Cheops is ESA's CHaracterising ExOPlanet Satellite. It is the first mission dedicated to studying bright, nearby stars that are already known to host exoplanets, in order to make high-precision observations of the planet's size as it passes in front of its host star. It will focus on planets in the super-Earth to Neptune size range, with its data enabling the bulk density of the planets to be derived – a first-step characterisation towards understanding these alien worlds.
Cheops paves the way for the next generation of ESA's exoplanet satellites, with two further missions – Plato and Ariel – planned for the next decade to tackle different aspects of the evolving field of exoplanet science.
Cheops is the first small, or S-class, mission in ESA’s science programme. It is a partnership between ESA and Switzerland, with a dedicated Consortium led by the University of Bern, and with important contributions from 10 other ESA Member States.