China will launch on 5th August their new communication satellite from Xichang Satellite Launch Center.
Spacecraft is known as Tiantong-1 and was described by various sources as civilian mobile communication satellite working on S band. According to Chinaspaceflight, satellite will be launched Xichang Satellite Launch Center, probably from LC3 pad, on atop of Long March 3B/G. Yesterday, according to published pictures, already one Y35B booster was installed on LC3 launch pad. It was not announced what kind of services satellite will support, but it is highly possible that it could be both new military spacecraft covered under civilian purpose or first satellite from planned constellation supporting new Chinese mobile communication system. It was unveiled, that satellite was designed and manufactured under cooperation of China Academy of Space Technology (CAST) and China Satellite Communications Co. Ltd. Whole system, which is planned to start operation in 2020, will be operated by China Satellite Communications and China Telecom Corporation Limited. Second Company will be responsible for ground segment of the system. It will offer voice services, data transmission and internet access over the Middle East, Africa, the Pacific and the Indian Ocean region.
System is developed by APMT consortium established in 1995 and is controlled probably in 75% by different Chinese government agencies and companies. From the beginning it was offering very low rates per minute (0.3$ to 0.5$ per minute comparing to competition with rates starting from 0.7$ in the year 2000) and was strongly promoted in Asia region. Interesting fact regarding system is fact, that even in case of simple handset-to-handset communication, signal is not simply transmitted via satellite, but it is always downlinked to ground segment first. According to some sources it gives opportunity to monitoring voice communication or data transfer. Also, it is worth to remind, that Hughes was contracted in 1999 to provide two APMT satellites with large 15 m antennas for space segment of the APMT, but US government did not agree to transfer technology to consortium owned by China (it was feared, that large antenna could be used for space intelligence not for civilian communication).
Satellite will be delivered to space by Long March 3B G version. It is most recent, recently upgraded, rocket from Long March 3 family. Construction of Long March 3B/G is based on three stages and four strap-on boosters. Boosters are utilizing single YF-21C engine (2961.9 kN of thrust), first stage is powered by four YF-21C engines (2961.6 kN thrust each). Second stage is equipped in one central YF-24E (thrust at 742 kN) and four YF-23C (thrust at 47.1 kN) for stabilization. Third stage is equipped in one YF-75 engine generating 167.17 kN of thrust. Rocket is liquid fueled and utilizing N2O4/UDMH for boosters and first two stages, LH2/LOX for third stage propulsion. Rocket is able to deliver to LEO 12 t. G version is longer for about 90 cm (10.4 m long with diameter at 4 m) due the extended payload fairing and its total length if 57.2 m with unchanged diameter at 3.35 m.