Gravity recovery capability of four generic satellite formation

Abstract

Of all potential satellite formations a GRACE-type in-plane leader-follower configuration is one of the weakest choices in terms of gravitational signal in the satellite-to-satellite tracking (SST) observable. In this paper we simulate four basic types of formation flying (FF) missions and analyse them in terms of sampling geometry (baseline orientation), gravitational signal content and gravity field recovery capability. The four FF types are, respectively a GRACE-type SST misison, a SWARM-like pendulum configuration, a Cartwheel formation on a 2:1 relative ellipse and a LISA-type formation. All formations have comparable orbit characteristics: near polar, near eccentric, and short baselines of typically 10–20 km length. The baseline orientations in the latter three FFtypes contain additional cross-track and/or radial information. They cover a larger azimuth-elevation sampling space. As a result, compared to the GRACEtype formation, all three other formations are superior in terms of more gravitational signal content, though not equally. The qualitative difference in the respective FFSST observable is reflected in the recovered gravity fields. Comparison between the input and output fields demonstrates that the recovery process using an observable with radial and/or cross-track information results in drastically improved accuracy and isotropy. The recovered solutions from the latter three formation types possess a lower error spectrum with a more homogeneous structure.