China is still far from full giving to public their space plans. Due this fact, sometimes about launches we are informed post factum.
This time China surprised public with information about launching Yaogan-28 satellite today at 07:06 UTC. According to China.org.cn, main objective in this mission are purely scientific:
“The satellite will be used for experiments, land surveys, crop yield estimates and disaster relief.”
Other sources claim that Yaogan satellites are utilized mainly for optical and electronic military reconnaissance. First satellite from Yaogan series was launched on 26th April 2006. Whole series is designed by Shanghai Academy of Spaceflight Technology (SAST). SAST known from their LM-2D launch rockets is designing also military missiles (FN-6 called also HY-6) and both civilian and military observation satellites. In 1993 SAST was considered as a military company and sanctioned by U.S. Government for exporting banned equipment to Pakistan but in 1994 sanctions were halted. Western doubts about civilian character of Yaogan-28 are not necessary unfounded, because first Yaogan satellite was funded by Chinese military forces (PLA). Chinese launch could be considered as mean of military pressure due the tensions between China and USA on South China Sea. But still there is no any official confirmation about military character of Yaogan-28.
Long March 4B rocket remains in service since 1999 and is mainly utilized for launching satellites into low Earth and sun synchronous orbits. Rocket height is at 45.8 m, diameter at 3.35 m and weight at 249,200 kg. It was designed as three stage rocket liquid fueled rocket with no additional boosters. First stage is powered by four YF-21C engines (thrust at 2961.6 kN), second stage is equipped with one central YF-22C, and four stabilizing YF-23C. This combination, also called YF-24C, offers thrust for central engine at 742.04 kN and for additional YF-23C at 47.1 kN per one engine. Third stage propulsion are two engines YF-40 with thrust at 100.85 kN. Rocket offers payload capability for LEO at 4200 kg, for SSO at 2800 kg and for GTO at 1500 kg.