Long March 4C delivers to orbit Fengyun-3D

On November 14, 2017 CNSA launched Long March 4C rocket with Fengyun-3D meteorological satellite under the payload fairing.

Launch was performed yesterday at 18:35 UTC  from the LC9 Launch Complex at the Taiyuan Satellite Launch Center in Shanxi Province.

Satellite is representing second generation of Chinese polar orbit weather satellites. It is fourth from FY-3 series which will be core of China's weather satellites constellation; another four satellites are planned to be launched before end of 2021.

Fengyun-3D is operated by China Meteorological Administration and National Satellite Meteorological Center. It will provide various data on air temperature, humidity, cloud thickness. Part of the data gathered by FY-3 satellites and latest CO2 level measuring satellite , TanSat, will be available for free for different users - it was announced in the end of October 2017 by Xian Di, head of the NSMC's satellite data-sharing department.

Each from eight FY-3 satellites was designed by Shanghai Academy of Spaceflight Technology. It is powered by single solar array attached on special arm to hexahedral main body. Dimensions after deployment of the solar arrays are  4.4 m x 10 m x 3.8 m. Total mass of the satellite is 2450 kg. Single solar array is providing 1100 W of power and is charging two 50 Ah NiCd batteries. Satellite is divided internally into three sections: propulsion module, payload module and service module. Satellite Operating from polar orbit (on 806 km altitude) satellite will be able to scan 3000 km ground swath with 250 m resolution and send data real-time using X and L band transmitters. Vehicle is equipped with 3 axis stabilization. Payload compartment contains following instruments:

  • VIRR (Visible and Infrared Radiometer) - imaging device
  • IRAS (Infrared Atmospheric Sounder) - for measuring humidity levels
  • MWTS (Microwave Temperature Sounder) - this device will measure temperature on different altitudes
  • MWHS (Microwave Humidity Sounder) - device will gather data to create humidity profiles of atmosphere
  • MERSI (Medium Resolution Spectral Imager) - secondary imaging device
  • SBUS (Solar Backscattering UV Sounder) - for measuring amount of ozone
  • TOU (Total Ozone Unit) - for monitoring ozone distribution
  • MWRI (Microwave Radiation Imager) - third imaging device
  • ASI (Atmospheric Sounding Interferometer) - it is spectrometer
  • ERM (Earth Radiation Measurement) - for measuring radiation
  • SEM (Space Environment Monitor) - for measuring space radiation
  • SIM (Solar Irradiation Monitor) - provide solar irradiance monitoring in the spectral range of 0.2~50 µm

Mission of the satellite will last at least 3 years.

Additional payload delivered to orbit with FY-3D was HEAD-1 commercial communications satellite.  Built by SAST will process 2 million AIS short messages  every 24 hours helping in identification of ships around the world. HEAD-1 is the first satellite in the Skywalker Constellation planned to cover 30 spacecrafts.

Long March 4C is upgraded Long March-4B with larger payload fairing and restartable upper stage. It is manufactured by Shanghai Academy of Spaceflight Technology; rocket is usually launched from two space centers: 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 equipped with boosters; first stage is powered by four YF-21C engines fueled with 182 t of N2O4/UDMH and providing thrust at 2962 kN; it is long for 28 m. Second stage is long for 11 m and its propulsion is single YF-24C fueled with 52.7 t of N2O4/UDMH and is providing thrust at 724.04 kN. Upper stage is slightly less wide with diameter at 2.9 m (length of 17.8 m) and is equipped with 2 YF-40A engines with 100.85 kN of thrust and burning 14 t of N2O4/UDMH. Long March 4C is able to deliver to space from 1500 kg (GTO) up to 4200 kg to LEO.

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