Development of Terrain-Relative Guidance for Planetary Landing Applications

The use of terrain sensing for navigation and guidance in planetary soft landing is a powerful capability for robotic space missions but one that took decades to mature across many different research tasks, technology developments, and field/flight test activities. This paper summarizes significant milestones in the development of this important capability for planetary exploration, which was first employed operationally in NASA’s Mars 2020 mission, as well as related applications that are just maturing and coming into use. A brief look at current work leading to future applications is included.