Computer systems used in space applications have become more complex and critical mainly due to the high number of requirements to be defined and met. One of the important concerns about requirements is the problems related to ambiguity, non-completeness and even the lack of non-functional requirements. In space computer systems, requirements related to dependability should be identified to avoid mission fail, human life threats, and system's environment damages. This paper presents a set of dependability attributes for space computer systems, according to quality factors approaches such as the European Space Agency (ESA), the National Aeronautics and Space Administration (NASA), the UK Ministry of Defence (MOD), the Brazilian Space Agency (AEB), and other studies of well-known researchers in this area. It was defined an attribute tree with three groups of common factors and inter-related concepts. The first group of factors includes fault-tolerance, safety, security, survivability, robustness and recoverability attributes. The second group comprises the availability, reliability, stability, efficiency, accuracy and maintainability attributes. And finally, the third group includes simplicity, completeness, consistency, correctness, self-description, modularity, portability, traceability, testability and usability attributes. To obtain an appropriate set of attributes for space computer systems as a whole were considered the components that interact with the hardware, the software, or that have some kind of system dependency relationship. Based on each definition, examples, metrics and relevance of each dependability attribute are discussed and explained in the paper.
展开▼
