Decentralized Satellite Constellation Replanning for Event Observation

Satellite observation planning is an active field of research that aims to improve the quantity and utility of observations by agile or taskable satellites. Most of the existing work focuses on observing static ground points with constant rewards, which is not sufficient to capture dynamic events on Earth’s surface. We introduce in this work a decentralized replanning method suitable for the observation of time-varying events by a constellation of homogeneous or heterogeneous satellites and compare it to an algorithm without replanning. We perform this comparison on a generalized scenario with varying parameters such as event duration and number of satellites. We also examine several realistic event scenarios, including lightning storms, fires, and high-flow events in rivers. We show that replanning outperforms no replanning in observing and re-observing events, with a median of 17% improvement in event observations. However, the magnitude of the improvement depends strongly on the event and constellation parameters, such as event duration and number of planes. A sensitivity analysis shows that replanning is most beneficial compared to no replanning in terms of generating more re-observations of events when there are more satellites per plane and when event durations are several hours. Ultimately, the proposed replanning strategies can greatly reduce our response time to—and increase our spatiotemporal sampling of—short-lived events and Earth system processes.