Beidou

Name of the project

Its name, Beidou , come from the Mandarin 北斗 ( běidǒu ) which indicates celebrates it Astérisme “pan” of the Constellation of the Grande Ourse (see Beidou (astronomy)).

The project is also known in Occident (in particular in Francophonie and Germany) under the name of Compass.

History

The component launching of the satellites this system began in the year 2000 and should be completed around 2010.

The Beidou project had been initiated in 1983 by the proposal of Chen Fangyun to develop a navigation system using two geostationary satellites . The idea was put into practice in 1989 with two communications satellites of the type DFH-2/2A. This test showed that the precision of this system with “two satellites” was comparable with that of the American GPS. In 1993, the Beidou program is officially launched. In the long term, it will be composed of four geostationary satellites from type DFH-3, two operational and two of help.

Composition

The system Beidou (Compass) will consist of a geostationary satellite and thirty satellites in average orbit (MEO) which should in the long term be integrated into systems GPS and Galileo (that thus defers us after 2012).

The system is currently composed of three satellites in orbit Géostationnaire (140° E., 80° E., 110,5° E.). The precision would be of about thirty meters. Three launchings took place with a rocket Chang Zheng (Long walk) 3A.

Beidou 1A, the October 30th 2000 (site of launching: Xichang; convey launching: CZ-3A; mass: 2.200 kg; perigee: 35.772 km; apogee: 35.803 km; slope: 0,1°).
Beidou 1B, the December 20th 2000 (site of launching: Xichang; convey launching: CZ-3A; mass: 2.200 kg; perigee: 35.753 km; apogee: 35.821 km; slope: 0,0°): the launching of this second Beidou supplements the prototype of navigation system to “two satellites” making it possible in particular to give information for road transport, railway and maritime.
Beidou 2A, the May 24th 2003 (site of launching: Xichang; convey launching: CZ-3A; mass: 2.200 kg; perigee: 35.760 km; apogee: 35.836 km; slope: 0,3°): it is about the third and last satellite launched for the moment, the last having to be placed in orbit in the years to come.

Satellite DFH-3

Satellite DFH-3 (Dong Fang Hong: “the red East”) is that used in the Beidou system, it is broader than its predecessor satellite DFH-2 and uses three axes of stabilization. It contains twenty-four Transpondeur S 6/4 GHz for the transmissions of the Télévision and the Téléphone. Finally its lifespan is roughly eight years (against four for its predecessors). To answer the strong demand of the Chinese market as regards broad band diffusion and communications satellites ( broadcasting ), the ministry for aeronautics signed in 1987 a contract of co-operation with DASA (Daimler-Benz Aerospace) in order to develop the DFH-3. It is about the first agreement of this type between China and a foreign country.

Because of its size, it was necessary to create new launchers, the old ones not being rather powerful. Launcher CZ-3A (that used for the placement of Beidou) was tested successfully the February 8th 1994 with a factitious DFH-3. The new version of the DFH-3, the DFH-3B (also known under the name of ChinaSat - 6) which was launched in 1997 knew problems of stabilization of altitude, that decreasing its lifespan. In conclusion, it should be known that China has today more than one hundred of satellites and that she works with her new communications satellite, the DFH 4.

Sources

Encyclopedia Astronautica
GlobalSecurity
Handy guide of the GPS (Paul Correia, Eyrolles 2006)

See too

GLONASS, the Russian system of positioning
Radionavigation

External bonds

projects of navigation systems
aerospace co-operation between Europe and China
Dispatch of ChinaDaily, 11/2006

Random links: