and validated, the satellite has been delivering an almost uninterrupted flow of science data since May 2001. Since this date, all science data have been made available to the more than 150 selected co-investigator teams around the globe through an international Announcement of Opportunity. The scientific goals of the CHAMP mission are to gain a better understanding of dynamic processes taking place in the Earth's interior and in the space near Earth. These goals can be achieved by improved observation of the Earth's gravity and magnetic fields and their time variability with high-performance on-board instru­ mentation and by exploring the structure of the Earth's atmosphere and ionosphere through radio occultation measurements.