MICROSCOPE instrument in-flight characterization

TL;DR

The paper details the in-flight characterization of the MICROSCOPE instrument, focusing on validating and updating control laws, identifying instrument characteristics, and ensuring measurement precision for testing fundamental physics.

Contribution

It presents the first comprehensive in-flight characterization of MICROSCOPE, including validation of control laws and identification of key instrument parameters affecting measurement accuracy.

Findings

Validated servo-control and updated PID laws

Identified biases, stiffnesses, and non-linearities

Assessed instrument sensitivities and couplings

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.