Double Star E

Double Star is a joint satellite-based space mission by the China National Space Administration (CNSA) and the European Space Agency (ESA). It is the first space mission launched by China to investigate Earth's magnetosphere. It consists of two satellites: an Equatorial satellite (TC-1) and a Polar satellite (TC-2). Double Star follows in the footsteps of ESA's Cluster mission by studying the effects of the Sun on the Earth's environment. After a nominal mission of one year (from the launch of TC-2 in July 2004), the Double Star mission was extended twice by both agencies till the end of September 2007.