ESA drawing 3D map of Earth
Four ESA (European Space Agency) spacecraft are, for the first time, beginning to map the magnetosphere, the invisible magnetic bubble that surrounds Earth. Planet Earth is bombarded by swarms of particles ejected from the Sun, which sweep towards us at supersonic speeds. Most of the particles in the solar wind are deflected by the planet's magnetic shield, the magnetosphere, but severe magnetic storms on our nearest star are potentially destructive on Earth, with possible power cuts, disrupted radio communications and damage to satellites. Over the next two years, the project, known as 'Cluster', will provide a unique three dimensional view of the battleground between the Earth and the Sun. The Cluster will allow scientists to understand the complexities of the relationship between Earth and the Sun. The key to the breakthrough is the Cluster's ability to fly in close formation along elongated orbits which take them between 19,000 and 119,000 kilometres from the planet. Their course exposes the spacecraft fully to the supersonic solar wind. As the flotilla flies around the planet, the collection of scientific sensors studies the changes taking place around each spacecraft. By comparing the times of these events, scientists are able to create the first three dimensional picture of near-Earth space. Early results have already confirmed the existence of waves along the constantly shifting boundary in space. 'They are like waves that form on the surface of a lake when the wind is blowing,' said Cluster project scientist Philippe Escoubet. 'The Cluster spacecraft give us for the first time the size and speed of these waves.'