China launches Shen Tong-1 military satellite via Long March-3A

by Rui C. Barbosa

China launched the second Shen Tong-1 military communications satellite via a CZ-3A Chang Zheng-3A (Y19) launch vehicle, providing secured voice/data communications services for PLA ground users in Ku-band. Receiving the designation ZX-20A ZhongZhing-20A, the satellite was launched from the Xi Chang Satellite Launch Center, in Sichuan Province at 00:09 loca time on Friday.

Chinese Launch:

The first Shen Tong strategic communications satellite was launched on November 14, 2003 by a CZ-3A Chang Zheng-3A launch vehicle from Xi Chang.

Shen Tong satellites are based on the Dong Fang Hong 3 (DFH-3) satellite bus developed by the China Academy of Space Technology, and have a heavier payload, increased power supply, better reliability, being three-axis stabilized satellite – weighing in at 2,300kg.

The spacecraft features a number of new technologies, providing Ku-band communication and utilizing the advanced multiple steerable spot beam antenna technology to enable ground users to communicate whilst on the move. These satellites are the first to use secured uplink transmission for satellite antenna control and have the most powerful onboard data processing capability.

China used a CZ-3A Chang Zheng-3A launch vehicle for the mission to carry the bird into its transfer orbit.

The CZ-3A is a large-scale three-stage liquid launch vehicle, which has inherited the mature technology of the CZ-3 Chang Zheng-3. An upgraded liquid hydrogen and liquid oxygen cryogenic third stage has been developed to enable CZ-3A performing greater geostationary transfer orbit (GTO) capability.

The CZ-3A is equipped with a more flexible and sophisticated control system which supports substantial attitude adjustments to orient the payloads before spacecraft separation and provides adjustable satellite spin-up rotation rate. It has paved the way for the development of CZ-3B Chang Zheng-3B and CZ-3C Chang Zheng-3C.

The CZ-3A is mainly used for GTO missions and can also can be used for LEO, SSO and polar orbit missions, as well as dual-launch and multiple-launch missions. The launch capacity of the CZ-3A to GTO is 2,650 kg, the lift-off mass is 241,000 kg, the overall length is 52.5 meters, the diameter of first stage and second stage is 3.35 meters, the diameter of third stage is 3.0 meters, and the maximum fairing diameter is 3.35 meters.

The first stage and second stage of CZ-3A employ storable propellants, i.e. unsymmetrical dimethy1 hydrazine (UDMH) and nitrogen tetroxide (N204), and the third stage uses cryogenic propellants, i.e. liquid hydrogen (LH2) and liquid oxygen (LOX).

On the first stage the CZ-3A uses a DaFY6-2 engine with a 2961,6 kN thrust, while the second stage is equipped with a DaFY20-1 main engine (742 kN) and four DaFY21-1 vernier engines (11.8 kN each). The third stage is equipped with two YF-75 engines (78.5 kN each).

The fairing diameter of the CZ-3A is 3.35 meters and has a length of 8.89 meters.

CZ-3A consists of rocket structure, propulsion system, control system, telemetry system, tracking and safely system, coast phase propellant management and attitude control system, cryogenic propellant utilization system, separation system and auxiliary system, etc.

The launch success rate of CZ-3A continues to be 100 percent since its maiden flight on February 8, 1994 when it successfully launched two experimental satellites. And it was awarded the “Gold Launch Vehicle” title by China Aerospace Science and Technology Corporation in June 2007.

China used a CZ-3A launch vehicle to successfully launch the Chang’e-1 lunar satellite on October 24, 2007, which indicated that has taken a substantial step towards lunar exploration.

This was the 136th successful Chinese orbital launch, the 135th launch of a Chang Zheng launch vehicle, the 58th successful orbital launch from the Xi Chang Satellite Launch Center, the seventh successful orbital launch from the Xi Chang in 2010 and the 14th successful orbital launch from China in 2010.

The Xi Chang Satellite Launch Centre is situated in the Sichuan Province, south-western China and is the country’s launch site for geosynchronous orbital launches.

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.

Other facilities on the Xi Chang 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.

The first launch from Xi Chang took place at 12:25UTC on January 29, 1984, when the CZ-3 Chang Zheng-3 (CZ3-1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit. The launch of the new BeiDou-2 satellite was the 52nd successful orbital launch from Xi Chang.

Until the end of the year is expected that China will launch a new satellite for the BeiDou navigation network. The launch is expected at the end of December.

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