Covariance Analysis Tool for Far Non-Cooperative Rendezvous

Non-cooperative rendezvous is a key aspect of space debris removal, which will be very important in the next decades as the number of orbiting objects keeps on growing rapidly. In this paper, emphasis is placed on the development of a modular navigation tool adapted to far non-cooperative rendezvous. Every classical rendezvous sensor is modelled: IMU, star tracker, infrared camera, visible camera and LiDAR. In case of angles-only navigation, performances are mainly limited by the fact that the relative range between the chaser and the target is not observed. A covariance analysis tool is developed with a three fold objective: 1) understand the observability issues in realistic rendezvous missions, 2) identify the key contributors to navigation performances, 3) allow a first sizing of navigation architecture by the establishment of a set of requirements on mission profile and sensor suite. The tool relies on a 42-state Kalman filter that includes dynamics based on Clohessy-Wiltshire equations, knowledge of the performed maneuvers through IMU measurements and the estimation of most sensor deflects. Applications focus on far non-cooperative rendezvous with International Space Station in a realistic configuration.