Utilizing a Preliminary Mission Reliability Estimate for the Design of High Value Science Distributed Satellite System Missions

Rapid advances in small satellite technology have enabled scientists to propose high value science mission concepts through the use of innovative Distributed Satellite System (DSS) architectures. Missions that previously would have been infeasible due to monolithic observatory size constraints or high individual satellite cost can now be accomplished using Distributed Satellite Systems.

A DSS is a mission architecture consisting of multiple space elements that collectively accomplish the mission's objectives. DSS architectures can be categorized by a variety of names including Constellations, Trains, Clusters, Swarms, etc. DSS science missions may require less than 10 to more than one hundred individual flight elements.

As exciting as the science possibilities for DSS architectures are, mission designers can under-estimate the overall reliability of the proposed architecture. Even a small percentage random failure rate for an individual satellite can be detrimental to the overall performance of the DSS mission over the desired lifetime. However, performing a thorough mission assurance analysis to assure reliability is beyond the scope of both Pre-Phase A and Phase A studies.

This paper presents a Preliminary Mission Reliability Estimate (PMRE) that DSS mission designers can use to determine if the proposed architecture is capable of meeting overall NASA system reliability expectations. The PMRE only focuses on estimating the likelihood that the proposed mission assets will survive for sufficient time to achieve the science objectives based on random errors. Historical small satellite reliability data is used to determine the random error rate.

Two approaches to calculating the PMRE are presented – an analytical and a Monte Carlo statistical analysis. The examples are provided to inform Principal Investigators and mission designers about the design trades that can be performed to increase overall mission reliability.