content 19-November-2018 08:06:46


CHaracterising ExOPlanet Satellite

Ultrahigh precision photometry of exoplanetary transits

Cosmic Vision Themes What are the conditions for planet formation and the emergence of life?
Primary goal Characterise transiting exoplanets orbiting bright host stars
Targets Known exoplanet host stars with a V-magnitude ≤ 12 anywhere in the sky
Wavelength 0.4 to 1.1 µm
Orbit Sun-synchronous, 650-800 km altitude, local time of ascending node: 06:00
Lifetime 3.5 years science operations (5 years goal)
Type Small (S-class) mission

CHEOPS - CHaracterising ExOPlanet Satellite - will be the first mission dedicated to searching for exoplanetary transits by performing ultrahigh precision photometry on bright stars already known to host planets.

Artist's impression of CHEOPS.
Credit: ESA/ATG medialab

CHEOPS will provide the unique capability of determining radii within ~10% accuracy for a subset of those planets, in the super-Earth to Neptune mass range, for which the mass has already been estimated using ground-based spectroscopic surveys. CHEOPS will also provide accurate radii for new planets discovered by the next generation of ground-based or space transits surveys (from super-Earth to Neptune-size). By unveiling transiting exoplanets with high potential for in-depth characterisation, CHEOPS will provide suitable targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres.

Knowing where to look and at what time to observe makes CHEOPS the most efficient instrument to search for shallow transits and to determine accurate radii for planets in the super-Earth to Neptune mass range.

On 19 October 2012, CHEOPS was selected for study as the first S-class mission in Cosmic Vision 2015-2025. The mission was formally adopted in early February 2014, with launch planned for 2019.

The CHEOPS mission baseline relies completely on components with flight heritage. This is valid for the platform as well as for the payload components. For the latter, the team can exploit significant heritage from the CoRoT mission, minimising both cost and risk.


The CHEOPS mission is envisaged as a partnership between Switzerland and ESA's Science Programme, with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom.

Last Update: 20 September 2018

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