Research on Starlink Ephemeris Published by SpaceX

Abstract

Faced with the significant disruption of normal space activities caused by Starlink satellites, the Starlink ephemeris published by SpaceX provides an opportunity for relevant research on Starlink satellites. However, due to the lack of clear instructions, it is challenging to utilize the data further. Analysis of the ephemeris file reveals that it primarily represents the predicted orbit for the next 3 d. Research on mean orbital elements indicates that the front part of the ephemeris is an extrapolated orbit with perturbations up to at least the 20th order of Earth's gravitational field, while the latter part is a design orbit with $J_2$ perturbation. The ephemeris includes covariance information, providing accuracy details. The covariance indicates that the accuracy of the ephemeris for satellites located in parking and working orbits is better than 2 km in the first day, while the accuracy of satellites in raising orbit increases rapidly to thousands of meters in less than half a day. Utilizing the designed orbit of the ephemeris enables a more accurate analysis of constellation configuration, especially the designated position of each satellite, thus facilitating the identification and tracking of Starlink satellites. The study provides valuable insights for the extensive application of Starlink ephemeris, serving as a beneficial reference for maneuver detection and collision warnings of Starlink satellites.