What is the knowledge about space flight?
China's space industry has developed under the conditions of weak basic industries, relatively backward scientific and technological level, special national conditions and specific historical conditions. China has independently carried out space activities, and in a relatively short period of time, it has embarked on a development path that is suitable for its own national conditions and has its own characteristics, and has made a series of important achievements. In many important technical fields, such as satellite recovery, multi-satellite with one arrow, low-temperature fuel rocket technology, bundled rocket technology and geostationary orbit satellite launch, measurement and control, China has become one of the advanced countries in the world. Great achievements have been made in the development and application of remote sensing satellites, communication satellites, manned spacecraft experiments and space microgravity experiments.
space technology
1. artificial earth satellite. China successfully developed and launched the first artificial earth satellite "Dongfanghong-1" on April 24th, 1970, becoming the fifth country in the world to independently develop and launch an artificial earth satellite. By June 5438+00, 2000, China * * * had developed and launched 47 different types of artificial earth satellites, with a success rate of over 90%. At present, China has initially formed four major satellite series-recoverable remote sensing satellite series, "Dongfanghong" communication and broadcasting satellite series, "Fengyun" meteorological satellite series, "practical" scientific exploration and technical test satellite series, and "resources" earth resources satellite series will soon be formed. China is the third country in the world to master satellite recycling technology, and the success rate of satellite recycling has reached the international advanced level; China is the fifth country in the world to independently develop and launch a geostationary orbit communication satellite. The main technical indexes of China Meteorological Satellite and Earth Resources Satellite have reached the international level in the early 1990s. In recent years, six communication, earth resources and meteorological satellites developed and launched by China have been put into use, with stable work and good performance, resulting in good social and economic benefits.
2. Launch vehicle. China has independently developed 12 Long March series launch vehicles of different models, which are suitable for launching near-earth orbit, geostationary orbit and sun-synchronous orbit. The maximum carrying capacity of the "Long March" series of launch vehicles in near-earth orbit reaches 9200 kg, and the maximum carrying capacity of geosynchronous transfer orbit reaches 5 100 kg, which can basically meet the needs of different users. Since 1985, the China government officially announced that the Long March series of launch vehicles have entered the international commercial launch market, 27 foreign-made satellites have been successfully launched into space, occupying a place in the international commercial satellite launch service market. So far, the "Long March" series of launch vehicles have been launched 63 times; From June 1996 to June 10, 2000, the "Long March" series of launch vehicles have been successfully launched for 2 consecutive times.
3. Spacecraft launch site. China has built three launch sites for spacecraft, Jiuquan, Xichang and Taiyuan, and successfully completed the flight tests of various launch vehicles and the launching tasks of various artificial satellites and test spacecraft. China Spacecraft Launch Site can not only complete the domestic launch mission, but also serve the international commercial launch and carry out other international space cooperation.
4. TT&C in Space. China has built a complete TT&C network, including TT&C stations on land and TT&C ships at sea, and successfully completed TT&C missions in space from near-earth orbit satellites to geostationary orbit satellites and from satellites to test spacecraft. China Aerospace TT&C Network has the ability of international networking and sharing TT&C resources, and TT&C technology has reached the advanced level in the world.
5. Manned spaceflight. From 65438 to 0992, China began to carry out manned spacecraft space engineering, developed manned spacecraft and highly reliable launch vehicles, conducted research on space medicine and space life science engineering, selected reserve astronauts, and developed a number of space remote sensing and space science experimental devices. 1999165438+21year1October 20th, China successfully launched and recovered the first unmanned experimental spacecraft, marking a breakthrough in the basic technology of manned spacecraft and an important step in the field of manned space flight.
Space application
China attaches great importance to the development of various application satellites and satellite application technologies, and has made great progress in satellite remote sensing, satellite communication, satellite navigation and positioning. Of the satellites developed and launched by China, remote sensing satellites and communication satellites account for about 7 1%. These satellites are widely used in various fields of economy, science and technology, culture and national defense construction, and have achieved remarkable social and economic benefits. Relevant state departments have also actively used various foreign application satellites to carry out applied technology research, and achieved good application results.
1. Satellite remote sensing. Since the early 1970s, China has been using domestic and foreign remote sensing satellites to carry out research, development and popularization of satellite remote sensing application technology, which has been widely used in meteorology, geology and mineral resources, surveying and mapping, agriculture and forestry, water conservancy, ocean, earthquake and urban construction. At present, the National Remote Sensing Center, National Satellite Meteorological Center, China Resources Satellite Application Center, Satellite Ocean Application Center, China Remote Sensing Satellite Ground Receiving Station and other institutions have been established, as well as satellite remote sensing application research institutions of relevant ministries and commissions in the State Council, some provinces and cities and Chinese Academy of Sciences. Using remote sensing satellites at home and abroad, these professional institutions have carried out applied research work in many aspects and fields, such as meteorological forecast, land survey, crop yield estimation, forest survey, disaster monitoring, environmental protection, ocean forecast, urban planning, map mapping and so on. In particular, the operational operation of the satellite meteorological ground application system has greatly improved the accuracy of disastrous weather forecasting and significantly reduced the economic losses of the country and people.
2. Satellite communication. Since the mid-1980s, China has used domestic and foreign communication satellites to develop satellite communication technology to meet the growing needs of communication, broadcasting and education. In terms of satellite fixed communication services, there are dozens of large and medium-sized satellite communication earth stations in China, and there are more than 27,000 international satellite communication channels connecting more than 80 countries and regions in the world. China has built a domestic public satellite communication network with more than 70,000 domestic satellite communication channels, which has initially solved the communication problems in remote areas. VSAT communication has developed rapidly in recent years. There are 30 VSAT communication divisions in China, serving 15000 small station users, including more than 6300 two-way small station users. At the same time, more than 80 special communication networks and tens of thousands of very small aperture terminals have been established in dozens of departments such as finance, meteorology, transportation, petroleum, water conservancy, civil aviation, electric power, health and news. In terms of satellite TV broadcasting services, China has built a satellite TV broadcasting system covering the whole world and a satellite TV education system covering the whole country. China began to transmit radio and television programs by satellite from 1985. At present, a satellite transmission coverage network occupying 33 communication satellite transponders has been formed, which is responsible for transmitting 47 sets of central and local TV programs, educational TV programs, 32 sets of domestic and foreign radio programs and nearly 40 sets of local radio programs. More than 30 million people have received education and training in universities and technical secondary schools since satellite educational television broadcasting was launched more than ten years ago. In recent years, China has built a satellite live broadcast experimental platform, which has brought TV programs transmitted by central and local satellites to vast rural areas that are not covered by wireless radio and television through digital compression, greatly improving the coverage of radio and television in China. There are about1890,000 satellite TV broadcasting receiving stations in China. On the experimental platform of satellite live broadcast, the broadband multimedia transmission network of China Education Satellite was established, which provided comprehensive services of distance education and information technology for the whole country.
3. Satellite navigation and positioning. China began to use foreign navigation satellites to develop satellite navigation and positioning application technology in the early 1980s. At present, it has been widely used in geodesy, ship navigation, aircraft navigation, earthquake monitoring, geological disaster prevention and monitoring, forest fire prevention and extinguishing, urban traffic management and other industries. China joined COSPAS-SARSAT in 1992, and then established China Mission Control Center, which greatly improved the distress alarm service capabilities of ships, planes and vehicles.
space science
In the early 1960s, China began to explore the upper atmosphere with sounding rockets and balloons. In the early 1970s, a series of space exploration and research were carried out by using the "Practice" series of scientific exploration and technical test satellites, and a large number of valuable environmental exploration data were obtained. In recent years, space weather forecast research and corresponding international cooperation have been carried out. Since the end of 1980s, many space science experiments have been carried out with recoverable remote sensing satellites, and good results have been achieved in crystal and protein growth, cell culture, crop breeding and so on. China's space science has made some innovations in basic theoretical research. National laboratories with a certain level of openness have been established in space physics, microgravity science, space life science and other fields, and space payload application centers have been established, which have the basic ability to support space science experiments. In recent years, the charged particles and their effects in the near-earth space environment have been detected in detail by using the "Practice" series of scientific exploration and technical test satellites, and the two-layer fluid space experiment of microgravity fluid physics has been completed for the first time, realizing the remote operation of the space experiment. June/KOOC-0/0 at 22:/KOOC-0/6 One of the most important purposes of the spacecraft is to transport astronauts and materials to the space station and the lunar base, and the cost is much lower than that of the space shuttle. The Mir space station currently in orbit, the previous salute series space station and the Skylab space station in the United States all use spacecraft as the means of transportation between heaven and earth. The Soyuz 15 spacecraft of the former Soviet Union flew back and forth, docked with Salute 7 and Mir Space Station, and became the first space bus in the world.
People who work and live in the space station for a long time may encounter dangers at any time, such as astronauts suddenly getting sick, and space debris or meteors penetrate the pressure bulkhead where astronauts live. At this time, astronauts need to evacuate the space station immediately and return to the ground. Because of its small size, light weight and low cost, the spacecraft is very suitable to dock on the space station as a lifeboat for a long time, and it will not bring too much burden to the space station. 1984, when the Soviet Salute 7 space station broke down, it was the Soyuz spacecraft docked at the space station that evacuated two astronauts to the ground. The International Space Station currently under construction will also use Soyuz -TM spacecraft as a lifeboat in the initial stage of operation. If the priceless space shuttle is docked in the space station as a lifeboat for a long time, it will not be worth the loss and the efficiency will be too low. Moreover, it will bring great burden to the space station and greatly increase the cost of attitude control and orbital altitude maintenance of the space station.
Because the spacecraft has a propulsion system, it can maneuver the orbit, but it can also quickly reduce its altitude and be used for military activities such as reconnaissance. During the in-orbit flight of American Gemini 7 spacecraft, the astronauts on the spacecraft used infrared remote sensors to monitor and track the launch of 1 submarine-launched missile, and the information obtained was faster than that reported by the observers on the submarine.
From now on and in the foreseeable future, the interplanetary manned flight will first be realized by spacecraft, and it is likely to be a manned Mars spacecraft.
In this century, humans have successfully launched two kinds of spacecraft, satellites and landing on the moon. 2 1 century, it is expected to develop interstellar spacecraft and send people to other planets for sightseeing.
Spacecraft carried by multipolar rockets have entered space and made an unparalleled voyage in the world. In its eyes, the earth is just a walnut, and all the stars have become smaller. Because of its development, human beings not only expanded the living space, but also accelerated the pace of human progress.
Spacecraft is similar to a recoverable satellite. Because it carries people, many special systems are added to meet the various needs of astronauts in space. For example, environmental control and life support systems, telegraph communication systems, instruments and lighting systems, spacesuits, manned mobile devices and escape and rescue systems for air renewal, wastewater treatment and regeneration, ventilation, temperature and humidity control. Space rendezvous and docking technology is a key technology in manned spacecraft engineering, because only in this way can it provide transportation functions for other spacecraft.
Of course, it is also important to master the technology of spacecraft reentry and safe return. Especially for the spacecraft, in addition to limiting the braking overload of the spacecraft in the return process to human tolerance, it should also make its landing accuracy higher than that of the returning satellite, so as to find and rescue astronauts in time. Manned spacecraft, the former Soviet Union, once trapped astronauts in a snowy forest and almost froze to death because of poor landing accuracy. At present, only the United States, the Russian Federation and China control spacecraft returning technique.
From the structural point of view, human beings have developed three types of spacecraft, namely cabin one, cabin two and cabin three. The first cabin is the simplest, only the astronaut's cockpit. This two-cabin spacecraft consists of a cockpit and a service cabin, which provides power, electricity, oxygen and water. Improve the working and living environment of astronauts. Leonov, the first astronaut in the world, took the "Ascension" spacecraft of the former Soviet Union and the "Gemini" spacecraft of the United States. The most complicated is the three-cabin spacecraft. It carries out space activities and scientific experiments on the basis of two-module spacecraft or adds an orbital module (satellite spacecraft), such as the former Soviet Union/Russia "Soyuz" series spacecraft; Or add a lunar module (moon landing spacecraft) for landing and leaving the moon, such as the Apollo spacecraft in the United States.
From the type point of view, in addition to manned spacecraft, there are cargo spacecraft and manned cargo hybrid spacecraft. According to different tasks, manned spacecraft can be divided into satellite manned spacecraft, lunar manned spacecraft and interstellar manned spacecraft. The first two have been successfully launched in the 20th century, and the latter is expected to be realized in 2 1 century, probably a manned Mars spacecraft.
Reporter: Although the spacecraft is simpler than the space shuttle and space station, the technical requirements must be very high, right?
Pang: Of course. Although manned spacecraft is the simplest manned spacecraft today, it has the characteristics of short flight time, return along ballistic or semi-ballistic path, one-time use and so on. In fact, it is also very complicated, so now only China, Russia and the United States have it.
When the spacecraft returns to the ground, in order to slow down, prevent heat and meet the structural needs, the smaller the return weight, the better. For this reason, only the cockpit can really return to the ground, which is also an important reason for subdivision design. It should be like the plane throwing away the auxiliary fuel tank in the air and the multi-stage rocket throwing away the stalled sub-rocket. Therefore, the shape design of spacecraft cockpit is very important.
Cockpit is the core of manned spacecraft, which usually adopts wingless large blunt rotating body, some are spherical and some are bell-shaped. Adopting this simple shape has the characteristics of simple structure and easy implementation in engineering. At the same time, the cockpit generally has portholes with a wide view, which is convenient for astronauts to observe the preparatory activities before launch, the rendezvous and docking in orbit, the attitude when returning to ignition and the ground situation when landing again. Russian astronauts have successfully docked manually through portholes many times when the automatic docking system fails. In addition, in order to keep the astronauts working efficiently, the pressure and composition in the cockpit, oxygen supply, removal of carbon dioxide and water vapor, water and food, space suits, etc. Both need careful research and very complicated technology to complete.
There are two doors in the airlock cabin of the spacecraft, one is the inner door connected with the cockpit, and the other is the outer door that can lead to space. Astronauts should put on spacesuits before leaving the cabin, then walk out of the inner gate, close the inner gate, and pump the air in the airlock into the cabin. When the pressure inside and outside the airlock is equal, they can open the outer door and go into space. When the astronauts return to the airlock, they will operate in the reverse order. The absolute reliability of the air tightness of the inner and outer gates is the basic condition for the air lock cabin to work. The gate must be opened and closed very carefully and skillfully, and it is very important to avoid air leakage, otherwise it will be extremely dangerous. The former Soviet "Ascent" -2 spacecraft took the lead in applying airlock cabin in March 1965. Astronaut leonov walked out of the cabin through it and became the first person in the world to walk in space.
During the ascent or return of the spacecraft, if something goes wrong and an emergency ejection is needed, the cockpit door should be able to open quickly; When operating in orbit or landing at sea, the cockpit door is required to be strictly sealed. Astronauts can climb out of the cockpit through the emergency escape besides entering and leaving through the cockpit door. The flight environment of manned spacecraft in three different flight stages: ascending, entering orbit and returning to earth is different, and its life-saving means are also different. For example, the rocket that launches the spacecraft is in danger after taking off. If the rocket flies below 20,000 meters, the astronaut can start the ejection seat to eject from the cockpit like an airplane pilot, and then open the parachute to return to the ground. If the flying height of the rocket exceeds 20,000 meters, the astronauts can only start the escape rocket at the top of the spacecraft, use it to pull the spacecraft away from the launch vehicle, fly to a safe area, and then open the parachute of the spacecraft to make a soft landing.
At present, the manned spacecraft is still disposable. In order to be reused, it is necessary to solve two key problems: the cockpit thermal protection layer can withstand the high temperature above 10 00℃ and the return cabin landing system can ensure accurate landing and extremely low landing speed, and it will not be damaged by burns. Foreign countries are developing reusable manned spacecraft from these two aspects.
Reporter: With the deepening of human space activities, spacecraft are used more and more widely. Can you elaborate on this?
Pang: Manned spacecraft has made indelible achievements in the history of manned space flight. After sending people into space, the spacecraft has been used in various scientific research and space technology experiments, such as earth observation, astronaut extravehicular activity, biological research and so on, and has achieved great results.
One of the most important uses of the spacecraft is to transport astronauts and materials to the space station and the lunar base, which is much lower than that of the space shuttle. At present, the international space station in orbit, such as Peace, Salute and Sky Laboratory in the United States, used spacecraft as the means of transportation between heaven and earth. Spacecraft, like a "bus" in space, has made great contributions.
People who work and live in the space station for a long time may be in danger at any time. For example, when an astronaut suddenly falls ill or a spaceship has an accident, the astronaut must leave the space station immediately and return to the ground. Because of its small size, light weight and low cost, the spacecraft is very suitable for long-term docking in the space station as a lifeboat. If the priceless space shuttle is left in the space station as a lifeboat for a long time, it will not be worth the candle. When the Salute -7 space station of the former Soviet Union broke down in 1984, two astronauts on the space station were evacuated to the ground by the Soyuz spacecraft docked at the space station. 1998 The International Space Station, which started construction, also uses Soyuz -TM spacecraft as lifeboats.
Because the spacecraft has a propulsion system, it can be maneuvered to change its orbit, so it can also be quickly lowered for military activities such as reconnaissance. During the in-orbit flight of Gemini -7 spacecraft, astronauts on the spacecraft used infrared remote sensors to monitor and track the launch of a submarine-launched missile, and the information obtained was faster than that reported by observers on the submarine.
Foreign countries began to use spaceships for space tourism. Since dennis tito, a California millionaire, boarded the International Space Station on Soyuz -TM spacecraft in April, 200012000, and became the first traveler to go into space, many people are full of expectations for space travel. To this end, Russia's Energia Rocket Space Company said that it plans to provide space services for future passengers for one week. Passengers can visit space in the Russian Soyuz spacecraft. In the spaceship, visitors can not only experience the feeling of weightlessness, but also see the beautiful earth through the porthole.
In addition, from the current and foreseeable future, the future interplanetary manned flight will first be realized by spacecraft, probably manned Mars spacecraft.
In short, the spacecraft has made great achievements in the past, present and future, which can be said to be in the ascendant.
Reporter: When it comes to spaceships, we can't help mentioning the "Shenzhou" that China people are most proud of. Could you please talk about it in detail?
Pang: China's Shenzhou is a relatively advanced manned spacecraft, which has been in space four times. Shenzhou spaceship consists of orbital module (also called working module), return module (also called cockpit), propulsion module (instrument module) and transition section. Among them, the manned orbital module and the return module can be described as "one room and one living room". As a "one-room" return module is the place where astronauts stay when launching, returning and driving, while as a "one-room" orbital module is the place where astronauts work and rest.
The orbital module is located in front of the return module to increase the space for astronauts. It is equipped with a variety of experimental equipment and instruments, which can be used for earth observation. Its two sides are equipped with retractable large-scale solar cell wings, solar sensors, various antennas and various docking mechanisms.
The return capsule is located in the middle of the spacecraft, which is the astronaut's accommodation and the control center of the spacecraft. Like other cabins, it not only bears all kinds of stresses and flight environment during takeoff, ascent and orbital operation, but also bears deceleration overload and aerodynamic heating when re-entering the atmosphere. It is a closed structure with a hatch at the front end for astronauts to enter and leave the orbital module.
The propulsion module is directly behind the return module, usually equipped with propulsion system, power supply, gas cylinder and water tank, which plays the role of guarantee and service, that is, providing power, attitude control, orbit change and braking for the spacecraft and oxygen and water for the astronauts. More than 20 square meters of main solar cell wings are also installed on both sides of the propulsion cabin. The transition section is located at the top of the spacecraft and used for docking with other spacecraft or space exploration.
There is also an 8-meter-high escape tower at the top of the spacecraft. Equipped with 10 engine. During the period from 900 seconds before launch to 160 seconds after launch (0 ~ 1 10 km), if something goes wrong, it can drag the return capsule and orbital module away from the rocket and fall to a safe place, so that the astronauts on the spacecraft can turn the corner. Reporter: Thank you for accepting our interview. I wish China's flying dream come true at an early date. Since the establishment of 1956, China's space industry has experienced several important periods, such as hard struggle, supporting development, reform and revitalization, and going abroad. Up to now, it has reached a considerable scale and level: a complete supporting research, design, production and test system has been formed; A spacecraft launch center capable of launching various satellites and manned spacecraft, as well as a monitoring and control network composed of various domestic ground stations and long-distance tracking and measuring ships, have been established. A variety of satellite application systems have been established, and remarkable social and economic benefits have been achieved; A space science research system with a certain level has been established and many innovative achievements have been made. A team of aerospace science and technology with good quality and high technical level has been trained.