Focus on our magnetic planet   Spacecraft faults are more common over the South Atlantic during times of high solar activity. It is there that a local weakness in Earth's magnetic field leads to an enhanced level of charged atomic particles which can cause damage to onboard electronic systems. This 'South Atlantic Anomaly' is illustrated here with a chart showing memory upsets to the veteran UoSAT-2 spacecraft. The image shows the distribution of memory upsets experienced by UOSAT-2. They cluster strongly over South America. Scientists and satellite operators try to shield instruments and computers against the penetrating particles and limit the use of these types of systems while drifting through the South Atlantic Anomaly.   Swarm is a constellation of three satellites. Two of them will fly at an initial altitude of 450 km, with the third at 550 km. This Earth Explorer mission should provide highly detailed visualisations of the Earth's magnetic field. Separating the different sources of magnetism     The Earth's magnetic field is mainly produced by a self-sustaining dynamo in the fluid outer-core.   Many different magnetic sources contribute to the overall magnetosphere. Remove more dominant fields, and weaker magnetic sources are revealed. The slideshow above is a set of five images of the globe with magnetic fields at increasing amplification. In order of presentation they are the Core (1x); Magnetosphere (1000x); Ionosphere (2000x); Crust (6000x); Ocean flow (30 000x).   Swarm is an Earth Explorer Opportunity Mission. The Swarm constellation will study the dynamics of the Earth's magnetic field and its interactions with the Earth system. Each Swarm satellite will be eight metres long and weigh 300 - 400 kilograms. Practical benefits     Release date: 23 March 2009