A case history of International Space Station requirement faults

There is never enough time or money to perform verification and validation (V&V) or independent verification and validation (IV&V) on all aspects of a software development project, particularity for complex computer systems. We have only high-level knowledge of how the potential existence of specific requirements faults increases project risks, and of how specific V&V techniques (requirements tracing, code analysis, etc.) contribute to improved software reliability and reduced risk. An approach to this problem, fault-based analysis, is proposed and a case history of the National Aeronautics and Space Administration's (NASA) International Space Station (ISS) project is presented to illustrate its use. Specifically, a tailored requirement fault taxonomy was used to perform trend analysis of the historical profiles of three ISS computer software configuration items as well as to build a prototype common cause tree. ISS engineers evaluated the results and extracted lessons learned.