ESA (European Space Agency) has announced they will lunch a satellite called  Cheops – (CHaracterising ExOPlanets Satellite) in 2017  The mission will study near, bright stars that are already know to have planets around them. The satellite will use the transit method of detection which  uses high-precision monitoring of the star’s brightness, scientists will search for the telltale signs of a planet as it passes briefly across the stars  face. This will allow an accurate measurement of the radius of the planet. For those planets with a known mass, the density will be revealed, providing an indication of the internal structure.

Cheops is the first of a what could be a new class of small missions to be developed as part of ESA’s Science Programme.

“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 Professor Alvaro Giménez-Cañete, ESA Director of Science and Robotic Exploration.

“The mission was selected from 26 proposals submitted in response to the Call for Small Missions in March, highlighting the strong interest of the scientific community in dedicated, quick-turnaround missions focusing on key open issues in space science.”

The mission will also provide unique targets for more detailed studies of exoplanet atmospheres by the next generation of telescopes now being built, such as the ground-based European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope.

Cheops will operate in a Sun-synchronous low-Earth orbit at an altitude of 800 km. It has a planned mission lifetime of 3.5 years and part of the observing time will be open to the wider scientific community.