Uses of weather satellites
The Fengyun-1 satellite is the first generation of quasi-polar sun-synchronous orbit meteorological satellite independently developed by my country, and it is also my country's first transmission-type polar orbit remote sensing satellite. Its main mission is to obtain domestic and foreign atmosphere, cloud, land, and ocean data, and collect relevant data for use in weather forecasting, climate prediction, natural disasters, and global environmental monitoring. Satellites can send real-time meteorological cloud images to cloud image receiving stations around the world, and can also detect ocean water color and conduct remote sensing research on sea temperatures. The satellites carry space particle composition monitors and can conduct research on the space environment. Currently, Japan has launched four, codenamed: FY-1A, FY-1B, FY-1C and FY-1D.
Development Overview
The FY-1 satellite formed an overall preliminary plan in 1977 and carried out comprehensive development work. In October 1985, the FY-1 satellite project was included in the key projects of satellite model development during the "Seventh Five-Year Plan" period.
(1) FY-1A and FY-1B
The two test satellites A and B, launched on September 7, 1988 and September 3, 1990, verified Satellite solutions and many new technologies adopted. The performance of the satellite-borne 5-channel visible light and infrared scanning radiometer and the main functions of the satellite are equivalent to those of the third-generation polar-orbiting weather satellites of the United States and are close to the level of commercial application; the satellite's visible light channel image quality is good, and the signal-to-noise ratio is higher than the design requirements. Shortly after the operation of Star A, it was discovered that water vapor had polluted the infrared detector. After 39 days of normal operation, the satellite's attitude control subsystem failed due to loss of control and failed to meet the predetermined working life requirements. The main performance of Star B is the same as that of Star A, but its quality is greatly improved and has achieved practical application results. Due to the anti-pollution design and anti-pollution technical measures adopted, the quality of visible light cloud images received by the ground is clearer than that of the first meteorological satellite, and the quality of infrared images is good, which is comparable to the internationally advanced satellites of the same type at that time. After 165 days of normal operation, the satellite lost control of its attitude due to a sudden failure of the onboard computer. It was later rescued and returned to normal operation. However, the satellite-borne computer is affected by the space environment and works unstable. The satellite works intermittently and does not meet the design life requirements.
(2) FY-1C and FY-1D
The performance of Fengyun-1 C/D satellite has been greatly improved, the detection channel has been increased, and the detection accuracy has been improved for more accurate It provides necessary basic information for medium and long-term weather forecasts and climate predictions, and can play a huge role in disaster monitoring and environmental remote sensing. Many countries in the Americas, Europe and Asia have established data receiving systems compatible with Fengyun 1C and 1D satellites and corresponding data processing and application systems. Fengyun-1 satellite data has become one of the important data for global disaster monitoring and environmental change research. one.
1. FY-1C star
Fengyun-1C star (FY-1C) was launched on May 10, 1999. The satellite has a total mass of 958 kilograms, an orbit height of 870 kilometers, and an inclination angle of 98.8 degrees. The main body of the satellite is cube-shaped, 2.02M long, 2M wide, and 2.215M high. The design life is 2 years. Due to the adoption of a series of effective technical measures, product quality, adaptability to the impact of the space environment and system reliability have been greatly improved. It has been working stably for more than two years and has been in service for an extended period. All backup machines have not yet been put into use.
The stability of Fengyun-1C's on-orbit operation and the accuracy of data acquisition have been widely recognized. In August 2000, the World Meteorological Organization officially listed Fengyun-1C as a world operational polar-orbiting meteorological instrument. A procession of satellites. This is China's first satellite included in the world meteorological operational application series and provides free meteorological data to countries around the world.
At present, the satellite is operating normally and continuously transmits high-definition image data to the ground throughout the day.
(1) The basic mission of the satellite
Send 10 channels of 1.1 km very high-resolution digital cloud maps in real time to meteorological stations around the world twice a day; record and store them abroad. Digital volume cloud images with 4 km resolution in 4 channels in the region are played back to my country’s ground stations in a delayed manner.
(2) Satellite orbit parameters
Orbital characteristics: sun-synchronous orbit
Orbital altitude: 863 km
Inclination angle: 98.79°
Orbital eccentricity: 0.00188
Orbital return period: 10.61 days
Local time at the descending node of the orbit: 8∶34 (1999-07-04)
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The drift amount of local time at the orbit descending node after 2 years: 23min15.84s (indicator is <1h)
(3) Satellite body
The satellite weighs 950 kg, average The power consumption is 256 W, the shape is 1.42 m × 1.42 m × 1.2 m hexahedron, and the total length of the solar panel is 10.556 m after it is extended.
The satellite is composed of 10 subsystems including remote sensing (including space particle detectors), image transmission, DCDS, antenna, structure, thermal control, power supply, attitude control, measurement and control and on-board computer. The first four subsystems are the payload of the satellite, and the last six subsystems are the satellite platform service subsystems.
①10-channel scanning radiometer
The main detectors of the satellite are two 10-channel scanning radiometers that serve as backups for each other. The on-orbit measured results of its main technical performance are as shown in Table 1. 2 shown. Among them, the visible light and near-infrared channel calibration accuracy reaches the index requirement of 10%; the infrared radiation calibration accuracy reaches the 1K index requirement; the spatial resolution HRPT image is better than 1.1km, and the GDPT image is better than 4km.
②Space particle component detector
The detection results of the space particle component detector are shown in Table 3.
③Image transmission characteristics
High-resolution image transmission (CHRPT): frequency 1700MHz, code rate 1.3308Mb/s, can be received in real time anywhere in the world.
Delayed image transmission (DPT): The frequency is 1708 MHz, the code rate is 1.3308Mb/s, and it is divided into two types: GDPT and LDPT. GDPT is used to store global data with 4 channels (channels 1, 2, 4, 5) and 4 km resolution uniformity on the satellite. 300 minutes of observation data can be stored on the satellite. It can be played back when the satellite passes through and can be obtained every day. A global profile.
④ Satellite attitude control performance The FY-1C satellite's three-axis attitude control system with stable ground orientation adopts an offset momentum wheel plus magnetic precession, nutation control and magnetic smooth unloading scheme. Three infrared horizons are the main attitude measurement instruments, and two computers form the attitude control central controller. Its on-orbit test results are shown in Table 4.
⑤Satellite life and cloud image data availability
The satellite design life is 2 years; the cloud image data availability rate during the life period is greater than 97.5%.
2. FY-1D satellite
The Fengyun-1D satellite has been designed since 2000, based on the successful experience and technology of the Fengyun-1C satellite. , 14 improvements were made to its technical status to further improve its stability. The satellite has a mass of 950 kilograms and was launched from the Taiyuan Satellite Launch Center on May 15, 2005 using a Long March 4B rocket.
Note: According to foreign media reports, China destroyed the Fengyun-1C star on January 11, 2007. The Chinese Ministry of Foreign Affairs confirmed it at a regular press conference on the 23rd.
The composition of artificial satellites can basically be divided into two parts: "satellite body" and "payload". The payload is the instrument used by the satellite to perform experiments or services, and the satellite itself is the vehicle that maintains the operation of the payload. The purpose of a satellite depends on the payload it carries.
The advantage of artificial satellites is that they can process a large amount of data at the same time and transmit it to any corner of the world. Using three satellites can cover all parts of the world. According to the purpose of use, artificial satellites can be roughly divided into the following categories:
Scientific satellites: satellites sent into space orbit to conduct experiments or tests on atmospheric physics, astrophysics, geophysics, etc., such as China Satellite 1, Hubble, etc.
Communication satellite: a satellite that serves as a telecommunications relay station, such as AsiaSat-1.
Military satellite: a satellite used for military photography and reconnaissance.
Meteorological satellite: a satellite that captures cloud maps and related meteorological data.
Resource satellite: A satellite that captures images of the surface or deep structures for earth resource exploration.
Interstellar satellite: a satellite that can sail to other planets for detection and photography. It is generally called a "planetary probe", such as Pioneer and Mars.