Developing an Open-Source Toolkit for Precise Orbit Determination and Positioning Using DORIS

For the last few years, Dionysos Satellite Observatory (DSO) of the National Technical University of Athens (NTUA) has undertaken the challenging task of developing a new, open-source and free software toolkit to facilitate the processing of DORIS observations for Precise Orbit Determination (POD) and positioning. The ongoing objective is to eventually deliver a state-of-the-art software to the scientific community, focusing on a fundamental technique of satellite geodesy. The significance of this technique across various geoscience disciplines is well-established and demonstrated by extensive publications in fields such as reference frames, altimetry, and geodynamics, among others. The software itself is designed in a way that accommodates scientific research, experimentation and validation, since it is generic enough to handle multiple data sources and models. Care is taken to design for efficiency and robustness, yet favouring re-usability and modularity, leveraging along the way modern software design principles. Additionally, we adopt modern standards and refined modeling approaches.

Analysis highlights include a rigorous treatment of the DORIS Doppler observation equation, dynamic orbit modeling, usage of the Extended Kalman Filter with process noise and state-of-the-art models and algorithms to handle tidal and non-tidal phenomena. Various validation tests are performed and presented, both for intermediate steps (e.g. different forces acting on the satellites) as well as using the estimated trajectories with respect to high-quality results from IDS Analysis Centers. In this study, we present preliminary results obtained using the toolkit, provide insights into its architecture and capabilities, and outline our immediate next steps.