Engineering Resilient Space Systems

Several distinct trends will influence space exploration missions in the next decade. Destinations are becoming more remote and mysterious, science questions more sophisticated, and, as mission experience accumulates, the most accessible targets are visited, advancing the knowledge frontier to more difficult, harsh, and inaccessible environments. This leads to new challenges including: hazardous conditions that limit mission lifetime, such as high radiation levels surrounding interesting destinations like Europa or toxic atmospheres of planetary bodies like Venus; unconstrained environments with navigation hazards, such as free-floating active small bodies; multielement missions required to answer more sophisticated questions, such as Mars Sample Return (MSR); and long-range missions, such as Kuiper belt exploration, that must survive equipment failures over the span of decades. These missions will need to be successful without a priori knowledge of the most efficient data collection techniques for optimum science return. Science objectives will have to be revised ‘on the fly’, with new data collection and navigation decisions on short timescales. Yet, even as science objectives are becoming more ambitious, several critical resources remain unchanged. Since physics imposes insurmountable light-time delays, anticipated improvements to the Deep Space Network (DSN) will only marginally improve the bandwidth and communications cadence to remote spacecraft. Fiscal resources are increasingly limited, resulting in fewer flagship missions, smaller spacecraft, and less subsystem redundancy. As missions visit more distant and formidable locations, the job of the operations team becomes more challenging, seemingly inconsistent with the trend of shrinking mission budgets for operations support. How can we continue to explore challenging new locations without increasing risk or system complexity? These challenges are present, to some degree, for the entire Decadal Survey mission portfolio, as documented in Vision and Voyages for Planetary Science in the Decade 2013–2022 (National Research Council, 2011), but are especially acute for the following mission examples, identified in our recently completed KISS Engineering Resilient Space Systems (ERSS) study: 1. A Venus lander, designed to sample the atmosphere and surface of Venus, would have to perform science operations as components and subsystems degrade and fail; 2. A Trojan asteroid tour spacecraft would spend significant time cruising to its ultimate destination (essentially hibernating to save on operations costs), then upon arrival, would have to act as its own surveyor, finding new objects and targets of opportunity as it approaches each asteroid, requiring response on short notice; and 3. A MSR campaign would not only be required to perform fast reconnaissance over long distances on the surface of Mars, interact with an unknown physical surface, and handle degradations and faults, but would also contain multiple components (launch vehicle, cruise stage, entry and landing vehicle, surface rover, ascent vehicle, orbiting cache, and Earth return vehicle) that dramatically increase the need for resilience to failure across the complex system. The concept of resilience and its relevance and application in various domains was a focus during the study, with several definitions of resilience proposed and discussed. While there was substantial variation in the specifics, there was a common conceptual core that emerged—adaptation in the presence of changing circumstances. These changes were couched in various ways—anomalies, disruptions, discoveries—but they all ultimately had to do with changes in underlying assumptions. Invalid assumptions, whether due to unexpected changes in the environment, or an inadequate understanding of interactions within the system, may cause unexpected or unintended system behavior. A system is resilient if it continues to perform the intended functions in the presence of invalid assumptions. Our study focused on areas of resilience that we felt needed additional exploration and integration, namely system and software architectures and capabilities, and autonomy technologies. (While also an important consideration, resilience in hardware is being addressed in multiple other venues, including 2 other KISS studies.) The study consisted of two workshops, separated by a seven-month focused study period. The first workshop (Workshop #1) explored the ‘problem space’ as an organizing theme, and the second workshop (Workshop #2) explored the ‘solution space’. In each workshop, focused discussions and exercises were interspersed with presentations from participants and invited speakers. The study period between the two workshops was organized as part of the synthesis activity during the first workshop. The study participants, after spending the initial days of the first workshop discussing the nature of resilience and its impact on future science missions, decided to split into three focus groups, each with a particular thrust, to explore specific ideas further and develop material needed for the second workshop. The three focus groups and areas of exploration were: 1. Reference missions: address/refine the resilience needs by exploring a set of reference missions 2. Capability survey: collect, document, and assess current efforts to develop capabilities and technology that could be used to address the documented needs, both inside and outside NASA 3. Architecture: analyze the impact of architecture on system resilience, and provide principles and guidance for architecting greater resilience in our future systems The key product of the second workshop was a set of capability roadmaps pertaining to the three reference missions selected for their representative coverage of the types of space missions envisioned for the future. From these three roadmaps, we have extracted several common capability patterns that would be appropriate targets for near-term technical development: one focused on graceful degradation of system functionality, a second focused on data understanding for science and engineering applications, and a third focused on hazard avoidance and environmental uncertainty. Continuing work is extending these roadmaps to identify candidate enablers of the capabilities from the following three categories: architecture solutions, technology solutions, and process solutions. The KISS study allowed a collection of diverse and engaged engineers, researchers, and scientists to think deeply about the theory, approaches, and technical issues involved in developing and applying resilience capabilities. The conclusions summarize the varied and disparate discussions that occurred during the study, and include new insights about the nature of the challenge and potential solutions: 1. There is a clear and definitive need for more resilient space systems. During our study period, the key scientists/engineers we engaged to understand potential future missions confirmed the scientific and risk reduction value of greater resilience in the systems used to perform these missions. 2. Resilience can be quantified in measurable terms—project cost, mission risk, and quality of science return. In order to consider resilience properly in the set of engineering trades performed during the design, integration, and operation of space systems, the benefits and costs of resilience need to be quantified. We believe, based on the work done during the study, that appropriate metrics to measure resilience must relate to risk, cost, and science quality/opportunity. Additional work is required to explicitly tie design decisions to these first-order concerns. 3. There are many existing basic technologies that can be applied to engineering resilient space systems. Through the discussions during the study, we found many varied approaches and research that address the various facets of resilience, some within NASA, and many more beyond. Examples from civil architecture, Department of Defense (DoD) / Defense Advanced Research Projects Agency (DARPA) initiatives, ‘smart’ power grid control, cyber-physical systems, software architecture, and application of formal verification methods for software were identified and discussed. The variety and scope of related efforts is encouraging and presents many opportunities for collaboration and development, and we expect many collaborative proposals and joint research as a result of the study. 4. Use of principled architectural approaches is key to managing complexity and integrating disparate technologies. The main challenge inherent in considering highly resilient space systems is that the increase in capability can result in an increase in complexity with all of the 3 risks and costs associated with more complex systems. What is needed is a better way of conceiving space systems that enables incorporation of capabilities without increasing complexity. We believe principled architecting approaches provide the needed means to convey a unified understanding of the system to primary stakeholders, thereby controlling complexity in the conception and development of resilient systems, and enabling the integration of disparate approaches and technologies. A representative architectural example is included in Appendix F. 5. Developing trusted resilience capabilities will require a diverse yet strategically directed research program. Despite the interest in, and benefits of, deploying resilience space systems, to date, there has been a notable lack of meaningful demonstrated progress in systems capable of working in hazardous uncertain situations. The roadmaps completed during the study, and documented in this report, provide the basis for a real funded plan that considers the required fundamental work and evolution of needed capabilities. Exploring space is a challenging and difficult endeavor. Future space missions will require more resilience in order to perform the desired science in new environments under constraints of development and operations cost, acceptable risk, and communications delays. Development of space systems with resilient capabilities has the potential to expand the limits of possibility, revolutionizing space science by enabling as yet unforeseen missions and breakthrough science observations. Our KISS study provided an essential venue for the consideration of these challenges and goals. Additional work and future steps are needed to realize the potential of resilient systems—this study provided the necessary catalyst to begin this process

12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"

Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin

Electric vehicles in Smart Grids: Performance considerations

Distributed power system is the basic architecture of current power systems and demands close cooperation among the generation, transmission and distribution systems. Excessive greenhouse gas emissions over the last decade have driven a move to a more sustainable energy system. This has involved integrating renewable energy sources like wind and solar power into the distributed generation system. Renewable sources offer more opportunities for end users to participate in the power delivery system and to make this distribution system even more efficient, the novel Smart Grid concept has emerged. A Smart Grid: offers a two-way communication between the source and the load; integrates renewable sources into the generation system; and provides reliability and sustainability in the entire power system from generation through to ultimate power consumption. Unreliability in continuous production poses challenges for deploying renewable sources in a real-time power delivery system. Different storage options could address this unreliability issue, but they consume electrical energy and create signifcant costs and carbon emissions. An alternative is using electric vehicles and plug-in electric vehicles, with two-way power transfer capability (Grid-to-Vehicle and Vehicle-to-Grid), as temporary distributed energy storage devices. A perfect fit can be charging the vehicle batteries from the renewable sources and discharging the batteries when the grid needs them the most. This will substantially reduce carbon emissions from both the energy and the transportation sector while enhancing the reliability of using renewables. However, participation of these vehicles into the grid discharge program is understandably limited by the concerns of vehicle owners over the battery lifetime and revenue outcomes. A major challenge is to find ways to make vehicle integration more effective and economic for both the vehicle owners and the utility grid. This research addresses problems such as how to increase the average lifetime of vehicles while discharging to the grid; how to make this two-way power transfer economically viable; how to increase the vehicle participation rate; and how to make the whole system more reliable and sustainable. Different methods and techniques are investigated to successfully integrate the electric vehicles into the power system. This research also investigates the economic benefits of using the vehicle batteries in their second life as energy storage units thus reducing storage energy costs for the grid operators, and creating revenue for the vehicle owners

Development of a Dynamic Performance Management Framework for Naval Ship Power System using Model-Based Predictive Control

Medium-Voltage Direct-Current (MVDC) power system has been considered as the trending technology for future All-Electric Ships (AES) to produce, convert and distribute electrical power. With the wide employment of highrequency power electronics converters and motor drives in DC system, accurate and fast assessment of system dynamic behaviors , as well as the optimization of system transient performance have become serious concerns for system-level studies, high-level control designs and power management algorithm development. The proposed technique presents a coordinated and automated approach to determine the system adjustment strategy for naval power systems to improve the transient performance and prevent potential instability following a system contingency. In contrast with the conventional design schemes that heavily rely on the human operators and pre-specified rules/set points, we focus on the development of the capability to automatically and efficiently detect and react to system state changes following disturbances and or damages by incooperating different system components to formulate an overall system-level solution. To achieve this objective, we propose a generic model-based predictive management framework that can be applied to a variety of Shipboard Power System (SPS) applications to meet the stringent performance requirements under different operating conditions. The proposed technique is proven to effectively prevent the system from instability caused by known and unknown disturbances with little or none human intervention under a variety of operation conditions. The management framework proposed in this dissertation is designed based on the concept of Model Predictive Control (MPC) techniques. A numerical approximation of the actual system is used to predict future system behaviors based on the current states and the candidate control input sequences. Based on the predictions the optimal control solution is chosen and applied as the current control input. The effectiveness and efficiency of the proposed framework can be evaluated conveniently based on a series of performance criteria such as fitness, robustness and computational overhead. An automatic system modeling, analysis and synthesis software environment is also introduced in this dissertation to facilitate the rapid implementation of the proposed performance management framework according to various testing scenarios

Recent Progress in Some Aircraft Technologies

The book describes the recent progress in some engine technologies and active flow control and morphing technologies and in topics related to aeroacoustics and aircraft controllers. Both the researchers and students should find the material useful in their work

Movement Analytics: Current Status, Application to Manufacturing, and Future Prospects from an AI Perspective

Data-driven decision making is becoming an integral part of manufacturing companies. Data is collected and commonly used to improve efficiency and produce high quality items for the customers. IoT-based and other forms of object tracking are an emerging tool for collecting movement data of objects/entities (e.g. human workers, moving vehicles, trolleys etc.) over space and time. Movement data can provide valuable insights like process bottlenecks, resource utilization, effective working time etc. that can be used for decision making and improving efficiency. Turning movement data into valuable information for industrial management and decision making requires analysis methods. We refer to this process as movement analytics. The purpose of this document is to review the current state of work for movement analytics both in manufacturing and more broadly. We survey relevant work from both a theoretical perspective and an application perspective. From the theoretical perspective, we put an emphasis on useful methods from two research areas: machine learning, and logic-based knowledge representation. We also review their combinations in view of movement analytics, and we discuss promising areas for future development and application. Furthermore, we touch on constraint optimization. From an application perspective, we review applications of these methods to movement analytics in a general sense and across various industries. We also describe currently available commercial off-the-shelf products for tracking in manufacturing, and we overview main concepts of digital twins and their applications

Technology Assessment of eVTOL Personal Air Transportation System

This thesis intended to provide a holistic vision on the potential consequences of the introduction of emerging electrical Vertical Takeoff and Landing (e VTOL) Personal Air Transportation System (PATS) to contribute to the forming of public and policy opinion, and to assess the impacts and the feasibility of that. Instead of looking from a detailed vehicle design viewpoint, we tried to understand the need, the impacts, and the perceptions and the concerns of stakeholders. Thus, it was set a framework and methodology starting with a technology assessment point of view in the light of transportation system analysis. Limitations of the current ground and airline transportation systems, increasing congestion, poor block speed, combined with expanding population and demand for affordable on- demand mobility are driving the development of future transportation technology and policy. The third wave of aeronautics might be the answer and could bring about great new capabilities for society that would bring aviation into a new age of being relevant in daily lives since eVTOL PATS is envisioned as the next logical step in the natural progression in the history of disruptive transportation system innovations. However, there are a lot of questions. Although there was difficulty since the system was an emerging air transportation mode, an interdisciplinary study has been conducted to assess the impacts of developing such a capability. The research questions were determined to address the research objectives. What is the current state of mobility and eVTOL air transportation mode? What are the potential benefits of eVTOL air transportation mode for user and society? What are the perceptions of service providers, regulator, and user? What are the main challenges including technology, regulation, operation, social and environment aspects to enable the system? What are the enabling technologies? Nevertheless, with the results obtained lately from the research activities, revolutionary technologies and regulations are bringing us closer to eVTOL PATS reality every day. It can be argued that a new socio-technical transition will come about like the transition from horse drawn carriers to cars. Even if it is still a long way to go, it seems rather likely that the time has been arriving in the next decade. Their existence and operation would therefore need to be taken into consideration for today’s planning considerations and construction projects to be able to have this emerging air transportation mode available in the future. As the technology underlying eVTOL PATS evolves, wider eVTOL adoption across various markets is likely to be supported further if a set of key challenges such as safety and security, ease of use and autonomy, noise, infrastructure, and air traffic management are overcome. Achieving drastic improvements in ease of use, safety and community acceptable noise are the most critical steps towards the future feasibility of this market. Multi-use demos and demonstrating successful operation with early vehicles, namely eVTOL PATS prototype field operations, will create public acceptance and understanding of potentials in emerging air transportation mode for public good, use and learn in multiple applications. The overall perception of the user, service provider and regulator are positive, and the support is high. Shortly, a successful implementation and sustainable transition will depend on overcoming technological hurdles, regulatory frameworks, operational safety, cost competitiveness, and sensibilities of the affected communities. There is a need to enable people and goods to have the convenience of on-demand, point-to-point safe travel, further, anywhere in less travel time, through a network of pocket airports/vertiports, and there is a significant potential benefit so that policy makers, regulators and metropoles’ transportation planning departments should consider an inclusion of eVTOL air transportation mode into the scenarios and policies of the future.Esta tese pretende fornecer uma visão holística sobre as potenciais consequências da introdução do Sistema de Transporte Aéreo Pessoal (PATS) de Decolagem e Pouso Vertical elétrico emergente (e VTOL) para contribuir para a formação de opinião pública e política, e para avaliar os impactos e a viabilidade disso. Em vez de olhar de um ponto de vista detalhado o projeto do veículo, tentamos entender a necessidade, os impactos, as percepções e as preocupações das partes interessadas. Assim, foi definido um quadro e uma metodologia partindo de um ponto de vista de avaliação de tecnologia à luz da análise do sistema de transporte. As limitações dos atuais sistemas de transporte terrestre e aéreo, o aumento do congestionamento, a baixa velocidade do tráfego, combinados com a expansão da população e a mobilidade com procura acessível estão impulsionando o desenvolvimento de futuras tecnologias e políticas de transporte. A terceira onda da aeronáutica pode ser a resposta e pode trazer grandes novas capacidades para a sociedade que trariam a aviação para uma nova era de ser relevante na vida cotidiana, uma vez que o VTOL PATS é visto como o próximo passo lógico na progressão natural na história das inovações disruptivas do sistema de transporte. No entanto, há muitas perguntas. Embora tenha havido dificuldade por se tratar de um modo de transporte aéreo emergente, um estudo interdisciplinar foi realizado para avaliar os impactos do desenvolvimento de tal capacidade. As questões de investigação foram determinadas para atender aos objetivos do projeto. Qual é o estado atual da mobilidade e do modo de transporte aéreo eVTOL? Quais são os benefícios potenciais do modo de transporte aéreo eVTOL para o utilizador e a sociedade? Quais são as percepções dos provedores de serviços, regulador e utilizador? Quais são os principais desafios, incluindo tecnologia, regulamentação, operação, aspectos sociais e ambientais para habilitar o sistema? Quais são as tecnologias facilitadoras? No entanto, com os resultados obtidos ultimamente nas atividades de pesquisa, tecnologias e regulamentações revolucionárias estão nos aproximando cada dia mais da realidade do VTOL PATS. Pode-se argumentar que uma nova transição sócio-técnica ocorrerá como a transição de carruagens puxadas por cavalos para automóveis. Mesmo que ainda seja um longo caminho a percorrer, parece bastante provável que a hora esteja chegando na próxima década. A sua existência e operação, portanto, precisam ser levadas em consideração para as questões de planeamento e projetos de construção de hoje para poder ter esse modo de transporte aéreo emergente disponível no futuro. À medida que a tecnologia subjacente ao eVTOL PATS evolui, é provável que a adoção mais ampla do eVTOL em vários mercados seja ainda mais apoiada se um conjunto de desafios importantes, como segurança e proteção, facilidade de uso e autonomia, ruído, infraestrutura e gestão de tráfego aéreo forem superados. Alcançar melhorias drásticas na facilidade de uso, segurança e ruído aceitável pela comunidade são os passos mais críticos para a viabilidade futura deste mercado. Demonstrações multi-uso e demonstração de operação bem- sucedida com veículos iniciais, ou seja, operações de campo do protótipo eVTOL PATS, criarão aceitação pública e compreensão dos potenciais no modo de transporte aéreo emergente para o bem público, uso e aprendizado em várias aplicações. A percepção geral do utilizador, prestador de serviço e regulador é positiva, e o suporte é alto. Uma implementação bem-sucedida e uma transição sustentável dependerá da superação de obstáculos tecnológicos, estruturas regulatórias, segurança operacional, competitividade de custos e sensibilidade das comunidades afetadas. Há uma necessidade de permitir que pessoas e mercadorias tenham a conveniência de viagens seguras de que necessitam, ponto a ponto, e além disso, em qualquer lugar em menos tempo de viagem. Isso pode ser feito por meio de uma rede de aeroportos/vertiports, e há um benefício potencial significativo para que os formuladores de políticas, reguladores e departamentos de planeamento de transporte das grandes metrópoles considerem a inclusão do modo de transporte aéreo eVTOL nos cenários e políticas do futuro