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Double Star

In early 2001 China discussed a dual-spacecraft mission known as Double Star, which would be China's first mission to explore the Earth's magnetosphere. The project consists of two satellites. An equatorial satellite [DSP-E] would be placed into a 550 x 60000 km orbit inclined at 28.5 degrees to the equator. The polar satellite [DSP-P] would be in a 350 x 25000 km orbit inclined at 90 degrees to the equator. Each 270 kg Double Star satellite will carry a payload of scientific experiments - ten on the equatorial spacecraft and nine on the polar spacecraft -- for studies of magnetic fields and charged particle populations in the magnetosphere. It is envisaged that half the instruments would be provided by European institutes, primarily flight spares from the four Cluster spacecraft.

As of late 2001 the target date for the launch of the 'equatorial' Double Star mission (DSP-1) from Xichang has now been moved to June 2003, followed six months later by the launch of the 'polar' spacecraft (DSP-2) from Taiyuan.

The first national deep space science mission may be a lunar orbiter, currently under study for a possible launch at the turn of the century (References 157-158). On 18 March 1998 Ma Xingrui, vice-president of the Chinese Academy of Space Technology (CAST) stated (Reference 159) that: "China ... will launch small lunar explorer when possible."

Double Star will follow in the footsteps of ESA's ground-breaking Cluster mission by studying the effects of the Sun on the Earth¡¯s environment. Conducting joint studies with Cluster and Double Star should increase the overall scientific return from both missions.

A key aspect of ESA's participation in the Double Star project is the inclusion of 10 instruments that are identical to those currently flying on the four Cluster spacecraft. A further eight experiments will be provided by Chinese institutes.

Six of the eleven Cluster principal investigators have agreed to provide flight spares or duplicates of the experiments that are currently revolutionising our understanding of near-Earth space. This reuse of Cluster instruments has a number of advantages for both European and Chinese scientists.

By flying experiments identical to those on Cluster, EAS can reduce costs and development time. This will minimise risk and help us to ensure that we are able to meet the spacecraft development schedule. ESA has agreed to contribute 8 million euros to the Double Star programme. This funding will be used for refurbishment and pre-integration of the European instruments, acquisition of data for 4 hours per day and coordination of scientific operations.

Double Star will be the first mission launched by China to explore the Earth's magnetosphere - the magnetic bubble that surrounds our planet. As its name suggests, Double Star will involve two satellites - each designed, developed, launched and operated by the CNSA - flying in complementary orbits around the Earth. This orbital configuration will enable scientists to obtain simultaneous data on the changing magnetic field and population of electrified particles in different regions of the magnetosphere.