CLUSTER II, replicating the first Cluster mission destroyed on the ill-fated test flight of Ariane 5 in 1996, consists of four identical spacecraft flying in a tetrahedral formation between 25,000 and 125,000 km above the Earth. They will study the effects of the solar wind and our planet's magnetosphere and electric surroundings in three dimensions for the first time. The four Clusters will be launched in two pairs by two Soyuz rockets in mid 2000.
