Cold Atom Interferometry Accelerometers for Future Low-Low Satellite-to-Satellite Tracking and Gradiometry Missions

Kurzfassung

The interest in a higher spatial and temporal resolution of the Earth's gravity field is large in various disciplines and especially important in relation to climate change. We analyze possible improvements of the accelerometers for future satellite gravity missions. The classical electrostatic accelerometers suffer from their low-frequency drift and are the limiting factor on the instrument side. The Cold Atom Interferometry (CAI) accelerometers with their long-term stability would complement the classical accelerometers very well. Different accelerometer performance models are tested within a closed-loop simulation and the corresponding gravity field solution is recovered. An improvement and the reduction of the North-South striping effects are shown when using a hybrid accelerometer. However, the low sampling rate of the CAI sensor leads to aliasing effects due to the variation of the acceleration signal. The well know scale factor of the CAI measurements, on the contrary, is a great advantage. According to these two aspects, several altitudes and drag compensation scenarios are investigated. Furthermore, a combination of the two measurement concepts low-low Satellite-to-Satellite Tracking and gradiometry is studied. A more isotropic error pattern is achieved when adding to a low-low Satellite-to-Satellite Tracking a hybrid gradiometer in cross-track direction.