  Interstellar objects (ISOs) are fascinating and under-explored celestial
objects, providing physical laboratories to understand the formation of our
solar system and probe the composition and properties of material formed in
exoplanetary systems. This paper will discuss the accessibility of and mission
design to ISOs with varying characteristics, including a discussion of state
covariance estimation over the course of a cruise, handoffs from traditional
navigation approaches to novel autonomous navigation for fast flyby regimes,
and overall recommendations about preparing for the future in situ exploration
of these targets. The lessons learned also apply to the fast flyby of other
small bodies including long-period comets and potentially hazardous asteroids,
which also require a tactical response with similar characteristics
