The DOUBLE STAR project is a Chinese National Space Administration mission. The ESA and the CNES are participating in the DOUBLE STAR programme by financing European instruments (supplying spare CLUSTER instrument models), part of the data acquisition and the coordination of the scientific operations.
The DOUBLE STAR mission follows in the footsteps of the European CLUSTER mission and is studying the effects of the Sun on the Earth's magnetosphere. Each satellite in the mission has its own orbit:
* one (TC-1) has an equatorial elliptical orbit for studying the Earth's magnetotail, a region where particles are accelerated in the direction of the Earth's magnetic poles by the so-called "reconnection" process;
* the other (TC-2) has a polar elliptical orbit and focuses on the physical processes that occur above the magnetic poles as well as on the development of aurorae Borealis and Australis.
The DOUBLE STAR satellites are equipped with 16 instruments, 7 of which are identical to the instruments on board CLUSTER. The DOUBLE STAR and CLUSTER satellites are synchronised making more detailed exploration of the key regions of the magnetosphere possible.
The two DOUBLE STAR satellites were launched by Chinese Long March 2C launchers from two different sites in China, satellite TC-1 was launched on 29 December 2003 from Xichang (Sichuan province) and satellite TC-2 on 25 July 2004 from Taiyuan (Shanxi province).