Impact of external perturbations on maximum revisit time in satellite constellations

Abstract

The growing demand for real-time Earth observation data has increased the need to understand the temporal performance of satellite constellations, particularly in terms of maximum revisit times across various latitudes. This study investigates the behavior of a Walker Star constellations in sun-synchronous orbits, focusing on maximum revisit times to provide insights into potential configurations and their implications for mission planning. Our analysis targets latitudes between -50º and 50º, which are critical for applications in environmental monitoring and communication services.

We evaluate four configurations, varying the number of orbital planes while maintaining two satellites per plane. High-fidelity simulations account for atmospheric drag, solar radiation pressure, Earth’s $J_2$ perturbation, and gravitational influences from the Sun and Moon to assess the long-term impact of these external forces on maximum revisit times.

The main goal of the present research is to investigate the impact of external perturbations on the maximum revisit time for satellite constellations. Results show that, over time, the interval between consecutive passes of two satellites increases significantly. For the Walker Star constellation, the maximum revisit time (in the initial configuration) decreases at lower latitudes and increases with higher latitudes \cite{1984JBIS...37..559W}. Moreover, the number of satellites is inversely related to the revisit time, with fewer satellites resulting in longer intervals between passes across all latitudes, as expected.

This study also enhances the understanding of maximum revisit times in Walker Star constellations for sun-synchronous orbits, offering valuable insights into designing satellite networks with improved temporal performance for diverse observational needs.