ESA GNC Conference Papers Repository

JUICE mission is planned to perform more than twenty fly-bys since its arrival in the Jupiter system up to its final orbit around Ganymede. On-board science instruments require good pointing performance to target specific areas of the Moon surface during each fly-by; the challenge in the pointing requirement comes from the guidance error component in the proximity of the close distance to the moon. The required performance is achieved thanks to a Vision-Based Navigation (VBN) concept using an innovative Image Processing based on Limb Tracking, named EAGLE (for Enhanced Attitude Guidance through Limb Extraction). An Extended Kalman Filter (EKF) permits to precisely propagate the S/C position & velocity states; when the navigation camera acquires a Moon image, its processing delivers a rough measure of the Moon position and the associated covariance. This information is used by the EKF to update its states. Thanks to the computation of the covariance, the update is optimally performed leading to position knowledge performances largely better than those reached with Earth-based measurements navigation computed three days prior the fly-by closest approach. This allows fulfilling the tight JUICE's APE requirements in the proximity of the close approach during Moons' fly-by. JUICE VBN is the key of a successful science sequence over the Jovian Moons.