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BeiDou Space Segment

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COMPASSCOMPASS
Title BeiDou Space Segment
Author(s) GMV
Level Basic
Year of Publication 2011
Logo GMV.png


The Compass Navigation Satellite System (CNSS), also named BeiDou-2,[1] is China’s second-generation satellite navigation system that will be capable of providing positioning, navigation, and timing services to users on a continuous worldwide basis.[1][2]

Although the upgrade of its regional navigation system towards a global solution started in 1997, the formal approval by the Government of the development and deployment of BeiDou-2/CNSS was done in 2004.[1] The system is currently under development evolving from a regional system called BeiDou-1, and in the first phase will provide high-accuracy positioning services for users in China and its neighboring regions by 2012.[1] In a second stage, the system will evolve to provide global navigation services by 2020, similarly to the GPS, GLONASS or Galileo systems.[1]

As of August 2011, nine satellites for Compass have been launched, the first eight of which completed the deployment foreseen for the first phase of BeiDou-2.[1][3][4]

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 Geosynchronous Orbit (IGSO), which will offer complete coverage of the globe.[3][2]

The system is to be deployed in two stages; the launches for the first phase will be completed by 2012[1] and will consist of 14 satellites serving the Asia-Pacific region.[3] The global navigation system should be finished by 2020.[1]

COMPASS Space Segment

As of April 2011, eight satellites for Compass have been launched. According to Globaltimes.cn[4], "the eighth Beidou satellite marks the completion of basic function of Beidou (Compass) Navigation Satellite System and will collaborate with five navigation satellites launched last year to establish a navigating system of three GEO (geostationary orbit) satellites plus three IGSO (Inclined Geo Synchronous orbit) satellites. The system will be able to provide services to most regions in China after a period of orbiting running tests and system integration."


List of Compass Satellites at April 2011 (information as appeared in BeiDou article in Wikipedia.[5] )
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, with one IGSO per plane. The intersection node is 118E. The MEOs are deployed as a Walker constellation; 24 MEOs in 3 planes plus 3 spares. The orbital parameters of the final constellation are shown in the following table:[3]

Final Compass constellation
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

  1. ^ a b c d e f g h Compass Satellite Navigation System (Beidou), on Sinodefence.com, updated on August 6th, 2011.
  2. ^ a b COMPASS Navigation system in Wikipedia
  3. ^ a b c d China Satellite Navigation Office, Development of BeiDou Navigation Satellite System, Munich Satellite Navigation Summit, 2011.
  4. ^ a b China completes basic Beidou (Compass) Navigation Satellite System, 2011-04-10 by Globaltimes.cn
  5. ^ Beidou Navigation System in Wikipedia