Transcript Sean Bruinsma

Density and Winds Inferred from GOCE
Accelerometer (thrusters) Data
Sean Bruinsma
CNES, Toulouse
Eelco Doornbos
Delft University of Technology
NADIR workshop - October 25-26, 2011
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Project information
ESA contract No. 4000102847/11/NL/EL with TU Delft
Consortium: TU Delft
CNES
HTG
- Management and production
- Product evaluation
- Non-gravitational force modeling
http://thermosphere.tudelft.nl/goceplustheme3/
NADIR workshop - October 25-26, 2011
(nb: register first)
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GOCE: ESA’s first Earth Explorer
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
NADIR workshop - October 25-26, 2011
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GOCE: ESA’s first Earth Explorer
NADIR workshop - October 25-26, 2011
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GOCE mission in perspective
NADIR workshop - October 25-26, 2011
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GOCE mission in perspective
NADIR workshop - October 25-26, 2011
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GOCE mission in perspective
NADIR workshop - October 25-26, 2011
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GOCE: drag and solar radiation
NADIR workshop - October 25-26, 2011
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GOCE: drag and solar radiation
NADIR workshop - October 25-26, 2011
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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
NADIR workshop - October 25-26, 2011
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GOCE thrusters data
NADIR workshop - October 25-26, 2011
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GOCE thrusters data
Thrust < 3mN: noise
(red line=3-point average
Thruster data sampling: 8 s
NADIR workshop - October 25-26, 2011
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Preliminary GOCE densities
NADIR workshop - October 25-26, 2011
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Preliminary GOCE densities
NADIR workshop - October 25-26, 2011
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Preliminary GOCE densities
NADIR workshop - October 25-26, 2011
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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
NADIR workshop - October 25-26, 2011
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