China establishes a new record for the number of launches

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Post Tue Jul 19, 2011 9:47 am

China establishes a new record for the number of launches

Friday 17th of December China realized the 15th and last launch of the year 2010, establishing an absolute record in the space history of the country (compared with the previous record- 11 launches in 2008). Launched at 20:20 GMT aboard the Long March 3A rocket from the Xichang space centre, a new Beidou satellite come to sustain the other 4 platforms launched this year.

The new satellite is part of the Chinese navigation system Beidou (in English “Big Dipper”) called also CNSS or Compass Navigation Satellite System. More precisely we speak about the second generation of the Beidou 2 which intends to assure the country independence from the equivalent systems of the concurrence: the American GPS, the European Galileo, the Russian Glonass and the Indian IRNSS-Indian Regional Navigational Satellite System.

The Chinese interest for the satellite navigation and positioning technique appeared for the first time in the late 60s. Following the GPS example, in the middle 80s China succeeded to develop a new regional navigation concept called “Twin Star” and which has been tested practically in flight on two telecommunication platforms DHF-2A in the year 1989.

The test has shown that the precision of the system was reaching the one of the public GPS service and this convinced the Chinese authorities to invest more money for research and development.

The first Beidou generation comprised the Beidou 1A launched on October 30 2000, the Beidou 1B launched on December 20 2000, the Beidou 1C launched on May 24 2003 and the Beidou 1D launched on 2nd of February 2007. After the launch of the third satellite the system became operational at the beginning of 2004, China being the third country with its own satellite navigation system. The reference system used was Beijing 1954 one aligned with the Beijing’s time.

The first two satellites have been placed at the orbital positions 80 degrees East and respectively 140 degrees East. The third and the fourth which were considered backup have been sent to 110.5 degrees East respectively 58.7 degrees East (the last one being recovered from a major problem- after the launch the solar panels could not be unfolded easily and it took some time until the engineers managed to do it).

In this configuration Beidou 1 was able to cover the area between 70 and 140 degrees East longitude and 5 to 55 degrees North longitude and had a precision of 100 m when 2 satellites were used, precision which could increase to 20 m when the full capacity (4 satellites and all the ground stations) was used. In total up to 150 users could be served simultaneously.

The technique behind the system was called “dual way transmission” and was a complicate solution: the ground terminals receive the signal from one of the two satellites then an answer wass sent back to both the satellites. This signal was sent further to a ground station and by comparing the time shift between the two signals one could calculate the plane position of the terminal. By comparing this position with a three-dimensional database incorporating detailed maps of the Chinese regions it can be found the spatial position of the terminal. Finally this position was sent by the ground station back to the satellite and from here the encrypted signal goes back to the terminal and the operator could read the spatial coordinates. In parallel the users can transmit encrypted text messages to the ground station.

As it can be seen, the system was quite primitive and had some deficiencies: the limitation in the number of simultaneously users, the necessity of using big and powerful antennas for transmitting the signal to the satellite and last but not least the risk involved by the use of the ground stations (this being exposed in the case of a military conflict).

The second generation includes the Beidou2 M1 launched on 13th of April 2007, the Beidou I1 launched on 31st of July 2010, Beidou G1 launched on 16th of January 2010, Beidou G2 launched on 14th of April 2009, Beidou G3 launched on 2nd of June 2010 and Beidou G4 launched on 31st of October 2010.

The Compass constellation will comprise finally in 2020 a number of 35 satellites in a unique architecture which combines 5 geostationary satellites and 30 satellites orbiting the Earth in MEO and grouped in 3 orbital planes.
For instance the first MEO satellite the BD2 M1 has been placed in an almost circular orbit 21545 km x 21519 km x 55.26 degrees. The IGSO (inclined geostationary orbit) satellites have a 35652 km x 35959 km x 55 degrees while the simple geostationary satellites (under the indicative G) have a null orbital inclination

The signals are transmitted at 4 distinct frequencies: 1195.14-1219.14 MHz, 1256.52-1280.52 MHz, 1559.05-1563.15 MHz and 1587.69-1591.79 MHz, some overlaping the frequencies of GPS or Galileo. As the ITU (International Telecommunication Union) law says the first operator which emits in a specific band will have priority, it will be interesting to see if the Chinese will succeed to occupy the frequencies before the European system Galileo will do it. Anyway, for sure it will be necessary to perform supplementary tests in order to prove the three systems functioning in parallel will not interfere.

The Beidou2 are based on the DFH3 (Dong Fang Hong), have the dimensions 2.2 x 1.72 x 2.0 m, with a wide-span of 18.1 m and weighting 2200 kg (1100 kg of fuel). The lifetime – 5 years in the case of the commercial satellites has been extended to 8 years for the military variant.

DFH3 is a platform derived from the American variant GE Astro Space 5000 (specially the attitude control system), supplementary technology coming from the Daimler Benz Aerospace AG (for the communication components and for the mechanism which unfolds the solar panels).
BD2 is three axis stabilized with the help of a propulsion system using a FY 25 liquid fuel engine which performs orbital maneuvers and orients the spacecraft toward the ground station. This technology has been initially imported from the German company MBB through a commercial contract and later extended by the Chinese specialists.
The power system gives up to 1700 W DC. The platform could integrate instruments weighting up to 170 kg and having a power consumption of up to 900 W.

In the first phase the coverage will be limited to the Chinese territory and the neighbor countries but later on it will be extended worldwide. As with the rest of the satellite navigation systems Compass will have two components: a civil one with an accuracy of 10 m (position), 0.2 m/s (speed) and 50 ns (time) and a more precise military component.

Credit CNSA
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Post Sat Jan 11, 2014 10:02 am

Re: China establishes a new record for the number of launche

spacesys wrote:Friday 17th of December China realized the 15th and last launch of the year 2010, establishing an absolute record in the space history of the country (compared with the previous record- 11 launches in 2008). Launched at 20:20 GMT aboard the Long March 3A rocket from the Xichang space centre, a new Beidou satellite come to sustain the other 4 platforms launched this year.

The new satellite is part of the Chinese navigation system Beidou (in English “Big Dipper”) called also CNSS or Compass Navigation Satellite System. More precisely we speak about the second generation of the Beidou 2 which intends to assure the country independence from the equivalent systems of the concurrence: the American GPS, the European Galileo, the Russian Glonass and the Indian IRNSS-Indian Regional Navigational Satellite System.

The Chinese interest for the satellite navigation and positioning technique appeared for the first time in the late 60s. Following the GPS example, in the middle 80s China succeeded to develop a new regional navigation concept called “Twin Star” and which has been tested practically in flight on two telecommunication platforms DHF-2A in the year 1989.

The test has shown that the precision of the system was reaching the one of the public GPS service and this convinced the Chinese authorities to invest more money for research and development.

The first Beidou generation comprised the Beidou 1A launched on October 30 2000, the Beidou 1B launched on December 20 2000, the Beidou 1C launched on May 24 2003 and the Beidou 1D launched on 2nd of February 2007. After the launch of the third satellite the system became operational at the beginning of 2004, China being the third country with its own satellite navigation system. The reference system used was Beijing 1954 one aligned with the Beijing’s time.

The first two satellites have been placed at the orbital positions 80 degrees East and respectively 140 degrees East. The third and the fourth which were considered backup have been sent to 110.5 degrees East respectively 58.7 degrees East (the last one being recovered from a major problem- after the launch the solar panels could not be unfolded easily and it took some time until the engineers managed to do it).

In this configuration Beidou 1 was able to cover the area between 70 and 140 degrees East longitude and 5 to 55 degrees North longitude and had a precision of 100 m when 2 satellites were used, precision which could increase to 20 m when the full capacity (4 satellites and all the ground stations) was used. In total up to 150 users could be served simultaneously.

The technique behind the system was called “dual way transmission” and was a complicate solution: the ground terminals receive the signal from one of the two satellites then an answer wass sent back to both the satellites. This signal was sent further to a ground station and by comparing the time shift between the two signals one could calculate the plane position of the terminal. By comparing this position with a three-dimensional database incorporating detailed maps of the Chinese regions it can be found the spatial position of the terminal. Finally this position was sent by the ground station back to the satellite and from here the encrypted signal goes back to the terminal and the operator could read the spatial coordinates. In parallel the users can transmit encrypted text messages to the ground station.

As it can be seen, the system was quite primitive and had some deficiencies: the limitation in the number of simultaneously users, the necessity of using big and powerful antennas for transmitting the signal to the satellite and last but not least the risk involved by the use of the ground stations (this being exposed in the case of a military conflict).

The second generation includes the Beidou2 M1 launched on 13th of April 2007, the Beidou I1 launched on 31st of July 2010, Beidou G1 launched on 16th of January 2010, Beidou G2 launched on 14th of April 2009, Beidou G3 launched on 2nd of June 2010 and Beidou G4 launched on 31st of October 2010.

The Compass constellation will comprise finally in 2020 a number of 35 satellites in a unique architecture which combines 5 geostationary satellites and 30 satellites orbiting the Earth in MEO and grouped in 3 orbital planes.
For instance the first MEO satellite the BD2 M1 has been placed in an almost circular orbit 21545 km x 21519 km x 55.26 degrees. The IGSO (inclined geostationary orbit) satellites have a 35652 km x 35959 km x 55 degrees while the simple geostationary satellites (under the indicative G) have a null orbital inclination

The signals are transmitted at 4 distinct frequencies: 1195.14-1219.14 MHz, 1256.52-1280.52 MHz, 1559.05-1563.15 MHz and 1587.69-1591.79 MHz, some overlaping the frequencies of GPS or Galileo. As the ITU (International Telecommunication Union) law says the first operator which emits in a specific band will have priority, it will be interesting to see if the Chinese will succeed to occupy the frequencies before the European system Galileo will do it. Anyway, for sure it will be necessary to perform supplementary tests in order to prove the three systems functioning in parallel will not interfere.

The Beidou2 are based on the DFH3 (Dong Fang Hong), have the dimensions 2.2 x 1.72 x 2.0 m, with a wide-span of 18.1 m and weighting 2200 kg (1100 kg of fuel). The lifetime – 5 years in the case of the commercial satellites has been extended to 8 years for the military variant.

DFH3 is a platform derived from the American variant GE Astro Space 5000 (specially the attitude control system), supplementary technology coming from the Daimler Benz Aerospace AG (for the communication components and for the mechanism which unfolds the solar panels).
BD2 is three axis stabilized with the help of a propulsion system using a FY 25 liquid fuel engine which performs orbital maneuvers and orients the spacecraft toward the ground station. This technology has been initially imported from the German company MBB through a commercial contract and later extended by the Chinese specialists.
The power system gives up to 1700 W DC. The platform could integrate instruments weighting up to 170 kg and having a power consumption of up to 900 W.

In the first phase the coverage will be limited to the Chinese territory and the neighbor countries but later on it will be extended worldwide. As with the rest of the satellite navigation systems Compass will have two components: a civil one with an accuracy of 10 m (position), 0.2 m/s (speed) and 50 ns (time) and a more precise military component.

Credit CNSA


I am not sure it is right or not but I still feel there is race going on between China and other developed countries..China is wasting lot money just to get ahead of these countries.

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Post Fri Jan 24, 2014 10:21 am

Re: China establishes a new record for the number of launche

Hi Paul, please pay attention the article refers to the year 2010. Meanwhile they managed to launch 19 rockets in 2011 (18 successful) and the same for 2012 (this time all successful). In 2013 China had 15 launches (approximately 18% of total number of launches performed worldwide).
2011 was the first year in the history when they launched more rockets than US.

http://translate.google.com/translate?s ... na-in-2012

It is clear they have a good project plan and they entered the new space race as an important actor.
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