MICROSCOPE instrument in-flight characterization

Abstract

Since the MICROSCOPE instrument aims to measure accelerations as low as a few 10 −15 m s −2 and cannot operate on ground, it was obvious to have a large time dedicated to its characterization in flight. After its release and first operation, the characterization experiments covered all the aspects of the instrument design in order to consolidate the scientific measurements and the subsequent conclusions drawn from them. Over the course of the mission we validated the servo-control and even updated the PID control laws for each inertial sensor. Thanks to several dedicated experiments and the analysis of the instrument sensitivities, we have been able to identify a number of instrument characteristics such as biases, gold wire and electrostatic stiffnesses, non linearities, couplings and free motion ranges of the test-masses, which may first impact the scientific objective and secondly the analysis of the instrument good operation.

Constraints on chameleon gravity from the measurement of the electrostatic stiffness of the MICROSCOPE mission accelerometers

“…It has been measured by applying a sinusoidal displacement of each test mass separately with an amplitude of 5 μm. The result of this series of tests has been compared to electrostatic models, and a discrepancy has been pinpointed [9]. In Ref.…”