Long March 3C launches China’s third tracking and data relay satellite

by Rui C. Barbosa

A Long March 3C (Chang Zheng 3C) has returned China back into action for the first time since their Shenzhou-9 manned rendezvous and docking mission. The launch of the TL-1 Tianlian-1 (3) ‘Sky Link’ sent the country’s third tracking and data relay satellite into orbit. Launch occured at 15:43 UTC on Wednesday from the Xichang Satellite Launch Center.

Chinese Launch:

The Chinese tracking and data relay satellite was developed by the China Academy of Space Technology (CAST). It is similar to the American Tracking and Data Relay Satellite System (TDRSS) in concept.

The system is designed to support near-real-time communications between orbiting spacecraft and the ground control, and will complement the ground-based space tracking and telemetry stations and ships to support future space projects.

Like its predecessors, the Tianlian-1 (3) satellite is based on the DFH-3 bus. The DFH-3 (Dongfanghong-3) platform is a medium-capacity telecommunications satellite platform designed and developed by CAST (Chinese Academy of Space Technology).

The spacecraft can carry multiple telecommunications payloads for providing many kinds of services, such as fixed communication, international satellite communication, national and regional communication, wideband data communication, mobile communication and direct broadcast; military communication, spacecraft tracking and data relay, etc.

The platform comprises six subsystems: control, power, propulsion, measurement & control, structure and thermal control subsystem. The platform configuration features module subdivision, which includes communication module, propulsion module, service module and solar array.

The platform adopts three-axis stabilized attitude control mode, having solar array output power of 1.7 kw by the end of its design lifetime of 8 years. Its mass is 2,100kg with payload capacity 220kg.

The DFH-3 satellite platform has been successfully applied in DFH-3 satellite, Beidou navigation test satellite, and other satellites, all of which are currently operating normally.

During numerous flight missions, the maturity and reliability of the DFH-3 platform has been proved. Moreover, it has strong expansion capacity and can be upgraded to some space exploration missions, such as meteorological satellite, lunar resource satellite services.

At present, Tianlian-1 (1) is positioned at 77 degrees East, after it was launched on April 25, 2008, by the first Chang Zheng-3C launch vehicle.

Tianlian-1 (2) is positioned at 176.77 degrees East, after it was launched on July 11, 2011, by the Chang Zheng-3C (Y8) launch vehicle. With the Tianlian-1 (3), China has full global coverage for its tracking and data relay system. A second generation TL-2 Tianlian-2 is being developed by CAST.

This was the ninth flight of the Chang Zheng-3C launch vehicle. This rocket was developed to fill the gap between the Chang Zheng-3A and the Chang Zheng-3B, having a payload capacity of 3,800 kg for GTO. This is a three stage launch vehicle identical to the CZ-3B but only using two strap-on boosters on its first stage.

CZ-3C provides two types of fairing and two kinds of fairing encapsulating process and four different payload interfaces, which is the same as LM-3B launch vehicle.

The various fairing and interface adapter and the suitable launch capacity make LM-3C a good choice for user to select the launch service.

The development of the CZ-3C started in February 1999. The rocket has a liftoff mass of 345,000 kg. The rocket structure functions to withstand the various internal and external loads on the launch vehicle during transportation, hoisting and flight.

The rocket structure also combines all sub-systems together and is composed of boosters, first stage, second stage, third stage and payload fairing. The first two stages as well as the two strap on boosters use hypergolic (N2O4/UDMH) fuel while the third stage uses cryogenic (LOX/LH2) fuel. The total length of the CZ-3A is 54.838 meters, with a diameter of 3.35 meters on the core stage and 3.00 meters on the third stage.

The first launch of the CZ-3C Chang Zheng-3C launch vehicle took place on April 25, 2008 when it orbited the first TL-1 Tian Lian-1 tracking and data relay satellite.

Wednesday’s launch was the 166th successful orbital mission for China, the 74th successful orbital launch from Xichang, the 11th successful orbital launch for China in 2012 and the 6th successful orbital launch from Xichang this year.

The Xichang 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.

Down range Tracking and Control stations of the launch center are located in Xichang City and Yibin City of Sichuan Province, and Guiyang City of Guizhou Province. Each of them houses tracking and measurement equipment for the powered phase of a launch vehicle flight.

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.

During 1993-1994 Xichang underwent extensive modernization and expansion, in part due to the requirements of the CZ-3 launcher family and in part to meet commercial customer needs.

The first launch from Xichang took place at 1225UTC on January 29, 1984, when the Chang Zheng-3 (CZ3-1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit.

(Images via ChinaNews.cn and CCTV).

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