The European Space Agency has selected a small telescope for launch in 2017 to study the structure of planets beyond our solar system.

Artist's concept of the Cheops satellite. Credit: University of Bern
 
The Cheops mission is the first of a proposed series of small-class science missions by ESA. The agency chose Cheops from 26 proposals submitted in response to a call issued in March to the European science community.

Cheops stands for the Characterizing Exoplanets Satellite, and the mission is a joint project between ESA and Switzerland.

ESA will decide in 2014 whether the Cheops mission will proceed into final development and launch. The cost of the small-class projects to ESA is capped at 50 million euros, or $65 million.

Including financial contributions from member states - in the case of Cheops, primarily Switzerland - the mission's cost is limited to approximately 150 million euros, or $195 million.

"This continues the 40-year success story of Swiss scientists and industry at the forefront of space science," said Willy Benz, Cheops principal investigator from the Center for Space and Habitability at the University of Bern.

Scientists will point the 13.2-inch telescope on Cheops toward bright nearby stars with known planets and make precise radius measurements of the worlds as they pass between Earth and their host stars.

Using measurements of a planet's radius and mass, astronomers can derive information on the world's internal structure.

Cheops will also contribute to research on the atmospheres, formation and evolution of exoplanets, according to ESA.

"By concentrating on specific known exoplanet host stars, Cheops will enable scientists to conduct comparative studies of planets down to the mass of Earth with a precision that simply cannot be achieved from the ground," said Alvaro Gimenez-Canete, ESA's director of science and robotic exploration.

Cheops will focus on "super-Earths" - planets several times the mass of Earth - up to Neptune-sized worlds.

The telescope will be mounted on a spacecraft weighing about 200 kilograms, or 440 pounds, in a 500-mile-high sun-synchronous orbit for a three-and-a-half year mission.