Quick-Look Identification and Orbit Determination of a Tethered Satellite

Abstract

A renewed interest in the deployment of tethered satellites has motivated recent studies addressing the problem of the accurate identification, orbit determination, and motion prediction of a tethered satellite system (TSS). If the motion of a TSS is not analyzed accurately, a tethered satellite could be incorrectly identified as an object on a re-entry trajectory. Classical orbit determination methods do not possess the capabilities to determine whether or not a tracked satellite is part of a TSS. The problem of identification is compounded by the fact that this process must be performed quickly using a short arc of observational data. Once this "quick-look" identification is achieved, it is also important to have the capabilities to precisely determine the orbit of the TSS for future tracking and orbit prediction purposes. This paper presents a three-stage methodology which has been developed to address the accurate identification, orbit determination, and long-term orbit prediction of a TSS. The first stage uses recently developed preliminary orbit determination (POD) methods which have the capability to determine whether an observed satellite is part of a TSS or not using only a few observations. The second stage utilizes ridge-type estimation methods, which have been shown to be capable of obtaining a more accurate state of the observed satellite using a short arc of observational data. The third-stage analysis utilizes an enhanced tether satellite dynamical model suited for the long-term orbit determination and motion prediction. The effectiveness of this proposed three-stage method is demonstrated using both simulated tether satellite data and actual data obtained from the Tether Physics Survivability (TiPS) Experiment.