Long March 3B set for experimental ChinaSat-16 launch

The Chinese are set to return to launch action with the lofting of a new experimental communications satellite from the Xichang Satellite Launch Center. The launch will be conducted by the Long March 3B G2 ‘Chang Zheng-3B/G2’ (Y43) from the LC2 Launch Complex at the Sichuan province site, with T-0 expected to occur at 11:02 UTC.

Chinese Launch:

The 4.6-tonne satellite was developed by the China Academy of Space Technology (CAST) and is based on the DFH-3B satellite platform. Shijian-13 was the satellite’s original designation, before being renamed Zhongxing-16 (ChinaSat-16).

The new satellite will test a new electric propulsion system to be used for orbit raising and station keeping at a geosynchronous altitude. It also carries the first high-throughput satellite payload (HTS) developed by China.

The satellite features a Ka-band broadband communications system capable of transmitting 20 gigabytes of data per second, making it the most powerful communications satellite the nation has developed to date.

According to Wang Min, deputy head of the CAST’s Institute of Telecommunication Satellite, ChinaSat-16 will provide better access to the Internet on planes and high-speed trains, with the increase in satellite throughput provided by the new satellite that will be located at 110.5° East.

The satellite is able to provide 26 user beams covering China and offshore areas – allowing it to also cover airborne and maritime communications and emergency communications, using Ka-band satellite broadband and multimedia services.

With a lifetime of 15 years, the satellite will be operated by China Satcom.

The satellite will also conduct space-to-ground laser communications experiments.

The DFH-3 (Dongfanghong-3) platform is a medium-capacity telecommunications satellite platform designed and developed by CAST.

The platform can be used for multiple telecommunications payloads for providing a range of services, including fixed communication, international satellite communication, national and regional communication, wideband data communication, mobile communication and direct broadcast; military communication, spacecraft tracking and data relay.

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

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

The DFH-3 satellite platform has been successfully applied in the 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 have been proved. Moreover, it has strong expansion capacity and can be upgraded to some space exploration missions, such as meteorological satellite and lunar resource satellite services.

Its onboard Ion thrusters are designed for a wide variety of missions.

These thrusters have high specific impulses, that is, ratio of thrust to the rate of propellant consumption, so they require significantly less propellant for a given mission than would be needed with chemical propulsion.

Ion propulsion is even considered to be mission enabling for some cases where sufficient chemical propellant cannot be carried on the spacecraft to accomplish the desired mission.

Launch vehicle and launch site:

To meet the demand of international satellite launch market, especially for high power and heavy communications satellites, the development of Long March-3B (Chang Zheng-3B) launch vehicle started in 1986 on the basis of the fight proven technology of Long March launch vehicles.

Developed from the Chang Zheng-3A, the Chang Zheng-3B is at the moment the most powerful launch vehicle on the Chinese space launch fleet.

The CZ-3B features enlarged launch propellant tanks, improved computer systems, a larger 4.2 meter diameter payload fairing and the addition of four strap-on boosters in the core stage that provide additional help during the first phase of the launch.

The rocket is capable of launching a 11,200 kg satellite to a low Earth orbit or a 5,100 kg cargo to a geosynchronous transfer orbit.

The CZ-3B/G2 (Enhanced Version) launch vehicle was developed from the CZ-3B with a lengthened first core stage and strap-on boosters, increasing the GTO capacity up to 5,500kg.

On May 14, 2007, the first flight of CZ-3B/G2 was performed successfully, accurately sending the NigcomSat-1 into pre-determined orbit. With the GTO launch capability of 5,500kg, CZ-3B/G2 is dedicated for launching heavy GEO communications satellite.

The rocket structure also combines all sub-systems together and is composed of four strap-on boosters, a first stage, a second stage, a third stage and payload fairing.

The first two stages, as well as the four strap-on boosters, use hypergolic (N2O4/UDMH) fuel while the third stage uses cryogenic (LOX/LH2) fuel. The total length of the CZ-3B is 54.838 meters, with a diameter of 3.35 meters on the core stage and 3.00 meters on the third stage.

On the first stage, the CZ-3B uses a YF-21C engine with a 2,961.6 kN thrust and a specific impulse of 2,556.5 Ns/kg. The first stage diameter is 3.35 m and the stage length is 23.272 m.

Each strap-on booster is equipped with a YF-25 engine with a 740.4 kN thrust and a specific impulse of 2,556.2 Ns/kg. The strap-on booster diameter is 2.25 m and the strap-on booster length is 15.326 m.

The second stage is equipped with a YF-24E (main engine – 742 kN / 2,922.57 Ns/kg; four vernier engines – 47.1 kN / 2,910.5 Ns/kg each). The second stage diameter is 3.35 m and the stage length is 12.920 m.

The third stage is equipped with a YF-75 engine developing 167.17 kN and with a specific impulse of 4,295 Ns/kg. The fairing diameter of the CZ-3B is 4.00 meters and has a length of 9.56 meters.

The CZ-3B can also use the new Yuanzheng-1 (“Expedition-1”) upper stage that uses a small thrust 6.5 kN engine burning UDMH/N2O4 with a specific impulse at 3,092 m/s.

The upper stage is able to conduct two burns, having a 6.5 hour lifetime and is capable of achieving a variety of orbits. This upper stage won’t be used on this launch.

The typical flight sequence for the CZ-3B/G2 sees the launch pitching over 10 seconds after liftoff from the Xichang Satellite Launch Centre. The boosters shutdown 2 minutes and 7 seconds after liftoff, with separation from the first stage one second later. First stage shutdown takes place at 1 minutes 25 seconds into the flight.

Separation between the first and second stage takes place at 1 minute 26 seconds, following fairing separation at T+3 minutes 35 seconds. Stage 2 main engine shutdown occurs 326 seconds into the flight, following by the shutdown of the vernier engines 15 seconds later.

Separation between the second and the third stage and the ignition of the third stage takes place one second after the shutdown of the vernier engines of the second stage. The first burn of the third stage will last for 4 minutes and 44 seconds.

After the end of the first burn of the third stage is followed by a coast phase that ends at T+20 minutes and 58 seconds with the third stage initiating its second burn. This will have a 179 seconds duration. After the end of the second burn of the third stage, the launcher initiates a 20 second velocity adjustment maneuver. Spacecraft separation usually takes place at T+25 minutes 38 seconds after launch.

The first launch from Xichang took place at 12:25 UTC on January 29, 1984, when the Chang Zheng-3 (Y-1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit.

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 center 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.

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