Autonomous on-board navigation for interplanetary missions

Autonomous navigation is one of the key technologies for future space exploration. Autonomous navigation during a close encounter with an asteroid was one of the Deep Space One mission experiment. This paper presents the first results of the ESA Technological Research Program "Autonomous Navigation for Interplanetary Missions". The objective of this study is to take a major step towards a European capability for autonomous onboard navigation. The study involves design, prototype implementation and test of the developed autonomous onboard navigation system covering all the phases of the mission: cruise, low thrust deep space manoeuvre, planetary or small bodies (asteroid or comet) encounters. Navigation is based on the measurements of a navigation camera (NavCam) supplemented by the platform star sensor when required. The main phases have been analysed to derive navigation requirements and specify the navigation camera. The On board Navigation (ObNav) system two main functions (GNC and Image Processing) are being designed to cover all the mission phases with the minimum set of functions. The system will be validated using simulated images and ground images and flight images from two space missions SMART-1 and Rosetta.