CHEOPS is the first scientific mission, in which Switzerland and the university of Bern play a leading role. The scientific goal of the mission is to measure the radii of exoplanets. Planets outside the solar system for which we already know the mass. Once we know the mass and the radius of the planet we can calculate its average density and based on the average density we can determine the characteristics of the internal structure of the planet.
Actually, CHEOPS is a flying space telescope with a mirror, 33 centimeters in diameters and a total length of about 1.5 meters.