Success For Early Double Star Launch

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 Experiments

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.”