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  • Equivalence Principle test with MICROSCOPE: Laboratory and engineering models preliminary results for evaluation of performance

    Paper number

    IAC-05-A2.1.02

    Author

    Mr. Ratana Chhun, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Coauthor

    Ms. Danya Hudson, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Coauthor

    Mr. Patrick Flinoise, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Coauthor

    Mr. Manuel Rodrigues, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Coauthor

    Mr. Pierre Touboul, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Coauthor

    Dr. Bernard Foulon, Office National d’Etudes et de Recherches Aérospatiales (ONERA), France

    Year

    2005

    Abstract

    MICROSCOPE is a space mission, scheduled for a launch in 2008, which aims to verify the Equivalence Principle (EP) with an accuracy of 10 −15, over a hundred times better than what has been realized on Earth today. The EP test is based on the measurement of the electrostatic forces to be applied on each test-mass of two concentric inertial sensors, in order to maintain these two masses on the same gravitational trajectory. The instrument formed by these two sensors is called a differential accelerometer. On board the MICROSCOPE satellite, two instruments will embark: one with two masses made of a different material, used for the test itself, and the other with two masses made of the same material, used as a performance reference. Several models for this instrument are foreseen, the first two having already been manufactured: a prototype model (proto), an engineering model (EM), a qualification model (QM) and a flight model (FM). Associated to the differential accelerometer, a performance model has also been developed. This software tool computes the error budget of the instrument, taking into account the precision of the mechanical parts machining, its thermal, magnetic, and self-gravity environment, as well as the drag-free and attitude control system performance. In order to reach the required performance, an in-orbit calibration phase is planned to improve the knowledge of the geometrical dissymmetries and orientation mismatches. The first tests performed on the EM parts and on the proto, for instance the turnover capacitance tests, will bring updated values to the currently considered geometrical inaccuracies. This better knowledge has a direct impact on the evaluation of electrostatic stiffness, accelerometer bias, and associated noise present in the performance model output. It also has an effect on the evaluation of the scale factor, which is particularly critical to the calibration phase. Detailed finite element thermal models of the FM accelerometers have been realized and currently provide relevant information on the behavior of accelerometer parts in response to the satellite thermal perturbations. This document will also describe the overall design, the first outputs from the analysis of the prototype and engineering models, and the resulting impact on the performance of the instrument.

    Abstract document

    IAC-05-A2.1.02.pdf

    Manuscript document

    IAC-05-A2.1.02.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.