Filtering Methods for the Orbit Determination of a Tethered Satellite

Abstract

The motion of a tethered satellite is affected by a force exerted on the satellite via the tether. This tether force causes the satellite to experience modified Keplerian motion. Current satellite tracking methods do not account for the modified Keplerian motion of tethered satellites and may result in inaccurate prediction of a tethered satellite’s trajectory. In order to distinguish between Keplerian and modified Keplerian motion, the performance of a batch-type filter was evaluated using a variety of state vectors in order to determine the best possible estimation model. Eight different state vectors were evaluated, and those determined to most accurately distinguish between the two types of motion were then used to calculate the length of the tether. Three of the eight models were determined to adequately differentiate between Keplerian and modified Keplerian motion. However, only one state vector was found to provide an accurate calculation of the tether length.