ESA to orbit space telescope
CHEOPS will be the first mission dedicated to search for transits by means of ultrahigh precision photometry on bright stars already known to host planets.
By being able to point at nearly any location on the sky, it will provide the unique capability of determining accurate radii for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys.
It will also provide precision radii for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller).
Voice of Russia, SSC