|Cluster is a mission of international cooperation between ESA and NASA. It is composed of four identical spacecraft flying in formation high above Earth's poles. Their role is to investigate the Sun-Earth interaction.
Cluster probes Earth's magnetic environment, known as the magnetosphere, and how it is affected by the perpetual stream of subatomic charged particles coming from the Sun, known as the ‘solar wind’. The beautiful polar auroras are an impressive consequence of this interaction, but there are other less-benign effects. A very energetic solar wind can trigger the disruption of electrical power systems and telecommunications, as well as damaging man-made satellites. By understanding the interaction between the solar wind and the magnetosphere, Cluster helps us to better forecast the effects of sudden bursts of solar activity.