Rapid-Response Reconnaissance Architecture Design for Planetary Defense with Nested Trajectory Optimization

Abstract Reconnaissance is a vital component in a comprehensive planetary defense mitigation strategy—aimed at preventing or reducing the impact threat posed by celestial objects on close-approach trajectories to Earth. It provides decision-makers with critical information on the physical and orbital properties of a near-Earth object (NEO), enabling better assessment of size, composition, and trajectory. This study investigates how to optimally pre-position a fleet of reconnaissance spacecraft prior to the discovery of a specific hazardous NEO. It evaluates response timelines and mission success rates for combinations of spacecraft launched from Earth and those maneuvering from pre-deployed locations within the Sun-Earth system. A synthetic population of asteroid threats is used to generate performance metrics for each candidate architecture. This study employs a nested multi-objective optimization framework coupling the fast elitist non-dominated sorting genetic algorithm (NSGA-II) for reconnaissance architecture design with particle swarm optimization (PSO) for transfer trajectory optimization. The developed Pareto-optimal architecture designs have trade-offs among response time, cost, and flyby success rate. Mission constraints consider approach lighting, flyby velocity, and $$\Delta v$$ . Results indicate that Earth-launched spacecraft provide the most cost-effective solution for rapid-response NEO reconnaissance. For a single-spacecraft configuration, an Earth-launched vehicle increases the success rate by 8.4% relative to a pre-deployed space-based spacecraft. Achieving 100% success for flyby coverage requires no more than two spacecraft: an Earth-launched heavy vehicle augmented with a pre-deployed space-based spacecraft. In comparison, a stand-alone Earth-launched spacecraft achieves a 99.9% success rate. When considering purely pre-deployed space-based architectures, a Distant Retrograde Orbit (DRO) replaces the effects of the Earth-launched spacecraft, though with reduced overall performance. Other optimal pre-deployed locations include regions near the Sun-Earth L3, L4, and L5 Lagrange points.