Space test of the equivalence principle

First results of the MICROSCOPE mission

Journal article (2019)

Authors

Pierre Touboul Office National d'Etudes et de Recherches Aerospatiales
Gilles Métris Laboratoire Lagrange
Valerio Cipolla CNES Centre National d'Etudes Spatiales
Thibault Damour Institut des Hautes Études Scientifiques
Pascale Danto CNES Centre National d'Etudes Spatiales
Pierre Yves Guidotti CNES Centre National d'Etudes Spatiales
Emilie Hardy Office National d'Etudes et de Recherches Aerospatiales
Alain Robert CNES Centre National d'Etudes Spatiales
P.N.A.M. Visser Astrodynamics & Space Missions - Aerospace Engineering
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Research Group
Astrodynamics & Space Missions (Aerospace Engineering) (TU Delft)
Experimental gravitation General relativity Equivalence principle Microsatellite MICROSCOPE Space accelerometers Drag-free
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Published Date

18-10-2019

Language

English

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Faculty

Aerospace Engineering

Department

Space Engineering

Research Group

Astrodynamics & Space Missions

Abstract

The weak equivalence principle (WEP), stating that two bodies of different compositions and/or mass fall at the same rate in a gravitational field (universality of free fall), is at the very foundation of general relativity. The MICROSCOPE mission aims to test its validity to a precision of 10-15, two orders of magnitude better than current on-ground tests, by using two masses of different compositions (titanium and platinum alloys) on a quasi-circular trajectory around the Earth. This is realised by measuring the accelerations inferred from the forces required to maintain the two masses exactly in the same orbit. Any significant difference between the measured accelerations, occurring at a defined frequency, would correspond to the detection of a violation of the WEP, or to the discovery of a tiny new type of force added to gravity. MICROSCOPE's first results show no hint for such a difference, expressed in terms of Eötvös parameter (both 1 uncertainties) for a titanium and platinum pair of materials. This result was obtained on a session with 120 orbital revolutions representing 7% of the current available data acquired during the whole mission. The quadratic combination of 1 uncertainties leads to a current limit on of about.