Brief introduction of satellite

The first satellite launched by all countries in the world

1, former Soviet Union: 1957 10 10 On October 4th, the world's first artificial earth satellite was successfully launched by the former Soviet Union. The satellite runs at an altitude of 900 kilometers from the ground; It takes 1 hour and 35 minutes to make a full revolution, and the inclination angle between its orbit and the equatorial plane is 65 degrees. It is a sphere with a diameter of 58 cm and a weight of 83.6 kg. Built-in two radio transmitters that continuously transmit radio signals. The frequencies are 20.005 MHz and 40.002 MHz respectively (the wavelengths are about 15 and 7.5 meters respectively). These signals are in the form of telegraph signals, each lasting about 0.3 seconds. The interval is the same as this. The successful launch of the first man-made earth satellite in the former Soviet Union opened the prelude for mankind to March into space, which greatly stimulated the enthusiasm of all countries in the world to develop and launch satellites.

2. United States: The United States successfully launched the first Explorer-1 artificial satellite in 1958 1 year1October. The star weighs 8.22kg, has a cylindrical cone top, is 203.2cm high, and has a diameter of 15.2cm. It orbits the earth in an elliptical orbit, with a perigee of 360.4km, an apogee of 253 1km, an inclination of 33.34 "and an operating period of114.

France: France/KLOC-0 successfully launched its first "experimental satellite"-1(A-L) on October 26th. The satellite weighs about 42kg, with an operating period of 108.6 1min, an elliptical orbit, a perigee of 526.24km, an apogee of 1808.85km and an orbital inclination of 34. 24"。 The launch vehicle for launching A/KOOC-0/satellite is a "Diamond, tA three-stage rocket", with a total length of/KOOC-0/8.7m, a diameter of/KOOC-0/.4m and a takeoff weight of about/KOOC-0/8t.

4. Japan: Japan successfully launched its first artificial satellite "Otsuka" in February 1970. The satellite weighs about 9.4 kilograms, with an orbital inclination of 3 1.07 ",a perigee of 339 kilometers, an apogee of 5 138 kilometers, and an operating period of 144.2 minutes. The launch vehicle for launching Dayu satellite is Landa -45 four-stage solid rocket, with a total length of16.5m, a diameter of 0.74m and a takeoff weight of 9.4t.. The first stage consists of a main engine and two boosters with thrust of 37 tons and 26 tons respectively; Second stage thrust 1 1.8 tons; The third and fourth thrust are 6.5 tons and 1 ton respectively.

5. China: 1 970 On April 24th, China's first artificial earth satellite "Dongfanghong"1was successfully launched by the Long March-1 carrier rocket. The satellite has a diameter of about 1m and a weight of 173kg. Its orbit is 439 kilometers from the nearest point of the earth and 2384 kilometers from the farthest point. The angle between the orbital plane and the equatorial plane of the earth is 68.5 degrees, and it takes 1 14 minutes to circle the earth. The satellite plays the music "Dongfanghong" at a frequency of 20009 megacycles. The long-range rocket for launching the "Dongfanghong" satellite/KOOC-0/is a "Long March"/KOOC-0/three-stage launch vehicle with a total length of 2,945 meters, a diameter of 2.25 meters, a takeoff weight of 8/KOOC-0/.6 tons and a launch thrust of/KOOC-0//KOOC-0/2 tons. The launch of "Dongfanghong" 1 fulfilled Mao Zedong's call of "We also want to build satellites". China is a star of science and an outstanding contribution made by the working class, the People's Liberation Army and intellectuals in China to the motherland.

6. Britain: Britain successfully launched its first artificial satellite "Prospero" on1October 28th, 197 1, with a weight of about 66kg, an orbital inclination of 82. 1 ",a perigee of 537km and an apogee of1. The operation period is 105.6 minutes. The launch site is located in Woomera rocket launch site in Australia, and the launch vehicle is the British Black Arrow launch vehicle. The main task is to test various new technological inventions, such as testing a new telemetry system and solar cells. It also carries a meteor detector to measure the density of this cosmic dust high-speed particle in the upper atmosphere of the earth. .

7. Others: In addition to the above countries, Canada, Italy, Australia, Germany, the Netherlands, Spain, India and Indonesia are also preparing to launch satellites by themselves or have commissioned other countries to launch satellites.

China's current mainstream satellites

1, Dongfanghong-4 platform/Xinnuo-2 satellite

Xinnuo-2 satellite mainly serves communication and broadcasting users in Chinese mainland, Hong Kong, Macao and Taiwan. The satellite adopts the public platform of a new generation of large-scale geostationary orbit satellites being developed in China, namely the Dongfanghong-4 satellite platform, and carries 22 Ku-band high-power transponders. At the end of the satellite life, the output power is 10500W, the launch weight is 5 100kg (Dongfanghong-3 is a medium-capacity communication satellite, which can carry 200 kg payload, and the whole satellite power is 1800 W, which can carry 24-way lieutenant colonel power transponders), and the design life is 15 years. Launched by xichang satellite launch center on the Long March CZ-3B carrier rocket, the whole satellite index and capability reached the international advanced level.

The platform is composed of power supply, measurement and control, data management, attitude and orbit control, propulsion, structure and mechanism, thermal control and other subsystems, with a full three-axis stable control mode. The total output power of the platform is 8000- 10000 watts, which can be extended to more than 10000 watts and can provide about 6000-8000 watts for the payload. The platform can carry 600-800 kilograms of payload, and the maximum launching weight of the whole satellite can reach 5200 kilograms. It can be launched by launch vehicles such as Long March 3B, Ariane and Proton. The design life of the platform is 15 years.

2. Beidou Navigation Test Satellite (Beidou)

"Beidou Navigation Test Satellite" was developed by China Association for Science and Technology, and the first generation satellite navigation and positioning system-"Beidou Navigation System" will be established by itself.

Beidou Navigation System is a regional navigation system that provides all-weather and all-weather satellite navigation information. After the system is completed, it will mainly provide navigation services for highway transportation, railway transportation, offshore operations and other fields, and will play a positive role in promoting China's national economic construction. The first successful launch of Beidou Navigation Test Satellite laid the foundation for the construction of Beidou Navigation System.

The launch of Beidou Navigation Test Satellite uses the Long March 3A carrier rocket. This launch is the 63rd flight of China Long March series launch vehicles.

3. ZTE 22

"Zhongxing-22" is a practical geosynchronous communication satellite and the follow-up star of "Dongfanghong-3". The satellite, with a mass of 2.3 tons and a designed service life of 8 years, is mainly used for ground communication services and operated by China Communication Broadcasting Satellite Company.

It is understood that after the satellite enters the transfer orbit, it will be fixed above the equator at 98 degrees east longitude under the tracking control of the An Satellite Measurement and Control Center and the space ocean survey ship.

4. Fengyun-2 (FY-2)

Fengyun-2 satellite is a cylinder with a diameter of 2. 1m and a height of1.6m. Including the antenna, the total height of the satellite is 3. 1m and it weighs about 600kg. The attitude and spin of the satellite are stable, the spin speed is 100 1 rpm, and the design life of the satellite is 3 years.

The satellite is equipped with multi-channel scanning radiometer and cloud image forwarding, which can obtain visible light cloud images, day and night infrared and water vapor cloud images. Broadcast and develop wide digital images, low-resolution cloud images and S-band weather maps: obtain observation data from meteorological, marine and hydrological data collection platforms; Collect space environmental monitoring data. The satellite works over the equator of east longitude105, and its position keeping accuracy is 0.5 from east to west and 0/from north to south.

Fengyun-2 satellite was jointly developed by China Association for Science and Technology and Shanghai Space Administration. CAST is responsible for satellite control, propulsion, forwarding, antenna, measurement and control and some structural subsystems. 1At 20: 00 on June 1997, Fengyun-2 satellite was launched by cz-3. Under the measurement and control management of satellite ground measurement and control station and Wangyuan No.2 survey ship, the satellite has completed the separation of satellite and arrow, satellite rotation and so on.

Fengyun-2 satellite inherited the spin stabilization mode of Dongfanghong-2 satellite and adopted some new technologies such as multi-channel scanning radiometer, three-channel microwave transmission and nutation control. The main performance indexes of this satellite have reached the level of similar geostationary meteorological satellites in the early 1990s.

Fengyun-2 meteorological satellite is a combination of space technology, remote sensing technology, communication technology and computer technology. It provides directional coverage and continuous remote sensing of the distribution of the earth's surface and atmosphere, and has the advantages of strong real-time, high time resolution, objectivity and vividness.

5. Fengyun-1

FY- 1 is a series of polar-orbiting meteorological satellites in China. Three satellites, FY- 1A, 1B and 1C, were launched.

FY- 1A and 1B were launched in September 1988 and September 1990 respectively. They are experimental meteorological satellites. The remote sensors carried by these two satellites have good imaging performance, and the experimental data and operational experience obtained provide meaningful data for the development and management of subsequent satellites.

FY-/KOOC-0/C was launched on/KOOC-0/May, 1999/KOOC-0/0, and operated in a sun-synchronous polar orbit of 90/KOOC-0/km, with a design life of 3 years. The main remote sensor of the satellite is a very high resolution visible-infrared scanner. The number of channels is increased from 5 FY- 1A/B to 10, and the resolution is 1 100 meters.

Remote sensing data obtained by satellites are mainly used for weather forecasting and environmental monitoring, such as vegetation, ice and snow cover, floods and forest fires.

6. Dongfanghong-1 Satellite (DFH- 1)

On April 24th, 0970, at 2 1 35, the Dongfanghong-1 satellite (DFH- 1) was successfully launched at the Dongfeng Range in Jiuquan, Gansu Province, which opened a new era in China's space history and made China the fifth country in the world to independently develop and launch artificial earth satellites after the Soviet Union, the United States, France and Japan.

The satellite adopts spin stabilization mode. The electronic tone generator is the core part of the whole satellite, which repeatedly plays the first eight bars of the music "Dongfanghong" to the ground through the 20MHz short wave transmission system.

7. Dongfanghong II

Dongfanghong-2 (DFH-2) was successfully launched for the first time on April 8, 1984. * * * Developed and launched three Dongfanghong-2 satellites. The development and launch of every three satellites took nearly 1970 years. The successful launch of "Dongfanghong II" started the history of satellite communication with our own communication satellite.

8. Dongfanghong II A (Dongfanghong -2A)

Dongfanghong-2 A is a modified satellite of Dongfanghong-2 satellite, and its pre-research work began at 1980.

The first Dongfanghong -2A satellite was successfully launched on1March 7th, 988. Soon after, the second and third satellites were successfully launched. They are fixed at 87.5 east longitude, 1 10.5 and 98 respectively. The fourth star failed to enter the scheduled orbit due to the third stage failure of the launch vehicle.

Over the past few years, the three satellites have worked well, reaching the design and use targets, and played a great role in China's TV transmission, satellite communication and foreign broadcasting.

9. Dongfanghong-3 satellite

Dongfanghong-3 satellite is a new generation communication satellite in China, which is mainly used for TV transmission, telephone, telegraph, fax, broadcasting and data transmission.

There are 24 C-band transponders on board, six of which are medium-power transponders. Other 18 channels are low-power repeaters. Service areas include: Chinese mainland, Hainan, Taiwan Province Province and offshore islands. Eirp≥37 dbw for medium power channel and 33.5 dbw for low power channel. During the shadow period, all transponders are working. The output power of the satellite at the end of its life is ≥ 1700W: the allowable payload mass of the satellite reaches 170kg.

The satellite works in the geostationary orbit, and its position accuracy is 0. 1 in the east-west and north-south directions. The antenna pointing error is 0. 15 in pitch and roll directions and 0.5 in yaw direction. The working life of the satellite is 8 years, and the single satellite reliability at the end of its life is 0.66.

Satellites can be docked with various launch vehicles (ZC-3A, Ariane -4, etc.). ), the satellite platform adopts the general platform of geostationary orbit satellite (basic type), which can be used for a variety of medium-sized applications.

Dongfanghong-3 satellite has the advanced level (medium capacity) of similar satellites in the world.

Shi Jian-1 Satellite (SJ- 1)

Shi Jian-1 satellite is a scientific exploration and technical test satellite. /kloc-0 was launched into orbit on March 3, 977, and the satellite's orbital life ended on May1/kloc-0. The ship's long-term telemetry system has been clearly sending telemetry information back to the ground.

Shijian-1 is a spin-stabilized satellite, and its successful launch took less than 10 months.

1 1, resource-1 satellite (ZY- 1)

ZY- 1 is the first transmission earth resource satellite in China. 1988, the governments of China and Brazil signed a protocol and decided to jointly develop China-Brazil Earth Resources Satellite (CBERS) on the basis of Resource-1 satellite.

Resources 1 are mainly used to monitor the change of land resources; Estimate forest stock and crop growth, quickly identify the estimated losses of floods and earthquakes, and put forward countermeasures; Provide dynamic information on coastal economic development, beach utilization, aquaculture and environmental pollution; At the same time, explore underground resources, so that they can be rationally developed and utilized. Resource-1 satellite weighs 1450 kg and has a life span of two years. The orbit is synchronized with the sun, with an altitude of 778 kilometers and an inclination of 98.5 degrees. The orbital period is 100.26min, and the regression period is 26 days. The local time of the downlink node is 1 1:20. The satellite is a cuboid with a single-wing solar panel. The satellite adopts three-axis stable attitude control mode and S-band and ultrashort wave measurement and control system.

The resource-1 satellite was successfully launched by the Long March 4B carrier rocket in1June+1April/October, 1999.

12, China-Brazil earth resources satellite

China-Pakistan Earth Resources Satellite (CBERS) was jointly developed by China and Pakistan on the basis of the original scheme of China Resources 1. It is also stipulated that after the China-Pakistan Earth Resources Satellite is put into operation, it will be jointly used by the two countries.

Resource-1 satellite is the first generation satellite to transmit earth resources in China. The three kinds of remote sensing cameras on board can observe the earth day and night, and the collected data are transmitted back to the earth ground receiving station by high-rate data transmission system, and processed into pictures needed by various users.

Because of its multi-spectral observation, wide range of earth observation and fast data collection, it is especially beneficial to the dynamic and rapid observation of surface information.

Because the satellite has the characteristics of multi-spectral observation, wide observation range of the earth, fast data acquisition and macroscopic intuition, it is especially beneficial to dynamically and quickly observe the earth's ground information.

The main uses of the satellite in China's national economy are: its image products can be used to monitor the changes of land resources and update the national utilization map every year; Calculate the cultivated land area, estimate the forest stock, crop growth, yield and grassland stock and their annual changes; Monitoring natural and man-made disasters; Quickly identify damages such as floods, earthquakes, forest fires and sandstorms, estimate losses and put forward countermeasures; Provide dynamic information on coastal economic development, beach utilization, aquaculture and environmental pollution; At the same time, explore underground resources, delineate resource areas such as gold, oil, coal and building materials, and supervise the rational development of resources.

GPS is the abbreviation of English Global Positioning System, which means Global Positioning System. It is a global, all-weather, all-day and high-precision navigation and positioning and time transfer system. These 24 satellites are located on six orbital planes with an inclination of 55 degrees, with an altitude of 20 182km and a period of nearly 12 hours. Satellites use two L-band frequencies to transmit one-way ranging signals, and code division multiple access is used to distinguish different satellites. This is a dual-use system, providing two levels of services. In order to improve the accuracy, availability and integrity of navigation, various countries have developed various differential systems, which can fully meet the general civil needs. At the same time, SA scrambling is gradually cancelled, and the civil accuracy is greatly improved. The working principle of GPS is not complicated. Simply put, it is to use the relevant signals received by satellites to locate with some basic principles of geometry and physics that we are familiar with.

As we all know, GPS system is the national defense navigation satellite system of the United States, and it is also used for civil navigation. GLONASS in Russia, similar to GPS, consists of a space part, a ground monitoring part and a user receiver part, all of which are composed of 24 satellites with a height of about 20,000 kilometers. GPS is distributed on six orbital planes, each with four satellites, GLONASS is distributed on three orbital planes, and each with eight satellites. The distribution of satellites makes it possible to observe more than four satellites anywhere in the world at any time, thus obtaining high-precision three-dimensional positioning data. This provides a global navigation capability that is continuous in time. The positioning accuracy of GPS can reach 15m, and the speed measurement accuracy is 0.1m/s; GLONASS navigation and positioning accuracy is low, about 30- 100 meters, and speed measurement accuracy is 0. 15 meters per second. These two systems provide all-weather, continuous, real-time, high-precision three-dimensional position, three-dimensional speed and accurate time for planes, ships, tanks, ground vehicles, infantry, missiles and space shuttles all over the world, so they have extremely high military value and civil prospects.

The GPS system includes three parts: the space part-GPS satellite constellation; Ground control part-ground monitoring system; User equipment part --GPS signal receiver.

1, GPS satellite constellation

A GPS satellite constellation is composed of 2 1 working satellites and 3 in-orbit standby satellites, and it is called (2 1+3)GPS constellation. These 24 satellites are evenly distributed on six orbital planes, with an orbital inclination of 55 degrees, and the orbital planes are separated by 60 degrees, that is, the orbital right ascension is separated by 60 degrees. The elevation distance between satellites in each orbital plane is 90 degrees, and the satellites in one orbital plane are 30 degrees ahead of the corresponding satellites in the adjacent orbital plane in the west.

At an altitude of 20,000 kilometers, for stars, when the earth rotates once, they will make a circle around the earth, that is, the time to make a circle around the earth is 12 sidereal time. In this way, for ground observers, they will see the same GPS satellite four minutes in advance every day. The number of satellites above the horizon varies with time and place. At least 4 satellites can be seen, and at most 1 1 satellite can be seen. When using GPS signals for navigation and positioning, in order to determine the three-dimensional coordinates of the site, four GPS satellites must be observed, which is called positioning constellation. The geometric position distribution of these four satellites in the observation process has certain influence on the positioning accuracy. At a certain time in a certain place, even the exact point coordinates can't be measured. This time period is called "gap period". But this time difference is very short, which does not affect the all-weather, high-precision, continuous and real-time navigation and positioning measurement in most parts of the world. The number of GPS working satellites is basically the same as that of test satellites.

2. Ground monitoring system

For navigation and positioning, GPS satellite is a dynamic known point. The position of the constant star is calculated according to the ephemeris transmitted by the satellite, which describes the motion and orbit parameters of the satellite. The ephemeris broadcast by each GPS satellite is provided by the ground monitoring system. Whether all kinds of equipment on the satellite work normally and whether the satellite has been running along the predetermined orbit should be monitored and controlled by the ground equipment. Another important function of the ground monitoring system is to keep all satellites in the same time standard-GPS time system. This requires the ground station to monitor the time of each satellite and find out the clock difference. Then it is sent to the satellite by the ground injection station, and the satellite sends it to the user equipment through the navigation message. The ground monitoring system of GPS working satellite includes a main control station, three injection stations and five monitoring stations.