Autonomous navigation of spacecraft formation in the proximity of minor bodies

The paper presents an autonomous navigation method for a spacecraft formation flying in the proximity of an asteroid. The measurements from an onboard high resolution camera and a LIDAR are used to estimate the relative position and velocity of the spacecraft with respect to the asteroid. The main innovation is the inclusion of inter-spacecraft measurements provided by the same sensors to evaluate the improvement of navigation performance. Several schemes are constructed to quantify the navigation performance affected by different combinations of measurements, which are obtained from each spacecraft within a 2-spacecraft formation. Unscented Kalman Filter (UKF) is then proposed to simultaneously estimate the position and velocity of each spacecraft with respect to the asteroid. Some examples demonstrate that a significant improvement of the navigation accuracy can be obtained by fusing the inter-spacecraft measurements with the spacecraft-to-asteroid measurements. The robustness of the proposed navigation strategy is then assessed by considering a range of different magnitudes of the noise in measurements and process.