Spacecraft State-of-health (SOH) Analysis via Data Mining

Spacecraft state-of-health (SOH) analysis typically consists of limit-checking to compare incoming measurand values against their predetermined limits. While useful, this approach requires significant engineering insight along with the ability to evolve limit values over time as components degrade and their operating environment changes. In addition, it fails to take into account the effects of measurand combinations, as multiple values together could signify an imminent problem. A more powerful approach is to apply data mining techniques to uncover hidden trends and patterns as well as interactions among groups of measurands. In an internal research and development effort, software engineers at Sandia National Laboratories explored ways to mine SOH data from a remote sensing spacecraft. Because our spacecraft uses variable sample rates and packetized telemetry to transmit values for 30,000 measurands across 700 unique packet IDs, our data is characterized by a wide disparity of time and value pairs. We discuss how we summarized and aligned this data to be efficiently applied to data mining algorithms. We apply supervised learning including decision tree and principal component analysis and unsupervised learning including kmeans and orthogonal partitioning clustering and one-class support vector machine to four different spacecraft SOH scenarios after the data preprocessing step. Our experiment results show that data mining is a very good low-cost and high-payoff approach to SOH analysis and provides an excellent way to exploit vast quantities of time-series data among groups of measurands in different scenarios. Our scenarios show that the supervised cases were particularly useful in identifying key contributors to anomalous events, and the unsupervised cases were well-suited for automated analysis of the system as a whole. The developed underlying models can be updated over time to accurately represent a changing operating environment and ultimately to extend the mission lifetime of our valuable space assets.