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Construction set to begin for CHEOPS exoplanet mission

Jenny Winder, News Writer
Jul 13, 2014, 15:00 UTC

Sen—The European Space Agency's CHaracterising ExOPlanet Satellite (CHEOPS) is ready for construction. The spacecraft has gone from selection to implementation in less than 18 months and is on course to be ready to launch by December 2017.

CHEOPS is the first in a possible class of small missions to be developed as part of ESA's Science Programme. These will be fast turn-around, highly focused missions that complement the Science Programme's medium and large missions.

Using ultrahigh precision photometry, CHEOPS will target nearby bright stars that are already known to have exoplanets in orbit around them.

Ground-based Doppler searches find planets by detecting wobbles in the central star. CHEOPS will provide complementary data by monitoring the parent stars for transits—the dip in starlight caused by a planet’s silhouette as it crosses the line of sight.

This will allow astronomers to determine the radius of the planet. With the mass known from ground-based Doppler searches, astronomers will be able to estimate the planet's density, allowing rocky planets to be distinguished from gas giants or any other type of planet.

CHEOPS is designed to be sensitive to planets ranging from a few times the size of the Earth up to the size of Neptune. It will also identify planets with significant atmospheres and constrain the migration of planets during the formation and evolution of their parent systems.

An artist's impression of CHEOPS operating in space. Image credit: ESA - C. Carreau

Capped to an ESA cost of €50 million, the mission is being developed in collaboration with the Swiss Space Office (SSO), a division of the Swiss State Secretariat for Education, Research and Innovation (SERI), and the University of Bern, Switzerland. The spacecraft will be built by Airbus Defence and Space, Spain.

The Principal Investigator for the science instrument is Professor Willy Benz from the University of Bern.

"CHEOPS is a unique high-precision photometric observatory that can point nearly anywhere in the sky. It will be used to search for transits on bright stars already known to host planets," says Benz.

"By knowing where to look and at what time, CHEOPS is the most efficient instrument to detect shallow transits. It will significantly increase the sample of exoplanets for which we know both mass and radius, providing new insights and constraints on formation models. It will also provide the best targets for subsequent spectroscopic studies by the next generation of ground- and space-based instruments."

"The cost and schedule constraints associated with a small mission in the Science Programme mean that all platform components and systems have to be 'off-the-shelf' and qualified for use in space. The only new development is the scientific instrument, which has to fulfil specific requirements but even that relies on available technologies," says Nicola Rando, ESA Definition Phase Manager for CHEOPS.

CHEOPS will be a small spacecraft. When stowed for launch, the satellite will measure about 1.5 m by 1.4 m by 1.5 m with a total mass of approximately 250 kg. It is expected to launch as a passenger on a Soyuz or Vega launcher from Kourou at the end of 2017. It will be deployed into a circular Sun-synchronous orbit, at an altitude of between 650 and 800 km.