The first joint Sino-European mission
Double Star was the first mission launched by China to explore the Earth's magnetosphere - the magnetic bubble that surrounds our planet. It complements the European Space Agency's (ESA) Cluster mission.
Double Star is a joint project between China, which built both satellites, and Europe. Seven of the 16 instruments on the satellites are copies of instruments on Cluster. UK science teams are leading several of the scientific investigations.
The four Cluster and two Double Star satellites have been working together to explore the Sun's effect on our environment. Combining the results from the two missions improves the scientific findings from both.
With its mission now at an end, the first Double Star satellite was decommissioned in October 2007 - turning to dust as it re-entered Earth's atmosphere. Double Star 2 remains operational.
For more information, visit ESA's Double Star homepage (link opens in a new window).
Mission facts
Technology
Each spacecraft consists of a cylinder 1.4 m in height with two long (2.5 m) booms sticking out from the sides.
The technology on Double Star is almost identical to that used on Cluster with one new instrument being designed by Europe specifically for the mission.
UK involvement
Three of the principal investigators from Double Star are from the UK - from the Mullard Space Science Laboratory, Imperial College and the University of Sheffield.
The STFC Rutherford Appleton Laboratory provided the European Payload Operations Centre which operated the seven European instruments used on board the two craft.