CHHUN , Ratana

The MICROSCOPE space mission aims at testing the Equivalence Principle with an accuracy of 10e-15. To be launched on April 2016, the CNES microsatellite embarks the instrument that should test for the first time in space the foundation of General Relativity. The expected results whether they confirm or not the Equivalence Principle will bring a...

Several space tests of gravity laws have already been performed but the MICROSCOPE mission is the first one to be fully dedicated to the test of the Equivalence Principle. The dedicated payload is now under qualification and the rather large micro satellite will be produced by Cnes for a launch at beginning of 2015. Each of the two differential...

This paper introduces the current special issue focussed on the MICROSCOPE mission. This mission is the first experimental test in space of the weak equivalence principle (WEP) using man-made test-masses—as opposed to astronomical tests—with the goal to reach a precision two orders of magnitude better than ground-based experiments. Selected in...

Launched in April 2016, the satellite of the MICROSCOPE space mission should end its operations in autumn 2018. The science objective is the test of the weak Equivalence Principle (EP) with an accuracy of 10-15. The EP is one cornerstone of General Relativity (GR); it states the equivalence between gravitational and inertial mass. Most of the...

The MICROSCOPE experiment was designed to test the weak equivalence principle in space, by comparing the low-frequency dynamics of cylindrical 'free-falling' test masses controlled by electrostatic forces. We use data taken during technical sessions aimed at estimating the electrostatic stiffness of MICROSCOPE's sensors to constrain a...

Testing the weak equivalence principle to a precision of 10$^{−15}$ requires a quantity of data that give enough confidence on the final result: ideally, the longer the measurement the better the rejection of the statistical noise. The science sessions had a duration of 120 orbits maximum and were regularly repeated and spaced out to...

After performing highly sensitive acceleration measurements during two years of drag-free flight around the Earth, MICROSCOPE provided the best constraint on the weak equivalence principle (WEP) to date. Beside being a technological challenge, this experiment required a specialised data analysis pipeline to look for a potential small signal...

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 necessary 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...

This paper focuses on the description of the design and performance of the MICROSCOPE satellite and its drag-free and attitude control system. The satellite is derived from CNES' Myriade platform family, albeit with significant upgrades dictated by the unprecedented MICROSCOPE's mission requirements. The 300 kg drag-free microsatellite has...

The MICROSCOPE mission aimed to test the weak equivalence principle (WEP) to a precision of 10$^{−15}$. The WEP states that two bodies fall at the same rate on a gravitational field independently of their mass or composition. In MICROSCOPE, two masses of different compositions (titanium and platinum alloys) are placed on a quasi-circular...

This paper focuses on the dedicated accelerometers developed for the MICROSCOPE mission taking into account the specific range of acceleration to be measured on board the satellite. Considering one micro-g and even less as the full range of the instrument with an objective of one femto-g resolution, that leads to a customized concept and a...

The MICROSCOPE mission aims to test the weak equivalence principle (WEP) in orbit with an unprecedented precision of 10$^{−15}$ on the Eötvös parameter thanks to electrostatic accelerometers on board a drag-free micro-satellite. The precision of the test is determined by statistical errors, due to the environment and instrument noises, and by...

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...

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10−15 precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit.A...

The space mission MICROSCOPE dedicated to the test of the equivalence principle (EP) operated from April 25, 2016 until the deactivation of the satellite on October 16, 2018. In this analysis we compare the free-fall accelerations (a$_{A}$ and a$_{B}$) of two test masses in terms of the Eötvös parameter . No EP violation has been detected for...

The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10-15 in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as...