A new military communications satellite – the Zhongxing-2A (Chinasat-2A) – was launched by a Chang Zheng-3B (Y17) (Long March 3B) launch vehicle on Saturday. Lift off from the Xichang Satellite Launch Center LC2 launch complex took place at 15:56 UTC.
The Chinasat-2A satellite was built on the DFH-4 platform, with a launch mass around 5,200 kg. It was manufactured by the China Great Wall Industry Corporation (CGWIC).
Due to its military nature, there is little technical information on the satellite. However, China use two types of satellites for secure military communications: the Fenghuo and the Shentong.
The Fenghuo series is used for tactical military communications, providing secured digital data and voice communication to Chinese military forces.
The Chinese are currently operating the DFH-4 based Fenghuo-2 second generation satellite, with the first of the series – the ZX-1A Zhongxing-1A (37804 2011-047A) – launched at 13:33 UTC on September 18th, 2011, by the Chang Zheng-3B (Y16) rocket.
The Shentong geostationary military communication satellites are operated by the Army and their aim is to provide secured voice and data communications services for ground users using Ku-band. The satellite was based on the DFH-3 (Dongfanghong-3) satellite platform that was developed by the China Academy of Space Technology (CAST), having a heavier payload with better reliability and increased power supply.
Chinasat-2A will be the first of a second generation DFH-4 based Shentong-2 satellite in operation.
To meet demand of international satellite launch market, especially for high power and heavy communications satellites, the development of Chang Zheng-3B launch vehicle was started in 1986 on the basis of the fight proven technology of Long March launch vehicles. The Chang Zheng-3B is the most powerful launch vehicle on the Chinese space launch fleet.
Each of the four boosters has a 15.326 meter length with a 2.25 meter diameter, consuming 37,700 kg of N2O4 / UDMH. Equipped with a YF-25 engine capable of a ground thrust of 740.4 kN and a ground specific impulse of 2,556.2 Ns/kg.
The first stage has a 23.272 meter length with a 3.35 meter diameter, consuming 171,800 kg of N2O4 / UDMH. Equipped with a YF-21C engine capable of a ground thrust of 2,961.6 kN and a ground specific impulse of 2,556.5 Ns/kg.
The second stage has a 19.92 meter length with a 3.35 meter diameter, consuming 49,400 kg of N2O4 / UDMH. Equipped with a YF-24E cluster engine with a main engine capable of a vacuum thrust of 742 kN and a vernier engine with a vacuum thrust of 47.1 kN (specific impulses of 2,922.6 Ns/kg and 2,910.5 Ns/kg, respectively).
The third stage has a 12.375 meter length with a 3.0 meter diameter, consuming 18,200 kg of LH2 / LOX. Equipped with a YF-75 engine capable of a vacuum thrust of 167.17 kN and a specific impulse in vacuum of 4,295 Ns/kg.
In recent years, the CZ-3B/E (Enhanced Version) launch vehicle was developed on the basis of CZ-3B, increasing the GTO capacity up to 5,,500kg. The CZ-3B/E has nearly the same configurations with CZ-3B except its enlarged core stage and boosters.
On May 14, 2007, the first flight of CZ-3B/E was performed successfully, accurately sending the NigcomSat-1 into pre-determined orbit. With the GTO launch capability of 5,500kg, CZ-3B/E is dedicated for launching heavy GEO communications satellite.
The CZ-3B and CZ-3B/E launch vehicles are comprised of the vehicle structure, propulsion system, control system, measurement system (telemetry system and tracking & range safety system), propellant management and reaction control system, propellant utilization system, separation system and auxiliary system, etc.
The third stage includes the payload adapter, the vehicle equipment bay (VEB) and the cryogenic propellant tanks and engines. The payload adapter mates the satellite to CZ-3B and bears the mechanical loads. This cargo adapter can be one of the international standard interfaces designated as 937B, 1194 or 1194A. The payload fairings consist of the dome, bi-conic section, cylindrical section, and reverse cone section and separation mechanisms.
This was the 163rd successful Chinese orbital launch, the 163rd launch of a Chang Zheng launch vehicle, the fifth launch from Xichang in 2011 (the 73rd overall from Xichang), and the eighth successful orbital launch for China in 2012.
Equipped with two launch pads (LC2 and LC3), the centre has a dedicated railway and highway lead directly to the launch site. The Command and Control Centre is located seven kilometers south-west of the launch pad, providing flight and safety control during launch rehearsal and launch. The CZ-3B launch pad is located at 28.25 deg. N – 102.02 deg. E and at an elevation of 1,825 meters.
Other facilities on the Xichang Satellite Launch Centre are the Launch Control Centre, propellant fuelling systems, communications systems for launch command, telephone and data communications for users, and support equipment for meteorological monitoring and forecasting.
(Images via ChinaNews)