Gaofen-3 SAR satellite launched from Taiyuan Satellite Launch Center

 

Next Chinese remote sensing satellite equipped with Synthetic Aperture Radar was launched today at 06:55 local time on atop of Long March 4C. 

Rocket with satellite under payload fairing was launched at 22:55 GMT on August 9 from Taiyuan Satellite Launch Center placed in Northern China; as previously launched Gaofen satellites (Gaofen means "high resolution" in Chinese) is part of the Earth Observation System Program (CHEOS)  started in 2010. System is sponsored by Chinese state; Gaofen-3 will be operated by State Oceanic Administration (SOA). Gaofen satellites are providing imaging and radar observation services in real time for various Chinese administration structures. Data provided by satellites are used for city planning, road network design, agriculture planning, weather forecasting, disaster relief and maritime monitoring. Last service (Gaofen-3 is able to provide high resolution radar images of sea even in rough weather conditions) is most desired in present situation on South Chinese Sea. China have built airfields in the Spratly Island on South Chinese Sea and additional satellite will probably serve for tracking movement of United States Pacific Fleet, which is continuously controlling Chinese actions in this region.

Gaofen-3 was launched on atop of Long March 4C rocket and was placed on Low Earth Orbit on altitude of 755 km. Satellite is first from Gaofen series with 8 years operational life and with weight of 2950 kg is probably heaviest satellite among other Gaofen spacecrafts. Satellite was designed by CAST (China Academy of Space Technology), and was based on CS-L3000B bus. It is powered by onboard lithium battery and two deployable solar arrays; power system was equipped with pulse power technology providing high output power in lasting for very short time impulses. It is particularly useful for radar, which requires short high power pulses.  Fuselage is cubical in shape with deployable radar antenna. Operating on C band with multipolarization SAR radar is able to work with resolution fitting in range from 1m to 500 m with swath up to 650 km (with minimal swatch of 10 km), satellite offers 12 modes of imaging. Spacecraft is equipped with 3 axis attitude control with control moment gyros and momentum wheels.

Long March 4C is upgraded LM-4B by adding larger payload fairing and upper stage with restart ability. It is manufactured by Shanghai Academy of Spaceflight Technology and launched from two Chinese space centers placed in Jiuquan and Taiyuan. Mass of the launch vehicle is 250 t with height of 45.8 m and diameter at 3.35 m. Rocket is not supported by boosters-first stage is powered by four YF-21C engines burning 182 t of N2O4/UDMH and providing thrust at 2962 kN; it is long for 28 m. Second stage, long for 11 m, is equipped with single YF-24C fueled with 52.7 t of N2O4/UDMH and providing thrust at 724.04 kN. Last stage is slightly less wide with diameter at 2.9 m (length of 17.8 m) with 2 YF-40A engines with 100.85 kN of thrust and burning 14 t of N2O4/UDMH. Long March 4C is able to lift from 1500 kg to GTO up to 4200 kg to LEO.

UPDATE: According to USSTRATCOM orbit parameters are: 735 km x 747 km with inclination at 98.41°.

On picture above: sample SAR 3D image.

Sources:
http://news.xinhuanet.com/english/2016-08/10/c_135582857.htm