A Study on the Improvement in Spatial Resolution of the Earth's Gravitational Field by the Next-Generation ACR-Cartwheel-A/B Twin-Satellite Formation

Since the Gravity Recovery and Climate Experiment (GRACE) collinear formation has some fatal drawbacks including north-south striping error, etc., this study carries out the feasibility demonstrations on the next-generation Along-Cross-Radial(ACR)-Cartwheel twin-satellite formation for improving the spatial resolution of the Earth's gravitational field by the intersatellite range-rate interpolation method. Firstly, the Earth's gravitational field from ACR-Cartwheel-A/B complete up to degree and order 120 is precisely recovered using the satellite orbital parameters and the measurement precision of key payloads from the twin GRACE satellites. The research results show that the accuracy of the Earth's gravitational field determination from the next-generation ACR-Cartwheel twin-satellite formation is averagely improved by 2.6 times than that from the EIGEN-GRACE02S model released by the German GeoForschungsZentrum (GFZ) in Potsdam, which sufficiently verifies that the next-generation ACR-Cartwheel twin-satellite formation is obviously better than the current GRACE collinear formation. Secondly, the Earth's gravitational field complete up to degree and order 120 is accurately measured based on the satellite orbital parameters (e.g. orbital altitude of 350 km, intersatellite range of 100 km, orbital inclination of 89° and orbital eccentricity of 0.0046), the measurement precision of key payloads (e.g. 10−7 m·s−1 in intersatellite range-rate, 10−3 m in orbital position, 10−6 m·s−1 in orbital velocity and 10−11 m·s−2 in non-conservative force), an observation time of 30 days and a sampling interval of 10 s by the Longitudinal-Along-Radial (Lo-AR)-Cartwheel-A/B, Latitudinal-Along-Radial (La-AR)-Cartwheel-A/B and ACR-Cartwheel-A/B twin-satellite formations using the intersatellite range-rate interpolation method, and the cumulative geoid height errors are 5.115×10−4 m, 4.923×10−4 m and 3.488×10−4 m, respectively. The results of this study are as follows. (1) Since the orbital stability of the La-AR-Cartwheel-A/B formation is superior to the Lo-AR-Cartwheel-A/B formation, the accuracy of satellite gravity recovery from the La-AR-Cartwheel-A/B formation is higher than that from the Lo-AR-Cartwheel-A/B formation. (2) Because the ACR-Cartwheel-A/B twin-satellite formation can synchronously obtain gravity information in the along-track, cross-track and radial-track directions, satellite observation data are provided with some strong points consisting of homogeneity, isotropy, and so on. In a word, the next-generation ACR-Cartwheel twin-satellite formation will prospectively play a significant role in producing the Earth gravity field model with higher accuracy and resolution.