping infinite-dimensional function spaces. Here, in this work, we employ two state-of-the-art neural operators, the deep operator network (DeepONet) and the Fourier neural operator (FNO) for the prediction of the nonlinear time history response of structural systems exposed to natural hazards, such as earthquakes and windstorms. Specifically, we propose two architectures, a self-adaptive FNO and a fast Fourier transform-based DeepONet (DeepFNOnet), where we employ a FNO beyond the DeepONet to learn the discrepancy between the ground truth and the solution predicted by the DeepONet. To demonstrate the efficiency and applicability of the architectures, two problems are considered. In the first, we use the proposed model to predict the seismic nonlinear dynamic response of a six-story shear building subject to stochastic ground motions. In the second problem, we employ the operators to predict the wind-induced nonlinear dynamic response of a high-rise building while explicitly accounting for the stochastic nature of the wind excitation. In both cases, the trained metamodels achieve high accuracy while being orders of magnitude faster than their corresponding high-fidelity models.

DeepONet↗

Man-made space debris - Does it restrict free access to space

Consideration is given to the hazards posed by existing and future man-made space debris to spacecraft operations. The components of the hazard are identified as those fragments resulting from spacecraft explosions and spent stages which can be tracked, those fragments which are too small to be tracked at their present distances, and future debris, which, if present trends in spacecraft design and operation continue, may lead to an unacceptably high probability of collision with operational spacecraft within a decade. It is argued that a coordinated effort must be undertaken by all space users to evaluate means of space debris control in order to allow for the future unrestricted use of near-earth space. A plan for immediate action to forestall the space debris problem by activities in the areas of education, debris monitoring and collection technology, space vehicle design, space operational procedures and practices and space policies and treaties is proposed.

Wolfe, M.↗

SimSup's Loop: A Control Theory Approach to Spacecraft Operator Training

Immersive simulation is a staple of training for many complex system operators, including astronauts and ground operators of spacecraft. However, while much has been written about simulators, simulation facilities, and operator certification programs, the topic of how one develops simulation scenarios to train a spacecraft operator is relatively understated in the literature. In this paper, an approach is presented for using control theory as the basis for developing the immersive simulation scenarios for a spacecraft operator training program. The operator is effectively modeled as a high level controller of lower level hardware and software control loops that affect a select set of system state variables. Simulation scenarios are derived from a STAMP-based hazard analysis of the operator's high and low level control loops. The immersive simulation aspect of the overall training program is characterized by selecting a set of scenarios that expose the operator to the various inadequate control actions that stem from control flaws and inadequate control executions in the different sections of the typical control loop. Results from the application of this approach to the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission are provided through an analysis of the simulation scenarios used for operator training and the actual anomalies that occurred during the mission. The simulation scenarios and inflight anomalies are mapped to specific control flaws and inadequate control executions in the different sections of the typical control loop to illustrate the characteristics of anomalies arising from the different sections of the typical control loop (and why it is important for operators to have exposure to these characteristics). Additionally, similarities between the simulation scenarios and inflight anomalies are highlighted to make the case that the simulation scenarios prepared the operators for the mission.

LADEE↗

Assessment of Technical Information Needs and Considerations for Front-End Activities for Molten Salt Fuel Types

This report details an assessment of the hazards and safety impacts related to front-end operations of molten salt reactors (MSR) as well as an assessment of existing safety guidance. Publicly available information was evaluated to make recommendations to the U.S. Nuclear Regulatory Commission (NRC) for guidance development and information gathering needs. Five different MSR technologies were evaluated along with information from 1960’s about the Atomic Energy Commission programs for the Aircraft Reactor Experiment and Molten Salt Reactor Experiment. Primary areas of evaluation include fuel cycle facilities, transportation and at reactor fuel mixing operations up to reactor startup. In general, there was difficulty synthesizing publicly available information due to the early stage of the MSR development and proprietary information associated with the reactor technology companies analyzed. There are a few specific recommendations from this report. One overarching paradigm shift that the NRC needs to evaluate is the possibility of collocating fuel cycle facilities with operating MSRs. Although there is no specific prohibition to this in the NRC regulations, the collocation of the fuel cycle facilities with the operating MSR presents a novel approach compared to the light water reactor baseline. More guidance and research into thorium operations and regulation is needed. The hazards associated with the stability of stored fuel constituents need to be evaluated. Some reactor fuel cycles use beryllium, and its use and the associated hazards need further analysis. NRC-approved designs for transportation packages for shipping molten salt fuels and factory-built and fueled reactors are not available.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Autonomous Cryogenic Leak Detector for Improving Launch Site Operations

NASA, military, and commercial satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. This project has developed a tapered optical fiber sensor for detecting hydrogen. The invention involves incorporating chemical indicators on the tapered end of an optical fiber using organically modified silicate nanomaterials. The Hazardous Gas Detection Lab (HGDL) at Kennedy Space Center is involved in the design and development of instrumentation that can detect and qualify various mission-critical chemicals. Historically, hydrogen, helium, nitrogen, oxygen, and argon are the first five gases of HGDL focus. The use of these cryogenic fluids in the area of propulsion offers challenges. Due to their extreme low temperatures, these fluids induce contraction of the materials they contact, a potential cause of leakage. Among them, hydrogen is of particular concern. Small sensors are needed in multiple locations without adding to the structural weight. The most vulnerable parts of the engine are the connection flanges on the transfer lines, which have to support cycles of large thermal amplitude. The thermal protection of the engine provides a closed area, increasing the likelihood of an explosive atmosphere. Thus, even a small leak represents an unacceptable hazardous condition during loading operations, in flight, or after an aborted launch. Tapered fibers were first fabricated from 1/1.3-mm core/cladding (silica/ plastic) optical fibers. Typically a 1-ft (approx. 30- cm) section of the 1-mm fiber is cut from the bundle and marked with a pen into five 2-.-in. (.5.7-cm) sections. A propane torch is applied at every alternate mark to burn the jacket and soften the glass core. While the core is softening, the two ends of the fiber are pulled apart slowly to create fine tapers of .- to .-in. (.6- to 12-mm) long on the 1-mm optical fiber. Following this, the non-tapered ends of the fibers are polished to a 0.3-micron finish. Then these fibers were coated with indicators sensitive to hydrogen. The tapered hydrogen detection system with its unique flexibility is the only system that can be placed in many locations inside the vehicles and detect the exact location of leaks, saving millions of dollars for launch vehicle industries.

Goswami, Kisholoy↗

Mitigation of Electrostatic Hazards on Spacecraft

Spacecraft are complex systems operating in challenging environments that require customized testing procedures designed to mitigate the unique hazards of a space launch environment. As an example of those testing procedures, we describe the test methodology and recommendations developed to mitigate electrostatic discharges that could have triggered an explosion of the Space Shuttle during launch, return to launch site, abort after one orbit, or during normal landing.

Calle, C. I.↗