Design and sensitivity analysis of spacecraft swarms for planetary moon reconnaissance through co-orbits

This work presents an automated mission design architecture for global surface mapping missions to planetary moons. Such missions need to address three important challenges: virtually absent spheres of influence, tidal locking, and self-shadowing. Therefore, a complex task such as global surface coverage is better handled using the swarm approach. The design of a swarm mission for such a dynamic environment is challenging. For this reason, we developed the Integrated Design Engineering and Automation of Swarms (IDEAS) software to facilitate the automated end-to-end design of swarm mission concepts. Specifically, it will use a sub-module known as the Automated Swarm Designer module to find optimal swarm configurations suited for a given mission. In our previous work, we developed the Automated Swarm Design module to find swarm configurations for asteroid mapping operations. Here, we will evaluate the capability of the Automated Swarm designer module to design missions to planetary moons, and also examine the sensitivity of the generated optimal design to various perturbations. Specifically, we explore the design space of resonant co-orbits where the spacecraft will have planned periodic encounters with the planetary moon due to the natural dynamics. The swarm will be deployed on resonant co-orbits using an aeroassist from the central planet. the maneuver cost with this deployment is broken down into two maneuvers: a planar orbit insertion maneuver using aerobraking, and an orientation change maneuver required to facilitate a planar orbit capture. The design space of such missions is examined, and the principles are illustrated using numerical case studies of a global surface mapping mission to the Martian moon Deimos. Using the described principles, a spacecraft swarm mission to map 90 % of the surface of Deimos is designed. The designed swarm consists of 5 spacecraft, which have a maximum estimated orientation change Δv of 1.97 km/s, and a worst-case orbit insertion Δv of 0.848 km/s if aerobraking is used. Overall implications on the mission, such as fuel requirements, and aerobraking timespans are then studied. Finally, the sensitivities of the designed swarm to different perturbations are studied, and peak disturbances that lead to coverage deterioration below a threshold of 80 % are noted.