A comparative analysis of Walker Delta and star satellite constellations for earth remote sensing

Abstract

The increasing demand for efficient Earth observation requires optimizing satellite constellations to enhance coverage and revisit times across various latitudes for many missions, including important applications like remote sensing and others. Understanding the performance differences between Delta and Star constellation configurations is crucial for mission planning and resource allocation.
This study aims to evaluate and compare the observation times, mean revisit times, and maximum revisit times of Delta and Star satellite constellations at different latitudes, providing insight into their suitability for diverse Earth observation missions.
 Numerical simulations were conducted over a one-year period (January 1 to December 31, 2025) for Sun-synchronous orbits at 600 km and 800 km altitude with an inclination of approximately ($97.72^\circ$) and $98.53^\circ$, respectively. These are the preferential orbits for remote sesing satellites. Three configurations were analyzed: six orbital planes with six satellites per plane, six orbital planes with twelve satellites per plane, and six orbital planes with eighteen satellites per plane. Performance metrics were assessed for each configuration across various latitudes. Specifically, for latitudes below \(60^\circ\), the Star configuration provides superior visibility, while the Delta configuration excels at higher latitudes. Around \(60^\circ\) latitude, both configurations exhibit comparable observation times. As expected, increasing the number of satellites enhances visibility time, improving overall performance for both configurations, which is quantified in the present research.
These findings offer valuable insights for optimizing satellite constellations design, highlighting the trade-offs between Delta and Star configurations and the impact of satellites on Earth observation capabilities across different latitudes.