Onboard distributed replanning for crosslinked small satellite constellations

Abstract

This work implements distributed onboard planning and scheduling approach for crosslinked small satellites Earth observation missions. The example cases used involve 65 small satellites in ISS and Sun Synchronous Orbits, as well as NASA's Near Earth Network groundstations, and three target cases. Target cases include urgent observations. This work focuses on handling dynamic modifications to an existing nominal plan. The disruptions considered include failures to complete an activity and new user requests. The Scheduling Planning Routing Intersatellite Networking Tool, or SPRINT, is the infrastructure used in this work. SPRINT's global planner advances the state of the art by addressing the combinatorially expensive crosslink routing planning challenges, given the constraints of small satellites. SPRINT's distributed onboard planner, the focus of this work, manages both proactive state sharing and reactive planning activities. By introducing robust onboard planning components, high-performance schedules are enabled. An atmospheric model is integrated to provide the SPRINT scenarios. Results are presented for performance of the onboard replanning system. Given arbitrary activity failures, improvement, by means of reduction of the penalty, of 6 to 10 times the unmitigated effects are demonstrated using the onboard planning approach. A path to flight software integration is developed.