Relative Navigation to Non-cooperative Targets in Leo: Achievable Accuracy from Radar Tracking Measurements

Any future space debris removal or on-orbit servicing mission faces the problem of the initial relative orbit determination of the servicing satellite to the noncooperative target. In this work we analyze the relative navigation accuracy that can be achieved in low Earth orbit, by using ground-based orbit determination from radar tracking measurements for the target, and classical GPS-based orbit determination for the servicing satellite. The analysis is based on the radar tracking measurements obtained from a 10x10x34 cm small object at an altitude of 635 km. The results show that the relative orbit can be determined with accuracy down to 2 m (RMS) in the semimajor axis, and down to 20 m (RMS) in both the radial and normal separations. From the results we derive requirements on radar-tracking campaigns.