European space telescope will measure distant worlds

Cheops is the European Space Agency's first mission dedicated to the study of extrasolar planets, or exoplanets - the worlds that exist outside our Solar System. The space telescope will observe bright stars that are already known to host planets. By measuring tiny dips in the brightness of these stars as the worlds pass in front of them, Cheops will begin to characterise the planets, suggesting answers to questions like "what are they made of?" Kate Isaak is Esa's project scientist on the Cheops mission. She spoke to our correspondent Jonathan Amos.