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BeiDou Space Segment
| COMPASS | |
|---|---|
| Title | BeiDou Space Segment |
| Author(s) | GMV. |
| Level | Basic |
| Year of Publication | 2011 |
The Compass Navigation Satellite System (CNSS), or BeiDou-2, is China’s second-generation satellite navigation system capable of providing continuous, real-time passive 3D geo-spatial positioning and speed measurement. The system will initially used to provide high-accuracy positioning services for users in China and its neighbouring regions, covering an area of about 120 degrees longitude in the Northern Hemisphere. The long-term goal is to develop an independent global navigation satellite network similar to the GPS and GLONASS. [1]
COMPASS Space Segment
The COMPASS Space Segment will consist of a constellation of 35 satellites, which include 5 geostationary orbit (GEO) satellites and 30 non-GSO satellites; 27 in Medium Earth Orbit (MEO) and 3 in Inclined GSO (IGSO),that will offer complete coverage of the globe.[2]
It is planned that Compass system will have more than 10 satellites by 2012 and may offer services for the Asia-Pacific region. The global navigation system should be finished by 2020.[3]
As of April 2011, eight satellites for Compass have been launched. According to an official report [4], "the eighth Beidou satellite marks the completion of basic function of Beidou (Compass) Navigation Satellite System...collaborate with five navigation satellites...will be able to provide services to most regions in China after a period of orbiting running tests and system integration."
| Date | Launcher | Satellite | Orbit | Usable | System |
|---|---|---|---|---|---|
| 4/14/2007 | Long March 3A (LM-3A) | Compass-M1 | MEO ~21,500 km | Testing only | Compass |
| 4/15/2009 | Long March 3C (LM-3C) | Compass-G2 | GEO Drifting | No | |
| 1/17/2010 | LM-3C | Compass-G1 | GEO 144.5°E | Yes | |
| 6/2/2010 | LM-3C | Compass-G3 | GEO 84°E | Yes | |
| 8/1/2010 | LM-3A | Compass-IGSO1 | IGSO 118°E incl 55° | Yes | |
| 11/1/2010 | LM-3C | Compass-G4 | GEO 160°E | Yes | |
| 12/18/2010 | LM-3A | Compass-IGSO2 | IGSO 118°E incl 55° | Yes | |
| 04/10/2011 | LM-3A | Compass-IGSO3 | IGSO 118°E incl 55°, 200~35,991km | Yes |
The nominal constellation includes 35 satellites, 5 GEOs, 3 IGSOs and 27 MEOs. The number of IGSO orbits is 3, and 1 IGSO per plane. The intersection node is 118E. While the MEO constellation is Walker constellation, 24 MEOs in 3 planes plus 3 spares. The orbital parameters of the final constellation are shown in the following table:
| Orbit parmts. | GEO | IGSO | MEO |
|---|---|---|---|
| Semi-Major Axis (Km) | 42164 | 42164 | 27878 |
| Eccentricity | 0 | 0 | 0 |
| Inclination (deg) | 0 | 55 | 55 |
| RAAN (deg) | 158.75E, 180E, 210.5E, 240E,260E | 218E,98E,338E | -- |
| Argument Perigee | 0 | 0 | |
| Mean anomaly (deg) | 0 | 218E:0,98E:120,338E:240 | |
| # Sats | 5 | 3 | 27 |
| # Planes | 1 | 3 | 3 |
Notes
References
- ^ Compass on the Chinese Defence Today website
- ^ BeiDou and Compass in Wikipedia
- ^ BeiDou navigation system covers Asia-Pacific region till 2012, 2010-03-03 by Xinhua News Agency
- ^ China completes basic Beidou (Compass) Navigation Satellite System, 2011-04-10 by Globaltimes.cn