Use of observation satellitesSpaceborne remote sensorObtaining surface information from space has many advantages, such as wide coverage, long duration, and freedom from airspace and national boundaries. It is widely used in earth resource exploration, military reconnaissance, disaster prevention and mitigation, environmental protection and other fields, and has become an important means of remote sensing information acquisition.
Chinese name
Observation satellite
Classification
Earth observation
Off the ground
The height is generally about 700km
Height
It is hundreds of times higher than the flight altitude of the aircraft
Due to the rapid development of industrial production and the increasing population, human beings havenatural resourcesThe demand for is increasing.However, due to the limitations of natural conditions, extremely rich natural resources are still sleeping in the deep mountains and forests, vast deserts and vast oceans.This urgently requires us to adopt effective methods to survey those resources[1]。useArtificial satelliteTo survey the earth's resources is an effective method.We call this satellite EarthResource satellite。[2-3]
The height of the earth resource satellite from the ground is generally about 700 kilometers, which is hundreds of times higher than the flight height of the aircraft.It only takes 300-500 photos to survey the resources of our country with earth resource satellites, while it takes 500000 to 1 million photos to survey the resources of our country with aircraft.
earthResource satelliteIt is possible to survey the pseudo resources in all regions of the earth without being restricted by natural conditions such as topography.At the same time, the earth resource satellite can also repeatedly survey the same area in different seasons, which is very suitable for observing crops that change with seasons.
In July 1972, the United States launched the first experimental“Earth resource satelliteI ", later renamed" Land I ".This satellite is based on the "Yuyun" meteorological satellite.Its shape is exactly the same as the "rain cloud".After the satellite entered orbit and worked, it obtained a lot of important information;It has found many importantMineral reservesInformation, for example, it is confirmed that there are two Banyan copper mines somewhere in Pakistan;Some geographical parameters have been corrected. For example, the original standard of Takcuo Lake in Gaize County of Tibet in China is 95.8 square kilometers, which should actually be 495.5 square kilometers;The serious pollution of the sea surface of Daifan Bay in Japan and a river in New York State in the United States was found;He also took photos of the capital of China.It was filmedBeijingIt can be clearly seen from the photos of the areathe Imperial Palace、Peking University, East Suburb Airport, etc.[4]
In 1978, the French government decided to develop the SPOT earth resource satellite to investigate natural resources, such as mineral resources, plant resources and crop yields."Sport 1" has been in service since 1986.[5]
When the "Sport" satellite was launched, its mass was 1850 kg, its length was 2 meters, its width was 2 meters, and its height was 4.5 meters. When two solar panels were expanded, their width was 35.6 meters, and their output power was 1800 watts.
Two high-resolution satellites are installed on the "Sport" satellitevideo camera。The focal length of the camera is 1m, and the aperture is f/3.5.They work invisible lightAnd near-infrared band, divided into fourSpectral band: 0.50-0.59 μ m, 0.61-0.68 μ m, 0.79-0.89 μ m and 0.51-0.73 μ m.The ground resolution of the first three bands is 20m, and the ground resolution of the last band is 10m.The "Sport" satellite operates in the sun synchronous orbit, with an orbit height of 832 km and an inclination of 98.7 °.Two cameras work at the same time, which can cover the world within 26 days.[5]
China began to launch a recoverable earth observation satellite in 1977.The satellite has a mass of about 1800 kg, an orbital inclination of 59.5 °, a perigee of 180 km and an apogee of 490 km.The satellite consists of instrument cabin and return ship.A visible ground object camera and a star camera are installed in the instrument cabin.The ground feature camera takes photos of the predetermined areas in China on the track.The star camera takes pictures of the star sky, which is used to analyze theAttitude error。The return cabin is equipped with brake rocket, self collecting system and film box for return.[6]
Military reconnaissance satellite
Camera reconnaissance satellite, equipped with visible light camera or TV camera, can take pictures of targets.In order to find and identify targets,cameraLens and image resolution requirements are very high.This kind of satellite generally operates in the orbit with perigee altitude of 150-280 kilometers. If equippedInfrared cameraAnd multispectral camera, it also has the ability of night reconnaissance and identification of camouflage.Photographic reconnaissance satellites are divided into and transmission types according to the way of sending reconnaissance information back to the ground.The return type is to store the film taken in the recovery cabin and return to the ground. It uses the principle of film imaging. Its advantages are high image resolution, intuitive, easy to identify and analyze, and its disadvantage is that the recovery is not timely, which is easy to delay the fighter.The transmission type uses the photoelectric imaging principle to record the image information on the tape, fly to the control area of the ground receiving station, and then send the image information to the ground for processing and recognition.Its advantage is that the ground receives information quickly, but the image resolution is not high.The United States has launched photographic reconnaissance satellites since February 1959, among which the representative is "Big Bird". It has two functions: film recovery and radio transmission. Its service life is 52-220 days. Its photos can clearly distinguish trains, cars, buildings and pedestrians.[7]
According to different reconnaissance means and tasks, reconnaissance satellites can be divided into photographic reconnaissanceElectronic reconnaissanceandearly warningAnd so on.
photographReconnaissance satellites.The satellite is equipped with various remote sensors such as visible light camera, multispectral camera, multispectral scanner and television camera.According to the different processing methods of photos taken by satellites, there are two types of photo reconnaissance satellites: return type and transmission type.The film taken by the recoverable satellite is sent into the recovery capsule of the satellite through the tunnel and returned to the ground together with the recovery capsule.For example, the "discoverer" photographic reconnaissance satellite uses this method.This method is generally used for visible light photographic reconnaissance.Returnable photo reconnaissance satellite must solve the technology of satellite returning from orbit to the ground.The transmission type photo reconnaissance satellite sends the photos directly back to the ground by radio.Therefore, this kind of reconnaissance satellite transmits information quickly, and can immediately report some active military targets, such as troop mobilization, missile nuclear submarine heading and other information to the ground.This method usually uses TV camera, multispectral camera and multispectral scanner as reconnaissance means.[7]
In order to make the camera on the satellite "see" the ground target as clearly as possible, the operation orbit of the photo reconnaissance satellite is not high, and it is generally about 200 km away from the ground.
Early reconnaissance satellites equipped with visible cameras, such as the "Big Bird" satellite of the United States, have a life span of nearly one year, and the KH-11 satellite has a life span of more than three years.
Photographic reconnaissance satellites have provided many extremely important military information for the Soviet Union and the United States.
Electronic reconnaissance satellite.Electronic reconnaissance satellite is a kind of reconnaissance satellite that uses the radio receiving equipment on the satellite to receive the radio waves sent by the enemy early warning radar and military radio.By analyzing these radio signals, we can know the pulse frequency used by the early warning radar.Important parameters such as pulse width and military radio communication information.In addition, the location of early warning radar and military radio can be determined.[7]
The operation orbit of the electronic reconnaissance satellite is higher than that of the photographic reconnaissance satellite, which is usually about 500 kilometers away from the ground.[7]
The "life" of electronic reconnaissance satellite is very long. As long as the radio receiver and antenna on the satellite do not fail and there is sufficient power supply, the satellite can work day and night, generally for about 5 years.
Early warning satellite.With the development of strategic nuclear weapons, an early warning satellite has emerged.This satellite is a dedicated sentry in geosynchronous orbit.Radio radars and infrared detectors mounted on early warning satellites monitor the enemy day and nightIntercontinental ballistic missileAnd nuclear submarines. Once the enemy's missile takes off, the early-warning satellite can find it within one and a half minutes, and notify the ground command center to take corresponding response measures.[4]
Geodesic satellite
Although human beings have lived on the earth for generations, they have not been able to fully understand the true face of the earth due to various natural conditions.It is very important for economic, scientific and military development to understand the true face of the earth.Geodesic satellite is a kind of satellite developed to understand the true face of the earth.
It can accurately measureGeographical coordinates。Due to the limitation of past measurement means, or for some reasons of confidentialityWorld mapMany of the geographical coordinates are not accurate, and should be corrected by geodesic satellites.
Geodesic satellites can measure thefield of gravityExact distribution of.The accurate data of the earth's gravity field is often used in the calculation of the missile's hit accuracy and the satellite's orbit.
Geodesic satellites can also measure the crustal drift.Crustal drift is often associated withearthquakeTherefore, the measured crustal drift can provide a basis for earthquake prediction.
Before 1975, some countries launched geodetic satellites, and the positioning error of their geographical coordinates was less than 10 meters.The geodesic satellite launched in 1976, using advanced laser ranging technology, can even measure the crustal movement that only drifts 5 cm a year.
Observations of other planets
Announce
edit
There are moon observation satellites, sun observation satellites and so on.
