  The MICROSCOPE space mission aims to test the Equivalence Principle with an
accuracy of $10^{-15}$. The drag-free micro-satellite will orbit around the
Earth and embark a differential electrostatic accelerometer including two
cylindrical test masses submitted to the same gravitational field and made of
different materials. The experience consists in testing the equality of the
electrostatic acceleration applied to the masses to maintain them relatively
motionless. The accuracy of the measurements exploited for the test of the
Equivalence Principle is limited by our a priori knowledge of several physical
parameters of the instrument. These parameters are partially estimated
on-ground, but with an insufficient accuracy, and an in-orbit calibration is
therefore required to correct the measurements. The calibration procedures have
been defined and their analytical performances have been evaluated. In
addition, a simulator software including the dynamics model of the instrument,
the satellite drag-free system and the perturbing environment has been
developed to numerically validate the analytical results. After an overall
presentation of the MICROSCOPE mission, this paper will describe the
calibration procedures and focus on the simulator. Such an in-flight
calibration is mandatory for similar space missions taking advantage of a
drag-free system.
