A Method to Improve the Accuracy of Orbit Determination and Propagation from TLE Data

Diogo Matos Delgado

Key information

Authors:

Diogo Matos Delgado (Diogo Matos Delgado)

Supervisors:

Rodrigo Martins de Matos Ventura (Rodrigo Martins de Matos Ventura); Paulo Jorge Soares Gil (Paulo Jorge Soares Gil)

Published in

July 11, 2024

Abstract

The rising number of objects orbiting Earth increases the risk of collision, which is exacerbated by limitations in tracking data accessibility. In this thesis we combine two methods using a high precision propagator to improve the overall propagation accuracy based on limited precision orbit information such as TLE data from NORAD. The high-precision propagator used is created with GODOT (ESA-ESOC Flight Dynamic Software Tool). The first method estimates the ballistic coefficient of space objects and is developed with the goal of finding the best estimate of the coefficient associated with the atmospheric model and propagator used. Improving ballistic coefficient estimation is relevant for the prediction since atmospheric drag is a prominent perturbation in LEO orbits. The second comprises of an optimization algorithm that finds the fitted orbit that best describes the TLE data. Both methods use a set of TLEs, spanning several days, immediately prior to the last available TLE, that are used to improve the accuracy of the propagation for the following time interval. As a way of evaluating the results, TLEs obtained for the following time interval are used as a source of true data to enable the comparison between the orbit derived from the proposed model and the one obtained by simply propagating the last available TLE with the SGP4 propagator. This is relevant in the context of the increasing risk of collision due to the rising number of space objects, where determining the risk and need for a collision avoidance maneuver is paramount.