Satellite anomalies are mission-degrading events that negatively affect on-orbit operational spacecraft. All satellites experience anomalies of some kind during their operational lifetime. They range in severity from temporary errors in noncritical subsystems to loss-of-contact and complete mission failure. There is a range of causes for these anomalies, and investigations by the satellite operator or manufacturer to determine the cause of a specific anomaly are sometimes conducted at significant expense.
David A. Galvan,Brett Hemenway,William Welser IV,et al. Satellite Anomalies: Benefits of a Centralized Anomaly Database and Methods for Securely Sharing Information Among Satellite Operators. 2014-01-01.