  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 non-vanishing result would correspond to a
violation of the Equivalence Principle, or to the discovery of a new long-range
force. Analysis of the first data gives $\delta\rm{(Ti,Pt)}= [-1 \pm 9
(\mathrm{stat}) \pm 9 (\mathrm{syst})] \times 10^{-15}$ (1$\sigma$ statistical
uncertainty) for the titanium-platinum E\"otv\"os parameter characterizing the
relative difference in their free-fall accelerations.
