The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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The Characterising Exoplanet Satellite, Cheops, will make measurements of alien worlds that will help determine their nature. It will focus on Earth-to-Neptune sized planets orbiting nearby bright stars, and will measure the size of the planet as it transits in front of the star.
Combined with known information about the mass of the planet, these data will enable scientists to distinguish between a dense rocky world or rather more gaseous, a water-world or an ice-rich planet – as represented from left to right in this artist impression.
Cheops will identify which planets are rather more similar in composition to Mercury, Venus, Earth and Mars in our own Solar System, or if they resemble small versions of the outer Solar System’s gas giants like Neptune or Uranus. It will also be able to identify hot-Jupiters – large gas planets similar in mass and size to Jupiter but orbiting very close to their host stars – or rather smaller and rocky lava worlds orbiting close to their star.
This first-step characterisation of these worlds – many with no Solar System equivalents – is a critical process towards understanding the formation, origin and evolution of these small exoplanets.