CUNY CSC 79000 - An Assessment of Space Shuttle Flight Software Development Processes

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An Assessment of Space Shuttle Flight Software Development ProcessesContent of this presentationAbout This ReportAbout the report ( cont.)About Nancy G. LeversonIntroductionTasksFindings and RecommendationsSlide 9NASA Guidelines and StandardsNASA Guidelines and StandardsOff-Nominal CasesOff-Nominal CasesSystem-Level Software V&VSlide 15The Independence of IV&VSlide 17Software Safety StandardsSlide 19Slide 20Software Safety ProceduresSlide 22PersonnelSlide 24System-Safety Organizational Roles and ResponsibilitiesSlide 26Organizational Roles And ResponsibilitiesSlide 28The Role of Headquarters S&MQ and the Center SR&QA OfficesSlide 30Community ResponsibilityPolicies, Guidelines, and EnforcementPolicies, Guidelines, and EnforcementFinal Thoughts And Future ConsiderationsSlide 35Final Thoughts And Future Considerations01/13/19 An Assessment of Space Shuttle Flight Software Development ProcessesPresented by Jun Wufor Reading in Computer ScienceCUNY Graduate CenterContent of this presentationInformation about the reportIntroductionFindings and RecommendationsAbout This ReportThe project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.About the report ( cont.)This study was supported by Contract NASW-4003 between the National Academy of Sciences and the National Aeronautics and Space Administration. Chair of the Committee for Review was Nancy G. LeversonLibrary of Congress Catalog Card Number 93-84549 International Standard Book Number 0-309-04880-XAbout Nancy G. Leverson She was Boeing Professor of Computer Science and Engineering at the University of Washington. In 2001, She moved to MIT, she is now Professor of of Aeronautics and Astronautics in MIT.Professor Leveson started a new area of research, software safety, which is concerned with the problems of building software for real-time systems where failures can result in loss of life or property.Introduction In early 1991, the National Aeronautics and Space Administration's (NASA's) Office of Space Flight commissioned the Aeronautics and Space Engineering Board (ASEB) of the National Research Council (NRC) to investigate the adequacy of the current process by which NASA develops and verifies changes and updates to the Space Shuttle flight software. The Committee for Review of Oversight Mechanisms for Space Shuttle Flight Software Processes (hereafter, the Committee) was convened in January 1992 to accomplish the following tasksTasks-Review the entire flight software development process from the initial requirements definition phase to final implementation. -Review and critique NASA's independent verification and validation process and mechanisms. -Determine the acceptability and adequacy of the complete flight software development process, -Consider whether independent verification and validation should continue.Findings and RecommendationsNASA guidelines and standards Off-nominal cases System-level software V&VThe independence of IV&V  software safety standards Software safety procedures PersonnelFindings and RecommendationsSystem-safety organizational roles and responsibilitiesOrganizational roles and responsibilities The role of headquarters S&MQ and the center SR&QA officesCommunity responsibility Policies, guidelines, and enforcement Final thoughts and future considerationsNASA Guidelines and Standards Finding #1: Each software development contractor provides its own development and coding guidelines for the Shuttle software. These guidelines are not consistent among the developers.NASA Guidelines and StandardsRecommendation #1: NASA should develop guidelines for software development and V&V procedures and should require contractors to share experiences gained while developing NASA-contracted software. V&V: Verification and ValidationOff-Nominal Cases Finding #2: V&V inspections by the development contractors pay little attention to off-nominal cases. (i.e., crew/ground errors, hardware failures, or software errors)Off-Nominal CasesRecommendation #2: The V&V performed by the development contractors should include off-nominal scenarios beyond loop termination and abort control sequence actions and should include a detailed coverage analysis.System-Level Software V&V Finding #3: V&V inspections by software development contractors focus on verifying the consistency of two descriptions at different levels of detail (e.g., consistency between a module's requirements and the design of its implementation). The correctness of the requirements with respect to the hardware and software platforms on which implementations run are generally not considered.System-Level Software V&V Recommendation #3: NASA should augment the current V&V process to expand the consideration of system-level issues and should provide adequate funding to allow for successful completion of these tasks.The Independence of IV&V Finding #4: Independence of the IV&V contractor is limited. For example, the functions the IV&V contractor is allowed to investigate are controlled by the Shuttle Avionics Software Control Board, thereby reducing the IV&V contractor's ability to fully investigate potential problems. IV&V: Independent Verification and ValidationThe Independence of IV&V Recommendation #4: In order to provide a greater level of independence, responsibility for IV&V should be vested in entities separate from the Shuttle program structure and the centers involved in the Shuttle software development and operation. However, these organizations should continue to conduct activities supporting IV&V.Software Safety Standards Finding #5: Current NASA safety standards and guidelines do not include software to any significant degree. A software safety guideline has been in draft form for four years. Decisions are being made and safety-critical software is being built without minimal levels of software safety analysis or management control being applied.Software Safety Standards Recommendation #5: NASA should establish and


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