<p>Launched on 18 December 2019, CHEOPS (CHaracterising ExOPlanet Satellite) is the first exoplanet mission dedicated to the search for&#160;transits of exoplanets by means of ultrahigh precision photometry of bright stars already known to host planets. It is S-(small) class&#160;mission in ESA&#8217;s Cosmic Vision 2015-2025, and a partnership between Switzerland and ESA, with important contributions from 10 other&#160;member states.<br class="" /><br class="" />CHEOPS will provide the unique capability of determining accurate radii for a subset of planets in the super-Earth to Neptune mass range, for&#160;which masses have already been estimated from ground- based spectroscopic surveys. It will also provide precision radii for new planets&#160;discovered by ground- and space-based transit surveys, including TESS. By combining known masses with CHEOPS sizes, it will be possible to&#160;determine accurate densities for these smaller planets, providing key insight into their composition and internal structure. By identifying transiting&#160;exoplanets with high potential for in-depth characterisation &#8211; e.g. those that are potentially rocky and have thin atmospheres - CHEOPS will also&#160;provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres.<br class="" /><br class="" /></p>
<div class="">80 % of the obsering time in the 3.5 year nominal mission lifetime on the satellite is dedicated to the Guaranteed Time Observing Programme defined by the CHEOPS Science Team. The remaining 20% is available to the Community through the ESA Guest Observers Programme, which comprises annual calls and a discretionary time component. &#160;&#160;</div>
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<p>In this first poster in a series of three, we present an overview of the mission, including its capabilities and scientific performances.</p>