Enabling Fast Flyby Small Body Science with Onboard Navigation

Small body exploration via fast flybys is a fast and relatively inexpensive way to explore small bodies. Typically, the most important data gained by the flyby happens at closest approach. However, because the speed of the flybys is often quite fast, when using standard ground navigation techniques science has to be compromised due to lack of knowledge of where the body is located at the point of closest approach. In the late 1990s, the advent of onboard navigation methods has greatly improved the science return in these types of missions by using images on approach to continually improve the onboard knowledge of the trajectory. The technique has enabled missions like Deep Impact to hit a small body at high speed, as well as continually maintain lock on the object for flybys. In this paper, the basic challenge of fast flybys is explained, and the results of using onboard navigation to solve this problem shown for several historic missions.