A Filtering Method for the Identification of a Tethered Satellite

Abstract

The dynamics of a tethered satellite are greatly affected by the perturbing force transmitted to the satellite through the tether. The existence of this tether force causes the satellite to behave in a non-Keplerian manner. Classical orbit determination methods are unable to account for this modified Keplerian motion and the subsequent estimation procedure will commonly result in an inaccurate prediction of the satellite’s trajectory. The satellite may even appear to be on a re-entry trajectory. In such cases, the speed at which an accurate identification of the satellite can be made may also be very important. In order to distinguish between the motion characteristic of a single (untethered) satellite and that of a tethered satellite, and to correctly identify a satellite as being tethered, a batch-type filter has been developed for use in the orbit determination process. This filter includes the effect the tether force has on the motion of the satellite. The filter’s performance is also evaluated in this study. Results are presented for cases of differing tether lengths, tether orientations, and types of observations being processed. In addition, results are presented using actual TSS data obtained from the Tether Physics and Survivability Experiment.