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Micro-Satellite à traînée Compensée pour l'Observation du Principe d'Equivalence


Designation 41457 / 16025B
Launch date 25 Apr 2016
Country of origin France
Mission Scientific: Physics
Perigee/Apogee 711 km, near polar orbit
Inclination 98.2°
Period 99 min
Launch vehicle Soyuz VS14

Will test the equivalence principle described by Albert Einstein.
In space, it is possible to study the relative motion of two bodies in almost perfect and permanent free fall aboard an orbiting satellite, shielded from perturbations encountered on Earth (notably seismic).

CNES is providing 90% of funding for this mission (EUR 70.4 million).

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Technical data


Prime contractor CNES
Platform Myriade
Mass at launch 303 kg
Dry mass  
Solar array  
DC power  
Design lifetime 1 year

The satellite carries two concentric cylindrical test masses made of different materials - one titanium and one a platinum-rhodium alloy. Their movement will be minutely controlled inside independent differential electrostatic accelerometers to keep them motionless with respect to the satellite. If the equivalence principle is verified, these two masses will be subjected to the same control acceleration; if different accelerations have to be applied, the principle will be violated - an event that would shake the foundations of physics.

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