Possible Detection of the Gravity Field Disturbance with Help of Gradiometer on the Galileo Orbit and Higher
Zielinski, J.B.¹; Galazka, R.R.²; Peron, R.^3
1Space Research Centre of the Polish Academy of Sciences; ²Institute of Physics, Polish Academy of Sciences; ³Istituto di Fisica dello Spazio Interplanetario, Istituto Nazionale di Astrofisica

Because of the Earth rotation its gravity field described in the inertial reference frame is changing. The changes are caused by the longitude dependent terms of the gravity field model and by temporal tidal variations. These changes produce the typical perturbations of any satellite orbit that can be treated by the theory of the orbital perturbations which is well developed. But the gravity field changes can be sensed more directly with help of the gradiometry if only the proper sensors will be installed on GNSS satellites. Because GNSS provides also a very accurate time scale we can try to measure the time interval between observation of the same gravity field signal on the GNSS satellite and on another satellite with higher altitude, e.g. geostationary satellite. In this paper we present estimates for the required accuracy of gravity acceleration gradient measurements, positions of satellites and time tagging for the determination of the propagation velocity of the gravity signal.