The Evolution of Deep Space Navigation: 2020-2021

The exploration of the planets of the solar system using robotic vehicles has been underway since the early 1960s. During this time the navigational capabilities employed have increased greatly in accuracy, as required by the scientific objectives of the missions and as enabled by improvements in technology. This paper is the eleventh in a chronological sequence dealing with the evolution of deep space navigation. The time interval covered extends from early 2020 to late 2021. The paper focuses on the observational techniques that have been used to obtain navigational information, propellant-efficient means for modifying spacecraft trajectories, and the computational methods that have been employed, tracing their evolution through six planetary missions.