The use of meteorological satellites

Fengyun-1 satellite is the first generation of quasi-polar sun-synchronous orbit meteorological satellite developed in China, and it is also the first transmission polar orbit remote sensing satellite in China. Its main task is to obtain atmospheric, cloud, land and ocean data at home and abroad, and collect relevant data for weather forecast, climate forecast, natural disasters and global environmental monitoring. Satellites can send real-time meteorological cloud pictures to cloud picture receiving stations all over the world, and can also detect ocean water color and conduct remote sensing research on ocean temperature; The satellite carries a space particle composition monitor, which can study the space environment. At present, * * * has launched four models, code-named FY- 1A, FY- 1B, FY- 1C and FY- 1d respectively.

General situation of development

The FY- 1 satellite formed an overall preliminary scheme in 1977, and the development work was in full swing. 1985 10, FY- 1 satellite project was included in the key project of satellite model development during the seventh five-year plan period.

(1) FY- 1A and FY- 1B

Two experimental satellites, A and B, were launched on September 7, 1988 and September 3, 1990, respectively, which verified the satellite scheme and many new technologies adopted. The performance and main functions of the spaceborne 5-channel visible and infrared scanning radiometer are equivalent to those of the third generation polar-orbiting meteorological satellite in the United States, and close to the level of business application. The image quality of satellite visible light channel is good, and the signal-to-noise ratio is higher than the design requirements. Shortly after the operation of a star, it was found that water vapor polluted the infrared detector. After 39 days of normal operation, the satellite failed because the attitude control subsystem was out of control and failed to meet the expected working life requirements. The main performance of star B is the same as that of star A, but its quality has been greatly improved, and the practical application effect has been achieved. Due to the anti-pollution design and anti-pollution technical measures, the quality of visible light cloud images received on the ground is clearer than that of the first meteorological satellite, and the quality of infrared images is good, which is equivalent to that of similar international advanced satellites at that time. After normal operation 165 days, the attitude of the satellite was out of control due to the sudden failure of the onboard computer, and it resumed normal work after rescue. However, due to the influence of space environment, the on-board computer is unstable, and the satellite works intermittently, which can not meet the design life requirements.

(2) FY- 1c and FY- 1d

The performance of Fengyun-1 C/D satellite has been greatly improved, with more detection channels and higher detection accuracy. It provides necessary basic data for more accurate medium and long-term weather forecast and climate forecast, and can play a great role in disaster monitoring and environmental remote sensing. Many countries in America, Europe and Asia have established data receiving systems and corresponding data processing and application systems for receiving Fengyun 1C and 1D satellites. Fengyun-1 satellite data has become one of the important data for global disaster monitoring and environmental change research.

1, FY- 1C star

Fengyun-1 C (FY- 1C) was launched on May 1999. The satellite has a total mass of 958kg, an orbital height of 870km and an inclination of 98.8 degrees. The main body of the satellite is a cube with a length of 2.02M, a width of 2m, a height of 2.215m and a design life of 2 years. Thanks to a series of effective technical measures, product quality, adaptability to 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 stand-alone machines have not yet been put into use.

The stability of Fengyun-1 C satellite in orbit and the accuracy of data obtained have been widely recognized. In August 2000, the World Meteorological Organization officially listed Fengyun-1 C satellite as a world operational polar-orbiting meteorological satellite. This is the first satellite in China to be included in the world meteorological service application series, providing meteorological data for all countries in the world free of charge.

At present, the satellite is running normally, sending high-definition image data to the ground all day.

(1) Basic tasks of satellites

Send 10 digital cloud images with the resolution of 1. 1 km to weather stations around the world twice a day; Record and store four foreign digital cloud images with 4 km resolution, and delay playback to China ground station.

(2) Satellite orbit parameters

Orbital characteristics: Sun synchronous orbit

Track height: 863 km

Track inclination: 98.79 degrees.

Track eccentricity: 0.00 188

Orbital regression period: 10.6 1 day.

Local time of the descending node of the track: 8 ∶ 34 (1999-07-04).

2 years later, the local time drift of the descending node of orbit: 23 minutes 15.84 seconds (index

(3) Satellite body

The satellite weighs 950 kg, the average power consumption is 256 W, the shape is1.42m×1.2m hexahedron, and the total length of solar panels after stretching is10.556m..

The satellite consists of remote sensing (including space particle detector), image transmission, DCDS, antenna, structure, thermal control, power supply, attitude control, measurement and control and on-board computer 10 subsystem. The first four subsystems are satellite payloads, and the last six subsystems are satellite platform service subsystems.

① 10 channel scanning radiometer

The main detectors of the satellite are two backup 10 channel scanning radiometers, and the on-orbit measurement results of their main technical performance are shown in table 1 and table 2. Among them, the calibration accuracy of visible light and near infrared channels reaches the index requirement of 10%; The calibration accuracy of infrared radiation meets the requirements of 1K; The spatial resolution of HRPT image is better than 1. 1km, and that of GDPT image is better than 4km.

② Space particle composition detector

The detection results of the space particle composition detector are shown in Table 3.

③ Image transmission characteristics

High resolution image transmission (CHRPT): The frequency is 1700MHz, and the code rate is L.3308 MB/s, which can be received in real time anywhere in the world.

Delayed image transmission (DPT): The frequency is 1708 MHz and the code rate is 1.3308Mb/s/s, which can be divided into GDPT and LDPT. GDPT is used for airborne storage of global data, with 4 channels (channel 1, 2, 4, 5) and 4 km resolution. On-board storage of 300-minute observation data can be carried out, and global data can be obtained once a day when the satellite transits.

④ Attitude control performance of FY-1C satellite. The attitude control system of three-axis stable orientation to the ground adopts biased momentum wheel plus magnetic precession, nutation control and magnetic smooth unloading scheme. Three infrared horizon meters are the main attitude measuring instruments, and two computers constitute the central controller of attitude control. The on-orbit test results are shown in Table 4.

⑤ Satellite lifetime and availability of cloud image data.

The design life of the satellite is 2 years; The availability rate of cloud image data is greater than 97.5% in the service period.

2.FY- 1d star

The prototype design of FY-1 1 D satellite began in 2000. Based on the successful experience and technology of Fengyun-1 C satellite, its technical status was improved by 14 to further improve its stability. The satellite, with a mass of 950 kilograms, was launched by the Long March 4 B rocket at Taiyuan Satellite Launch Center on May 6, 2005.

Note: According to foreign media reports, China destroyed Fengyun-1 C star on June 5438+1October 65438+1October 2007, which was confirmed by the Ministry of Foreign Affairs of China at a regular press conference on the 23rd.

The composition of artificial satellite can be basically divided into two parts: satellite body and payload. Payload is an instrument used by satellites to do experiments or services, and satellites themselves are vehicles to maintain the operation of payloads. The use of a satellite depends on the payload it carries.

The advantage of artificial satellite is that it 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 for atmospheric physics, astrophysics and geophysics experiments or tests, such as China Satellite-1 and Hubble.

Communication satellite: A satellite used as a telecommunication relay station, such as Yahweh I..

Military satellite: A satellite used for military photography and reconnaissance.

Meteorological satellite: A satellite that photographs clouds and related meteorological data.

Resource satellite: a satellite that takes images of the earth's surface or depth for the exploration of earth resources.

Interstellar satellite: a satellite that can sail to other planets for exploration and photography. It is generally called a "planetary probe", such as Pioneer and Mars.