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GOCE satellite orbit in the aspect of selected gravitational perturbations

Bobojć A., Drożyner A.

Acta Geophysica

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2011

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Vol. 59, no. 2

428-452

EN

In this work, the GOCE satellite orbit is described in the aspect of perturbations in the Keplerian osculating elements. The perturbations come from the Earth and ocean tides, the gravitation of the Moon, the gravitation of the Sun, the gravitation of planets and Pluto, and the relativity effects. These perturbations are computed for the 30-day interval with a sampling of 2 min. To obtain the simulated orbit, the Cowell numerical integration method of 8th order is used. The first part of the work contains the root mean square (RMS) values of aforementioned perturbations due to the specified forces. The perturbations were compared taking into account their RMS characteristics. Perturbations in elements of the GOCE osculating orbit are also presented on the plots for successive epochs of the 30-day interval. Changes of the obtained perturbations were described and their characteristic periodic components were distinguished.

2

Determination of the GOCE satellite orbit sensitivity under the influence of perturbing forces

Bobojć A., Drożyner A.

Artificial Satellites : Journal of Planetary Geodesy

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2007

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Vol. 42, No. 2

121--128

EN

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.

3

Badania gradiometryczne w kontekście misji kosmicznej GOCE

Bobojć A., Drożyner A.

Geodezja / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2001

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T. 7, z. 2

151-158

PL

W najbliższych latach należy oczekiwać realizacji, przez Europejską Agencję Kosmiczną, misji kosmicznej Gravity Field and Steady-State Ocean Circulation Mission (GOCE). Satelita GOCE będzie wyposażony między innymi w elektrostatyczny gradiometr. W niniejszej pracy przeanalizowano możliwości wykorzystania obserwacji gradiometrycznych do wyznaczania orbity satelity. Przeprowadzone symulacje pozwalają określić optymalną długość łuku orbitalnego, preferowaną strategię pomiarową oraz oczekiwane dokładności wyznaczenia pozycji satelity. Wskazuje się także na perspektywy dalszych badań symulacyjnych gradiometrii satelitarnej w powiązaniu z planowaną misją GOCE

EN

The launch of the first satellite with the gradiometer on the board is planned between 2004 and 2005 year. This satellite will realize the Gravity Field and Steady-State Ocean Circulation Mission (GOCE). The presented work contains the theoretical aspects and simulation research of the satellite orbit determination by means of the Satellite Gravity Gradiometry observations. The process of the satellite orbit determination includes the estimation of the initial dynamic state vector corrections using the leas squares method. The performed simulations allow to obtain an optimal orbital arc, preferred measurement strategy and accuracy of the satellite position determination. The planned mission GOCE is the main reason for performing the future simulation investigations of the Satellite Gravity Gradiometry