Swarm - a constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system

The objective of the swarm mission is to provide the best survey ever of the geomagnetic field and its temporal evolution, enabling a better look at the global dynamics of the fluid core. Magnetic fields play an important role in physical processes, throughout the Universe. The magnetic field measurement at or near the surface of the Earth is the superposition of contributions from a variety of sources, the fluid core, the magnetisation of rocks in the Earth's crust, electric currents induced in the Earth by the time variations of the field, and electric currents induced by the oceanic circulation. The scientific challenge is the sophisticated separation of these various sources and the accurate determination of the spatial and temporal structure of them all. The swarm concept consists of a constellation of four satellites in two different polar orbits between 400 and 550 Km altitude. Each satellite provides high-precision and high-resolution measurements of the vector magnetic field. In combination, they provide the necessary observations for the global high-precision survey of the geomagnetic field that is needed to model the various sources of the geomagnetic field. A few additional instruments like GPS receivers, an accelerometer, and an electric field instrument provide supplementary information for studying the interaction of the magnetic field with other physical quantities describing the Earth system.