Basic Challenge 1

This challenge is mainly designed for beginners and interested students who would like to develop their own software for gravity field recovery from satellite data. More experience analysis centres should find this challenge easy and quick to complete, and we would welcome their feedback and contributions as well. To this end, the simulated data are kept very simple where only an Earth gravity model is used to generate the orbit and the inter-satellite ranging data. No other disturbing forces such as tidal forces and non-gravitational accelerations are included. The data are corrupted with simplified noise models and the participants are asked to estimate the gravity field coefficients (spherical harmonic coefficients) using the known approaches for gravity field recovery (acceleration approach, the energy balance approach, the classical approach etc.). We collect the solutions from all participants and compare them with the Earth gravity field model which has been used for the simulation. The results of comparison will be published on this webpage and we also plan to publish and discuss the main findings in a journal paper or a technical report.

Even after the publication of the results, this challenge will be open for all interested students and new-comers of this field for a long time and they can compare their solutions with the published comparisons.

The simulated data provided for the first challenge are obtained using a numerical orbit integration in which only the Earth gravity field is the effective force on the satellites. The gravity field model and its maximum degree used in the integration as well as the noise models used to corrupt the data remain hidden. The figure below illustrated the simulation scenario.