Cluster II

Mission Profile

Cluster II is a constellation of four identical ESA spacecraft launched in pairs in July-August 2000 aboard Soyuz-U rockets from Baikonur, designed to study the Earth's magnetosphere in three dimensions by making simultaneous measurements at four different positions. Flying in a tetrahedral formation whose size varies from a few hundred to 20,000 kilometers, Cluster II enables calculation of spatial gradients of plasma quantities that are impossible to determine with a single spacecraft. The mission has produced landmark observations of magnetic reconnection in the magnetotail, boundary layer turbulence, and the structure of shocks in the solar wind, directly advancing fundamental plasma physics. Cluster II succeeded the original Cluster constellation, which was destroyed in the first Ariane 5 launch failure in 1996, and has operated for over two decades.