CoRoT: a first space mission to find terrestrial planets

CoRoT is a space mission devoted to broadband star photometry in visible light during long observing runs. Developed by CNES with a wide european cooperation, it will be launched in 2006 with two pionneering scientific programs: star seismology and detection of terrestrial planets. CoRoT will use the transit method looking for terrestrial planets slightly larger than the Earth. It will check the existence (or absence) of big ``hot-terrestrials" and will discover, quite certainly, a large number of close-in giants. Our understanding on the origin and evolution of these ``hot" planets will certainly be greatly improved thanks to the strong sample enlargement and to the possibility to measure the planet mass from Doppler follow-up. We give in this paper a brief overview of the instrument, the satellite and the expected detection capabilities. Planetary radii will be measured down to Uranus size around solar type stars and down to Earth size around M type stars. Orbital periods will be determined up to 75 days