Cost of Safety for Space Transportation

57th International Astronautical Congress October 2006, Valencia, Spain.This paper proposes a methodology that explores the tradeoff between increasing component reliability and utilizing component redundancy as the strategy to meet space transportation reliability requirements. This technique would be employed by design engineers to make decisions about a reliability approach. The tradeoff between component redundancy and making parts more reliable warrants more investigation. System level reliability decisions are being made without a thorough exploration of cost saving opportunities. The impact of using redundancy on a system, including how it affects metrics such as development and operations cost, is presented. Additionally, there is little understood about the resources required to improve component reliability to acceptable levels. The process of making parts more reliable is studied and quantified. To incorporate the uncertainty that exists from reliability applications, a stochastic approach is used. Case studies of historical space systems are presented to demonstrate how this methodology is applicable. The findings show how a different reliability approach may have resulted in significant cost reductions. Conclusions are drawn about how to best meet reliability requirements while remaining within strict budgetary guidelines