The MICROSCOPE space mission to test the Equivalence Principle

Abstract

The MICROSCOPE space experiment aimed to test the Equivalence Principle with a much better accuracy than ever before. Its principle is to compare the free fall of concentric test masses embedded in a space accelerometer onboard a satellite orbiting the Earth. The effect of non-gravitational forces on the motion of the satellite is strongly reduced thanks to the so-called drag-free system. MICROSCOPE ran from April 2017 until October 2019. The analysis of the first series of measurements leads to an improvement of about an order of magnitude on the accuracy of the test of the Equivalence Principle. No violation has been detected for the pair of masses in platinum and titanium at the level of $10^{-14}$.MICROSCOPE, proposed by ONERA and OCA as science leaders and developed by CNES as project manager, is the first European space mission dedicated to fundamental physics on low Earth orbit. ZARM, PTB and ESA are the main European contributors.

Keywords

• Equivalence principle
• Space experiment
• Satellite
• Accelerometers
• Drag free
• Inertial mass
• Gravitationnal mass