Encyclopedia Astronautica
Beidou



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DFH-3
Credit: via Chen Lan
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Beidou
Differences between the MEO and GEO versions of Beidou.
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Beidou
The Beidou constellation.
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Beidou
Position of the inclined geostationary satellites of the Beidou system at a particular moment of time on their ground trace.
Chinese navigation satellite. Operational, first launch 2000.10.30. Beidou ('Big Dipper') was the satellite component of an independent Chinese satellite navigation and positioning system.

The initial Beidou-1 test system of 2000-2010 consisted of two geosynchronous satellites and one spare, which provided service to tens of thousands of users in the Chinese military and government. Beidou-2, consisting of five geosynchronous satellites, three inclined geosynchronous orbit satellites, and 27 medium earth orbit satellites, was deployed 2010-2020. This provided a 10-m-accuracy public and precision military navigation service to east Asia by 2012, with global service by 2020. The end result: a Chinese indigenous satellite navigation and positioning system and industry.

Beidou-1 System

Beidou began in 1983 with a proposal by Chen Fangyun to develop a Twinsat regional navigation system using two geostationary satellites. The concept was proven in 1989 in a test using two in-orbit DFH-2/2A communications satellites. This test showed that the precision of the Twinsat system would be comparable to the American Global Positioning System. In 1993, the Beidou program was officially started. Beidou used the DFH-3 bus and had similar basic performance. Experimental launch of the first two indigenous geosynchronous Beidou navigation satellites was in 2000. A third test satellite was launched in 2003. This demonstration system provided basic services to the Chinese government and military including positioning, timing and short message communication within the East Asian landmass.

The initial two satellite system was based on an iterative determination of a user's altitude. Each of the satellites continuously broadcast signals to all parts of the Earth that were visible to it (the entire Asian landmass). A user's station excerpted a certain portion of those signals and transmitted it back to the satellite. The satellite, in turn, forwarded the received signal to the system's control center. Computers at the system's control center then determined the distance between the user and the satellite by inferring the time-of-flight difference between satellite and user from the time the signal was originally broadcast, which was stamped with the broadcast time, and when the relayed user's signal reached the control center.

The control center then combined an initial guess of the user's altitude (and hence the distance from the Earth's center), either from the last reported altitude or perhaps by using an arbitrary guess such as sea level, with the distances from the two satellites to get three distance estimates for the user's position. This determined the first estimate of the user's latitude and longitude. A map of the user's region (presumably stored digitally) was then used to make an improved estimate of the user's altitude, which could then be fed back into the latitude and longitude calculation to make an improved estimate of those quantities.

Although such a system could achieve GPS-like accuracies (except in steep terrain), it obviously had serious operational constraints. The user had to emit in order to achieve a location fix. And the control center provided a single point target that would bring the entire system down. However it was a way to obtain, in only two satellite launches, an indigenous, independent, high-accuracy military navigation system that would function in anything less than total war with a major power. Beidou also had an active communications capability, allowing the leadership to send secure orders and receive confirmations and status reports.

The US Department of Defense estimated that the initial Beidou system had an accuracy of 20 meters over China and surrounding areas. The initial terminals cost $ 3,000; this had been brought down to $ 400 by 2009. By 2009 over 50,000 terminals were in use by the Chinese military, border guards, and government agencies. Vehicle-, ship-, container-, and handheld terminals had been produced.

A private company, BDStar Navigation, was formed to develop the Beidou ground segment and to market receivers to commercial operators. The company had originated as a joint venture with Canada Novatel in October 2000 to develop and market GPS receivers. A year later the draft project for the Beidou 1 Information Service System was completed, which provided the basis for open applications of the Beidou navigation system. A joint state-industrial committee approved the final project plan in January 2003.

Funding from the Ministry of Science and Technology led to work beginning on a Beidou Satellite Integrated Information Application Service as part of the Chinese National 863 Development Plan. The system passed acceptance testing in December 2005, leading to potential application of Beidou receivers for Chinese ocean fishery vessels. In June 2006 the commercial demonstration project for a Beidou Ocean Fishery Secure Production and Transaction Information Service was started.

Beidou-2 System

Given the operational constraints of the geostationary Beidou system, it was perhaps unsurprising when China announced a new concept for Beidou in 2006. These satellites would use the same navigation principle as Navstar, GLONASS, and Galileo, with internal high precision clocks and orbital information beaming the precise position information of the satellites to the passive receivers of users. Combining signals from multiple satellites allowed the user receiver to calculate its position on earth with high precision. Meetings between China and the International Telecommunications Union, the USA, Russia, and the EU in 2007-2009 established the compatibility and interoperability of Beidou-2 signals with those of other nations. Beidou-2 would operate in three frequency ranges: 1559.052-1591.788MHz; 1166.22-1217.37MHz; and 1250.618-1286.423MHz.

The Beidou-2 operational system consisted of satellites deployed in three different types of orbit:

  • Five GEO (geosynchronous orbit) satellites, also incorporating the Beidou-1 location and messaging technology for backward compatibility with existing receivers. Five of these were operational as of the end of 2010: the two experimental satellites launched in December 2000 and May 2003; and the operational satellites launched in January, June, and November 2010. The first Beidou, launched in October 2000, was no longer in use; and those launched in February 2007 and April 2009 experienced control failures and were unusable. Presumably two further launches would be made by 2012 to replace the older satellites and the two failed launches.
  • Three IGSO (inclined geosynchromous orbit) deployed in three planes, in 24-hour orbits at 38,300 km altitude but inclined at 55 degrees to the equator. The orbits were such that one satellite would be over Chinese territory at all times, providing an overhead signal allowing navigation even when surrounded by tall buildings or rugged terrain. These were launched in July and December 2010, and April 2011.
  • 27 MEO (medium-earth orbit satellites), deployed in three planes, in 21,500 km altitude orbits inclined at 55 degrees to the equator. The first test satellite was launched in April 2011. Four were to be deployed by 2012 to provide the first regional coverage for the system, and all 27 by 2020, to provide global coverage.

China intended to market Beidou receivers in competition with GPS, Glonass, and Galileo. Two levels of service were to be provided. The public service for civilian use would be free to all users with a Beidou receiver and would have a 10 meter location accuracy, provide clock synchronization signals with an accuracy of 20 ns, and measure speeds within 0.2 m/s. The licensed military service would be more accurate than the free service, also provide system status information, and a military communications capability. Total Beidou users in China were expected to total 900 million by 2025 with annual sales of related applications and services of $80 billion.

Gross mass: 2,200 kg (4,800 lb).
Unfuelled mass: 1,100 kg (2,400 lb).
First Launch: 2000.10.30.
Last Launch: 2011.07.26.
Number: 13 .

More... - Chronology...


Associated Countries
See also
  • CZ China's first ICBM, the DF-5, first flew in 1971. It was a two-stage storable-propellant rocket in the same class as the American Titan, the Russian R-36, or the European Ariane. The DF-5 spawned a long series of Long March ("Chang Zheng") CZ-2, CZ-3, and CZ-4 launch vehicles. These used cryogenic engines for upper stages and liquid-propellant strap-on motors to create a family of 12 Long-March rocket configurations capable of placing up to 9,200 kg into orbit. In 2000 China began development of a new generation of expendable launch vehicles using non-toxic, high-performance propellants with supposedly lower operating costs. However these encountered development delays, and it seemed the reliable Long March series of rockets would continue in operational use for nearly fifty years before being replaced. More...

Associated Launch Vehicles
  • CZ Chinese orbital launch vehicle. China's first ICBM, the DF-5, first flew in 1971. It was a two-stage storable-propellant rocket in the same class as the American Titan, the Russian R-36, or the European Ariane. The DF-5 spawned a long series of Long March ("Chang Zheng") CZ-2, CZ-3, and CZ-4 launch vehicles. These used cryogenic engines for upper stages and liquid-propellant strap-on motors to create a family of 12 Long-March rocket configurations capable of placing up to 9,200 kg into orbit. In 2000 China began development of a new generation of expendable launch vehicles using non-toxic, high-performance propellants with supposedly lower operating costs. However these encountered development delays, and it seemed the reliable Long March series of rockets would continue in operational use for nearly fifty years before being replaced. More...
  • CZ-3A Chinese three-stage orbital launch vehicle. The Long March 3A, by incorporating the mature technologies of the CZ-3 and adding a more powerful cryogenic third stage and more capable control system, had a greater geosynchronous transfer orbit capability, greater flexibility for attitude control, and better adaptability to a variety of launch missions. More...
  • CZ-3C Chinese orbital launch vehicle. Launch vehicle combining CZ-3B core with two boosters from CZ-2E. The standard fairing was 9.56 m long, 4.0 m in diameter. On August 23, 2001, the CZ-3C launcher passed its critical design review. CZ-3C development had begun in 1995 but was suspended in 1996-2000 due to the 1996 CZ-3B failure. First launch was in 2008. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Web Address when accessed: here.
  • Chen Lan, Dragon in Space, Web Address when accessed: here.
  • China's Space Activities, The State Council Information Office, P.R.C., November, 2000.
  • NASA/GSFC Orbital Information Group Website, Web Address when accessed: here.
  • Space-Launcher.com, Orbital Report News Agency. Web Address when accessed: here.
  • Forden, Geoffrey, "The Military Capabilities and Implications of China's Indigenous Satellite-Based Navigation System", Science and Global Security, 12:219, 250, 2004.

Associated Launch Sites
  • Xichang China's launch site for geosynchronous orbit launches. Xichang Satellite Launch Centre is situated in Xichang, Sichuan Province, south-western China. The launch pad is at 102.0 degrees East and 28.2 degrees North. The head office of the launch centre is located in Xichang City, about 65 kilometers away. Xichang Airport is 50 km away. A dedicated railway and highway lead directly to the launch site. More...

Beidou Chronology


2000 October 30 - . Launch Site: Xichang. Launch Complex: Xichang LC2. LV Family: CZ. Launch Vehicle: CZ-3A. LV Configuration: Chang Zheng 3A CZ3A-5 (63).
  • Beidou 1A - . Mass: 2,200 kg (4,800 lb). Nation: China. Agency: CNSA. Manufacturer: CAST. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 26599 . COSPAR: 2000-069A. Apogee: 35,805 km (22,248 mi). Perigee: 35,774 km (22,228 mi). Inclination: 2.6000 deg. Period: 1,436.20 min. Beidou was China's first experimental navigation technology satellite, developed by CAST/Beijing. The satellite was placed in an initial 195 x 41889 km x 25.0 deg orbit geostationary transfer orbit before entering its final geosynchornous orbit at around 0500 GMT on November 6. Stationed at 140 deg E, still maintaining its position within 0.1 deg as of 2007.

2000 December 20 - . Launch Site: Xichang. Launch Complex: Xichang LC2. LV Family: CZ. Launch Vehicle: CZ-3A. LV Configuration: Chang Zheng 3A CZ3A-6 (64).
  • Beidou 1B - . Mass: 2,200 kg (4,800 lb). Nation: China. Agency: CNSA. Manufacturer: CAST. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 26643 . COSPAR: 2000-082A. Apogee: 35,821 km (22,258 mi). Perigee: 35,753 km (22,215 mi). Inclination: 0.0000 deg. Period: 1,436.10 min. Second Beidou geosynchronous navigation satellite. The CZ-3A rocket's third stage put Beidou in geostationary transfer orbit at around 1642 GMT. The Beidou satellite was based on the DFH-3 comsat and had a mass of around 2200 kg including its FY-25 solid apogee motor. On December 25 Beidou was in a 190 x 41870 km x 25.0 deg transfer orbit. The launch of this second Beidou completed the prototype two-satellite navigational system which was to provide positional information for highway, railway and marine transportation. Positioned in geosynchronous orbit at 80 deg E, still maintaining its position within 0.1 deg as of 2007.

2003 May 24 - . Launch Site: Xichang. Launch Complex: Xichang LC2. LV Family: CZ. Launch Vehicle: CZ-3A. LV Configuration: Chang Zheng 3A CZ3A-7 (70).
  • Beidou 2A - . Mass: 2,200 kg (4,800 lb). Nation: China. Agency: SISE. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 27813 . COSPAR: 2003-021A. Apogee: 35,836 km (22,267 mi). Perigee: 35,760 km (22,220 mi). Inclination: 0.3000 deg. Period: 1,436.70 min. Summary: Navigation technology satellite, joined Beidou 1A and 1B launched in December 2000. This third satellite was considered a back-up element, Positioned at 110 deg E, still maintaining its position within 0.1 deg as of 2007..

2007 February 2 - . 16:28 GMT - . Launch Site: Xichang. Launch Complex: Xichang LC2. LV Family: CZ. Launch Vehicle: CZ-3A. LV Configuration: Chang Zheng 3A CZ3A-12 (95).
  • Beidou G1 - . Payload: Beiduou 1D. Mass: 2,200 kg (4,800 lb). Nation: China. Agency: SISE. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 30323 . COSPAR: 2007-003A. Apogee: 36,248 km (22,523 mi). Perigee: 35,326 km (21,950 mi). Inclination: 6.2000 deg. Period: 1,436.10 min. Summary: Fourth Beidou satellite. It did not reach geostationary orbit until early April following deployment problems with its solar panels and reports of US detection of a debris cloud at the time of the original expected apogee firing..

2007 April 12 - . 20:11 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3A. LV Configuration: Chang Zheng 3A CZ3A-13 (97).
  • Beidou M1 - . Payload: Beidou M1. Mass: 2,200 kg (4,800 lb). Nation: China. Agency: CASC. Manufacturer: CAST. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 31115 . COSPAR: 2007-011A. Apogee: 21,544 km (13,386 mi). Perigee: 21,519 km (13,371 mi). Inclination: 55.3000 deg. Period: 773.40 min. Summary: The fifth Beidou satellite, but the first in the 12-hour, 55 deg inclination MEO portion of the constellation. All previous launches had been to populate the geostationary portion of the system..

2009 April 14 - . 16:16 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-2C. LV Configuration: CZ-2C s/n CZ3C2.
  • Beidou G2 - . Mass: 3,100 kg (6,800 lb). Nation: China. Agency: SISE. Spacecraft: Beidou. USAF Sat Cat: 34779 . COSPAR: 2009-018A. Apogee: 35,799 km (22,244 mi). Perigee: 35,783 km (22,234 mi). Inclination: 0.7000 deg. Period: 1,436.30 min. Summary: Second of second generation operational Beidou navigation satellites..

2010 January 16 - . 16:12 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3C. LV Configuration: CZ-3C s/n CZ3C3.
  • Beidou G3 - . Nation: China. Agency: SISE. Spacecraft: Beidou. USAF Sat Cat: 36287 . COSPAR: 2010-001A. Apogee: 35,972 km (22,351 mi). Perigee: 35,600 km (22,100 mi). Inclination: 1.8000 deg. Period: 1,436.10 min.

2010 June 2 - . 15:53 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3C. LV Configuration: CZ-3C s/n CZ3C4.
  • Beidou G4 - . Nation: China. Agency: SISE. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 36590 . COSPAR: 2010-024A. Apogee: 35,796 km (22,242 mi). Perigee: 35,776 km (22,230 mi). Inclination: 1.8000 deg. Period: 1,436.00 min.

2010 July 31 - . 21:30 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3A.
  • Beidou IGS 1 - . Payload: Beidou DW5. Nation: China. Agency: SISE. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 36828 . COSPAR: 2010-036A. Apogee: 35,901 km (22,307 mi). Perigee: 35,680 km (22,170 mi). Inclination: 55.0000 deg. Period: 1,436.30 min. Summary: Fifth Beidou navigation satellite, placed in an inclined geosynchronous orbit..

2010 October 31 - . 16:26 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3C.
  • Beidou G4 - . Payload: Beidou DW6. Nation: China. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 37210 . COSPAR: 2010-057A. Apogee: 35,793 km (22,240 mi). Perigee: 35,781 km (22,233 mi). Inclination: 1.6000 deg. Period: 1,436.10 min. Summary: Navigation satellite..

2010 December 17 - . 20:20 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3A.
  • Beidou IGS 2 - . Payload: Beidou DW7. Nation: China. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 37256 . COSPAR: 2010-068A. Apogee: 35,857 km (22,280 mi). Perigee: 35,722 km (22,196 mi). Inclination: 55.2000 deg. Period: 1,436.20 min. Summary: Second Beidou launched to inclined synchronous orbit..

2011 April 9 - . 20:47 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3A.
  • Beidou IGS 3 - . Payload: Beidou DW8. Nation: China. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 37384 . COSPAR: 2011-013A. Apogee: 35,874 km (22,291 mi). Perigee: 35,696 km (22,180 mi). Inclination: 55.3000 deg. Period: 1,436.00 min. Summary: Beidou-2 second generation navigation satellite..

2011 July 26 - . 21:44 GMT - . Launch Site: Xichang. LV Family: CZ. Launch Vehicle: CZ-3A.
  • Beidou IGS 4 - . Nation: China. Class: Navigation. Type: Navigation satellite. Spacecraft: Beidou. USAF Sat Cat: 37763 . COSPAR: 2011-038A. Apogee: 35,864 km (22,284 mi). Perigee: 35,698 km (22,181 mi). Inclination: 55.2000 deg. Period: 1,435.80 min.

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