Short answers, pulled from the story.
The Microscope satellite was a minisatellite launched to test the equivalence principle, a cornerstone of Albert Einstein's general theory of relativity. It carried two cylinders of metal designed to fall at exactly the same rate to verify the universality of free fall with unprecedented precision.
The Microscope satellite was successfully launched on the 25th of April 2016 at 21:02:13 UTC from the Guiana Space Centre outside Kourou, French Guiana. It was carried into orbit by a Soyuz ST-A booster equipped with a Fregat-M upper stage.
The experiment used two alloys with different neutron-to-proton ratios, specifically a platinum-rhodium alloy and a titanium-aluminium-vanadium alloy designated TA6V. These materials served as concentric cylindrical masses within the Twin-Space Accelerometer for Gravity Experiment instrument.
The satellite was decommissioned on the 18th of October 2018 after exhausting its supply of nitrogen fuel. Two IDEAS inflatable booms were deployed to increase drag and ensure the spacecraft re-entered Earth's atmosphere within 25 years.
The first results published on the 4th of December 2017 confirmed that the equivalence principle held true within a precision of 10 to the minus 15. This measurement improved upon prior measurements by an order of magnitude and reinforced the validity of Einstein's general theory of relativity.