Determination of the Goce Satellite Orbit Sensitivity Under the Influence of Perturbing Forces

The work contains the results of research into the simulated orbit of the GOCE satellite. Satellite accelerations due to atmospheric drag, the gravitation of the Moon, the gravitation of the Sun, the gravitation of the planets, the Earth tides, the ocean tides, the solar radiation pressure, the reflected solar radiation pressure and the relativity effects were computed. Besides the reference orbit (i.e. the orbit as close as possible to the GOCE planned orbit), the various variants of the satellite orbit (called the modified reference orbits - with different motion models) were obtained. The motion models contained the forces determining the satellite motion. For the orbital computations, the Cowell numerical integration of the eighth order was used. The geopotential was described by means of the EGM96 model.

In order to obtain the influence of the aforementioned forces on the GOCE orbit, the percentage contributions of the accelerations due to these forces in the sum of all accelerations were computed.

The maximum values of the mentioned accelerations were computed for the GOCE orbit variant with the motion model containing all given above forces. These values were compared with the measurement error of the linear accelerations by the GOCE satellite control system.

The comparison between the reference orbit and the computed variants of the orbit was performed. In order to perform this comparison, the distances between the satellite position in the reference orbit and the satellite position in the given modified reference orbit (i.e. in a given orbit variant) were determined. These distances were compared with the total error of the GOCE satellite position determination. The orbital arc lengths, for which the selected forces can be neglected in the satellite motion model, were determined from this comparison. For these orbital arc lengths, the distance between the satellite position in the reference orbit and the satellite position in the given modified reference orbit is less or equal to the total error of the GOCE satellite position determination.