Approach to exploring interstellar objects and long-period comets

This paper aims to identify the best approaches for exploring planetary bodies with very long orbital periods, i.e., bodies that approach Earth only once in a lifetime. This includes long-period comets (LPCs), and the newly discovered classes of Manx comets and interstellar objects (ISOs). Long-period comets are high scientific value targets, as indicated in the current Planetary Science Decadal Survey. Interstellar objects open the fascinating possibility to sample exoplanetary systems. Manxes hold the key to resolving long-time questions about the early history of our solar system. Specific strategies need to be implemented in order to approach bodies whose orbital properties are at the same time extreme and unpredictable. As ground-based telescope capabilities are greatly improving, it will soon become possible to detect LPCs more than ten years before they reach perihelion. On the other hand, the non- or weakly active Manx comets and ISOs require reactive exploration strategies. All of these bodies offer many challenges for close proximity observations that can be addressed by the deployment of multi-spacecraft architectures. We describe several concepts that leverage the many advantages offered by distributed sensors, fractionated payload, and various mother-daughter configurations to achieve high impact science within the reach of low-cost missions.