The Microscope Mission and Its Uncertainty Analysis

The accurate test of the Universality of Free Fall may demonstrate a violation of Einstein Equivalence Principle (EP) as most attempts of Grand Unification theories seem to conduct. The MICROSCOPE space mission aims at an accuracy of 10−15 with a small drag free satellite and a payload based on electrostatic inertial sensors. The two test-masses made of Platinum and Titanium alloys are forced to follow accurately the same orbit. The sets of surrounding electrodes carried by gold coated silica parts allows the generation of electrical fields and electrostatic pressures on the masses. Common forces and torques are exploited to control the satellite drag compensation system and its fine inertial or rotating pointing. Difference in the force along the Earth gravity monopole is accurately measured and interpreted for the test. After a short presentation of the mission and the instrument, most of the relevant parameters to the experiment performance are detailed as well as the associated technologies to reach the expected levels of accuracy. Present error budgets confirm the test expected accuracy of better than 10−15.