Fengyun-3E | Long March 4C

Featured image credit: Xinhua

Lift Off Time (Subject to change)	July 04, 2021 – 23:15 UTC July 05, 2021 – 07:15 BJT
Mission Name	Fengyun 3E, a Sun-synchronous meteorology satellite
Launch Provider (What rocket company is launching it?)	China Aerospace Science and Technology Corporation (CASC)
Customer (Who’s paying for this?)	China Meteorological Administration (CMA)
Rocket	Long March 4C
Launch Location	Jiuquan Satellite Launch Center, China
Payload mass	2,300 kg (~5,070 lb)
Where is the satellite going?	836 km Sun-synchronous orbit (SSO), at an inclination of 98.8°
Will they be attempting to recover the first stage?	No, this is not a capability of the Long March 3B/E rocket
Where will the first stage land?	It will crash back on land over mainland China
Will they be attempting to recover the fairings?	No, this is not a capability of the Long March 3B/E rocket
Are these fairings new?	Yes
How’s the weather looking?	N/A
This will be the:	– 20th Chinese launch of 2021 – 6th launch of a Long March 4C in 2021 – 34th launch of a Long March 4C – 5th launch of a Fengyun-3 satellite – 64th orbital launch attempt of 2021
Where to watch	If available, an official livestream will be listed here

What does all this mean?

Fengyun-3E is one China’s next generation weather satellite after Fengyun-4B, which was launched in June this year. It will be launched on top of a Long March 4C rocket from Taiyuan Satellite Launch Center, China and deployed into a 836 km Sun-synchronous orbit (SSO). It will add to the nine Fengyun weather satellites that are already and still in orbit around Earth, of which 8 are operational. Fengyun-4B is still in transit to its final orbit.

Fengyun-3E

The Fengyun-3E meteorology satellite is China’s 2nd generation of SSO weather satellites with a planned lifespan of at least 5 years. The first Fengyun-3 satellite, Fengyun-3A, was a tech demonstration satellite that was launched in 2008 and is not in service anymore. Fengyun-3E will complement three other Fengyun-3 satellites and will further improve weather monitoring and forecasting for the China Meteorological Administration (CMA).

Equipped with a deployable solar array, Fengyun-3E can provide 2500 W of power for its numerous scientific instruments.

Fengyun-3E Instruments

Acronym	Full Name	Primary Purpose
MWHS-2	Micro-Wave Humidity Sounder -2	Humidity and temperature measurments through micro-wave sounding
SIM-2	Solar Irradiance Monitor – 2	Measuring the Sun’s irradiance
WindRAD	Wind Radar	Measuring near surface winds
SWS/SEM/HEPD	Space Weather Suite / Space Environment Monitor / High Energy Particle Detector	Monitoring charged particle levels in the spacecraft’s orbit
SWS/SEM/IMS	Space Weather Suite / Space Environment Monitor / Ionosphere Measurement Sensor	Measuring ionospheric electron temperature and density
SWS/Tri-IPM	Space Weather Suite – Triple-angle Ionospheric PhotoMeter	Conducting UV spectrometry of Earth’s Ionosphere
XEUVI	Solar X-ray and Extreme Ultraviolet Imager	Solar imagery in the X-ray and EUV spectrum
MWTS-3	Micro-Wave Temperature Sounder – 3	Measuring of atmospheric temperature levels
HIRAS-2	Hyperspectral Infrared Atmospheric Sounder – 2	Temperature/humidity sounding, ozone profile and total-column green-house gases
MERSI-LL	Medium Resolution Spectral Imager – Low-Light	Monitoring clouds and sea surface temperature
SSIM	Solar Spectral Irradiance Monitor	Measuring the Sun’s short-wave irradiance
SWS/SEM/MFD	Space Weather Suite / Space Environment Monitor / Magnetic Field Detector	Measuring the magnetic field in the spacecraft’s orbit
GNOS-2	GNSS Radio Occultation Sounder – 2	Temperature/humidity sounding, monitoring space weather and sea surface wind speed

Fengyun Satellite Family

Fengyun is Chinese for “Winds and Clouds” and is the name of China’s weather forecasting satellite family. The constellation comprises Fengyun-1, Fengyun-2, Fengyun-3, and Fengyun-4 satellites. While Fengyun-1 and -2 have been the first generation of LEO and GEO weather satellites respectively, Fengyun-3 and -4 are China’s second generation weather satellites in the same orbits, with FY-3s being positioned in SSO and FY-4s in GEO.

Name	Orbit	Stabilization Method	Status	First Launched
Fengyun-1A/D	SSO	Three-Axis Stabilized	Not Operational	September 06, 1988
Fengyun-2A/C	GEO	Spin-Stabilized	Not Operational	June 10, 1997
Fengyun-2D/G	GEO	Spin-Stabilized	Operational	December 08, 2006
Fengyun-3A	SSO	Three-Axis Stabilized	Not Operational	May 27, 2008
Fengyun-3B/D	SSO	Three-Axis Stabilized	Operational	November 04, 2010
Fengyun-4A/B	GEO	Three-Axis Stabilized	Operational	December 10, 2016
Fengyun-4C/G	GEO	Three-Axis Stabilized	Planned	NET 2022

The China Meteorological Administration plans to launch Fengyun-3F to Fengyun-3J, as well as Fengyun-4C to Fengyun-4G in the upcoming years and decades, covering their need for meteorology satellites until 2040, with the last satellites planned to launch in 2030 and 2033 respecively.

Long March 4C

The Long March 4C is a 3 stage medium-lift launch vehicle derived from China’s Long March 4B vehicle. It is able to put up to 4,200 kg into low-Earth orbit, and up to 1,500 kg into geostationary transfer obit (GTO).

First Stage

The first stage has 4 open cycle YF-21C engines. Each engine runs on dinitrogen tetroxide (N₂O₄) and unsymmetrical dimethylhydrazine (UDMH), producing 740 kN of thrust each, with a specific impulse (ISP) of 260 seconds. Overall, the first stage produces 2,960 kN of thrust and carries 182,000 kg of propellent. The first stage is 27.91 meters tall, and 3.35 meters in diameter.

Second Stage

The second stage runs on a single YF-24C engine, which contains 1 main YF-22C engine for thrust, and 4 YF-23C attitude control thrusters. The main engine produces 742 kN of thrust and the attitude control thrusters each produce 47 kN, and both run on N₂O₄ and UDMH. The main engine’s ISP is 300 seconds, and the attitude control thrusters have an ISP of 289 seconds. The second stage is 10.9 meters tall, 3.35 meters in diameter, and carries 52,700 kg of propellent.

Third Stage

The third stage has two open cycle YF-40A engines that also run on N₂O₄ and UDMH. Each engine produces just over 100 kN of thrust and has an ISP of 303 seconds. The third stage is 14.8 meters tall and 2.9 meters wide.