GRAVITY ADVANCED PACKAGE, AN ACCELEROMETER PACKAGE FOR LAPLACE OR TANDEM MISSIONS

The Einsteinian theory of gravitation, General Relativity (GR), is well verified at scales ranging up to the size of planetary orbits but it is challenged by larger-scale observations. In the Solar System, several anomalies have also been detected in the trajectories of some spacecraft: a small anomalous Doppler acceleration has been detected on Pioneer 10 and 11, and several spacecrafts have an unpredicted increment of velocity after their Earth flyby. Therefore, it is extremely interesting to test the gravity laws at interplanetary scales in the solar system. In the frame of Cosmic Vision selection, the Fundamental Physic Advisory Group of ESA suggested to use an accelerometer, as presented in Odyssey mission proposal, on the future interplanetary mission, Laplace or Tandem mission, pre-selected by ESA, in order to achieve this scientific objective. For such objective, an accelerometer without bias is mandatory in order to discriminate between con- ventional forces applied on the spacecraft and gravity forces, in the low-frequency domain. The Gravity Ad- vanced Package takes advantage of mature technology developed at ONERA for ultra-sensitive accelerometry and a bias rejection system is added in order to obtain the performance in the expected bandwidth.