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Density and Winds Inferred from GOCE Accelerometer (thrusters) Data

Sean BruinsmaCNES, Toulouse

Eelco DoornbosDelft University of Technology

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ESA contract No. 4000102847/11/NL/EL with TU Delft

Consortium: TU Delft - Management and productionCNES - Product evaluationHTG - Non-gravitational force modeling

Project information

http://thermosphere.tudelft.nl/goceplustheme3/ (nb: register first)

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Launch: 17 march 2009 (Plesetsk)Mission objectives:Determine geoid with an accuracy of 2 cm and gravity anomalies with an accuracy of 1-2 mGal (1-2 10-5 m/s2) at a resolution of 100 km (degree 200)

Mission orbit:Sun-synchronous (i=96.5°), dawn/dusk, 255 km altitude

Payload:Gradiometer (accelerometers), GPS receiver, laser retroreflector

Drag control:Ion thrusters commanded in closed-loop

GOCE: ESA’s first Earth Explorer

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GOCE: ESA’s first Earth Explorer

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GOCE mission in perspective

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GOCE mission in perspective

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GOCE mission in perspective

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GOCE: drag and solar radiation

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GOCE: drag and solar radiation

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GOCE natural decay & drag-free

Natural decay (about 3 months, not shown) followed by drag-free flight starting 13 September 2009 at the mission altitude of 254.9 km(NB: the figure shows mean spherical altitude)

Density inferred from accelerometer data

Density inferred from thrusters+accelerometer data

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GOCE thrusters data

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GOCE thrusters data

Thrust < 3mN: noise(red line=3-point average

Thruster data sampling: 8 s

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Preliminary GOCE densities

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Preliminary GOCE densities

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Preliminary GOCE densities

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GOCE densities

To do:• Implement satellite model• Combine thrusters and accelerometer data• Compute densities and winds• Validate products

Poster in session SA10 at the AGU Fall Meeting