What achievements has China made in space technology?

1. Launch a series of recoverable remote sensing satellites. The first and second satellites launched by China in the early 1970s represent the initial level of China's space activities. Then, China astronauts began to move towards a higher goal, and developed a recoverable remote sensing satellite and its large launch vehicle, which was 10 times heavier than satellites I and II, and the technology was more complicated. 1975165438+1October 26th, China successfully launched a recoverable remote sensing satellite, which is another major breakthrough in the history of China's space technology development. By1August 9, 1992, China had launched 13 recoverable remote sensing satellites, with a success rate of 100%.

It is not easy to develop a recoverable remote sensing satellite, and a series of complex technical problems need to be solved. As for the launch vehicle, it is necessary to develop a large rocket with greater thrust and precise guidance to ensure that the satellite can be accurately sent into the scheduled orbit. "Long March II" is a two-stage launch vehicle specially used to launch heavy satellites into near-earth orbit in China, and it is used to launch recoverable remote sensing satellites. For example, on August 6, 1992,/kloc-0, China's second-generation recoverable scientific experimental satellite was launched by the Long March II carrier rocket. Including the satellite, it is about 38 meters long and has a take-off mass of 232 tons. As far as satellites are concerned, it is necessary to develop space remote sensing instruments with high technical requirements in order to complete the earth observation task; The satellite must maintain a high-precision attitude in operation and work accurately according to a predetermined program. In order to make the satellite return to the ground safely from orbit, in addition to solving the technical problems of general satellites, we must first break through the technical difficulties such as satellite attitude adjustment, braking, heat protection, soft landing, positioning and search. For example, it is necessary to brake (reverse thrust) the rocket engine to make the satellite have the ability to leave the original orbit; It is necessary to solve the aerodynamic and thermal problems of the re-entry of the recovery cabin into the atmosphere and develop high-temperature resistant materials; There should be a safe and reliable recycling system, and a recycling team with open space should be deployed in a certain area; It is necessary to accurately measure and track the satellite in a long running arc, and control and manage the program-controlled data bound to the satellite according to the measured orbit parameters. Therefore, a ground monitoring and control network with wider scope and more functions should be established.

There are three main uses of recoverable satellites: one is as a space platform for observing the earth. Because the satellite flies high, "sees" far and has a large angle of view, it can repeatedly and widely observe the ground and the atmosphere, obtain remote sensing data, bring them back to the ground for processing and analysis, and provide them to all departments of the national economy for use. Second, as a microgravity test platform, it conducts various scientific experiments in space and produces materials and articles that are difficult to obtain on the ground. The experimental results show that the microgravity experimental conditions of the recoverable satellite are better than those of the space shuttle. China's recoverable satellites have provided carrier services for domestic and foreign users many times, and all of them have achieved satisfactory results. Thirdly, satellite return technology is a necessary technology to develop manned space flight, because astronauts always have to return to the ground. Developing satellite return technology will lay a technical foundation for manned space flight. Therefore, recoverable satellites play an important role in all kinds of spacecraft in the world. At present, only the United States, the former Soviet Union and China have mastered the satellite recycling technology.

2. Launch a series of geosynchronous communication satellites. Entering the geostationary orbit and launching geosynchronous communication satellites is another major goal set by China's space science and technology workers. To put a communication satellite into a geostationary orbit at a height of 35,860 kilometers, we must first develop a new type of launch vehicle with a much larger carrying capacity than the existing rockets. Long March III is a launch vehicle used by China to launch a communication satellite into geostationary orbit. Its first and second stages use the achievements of China long-range liquid fuel rocket, and the third stage uses high-energy low-temperature fuel, which is a new technical field. Due to a series of complex technical problems caused by cryogenic fuel, the development of the third stage cryogenic rocket has become the key to the whole satellite communication project. Especially the cryogenic rocket engine, which took 7 years to tackle key problems, passed 100 test runs and went through a difficult course, and finally succeeded. 1In August 1983, the "Long March 3" rocket was successfully tested in the whole system, which created the most important conditions for launching geostationary orbit satellites.

Dongfanghong-2 satellite is the first experimental communication satellite in China. Because of the long working life of satellites and the extremely high requirements for satellite positioning and orientation, it is very difficult to develop instruments for various systems on board. Spaceborne apogee solid rocket engine requires high reliability. After several years of technical research, China scientific and technological personnel have made a successful breakthrough. 1983, the "Dongfanghong II" satellite entered the final assembly test stage.

As the rocket, satellite and launch site facilities of satellite communication engineering are newly developed, in order to test the coordination of the three systems,1984,65438+China first launched an experimental satellite on129 October, and entered an elliptical orbit with an apogee of 6,480 kilometers, and carried out technical tests such as communication, broadcasting and television transmission, and achieved important results.

1On April 8th, 984, cz-3 launched China's first experimental communication satellite into a large elliptical transition orbit, and the apogee solid rocket engine successfully launched the satellite into a quasi-stationary orbit. In April of 16, that is, from the date of launch, it took only eight days to successfully locate the experimental communication satellite over the equator of east longitude 125, indicating that the satellite measurement and control technology in China has reached a quite high level. After the satellite was fixed, the ground communication stations successfully carried out communication, broadcasting and television transmission experiments by using the satellite. Experiments show that satellite broadcast images are clear, rich in color and good in sound quality. The development and launch of the experimental communication satellite, with its large scale, complex technology and strict organization, is unprecedented in China's space history, marking a new leap in China's space technology, making China one of the few countries in the world that can independently launch synchronous fixed-point satellites and master advanced cryogenic rocket technology. 1984 from April 8 to the end of the 20th century, cz-3 successfully put six experimental and practical communication satellites into geosynchronous orbit, including the world-famous "Asia 1" communication satellite. In the only geostationary orbit in outer space, China's satellites occupy their proper orbital position, which is the pride of the Chinese nation. The launch of the geosynchronous communication satellite in China meets the needs of TV, radio, telephone, fax and other communication services scheduled by the Ministry of Radio, Film and Television, the Ministry of Water and Electricity, Xinhua News Agency and the Communications Department of the General Staff Department. At present, the beam of China satellite transponder has covered the whole country. In addition to two CCTV programs and two educational TV programs, a set of local TV programs has been set up for Xinjiang, Yunnan, Guizhou and Tibet. To this end, there are 20,000 TV receiving stations with a diameter of 3-6 meters. In addition, 30 china national radio programs and satellite communication lines dedicated to the People's Bank of China have been opened.

The Long March 4 rocket launched a meteorological satellite. "Long March 4" is a three-stage launch vehicle with multi-function launch capability developed by China. Since1September 1988, Long March 4 has successfully put two Fengyun meteorological satellites into orbit. These are two sun-synchronous orbits passing through the polar regions.

4. "Long March II" bundled launch vehicle was put into international commercial service. China successfully developed the Long March II rocket with high thrust. It takes the first-stage rocket of Long March II as the core stage, bundles four small boosters, increases the first-stage thrust, and can send 9.2 tons of payload into low orbit. It is the rocket with the largest carrying capacity in China at present, and it is also one of the large commercial rockets in the world. Its takeoff mass is 460 tons and takeoff thrust is 600 tons. 1992 August 14 At 7: 00 a.m., under the eyes of the public, the "Long March II" E-rocket was launched in xichang satellite launch center, China, successfully putting the large-tonnage and high-capacity new-generation Australian satellite "Aarseth B 1" made by Hughes Company of the United States into the scheduled orbit, marking that China has the ability to launch heavy satellites and officially entered the international commercial service market.

The Long March II bundled rocket also has a strong potential launch capability. It is equipped with a domestic solid top rocket, which can directly send a 3.37-ton satellite into a geosynchronous transfer orbit 36,000 kilometers above the ground, and is very suitable for launching a heavyweight communication satellite, Austar. If it is equipped with a hydrogen-oxygen top rocket, it can directly send a 4.8-ton satellite into geosynchronous transfer orbit, and its carrying capacity is 3.2 times that of the "Long March III" rocket, which can meet the launch service demand of a larger heavyweight international communication satellite.

The "Long March II" bundled rocket can also launch a group of small low-orbit communication satellites, which can launch 7 to 9 small communication satellites at a time. According to experts' analysis, the satellite communication system consisting of nearly 100 earth-orbiting satellites can be launched to international users within two years, so it has broad development prospects in the international market. China's launch service is gradually recognized and praised by the international space technology, commerce, insurance and investment circles.