Reliability Analysis and Failure Mitigation Strategies for the PROVE Pathfinder CubeSat Payload

The University of Bristol is developing the PROVE (Pointable Radiometer for Observation of Volcanic Emissions) Pathfinder payload, a part of a 6U CubeSat hoped to launch in the next year. PROVE Pathfinder's aim is to image volcanic ash plumes from several different locations and aspects along its orbital trajectory. These images will be used to gain more knowledge of the ash cloud, useful in protecting civil aviation in the case of large-scale volcanic eruptions with ash associated. As CubeSats have historically suffered from a high failure rate, a thorough understanding of the reliability of the PROVE Pathfinder system is essential to mitigating the mission risk. This paper presents the analysis, results and recommended failure mitigation strategies from a reliability study carried out on the PROVE Pathfinder payload system. Several different analysis approaches were used to study the reliability of the system. These included Failure Mode Effects and Criticality Analysis (FMECA), Fault Tree Analysis (FTA), Monte Carlo simulation and a reliability model of PROVE Pathfinder devised using Model Based Systems Engineering (MBSE). Various estimates of system reliability were produced, with a final figure of 80% reliability. This estimate took account of the numerous mitigation strategies identified during the study, including cold redundancy in payload controllers and aluminum radiation shielding. While some discrepancies in qualitative reliability estimates were found, the insight gained during the study greatly assisted with identifying mitigation strategies and generally improved system reliability. A framework for reliability analysis approaches and mitigation strategy identification for general use on spacecraft systems is proposed, with opportunity for future development.