Designing Planetary Missions for Uncertain Environments: Lessons Learned and Path Forward

Unknowns in the science environment have shaped many planetary science missions, with outcomes ranging from significant scientific discoveries to partial or complete loss of mission objectives. The magnitude of these effects depends on the mission context, including the scientific scope, the degree of operational flexibility, how environmental uncertainty is addressed during formulation, and how the mission responds to unexpected conditions in flight. This paper examines several planetary science missions that encountered environments or physical processes that differed from expectations to identify factors that influence adaptability in the concept of operations. The missions considered are Pioneer, Galileo, Cassini, New Horizons, Dawn, OSIRIS-REx, and Europa Clipper. A cross-mission analysis compares the unexpected conditions encountered, the strategies used to account for uncertainty before launch, the in-flight responses, and the resulting impacts. Insights from these case studies support a framework for evaluating the adaptability potential of a mission’s concept of operations. Four design pillars, flexibility, observability, responsiveness, and commitment, are identified, from which design principles are derived, offering guidance for designing planetary missions that can adapt effectively to unexpected environments.