Simulation analysis of recovering time-varying gravity fields based on Starlink-like constellation

Summary Time-varying gravity fields play a crucial role in understanding and analyzing geodynamic processes, particularly the migration of matter across the Earth's surface. However, the current limitations in spatiotemporal resolution hinder their accurate representation. In this context, the use of a giant constellation of low-orbit satellites holds great potential for accurately recovering time-varying gravity fields with high spatiotemporal resolution. Based on the orbital parameters of 5199 satellites in 123 different orbital planes in the first phase configuration of the Starlink constellation and the orbital parameters of the Bender constellation in the next generation gravity mission, we conducted a closed-loop simulation to analyze the recovery ability of time-varying gravity field in 9 days using the short-arc integral method. The errors of aliasing AOHIS signal (Atmosphere, Ocean, Hydrology, Ice, and Solid Earth), ocean tide models, orbit positions, inter-satellite range rates, and accelerometer observations were considered in the numerical simulation. Compared with the Bender constellation, the Starlink-like constellation can effectively decrease the aliasing errors in the spatial- and frequency-domain when the observation noise is not considered. The Starlink-like constellation can also effectively improve the reliability of low-degree coefficients (below degree 15) of retrieved time-varying gravity field models and present higher time resolution (within 9 days) for the full degree spherical harmonic solutions than the Bender constellation when the observation noise is considered. The aliasing effect on the low-degree part of the Bender constellation can be significantly decreased by combining the Starlink-like and Bender constellations, and the accuracy of the recovered time-varying gravity field within degree 30 can be improved by about 0.5 ∼ 1 order of magnitude. Our results can provide a technical reference for the design of future gravity satellite mission.