Surprise from China – 22nd Beidou satellite on orbit !

China launched on Tuesday, 29 March 2016, their next navigation satellite to support development of Beidou navigation system.

CNSA is not slowing down and still gives impressive pace in competition on navigation system market. Yesterday on 29 March 2016 punctually at 20:11 GMT, CNSA launched on atop of Long March 3A rocket their next Beidou satellite from Xichang Satellite Launch Center. It is already second launch of Beidou satellite in 2016. It was already confirmed by NORAD with ID 41434; Chinese news agency Xinhua announced that mission of the satellite was successful and spacecraft remains in good health. First launch of the Beidou satellite in 2016, BD-3 M3 was performed on February 1 also from Xichang Satellite Center.

As usual launch was not officially announced in Chinese media before; Launched satellite belongs to geostationary series of Beidou spacecrafts. Satellite is called also Compass-I and was designed and manufactured by China Academy of Space Technology (CAST). Base for creating satellite was proven DFH-3bus. Mass of satellite is around 2200 kg with full tanks. Beidou BD-2 I6 (code name for satellite launched yesterday) has  following dimension: 2.25 m x 1.0 m x 2.2 m. Satellite is powered by onboard battery and two deployable solar arrays with wingspan at around 18 m. Satellite will be sixth navigation satellite under Beidou program remaining on orbit of 200 km x 35798 km and inclination at 55.035°. It will reach designated inclined geosynchronous  using own chemical engine with thrust at 490 N. Satellite is equipped with lase retro reflector and phased array antenna to provide navigational signal for receiving devices remaining on high altitudes.  Main objective for mission of BD-2 I6 is to replace one from previously launched IGSO satellites; As far as the predicted operational life of this series is about 8 years, we can compare which satellite launched in previous years is reaching to the end. First BD-2 was launched on 31 July 2010, second on 17 December 2010. Next three were launched on 2011: 9 April, 26 July and 1 December. China seems to have at least two satellites with 6years of mission which can potentially have problems in nearest future. It is worth to remind that satellites remaining on GSO orbit are much more exposed to cosmic rays and their operational life is significantly shorter than satellites remaining on lower orbits.

CNSA decided to utilize Long March 3A rocket during this mission. It is launch vehicle designed by China Academy of Launch Vehicle Technology (CALT) in late eighties with first mission performed in 1994. Rocket is long for 52 m and is based on three stages. Rocket is not supported by boosters which are characteristic feature of Long March 3B and Long March 3C. All three stages are liquid fueled and have almost same diameter - 3.35 m. Only third stage is slightly thinner and its diameter is equal to 3 m. With mass of 240 t, rocket is able to lift up to 8.5 t to LEO, 2.6 t to GTO and 1.6 t to HCO. First stage propulsion is basing on four YF-21C engines with sum thrust at 2961.6 kN fueled with N2O4/UDMH. Second stage is fueled with same propellant but it is powered by central YF-24E (742 kN) and four stabilizing YF-23C (47.1 kN). Third stage is powered by single YF-75 engine fueled with LH2/LOX - provided thrust is at 167.17 kN. Mission of BD-2 I6 was 225th mission of Long March rocket.

Sources:
http://news.xinhuanet.com/english/2016-03/30/c_135234635.htm
https://en.wikipedia.org/wiki/Long_March_3A
http://bbs.9ifly.cn/forum.php?mod=viewthread&tid=13167&page=6#pid455781