Charles Constant, University College London; Santosh Bhattarai, University College London; Marek Ziebart, University College London
Keywords: Mega-constellations, Low Earth Orbit, Space Traffic Management, Space Situational Awareness, Uncooperative Tracking, Two-Line-Element, Geodesy, Starlink, OneWeb, Accuracy, Precision
Abstract:
In the context of Space Traffic Management (STM) and its crucial reliance on orbit prediction, this study evaluates current practices in uncooperative tracking for Low Earth Orbit (LEO) mega-constellation management. By assessing Two-Line-Element (TLE) data from cooperative and uncooperative tracking of a Starlink constellation subset, we observe a mean 52% increase in positional accuracy with cooperative tracking.
We present a 400-day time-series analysis of TLE data for the Starlink and OneWeb constellations, uncovering significant positional discrepancies and variance between cooperative and uncooperative TLE sets. A Fourier analysis reveals systematic once-per-rev signals.
Examining the TLE generation process, we discuss the influence of measurement quality, force modeling, latency, and location on these discrepancies and their implications for prediction error. We advocate for a universally accepted set of reference orbits across LEO to ensure robust SSA data source characterization amid increasing satellite launches.
The presence of inconsistencies and spatio-temporal variations in the data highlight the need for enhanced transparency and a 3- to 5-fold improvement in TLE data accuracy. This research, aims to bridge the gap between required and supplied accuracy of positional data, and to refine STM strategies and fortify mega-constellation operations safety in LEO.
The facilitating codebase is available in a GitHub repository, encouraging scrutiny and contributions towards improved space situational awareness.
Date of Conference: September 19-22, 2023
Best Student Paper Award Winner 2023
Track: Astrodynamics