Fengyun (Wind Cloud)
Fengyun (FY, “Wind Cloud”) is China’s meteorological satellite programme, designed to monitor the weather and climate of the Earth by capturing images of clouds and cloud systems. The programme includes both polar-orbiting satellites operating on a Sun Synchronous Orbit (SSO) and geostationary satellites. The prime contractor is Shanghai Academy of Spaceflight Technology (SAST).
Name:...............Fengyun (FY) Discipline:.........Meteorology Type:...............Government / military No. of missions:....14 First mission.......1988 Last mission........2014 Sponsor agency(s)...National Satellite Meteorological Centre (NSMC) China Meteorological Administration (CMA) Contractor(s).......SAST (prime) SITP (FY-1/3 mission payload) CAST (FY-2 mission payload)
Fengyun 1 (FY-1) was China’s first polar orbit meteorological satellite. Its mission payload was developed by the Shanghai Institute of Technical Physics (SITP) of the Chinese Academy of Sciences (CAS). The development programme (Project 711) began in 1975 and the first satellite was produced in 1988. A total of four satellites were built and launched, with two in the experimental Batch-01 variant, and two in the operational Batch-02 variant featuring slightly increased mass and improved mission payload.
Fenyun-1 was a three-axis stabilised spacecraft operating in the sun-synchronous orbit (SSO). The satellite employed an X-band data transmitter for image downlink. Nickel-cadmium batteries were used for electrical power storage. Attitude control was maintained by a combination of nitrogen cold gas thrusters and reaction wheels (from Fengyun 1B onwards).
The Batch-01 variant was 1.4 m x 1.4 m x 1.2 m in size and powered by two solar panel wings about 3.5 m long each. It had a designed operational life of one year. Onboard payload consisted of two very high resolution scanning radiometers (VHRSR) with a combined mass of 95 kg. These optical-mechanical scanners operated at 360 rpm with a 20 cm diameter primary mirror in five spectral bands in visible and new infrared spectra. The system’s swath width was 2,860 km with a 1.08 km resolution in the high-resolution picture transmission (HRPT) mode and 4 km resolution in the automatic picture transmission (APT) mode.
The Batch-02 variant carried a 10-channel scanning radiometer and had an extended design life of two years.
The ground segment of the Fengyun 1 system consisted of three ground stations located in Beijing, Guangzhou and Urumqi and a Data Processing Centre (DPC) in National Satellite Meteorological Centre in Beijing. The data received at the ground stations were relayed in real-time to the Beijing DPC for processing, distributing, and archiving. Products from the DPC included cloud image mosaic, meteorological parameters such as sea surface temperature, cloud top temperature and total water vapour, and regional environmental parameters such as vegetation index, snow cover, sea ice, land cover, etc. All raw data and products were archived on digital tapes.
Satellite bus:......FY-1 Mass:...............750 kg (FY-1A) 850 kg (FY-1B) 950 kg (FY-1C/D) Dimensions:.........1.4 m x 1.4 m x 1.2 m Solar panel span:...8.6 m (FY-1A/B) 10.556 m (FY-1C/D) Orbit:..............800 to 900 km Inclination:........98.8 to 99.1º Stabilisation.......3-axis Designed life.......6 months (FY-1A) 1 year (FY-1B) 2 years (FY-1C/D)
Fengyun 2 (FY-2) was the geostationary meteorological satellite developed in the 1980s-90s as a supplement to the polar meteorological satellite Fengyun 1. The satellite was developed by the Shanghai Academy of Spaceflight Technology (SAST, or the Eighth Academy), with other 18 organisations also involved in its development.
The concept of the geostationary meteorological satellite was first developed by the Shanghai-based 509 Institute (Shanghai Institute of Satellite Engineering of CAST) in 1982. The Sate Council and Central Military Commission authorised the development programme in 1989. Wei Zhongquan was appointed the Chief Designer and Qi Faren the Chief Director. After Qi was appointed the Chief Designer of the Shenzhou manned spacecraft, his position was filled by Zhu Aikang.
The design proposal was approved by the Ministry of Aerospace in February 1992. The first experimental satellite (Fengyun 2-01) was completed in 1994 and was delivered to the Xichang Satellite Launch Centre (XSLC) for pre-launch test and processing. However, the satellite was destroyed in a fire accident, which killed one technician and injured 20 others.
In January 1995, the Fengyun 2 project and 509 Institute were transferred to SAST, while the CAST continued with the development of the mission payload. The second satellite Fengyun 2-02 was launched atop a CZ-3 launch vehicle from Xichang on 10 June 1997, and positioned at 105°E on the geostationary orbit on 17 June. It was officially handed over to its user on 1 December under the designation Fengyun 2A. However, the onboard imager failed completely only 10 months after the launch, even though the satellite bus remained fully operational until 2002.
The third satellite (Fengyun 2-03) was launched on 25 June 2000. The satellite ignited its FG-36 apogee kick motor on 26 June and after 8 days of drifting the satellite entered its position at 105°E on the GEO on 3 July. Under the control of the Xi’an Satellite Control Centre, the satellite began to spin at a rate of 100 rounds/minute, pointed its antenna towards the Earth and switched on its imager. After in-orbit test, the satellite was handed over to its user on 1 January 2001 using the designation Fengyun 2B.
Following the success of two experimental satellites, three operational satellites (Fengyun 2C, 2D and 2E) were launched between 1997 and 2008. A complete Fengyun 2 constellation would include two operational satellites, positioned at 105°E and 86.5°E respectively, and a backup satellite. As the first batch of operational satellites approach the end of their operational life, and due to the delay in the Fengyun 4 programme, a second set of three satellites (Fengyun 2F, 2G and 2H) were scheduled for launch between 2012 and 2016 as a stopgap.
Fengyun 2 is a cylinder-shaped, spin-stabilised geostationary satellite, with a designed operational life of three years. The satellite has a launch mass of 1,369 kg and an orbital mass of 536 kg. It is 2.1 m in diameter, and 4.376 m in length with the apogee kick motor (AKM), or 3.081 m in length without AKM. The satellite consists of 11 sub-systems: space frame, thermal-control, power supply, altitude control, propulsions, telemetry and control, FG-36 AKM, mission payload, data transmitters, data collection and transponder, and antenna.
The satellite carries a five-channel Stretched Visible and Infrared Spin Scan Radiometer (S-VISSR), with an S-band and a UHF data transmitter. The two principal sensors worked in visible and infrared spectrum, with best resolution of 1.25 km and 5.0 km respectively. A water vapour sensor was also carried onboard the satellite. It also carried an X-ray detector to monitor the activities of the Sun, and detect solar flares.
Satellite bus:......FY-2 Mass (gross)........1,369 kg Mass (orbital)......536 kg Dimensions:.........2.1 m x 4.376 m Orbit:..............GEO Stabilisation.......Spin Designed life.......2 years
Fenyun 3 (FY-3) is the second-generation polar orbit meteorological satellite developed and built by SAST. The Fengyun 3 project was initiated in 1998 and the engineering development of the first satellite began in 1999. The first satellite Fengyun 3A was launched on 27 May 2008 from the Taiyuan Satellite Launch Centre atop a CZ-4C launch vehicle. With a total mass of 2,295 kg, the satellite was estimated to be comparable in performance and technology to the U.S. NPOESS and European METOP satellite.
The three-axis stabilised satellite is equipped with new global, all-weather, multi-spectral, three-dimensional sensors. The role of the satellite is to acquire measures such as air temperature, vapour, clouds, atmospheric and terrestrial radiation, etc. for intermediate- to long-term weather forecasts. It can also be used to monitor land features, natural disasters, pollutions, and other types of environmental information to help the studies on global and regional climate.
Initially two experimental satellites, Fengyun 3A and 3B, were launched to form a constellation in orbit, with one in the morning slot (Local Time on Descending Node, LTDN = 10:00 hours) and one in the afternoon slot (LTDN=14:00 hours). In the operational phase, two improved satellites with better sounding and imaging capabilities will be launched. In addition, a third satellite operating on a low-altitude (~400 km) large-inclination (50—60°) orbit will observe rainfall information on Earth. The three satellites would form a complete Earth-observation constellation to capture comprehensive remotely-sensed meteorological and space environmental data. A total of 9 satellites in three sets were planned to be launched from 2012 onwards.
Fengyun 3 is in a box-shape 4,440 mm x 10,000 mm x 3,790 mm in dimension. The satellite has a launch mass of 2,353 kg and an orbital mass of 2,295 kg. It operats in an 836-870 km near-circular SSO inclined at 98.753°, with a designed life of 3 years (5 years for the operational variant). The satellite would circle the Earth 14 times every day, covering the whole globe twice a day.
The three-axis stabilised satellite is powered by a single four-panel solar wing so that a side of the satellite can remain facing away from the Sun to cool the system. This required more advanced stabilisation and orbital control techniques. The satellite has a three-axis pointing accuracy of less than 0.3° and a three-axis measurement accuracy of less than 0.05°.
Fengyun 3 carries 11 remote sensing sensors, operating in spectrum from the ultraviolet to the far infrared. Its payload includes optical scanning radiometer, infrared spectrometer, medium-resolution imaging spectrometer, microwave radiometer, microwave hygrometer, microwave imager, vertical ozone ultraviolet (UV) detectors, overall ozone UV detectors, solar radiation intensity monitor, Earth radiation detectors, and space environment monitor. These sensors can obtain the 3D stereo vertical distribution atmospheric temperature and humidity, as well as information on the Earth ozone.
The ground swath of the onboard optical-mechanical scanners is 3,000 km with a 250 m resolution in the High Resolution Picture Transmission (HRPT) mode. The satellite has two X-band transmitters (one real-time and one delayed) and an L-band transmitter (real-time). The onboard data management computer, altitude and orbital control computer, and all the remote-sensing sensors were connected via a MIL-STD-1553B data bus system, which allowed autonomous management of data collection and calculating orbital parameters by the onboard computers.
Satellite bus:......FY-3 Mass (gross)........2,353 kg Mass (orbital)......2,295 kg Dimensions:.........4.44 m x 3.79 m Solar panel span:...10 m Orbit:..............836 to 870 km Inclination:........98.753º Stabilisation.......3-axis Designed life.......3 to 5 years
Fengyun 4 (FY-4) is China’s second-generation three-axis stabilised, geostationary meteorological satellite currently under development. The satellite will be equipped with an enhanced imagery scanning capability for monitoring small- and medium-scale weather systems. The satellite will be capable of vertical atmospheric sounding and microwave sensors to provide a 3D remote-sensing capability from GEO. The satellite will also be capable of solar observations to monitor extreme ultraviolet and X-rays to offer enhanced space weather monitor and warning capability.
Two variants of the satellite have been planned: optical and microwave. The optical variant will carry a 10-channel 2D scanning imager, an interferometric vertical detector, a lightning imager, CCD camera and an earth radiation monitor instrument. The satellite will be able to produce Earth surface imageries every 15 minutes.
Satellite bus:......FY-4 Mass:...............N/A Dimensions:.........N/A Solar panel span:...N/A Orbit:..............GEO Stabilisation.......N/A Designed life.......N/A