Dependent-failures in spacecraft: root causes, coupling factors, defenses, and design implications

This paper provides: (1) the results of dependent failure analysis of Space Shuttle Orbiter in-flight anomaly (IFA) data; (2) revised and new classification systems for root causes, coupling factors, and defenses; (3) dependent failure design guidelines for the analysis of existing spacecraft systems and the design of new ones; (4) insights from the study; and (5) parameters for use in common cause failure models for spacecraft. The Space Shuttle served as the primary subject of this study because: (1) problem/failure data were abundant and readily available; (2) in-flight failures are thoroughly analyzed and relatively well documented upon the vehicle's return to Earth; and perhaps most importantly; and (3) the Space Shuttle is a valuable national resource.