Gravity and Steady-State Ocean Circulation Explorer GOCE
GOCE has been launched on March 17, 2009. It is the first satellite of ESA’s Living Planet Programme. It is aiming at a better understanding of the Earth system. The mission objective of GOCE is the determination of the Earth’s gravity field and geoid with high accuracy and maximum spatial resolution. The geoid, combined with the actual mean ocean surface as derived from twenty years of satellite radar altimetry, will yield global dynamic ocean topography. It will serve ocean circulation and ocean transport studies and sea level research. GOCE geoid heights will allow conversion of GPS heights to high precision heights above sea level. Gravity anomalies from GOCE will be used for gravity-to-density inversion and in particular for studies of the Earth’s lithosphere and upper mantle.
GOCE is the first satellite carrying a gravitational gradiometer. In essence the spacecraft together with all its sensors can be regarded as a satellite gravimeter. The mission is unique and novel in several ways. Precise GPS-tracking with a newly developed European receiver is providing the orbit with cm-precision. Orbit analysis will give the long wavelength part of the gravity field and be complementary to the high resolution gravimetric data of the gradiometer. The spacecraft, in an extremely low orbit of only 255 km, is kept free of drag influence by ion-thrusters and is guided smoothly around the Earth by magneto torquers. The gradiometer and star sensors deliver the data necessary for drag-free and angular control. The high demand on the purity of the gravimetric signal is achieved via extreme levels of thermal control and material stiffness.
In the context of the German Geotechnology-Programme methods have been developed for optimal sensor and data analysis, for combination with complementary data sets and for calibration and validation.
KeywordsGOCE Gravitational gradiometry
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