Introduction to special section on Double Star‐Cluster Coordinated Studies on Magnetospheric Dynamic Processes

Abstract

[1] The Double Star Program (DSP) is not only the first Chinese scientific satellite program but also the first collaborative mission between the China National Space Administration (CNSA) and the European Space Agency (ESA) [Liu et al., 2005]. This mission consists of two spacecraft, designed to investigate magnetospheric, global dynamic processes, and their response to solar wind-forcing and interplanetary magnetic field (IMF) disturbances, in conjunction with the previously launched four-satellite ESA Cluster Mission (Figure 1). The first spacecraft of DSP, called in Chinese ‘‘Tan Ce –1’’ (TC-1–Explorer-1), was launched successfully by a Chinese Long March 2C rocket at 2006 CET on 29 December 2003, into an elliptical orbit with perigee height of 550 km and apogee of 66,970 km, and inclined at 28.5 degrees to the equator (orbital period 27.4 h). TC-2 was launched also by a Chinese Long March 2C rocket at 1515 CET on 25 July 2004 into a polar orbit, having a perigee height of 700 km and apogee height of 39,000 km, with a period of 11.7 h. [2] The orbits of the two Double Star spacecraft have been specially designed to complement the ESA Cluster mission by maximizing the time periods when both Cluster and Double Star are in the same magnetospheric regions or connected magnetically with each other. The two missions together allow simultaneous observations of the Earth magnetosphere from six points in space in a three-dimensional manner. Together with the four Cluster spacecraft, on the dayside, the TC-1 orbit enables prolonged observations of the Earth’s bow shock and simultaneous observations of magnetic reconnection near the subsolar point and near the cusp, as well as on the flanks of the magnetosphere at both high and low latitudes. On the nightside, the combined spacecraft allow Earth’s dynamic magnetotail to be investigated, simultaneously in key regions where magnetospheric substorm onset and particle acceleration are thought to occur. The TC-2 orbit design focused on physical processes taking place over the high-latitude magnetospheric region, the development of auroral substorms, and the intensification of the ring current. [3] Both Double Star satellites are cylindrical in shape with a diameter of 2.1 m, a height of 1.2 m, and a mass of 340 kg (Figure 2). The two Double Star spacecraft structures are identical and only differ in the communication booms. TC-1 carries one communication boom and TC-2 has two booms. In addition, two deployable 3.5 m booms are attached at the bottom of the spacecraft and carry the fluxgate and search coil magnetometers. The spin axis is set to lie perpendicular to the ecliptic and the spacecraft makes 15 rotations per minute (the same as Cluster) enabling the full, three-dimensional particle distribution functions to be measured every 4 s. [4] Each Double Star spacecraft carries eight scientific instruments to measure the magnetic field, waves, electron, ions of low and high energy, and energetic neutral atoms. The highlight aspect of Europe’s participation in Double Star program was to provide seven identical instruments (spares or duplicates) to those flying on the Cluster spacecraft.