||Swarm is a minisatellite constellation mission within the Earth Explorer Opportunity Program of ESA, proposed under the lead of DNSC (Danish National Space Center) of Copenhagen, Denmark (formerly DSRI). The Swarm mission was selected as the 5th mission in ESA's Earth Explorer Program in 2004.
The first mission to ever map the Earth's magnetic field vector at LEO was the NASA MagSat spacecraft (launch Oct. 30 1979). Due to the low perigee (perigee=350 km, apogee=551 km), MagSat remained in orbit for only seven and a half months until June 11, 1980. About 20 years later, the Danish Ørsted micro satellite (1999-), the German CHAMP (2000-), the Argentine SAC-C (2000-5) have been designed specifically for mapping the LEO magnetic field. Common to these recent missions is the magnetometry package, which utilizes a vector field magnetometer co-mounted with a star tracker (2 in the case of CHAMP) on an optical bench. As the accuracy of the instrument package has constantly increased, as well as the modelling methods have been improved towards optimized signal decomposition, it has been realized that simultaneous data from several points in space is needed, if the ultimate modelling barrier, the spatial-temporal ambiguity, has to be broken.
The overall objective of the Swarm mission is to build on the Ørsted mission experiences and to provide the best ever survey of the geomagnetic field (multi-point measurements) and its temporal evolution, to gain new insights into the Earth system by improving our understanding of the Earth's interior and climate.