Double Star followed in the footsteps of ESA's Cluster mission by studying the effects of the Sun on the Earth's environment.

[1] The Double Star mission used two satellites in Earth orbit - each designed, developed, launched, and operated by the China National Space Administration.

This funding was used for refurbishment and pre-integration of the European instruments, acquisition of data for four hours per day and co-ordination of scientific operations.

The second polar spacecraft (Double Star 2, also known as DoubleStar2, Explorer 2, Tan Ce 2, TC-2) was launched July 25, 2004 at 07:05 UTC, also by a Long March 2C.

The mission formally ended on October 14, 2007, when the TC-1 spacecraft re-entered the Earth's atmosphere after being decommissioned (an unavoidable consequence of its equatorial orbit).