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Gravity Field and Steady State Ocean Circulation Explorer


Designation 34602 / 09013A
Launch date 17 Mar 2009
Country of origin Europe
Mission Scientific: Earth gravity field measurement
Perigee/Apogee 263 km, sun-synchronous
Inclination 96.7°
Launch vehicle Rokot #14

Initially planned for launch in 2005. Exploitation started on 23 Nov 2009.

The gravity gradiometer (main instrument) measures the terrestrial gravitational field thanks to a set of 6 ultra-sensitive capacitive sensors. The gradiometer is combined with a precise GPS instrument.

Part of ESA's Living Planet program.

Within 2 years, it successfully mapped the Earth's gravity.

End of life

End of life 01 Oct 2012
Decay 11 Nov 2013

External resources


sat-index articles

Technical data


Prime contractor Alenia Spazio (Thales Alenia Space)
Platform From Astrium
Mass at launch 1052 kg
Dry mass  
Solar array  
DC power EOL: 1300 W
Design lifetime 20 months

The main payload instrument is a state-of-the-art Electrostatic Gravity Gradiometer incorporating six highly sensitive accelerometers, mounted in pairs along three perpendicular axes on an ultra-stable carbon-carbon structure. The mission will measure not gravity itself but the tiny differences in gravity between the accelerometer pairs 50 cm apart.
The data collected will yield accuracy of 1 to 2 cm in the geoid altitude and 1 mGal for the detection of gravity-field anomalies (mountains, for instance, usually cause local gravitational variations ranging from tens of milligals to approximately one hundred). The spatial resolution will be improved from several hundreds or thousands of kilometres on previous missions to 100 km with GOCE.

The spacecraft incorporates two low-power xenon ion engines, one primary and one backup, each able to deliver 1 to 20 mN of thrust. These thrusters are used to make real-time compensation for atmospheric drag, based on the mean acceleration detected by the two accelerometers mounted along the velocity axis. The system actually works and enabled a drag-free flight.

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