Time Efficiency and Mission Duty Cycle Evolution for Observatory and Deep-Space Electric Propulsion Missions

A key operational resource for deep-space electric propulsion and observatory missions is mission duty cycle, which is the fraction of time dedicated to thrusting or observing when required, respectively. This paper presents a new dataset of time duty cycle estimates and realized values at different milestones over the lifecycles of multiple civil space projects, and integrates these data with already-published values from other missions. Project-specific factors that led to the trend seen for each mission are discussed, as well as common threads and lessons learned for future missions that require a high mission duty cycle.