Covariance Analysis for Gravity Field Reconstruction Around Tumbling Bodies: Applications to Asteroid (99942) Apophis

On April 13, 2029 the asteroid (99942) Apophis will have a close approach to Earth providing a unique opportunity to achieve breakthrough science and to understand the effects of planetary encounters on asteroids. In this work, we identify natural dynamical structures that could be leveraged during the preliminary characterization of Apophis’s shape and spin. In particular, we identified terminator orbits and performed an error analysis for the gravity field reconstruction relying on spacecraft DSN and optical landmark measurements before its Earth closest approach. In the study we discuss different potential spacecraft trajectories that can offer better global coverage as well as the order to which the gravity field could be estimated based on different mission observation times and orbit choices.