A Multiple Inclination Orbit Constellation With High-Low Satellite-to-Satellite Tracking for Weekly Gravity Field Recovery

Due to error sources arising from undersampling of target signals and imperfections in background models, the single-pair satellite gravity missions equipped with the low-low satellite-to-satellite tracking technology are of limited performance, such as the Gravity Recovery and Climate Experiment Follow-on (GFO). Adding a lower-inclination GFO-like mission to form the Bender constellation is a promising solution, but it entails high costs and long development cycles. To address this limitation, we propose a cost-effective solution, the multiple inclination orbit (MIO) constellation, which is equipped with mature high-low satellite-to-satellite tracking technology. The MIO constellation consists of 80 satellites across four orbital inclination groups (70&#x00B0;, 75&#x00B0;, 80&#x00B0;, 85&#x00B0;). The performance of these constellations in recovering 7-day time-variable gravity fields was evaluated through numerical simulations, using the root-mean-square error (RMSE) and the Nash&#x2013;Sutcliffe efficiency coefficient as metrics for regional application. Spectral-domain results show that the GFO+MIO constellation improves spatial resolution to &#x223C;666 km, approaching the &#x223C;500 km resolution of the Bender solution. Spatial-domain results further demonstrate that the GFO+MIO solutions achieve performance comparable to the Bender constellation in: 1) hydrology applications in terms of equivalent water height [RMSE/NSE: 67.89 mm/0.64 (GFO+MIO) versus 59.28 mm/0.73 (Bender)] smoothed by a 300 km Gaussian filter; 2) gravity anomaly arising from the 2004 Sumatra Mw9.2 earthquake [RMSE/NSE: 4.16 <inline-formula><tex-math notation="LaTeX">$\mu Gal$</tex-math></inline-formula>/0.92 (GFO+MIO) versus 5.23 <inline-formula><tex-math notation="LaTeX">$\mu Gal$</tex-math></inline-formula>/0.87 (Bender)] smoothed by a 100 km Gaussian filter. The study provides critical insights for future mission designs aimed at advancing time-variable gravity field recovery for geophysics applications.