NSTAR diagnostic package architecture and Deep Space One spacecraft event detection

The Deep Space One mission is demonstrating the long-duration use of an Ion Propulsion Subsystem (IPS). The NASA Solar Electric Propulsion Technology Applications Readiness Project developed the NSTAR Diagnostics Package (NDP) to monitor the effects of the IPS on the spacecraft environment. The NDP measures contamination, plasma characteristics, electric fields, and magnetic fields. This paper describes the NDP requirements, development process, and flight systems' functionality. NDP functionality exceeded expectations; it became an effective tool in the detection and diagnosis of spacecraft functionality and system anomalies. NDP detects hydrazine thruster firings (planned and not planned), ion engine gimbal stepper motor currents, solar array currents, spacecraft charging, as well as a number of other phenomena. Examples of selected ion engine and spacecraft signatures and their interpretations are discussed.