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Last Updated on Thursday, 15 April 2010 20:16
Published on Wednesday, 02 March 2005 00:00

A rare event in the history of space exploration took place yesterday (25 July) when the second European-Chinese Double Star spacecraft lifted off a day early from Taiyuan spaceport, west of Beijing, on a Long March 2C rocket.

The launch of the spacecraft, officially called Tan Ce 2 (Explorer 2), was brought forward one day to avoid bad weather. Lift off occurred at 08:05:18 BST (07:05:18 GMT or 15.05:18 local time).

Preliminary analysis of spacecraft data indicate that the spacecraft has been successfully inserted into a polar orbit ranging from 681 km to 38,278 km above the Earth, and that its experiment booms have deployed correctly.

Tan Ce 2 is the second spacecraft to be built for the Double Star programme, a unique collaboration between Chinese and European scientists. Its predecessor, Tan Ce 1 (Explorer 1), was successfully launched on a similar rocket from a launch site in Xichang on 29 December 2003 and is now returning a rich stream of data.

Eagerly awaited by UK scientists, who have played a major role in the Double Star missions, Tan Ce 2 will complete a six spacecraft Sino-European constellation designed to solve a 30 year-old space mystery: what happens when magnetic storms are generated above the Earth?

"We are delighted that everything seems to be going according to plan," said Andrew Fazakerley (MSSL-ICL), one of the UK principal investigators for both Double Star and Cluster.


UK teams play major roles in both Double Star and Cluster, through provision of instruments and involvement in science operations.

Seven of the eight European instruments on the pair of Double Star spacecraft (including five led by the UK) are copies of instruments on Cluster.

The Plasma Electron and Current Experiment (PEACE) on TC-1 and TC-2 was provided by the Cluster team at Mullard Space Science Laboratory, led by Andrew Fazakerley. This measures the speed, direction and population of electrons around the spacecraft.

Principal Investigator for the Fluxgate Magnetometer (FGM) experiments on TC-1 and lead Co-Investigator for the TC-2 FGM is Chris Carr from the Cluster team at Imperial College London. These instruments can measure a magnetic field in space 1,000 times weaker than the field at the Earth's surface.

An experiment on TC-1 that measures waves (rapid variations in the magnetic field) includes the Digital Wave Processor (DWP) instrument, developed by the Cluster team at the University of Sheffield, under the leadership of Hugo Alleyne.

In addition, Double Star will draw on science operations expertise at the Rutherford Appleton Laboratory (RAL). RAL has been running the Cluster Joint Science Operations Centre (JSOC) since the beginning of 2001 and has adapted this to provide a similar service for Double Star. This European Payload Operations Service (EPOS) works with the European instrument teams on Double Star to co-ordinate the commanding of their instruments and delivers the finalised commanding to the Double Star Science Application System in Beijing.

RAL is also providing the Double Star Data Management System that will exchange key data products generated by the instrument teams between national data centres in Austria, France and the UK, and enable scientists and the general public to browse and retrieve those products.

Mike Hapgood, lead scientist for both the Cluster JSOC and Double Star EPOS, says, "This is a great opportunity to advance our understanding of the large-scale behaviour of the Earth's magnetosphere."


Double Star is the first major collaboration between Europe and China on a scientific space mission. A major challenge has been to compare the methods used to develop space missions in Europe and China and to develop efficient ways of working together.

Each Double Star spacecraft is a spinning cylinder about 2 metres across and 1 metre high.

Tan Ce 1 (TC-1) is flying in a highly elliptical equatorial orbit of 570 x 78,850 km altitude (354 x 48,997 miles), inclined at 28.5 degrees to the equator. Over a lifetime of at least 18 months, it will sample key regions on the day and night sides of the Earth where the process of magnetic reconnection occurs. These reconnection processes dominate the dynamics of the magnetosphere.

The 343 kg drum-shaped Tan Ce 2 (TC-2) will observe the Earth's the changing magnetosphere from a highly elliptical polar orbit. Over a period of at least one year, it will sample the polar cap and cusps - the main regions where energy from the Sun flows into the magnetosphere. Those energy flows are largely controlled by the reconnection processes to be studied by TC-1.

European institutes contribute eight of the 16 Double Star scientific instruments and part of the network of data systems on the ground. These instruments are almost identical to some of those that have been flying on the Cluster quartet since the summer of 2000.

The four identical Cluster spacecraft - Rumba, Salsa, Samba and Tango - pirouette around the Earth in close formation, carrying out unique multi-scale, 3-D observations of the electrically charged particles in the solar wind and their battle with the magnetosphere.

In order to allow the combined observations by six spacecraft, the lifetime of ESA's Cluster mission has been extended three years until the end of 2005. If all goes well, the lifetime of all the spacecraft may be further extended to increase the scientific return of this unique constellation.

The turbulent interaction between the supersonic solar wind and Earth's protective magnetic shield is revealed in various ways. The arrival of huge clouds of magnetised particles (known as coronal mass ejections) at the Earth gives rise to the beautiful aurorae - the Northern and Southern Lights - but it can also produce magnetic storms that may have serious consequences for human activities, from power cuts to damaged satellites and communication breakdowns.

Chris CarrPI for the Fluxgate Magnetometer [FGM] (TC-1)Space and Atmospheric Physics GroupImperial CollegeLondon, SW7 2BZTel: +44 (0)20-7594-7765Mobile: +44 (0)7714-713377E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Dr. Andrew FazakerleyPI for the Plasma Electron and Current Experiment [PEACE] (TC-1 and TC-2)Mullard Space Science Laboratory / University College LondonHolmbury St. MaryDorkingSurrey, RH5 6NTTel.: +44 (0)1483-204175Mobile: +44 (0)7712-760269E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Dr. Christopher J. OwenCo-I for PEACE (see above)Mullard Space Science Laboratory / University College LondonTel.: +44 (0)1483-204281Mobile: +44 (0)7793-671072E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Dr. Hugo AlleynePI for the Digital Wave Processor [DWP] (TC-1)Space Systems GroupDepartment of Automatic Control & Systems EngineeringUniversity of SheffieldMappin StreetSheffield, S1 3JDTel: +44 (0)114-222-5630Fax: +44 (0)114-222-5661Email: This email address is being protected from spambots. You need JavaScript enabled to view it. Dr. Mike HapgoodLead Scientist, Satellite Operations GroupRutherford Appleton LaboratoryChiltonDidcotOXON, OX11 0QXTel.: +44 (0)1235-446520Mobile: +44 (0)789-9908780.E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it. Trevor DimbylowManager, RAL science operations projectsRutherford Appleton Laboratory (see above)Tel.: +44 (0)1235-445827E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Chinese National Space Administration:

Double Star data and orbit visualisations:

Rutherford Appleton Laboratory (Cluster / Joint Science Operations Centre):

Date: 26th July 2004

Issued by Peter Bond, RAS Press Officer.