Redundancy design for the Vela spacecraft

Various redundancy tradeoffs with respect to weight, power, reliability, and testing ability are discussed for the Vela spacecraft. The types of redundancy considered were complete circuit (such as quads), standby automatic switchable, standby command switchable, and fully automatic. Complete circuit redundancy was rejected because of weight and power limitations. Standby automatic switchable redundancy was rejected because of possible failure modes and complexity of the automatic detection circuits. Fully automatic redundancy was applied to those portions of the system where a failure would cause loss of the mission. Standby command switchable redundancy was applied to those portions of the system where a failure could be detected and corrected by command switching. The final redundant system is compared with a nonredundant system to indicate the additional weight and power required to accomplish the redundancy design.