Double Star 2, also known as Explorer 2 and as Tan Ce 2 (TC 2) , is a
European-Chinese (PRC) (ESA-CNSA) satellite that was launched by a Long March 2C
rocket from Taiyuan Satellite Launching Center at 07:05 UT on 25 July 2004.
The 330 kg, 260 W
satellite is cylindrical, with a diameter of 2.1 m, a height of 1.4 m, and spins at a rate
of 15 rpm. It carries eight instruments to probe Earth's magnetosphere, five from ESA and
three from CNSA. (The ESA instruments are legacies from ESA's Cluster mission.) This
joint mission is similar to the equatorial orbiter, Double Star 1, except that Double
Star 2 is a polar orbiter.