GOCE Mission: on-ground characterization results for the GRADIO accelerometer flight models
- Paper number
IAC-05-B1.3.01
- Author
Dr. Bernard Foulon, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France
- Coauthor
Mr. Jean-Pierre Marque, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France
- Coauthor
Mr. Bruno Christophe, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France
- Coauthor
Mrs. Françoise Liorzou, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France
- Coauthor
Mr. Guillaume Hermand, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France
- Year
2005
- Abstract
The aim of ESA’s Gravity Field and Steady-State Ocean Circulation Explorer mission (GOCE) is to generate an accurate and global mapping of the Earth’s gravity field for oceanographic, geophysical, hydrological and climatological applications. The mission consists of measuring in orbit the components of the gravity gradient tensor. Due for launch in Summer 2006 by a Rockot launch vehicle, to a sun-synchronous, 250 km altitude circular polar orbit, the GOCE Satellite will carry, for the first time in a space mission, a three-axis gradiometer consisting of six ultra sensitive electrostatic accelerometers offering an outstanding resolution of 2×10 −12 ms −2/Hz 1/2.
The principle of operation of the accelerometers is to measure the forces that maintain a proof mass at the centre of a very stable electrode cage. The mass position is detected by capacitive sensing and servo-controlled electrostatic suspension controls the proof mass linear and rotational motion. Before being mounted by pairs on the three orthogonal arms which constitute the gradiometer ultra-stable structure, the accelerometers are tested and characterised in specific facilities: pendulum seismic benches and the Bremen free-fall tower.
This article presents a synthesis of the results obtained during the on-ground tests of the flight models, which are performed to finely characterize the instruments. Due to the normal gravity and ground residual seismic noise, the final performance of the accelerometer cannot be achieved directly on ground. Nevertheless, the comparison of the test measurements to the detailed analysis and error budget model of the instrument will give the necessary confidence in the in-orbit performance of the GRADIO accelerometer.
- Abstract document