Long March 3B launches Fengyun-4A meteorological spacecraft

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China launched the first of a new generation geosynchronous meteorological satellites on Saturday. The launch of Fengyun-4A satellite took place at 16:11 UTC using the Long March-3B/G2 (Y42) – or Chang Zheng-3B/G2 per its Chinese name – from the LC3 Launch Complex at the Xichang Satellite Launch Center.

Chinese Launch:

Fengyun-4 (Wind and Cloud) series is China’s second-generation geostationary meteorological satellites after Fengyun-2 satellite series. The performance of Feng Yun-4 has been improved in relation to FY-2 in terms of data amount, network transmission bandwidth, product type and quantity and archiving data and applications.

The satellite attitude is three-axis stabilized to improve the time resolution of observations and regional mobility.

The new generation satellites are designed with an enhanced imagery scanning capability, desirable for monitoring small and medium scale weather systems. It is equipped with vertical atmospheric sounding and microwave detection capabilities to address 3D remote sensing at high altitudes.

The satellite also carries instrumentation for solar observations for extreme ultraviolet and X-rays, in a bid to enhance China’s space weather watch and warning capability.

The new FY-4 series will comprise satellites will optical and microwave variants. An optical satellite will carry onboard a 10-channel 2D scanning imager, an interferometric vertical detector, a lightning imager, CCD camera and an earth radiation budget instrument. The satellite produces earth disc imageries every 15 minutes.

The optical variant will include two satellites. This includes an “East” satellite covering a region including western China, the Indian Ocean, the Red Sea and the Middle East; and ‘a “West” satellite covering a region including middle and eastern China and the Pacific. The microwave variant FengYun-4 will cover China and its peripheral areas.

In general the main tasks of the Fengyun-4 series will be to take multiple spectral band measurements of high temporal resolution and accuracy, to obtain imagery of the earth’s surface and cloud, including the segment images and increase the overall capability of the China Meteorological Administration in space-based quantitative observation and application.

It will also measure the vertical profile of temperature and humidity of the atmosphere with improved detection accuracy and vertical resolution; to detect the lightning to obtain the map that positions the lightning occurrences; to transmit the observational images, data and derived products with on-board transmitter; to collect the earth environmental measurements from automatic data collection platforms and transmit to users; and to monitor solar activities and space environment to provide the data for space weather research and service.

The main tasks for the new satellites are to obtain the multi-spectrum and high-accurate quantitative images of the earth and clouds; to measure the humidity parameter of atmosphere; to enhance the ability of detecting the space weather and environment; to collect various earth environmental parameters; and to transmit images, weather products, and the devastating weather forecasting.

The main instruments on Fengyun-4A are the Advanced Geosynchronous Radiation Imager (AGRI), with 14 channels with a spectral range set between 0.55μm and 13.8μm; the Interferometric Infrared Sounder (GIIRS); the Lightning Mapping Imager (LMI); the Space Environment Package (SEP); the Solar X-EUV imaging telescope (SXEUV); and the Data Collection Service (DCS).

AGRI was developed by the constructed by Harris Corporation and uses an off-axis telescope, two scan mirrors, 216 detectors in 14 spectral bands, and full-path on-orbit calibration. The instrument is replacing the S-VISSR sensor, flown on the FY-2A to H series. It has 14 channels and two observation modes. The temporal resolutions are 1 – 5 minutes over a regional domain and 15 minutes over the full-disk domain.

GIIRS was developed by National Space Science Center of the China Academy of Sciences and is the main payload onboard of FY-4A satellite. It will monitor and measure internal constitution and precipitation parameters of the atmosphere cloud cluster. GIIRS can be used for vertical atmospheric sounding and it is the first high-resolution sounding sensor onboard the geostationary satellite.

There are two observation modes of GIIRS. One mode is designed for China area, whose temporal resolution is 55 minutes and the coverage is 4500 x 4500 km. The other observation mode is mesoscale mode, whose temporal resolution is 30 minutes and the coverage is 1000 x 1000 km.

LMI is the first lightning detection sensor on China’s satellites. It will be used to observe regional lightning activity in China. Information obtained will be used in forecasting and warning of convection precipitation, and studying of Earth’s electric field.

The SEP will monitor the charged particles at platform level. Set of counters for electrons (0.4-4 MeV) and protons (1-165 MeV). The instrument packaged is composed of a High-energy Proton Detector (8 channels in the energy range of 1-165 MeV; the FOV is conical at 60º), an High-energy Electron Detector (9 channels in the energy range of 0.4 – 4 MeV; the FOV is conical at 25º) and a package of instruments including a FGM (Flux Gate Magnetometer), and radiation dosimeter and surface charging sensors. The dynamic range of FGM: ±0.01 to ±600 nT for each component, with a maximum resolution of ±0.06 @ of the dynamics.

Data collection from DCPs (Data Collection Platforms) in the ground segment has two types of DCPs that will be served at either regional or international (i.e. migrating across the field of view of more geostationary satellites).

Launch vehicle and launch site:

To meet the demand of international satellite launch market, especially for high power and heavy communications satellites, the development of Long March-3B (Chang Zheng-3B) launch vehicle was started in 1986 on the basis of the fight proven technology of Long March launch vehicles.

Developed from the Chang Zheng-3A, the Chang Zheng-3B is at the moment the most powerful launch vehicle on the Chinese space launch fleet.

The CZ-3B features enlarged launch propellant tanks, improved computer systems, a larger 4.2 meter diameter payload fairing and the addition of four strap-on boosters in the core stage that provide additional help during the first phase of the launch.

The rocket is capable of launching a 11,200 kg satellite to a low Earth orbit or a 5,100 kg cargo to a geosynchronous transfer orbit.

The CZ-3B/G2 (Enhanced Version) launch vehicle was developed from the CZ-3B with a lengthened first core stage and strap-on boosters, increasing the GTO capacity up to 5,500kg.

On May 14, 2007, the first flight of CZ-3B/G2 was performed successfully, accurately sending the NigcomSat-1 into pre-determined orbit. With the GTO launch capability of 5,500kg, CZ-3B/G2 is dedicated for launching heavy GEO communications satellite.

The rocket structure also combines all sub-systems together and is composed of four strap-on boosters, a first stage, a second stage, a third stage and payload fairing.

The first two stages as well as the four strap-on boosters use hypergolic (N2O4/UDMH) fuel while the third stage uses cryogenic (LOX/LH2) fuel. The total length of the CZ-3B is 54.838 meters, with a diameter of 3.35 meters on the core stage and 3.00 meters on the third stage.

On the first stage, the CZ-3B uses a YF-21C engine with a 2,961.6 kN thrust and a specific impulse of 2,556.5 Ns/kg. The first stage diameter is 3.35 m and the stage length is 23.272 m.

Each strap-on booster is equipped with a YF-25 engine with a 740.4 kN thrust and a specific impulse of 2,556.2 Ns/kg. The strap-on booster diameter is 2.25 m and the strap-on booster length is 15.326 m.

The second stage is equipped with a YF-24E (main engine – 742 kN / 2,922.57 Ns/kg; four vernier engines – 47.1 kN / 2,910.5 Ns/kg each). The second stage diameter is 3.35 m and the stage length is 12.920 m.

The third stage is equipped with a YF-75 engine developing 167.17 kN and with a specific impulse of 4,295 Ns/kg. The fairing diameter of the CZ-3B is 4.00 meters and has a length of 9.56 meters.

The CZ-3B can also use the new Yuanzheng-1 (“Expedition-1″) upper stage that uses a small thrust 6.5 kN engine burning UDMH/N2O4 with specific impulse at 3,092 m/s. The upper stage is able to conduct two burns, having a 6.5 hour lifetime and is capable of achieving a variety of orbits. This upper stage was not used on this launch.
Typical flight sequence for the CZ-3B/G2 sees the launch pitching over 10 seconds after liftoff from the Xichang Satellite Launch Centre. Boosters shutdown 2 minutes and 7 seconds after liftoff, separation from the first stage one second latter. First stage shutdown takes place at 1 minutes 25 seconds into the flight.

Separation between the first and second stage takes place at 1 minute 26 seconds, following fairing separation at T+3 minutes 35 seconds. Stage 2 main engine shutdown occurs 326 seconds into the flight, following by the shutdown of the vernier engines 15 seconds later.

Separation between the second and the third stage and the ignition of the third stage takes place one second after the shutdown of the vernier engines of the second stage. The first burn of the third stage will last for 4 minutes and 44 seconds.

After the end of the first burn of the third stage follows a coast phase that ends at T+20 minutes and 58 seconds with the third stage initiating its second burn. This will have a 179 seconds duration. After the end of the second burn of the third stage, the launcher initiates a 20 second velocity adjustment maneuver. Spacecraft separation usually takes place at T+25 minutes 38 seconds after launch.

The first launch from Xichang took place at 12:25UTC on January 29, 1984, when the Chang Zheng-3 (Y-1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit.

The Xichang Satellite Launch Center is situated in the Sichuan Province, south-western China and is the country’s launch site for geosynchronous orbital launches.

Equipped with two launch pads (LC2 and LC3), the center has a dedicated railway and highway lead directly to the launch site.

The Command and Control Centre is located seven kilometers southwest of the launch pad, providing flight and safety control during launch rehearsal and launch.

The CZ-3B launch pad is located at 28.25 deg. N – 102.02 deg. E and at an elevation of 1,825 meters.

Other facilities on the Xichang Satellite Launch Centre are the Launch Control Centre, propellant fuelling systems, communications systems for launch command, telephone and data communications for users, and support equipment for meteorological monitoring and forecasting.

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