The space technology arising from this has developed rapidly in the next half century.The development of space technology has freed mankindGravity of the earthInto the vastouter spaceAt the same time, it also provides a new place for military activities.Outer space has become a new battlefield.
Space technology is the technology to explore, develop and use space, also known asSpace technologyAnd aerospace technology.When talking about aerospace, what is the sky?There are two definitions.One definition holds that the sky refers to the infinite space beyond the earth's atmosphere.Another definition holds that the sky refers to the space from outside the earth's atmosphere to within the solar system.According to the latter definition, navigation outside the atmosphere and within the solar system is called aerospace, while navigation outside the solar system is called aerospace.For quite a long historical period, mankind can only achieve space activities.
Because any kind of navigation activity is closely related to its propulsion technology, only when the propulsion technology advances to a certain extent and the speed of moving objects increases to a certain level, can there be a specific navigation activity.When the aircraft reachesFirst cosmic velocity(7.9 km/s)Gravity of the earthWhile flying around the earth without falling back to the earth's surface;Improve toSecond cosmic speed(11.2 km/s) can fly away from the earth to other planets in the solar system;Improve toThird cosmic speed(16.7 km/s) can fly away from the solar system.Although the third cosmic speed can theoretically realize navigation activities outside the solar system, the solar system is too large, and modern spacecraft fly at the third cosmic speed, and it takes more than 10000 years to leave the solar system.
For communication outside the solar system, it takes more than one year for signals to go back and forth once.Therefore, it is too early to discuss navigation activities outside the solar system. Today's technology is far from enough.The ultimate goal of developing space technology is to realize space transfer.Therefore, it is more accurate to define aerospace as the navigation activities from outside the earth's atmosphere to within the solar system.The scope of space technology in contemporary research also refers to the solar system.
space resources
Announce
edit
For quite a long time, mankind has mainly carried out space activities centered on the earth.To achieve space activities, it is necessary to establish a large space vehicle centeredSpace system。It consists of a specific spacecraft (satellitespace station、detector）, means of delivery (rocketsspace shuttle），Space launch site, ground measurement and control network (ground station, ship), ground application station network and other relatedsystem composition , it is a bigsystems engineering。
1. The vehicle accelerates the spacecraft toCosmic velocityAnd send it to the predetermined running track.Modern space launch vehicles are divided into launch vehicles and space shuttles. The former is disposable, and the latter can be used for many times.Launch vehicles were first developed and have been widely used.Each space major country has its own carrier rocket andLaunch site。The launch vehicle is generally composed of 2-3 stages, and each stage haspropulsion system , last levelInterior decorationRocketguidance and control , tracking, telemetry, power supply and other systems.At the same time, the transported spacecraft is installed on the top of the last stage.
2. Spacecraft refers to the earthatmosphereByCelestial mechanicsRegular flying vehicles include various artificial satellites, manned spacecraft, space stations, planetary probes, etc.Among them, the number of man-made satellites launched is the largest, and they have been widely used, producing huge benefits.There are many kinds of artificial satellites, includingCommunication satellite、Remote sensing satellite、Navigation and positioning satellite, scientific satellites, etc.
Remote sensing satellites take photos of the earth's surface in space to obtain various information such as weather, ocean, environment, resources and military targets, serving economic construction, scientific research and military activities.Remote sensing satellites are divided into meteorological satellitesOcean satellite, resource satelliteMilitary reconnaissance satelliteEtc.
Navigation and positioning satellites are satellites that provide navigation and positioning for ground, ocean, air and space users.It is composed of several satellites and operates in different orbits.The coordinate position of each satellite in space is strictly determined. It transmits a specific radio signal, which the user receives, processes, and determines its position.
Space technology belongs to high technology, butTechnical updatesThe progress is very fast, so it is also a new technology.What are the characteristics of space technology?
In the past 40 years, spacetechnological development Soon, it has many characteristics. Here we emphasize three outstanding characteristics.
Second, space technology is a science and technology that plays a macro role in national modernization and social progress.becausespacecraftIt can cover the surface of the earth quickly and widely because of its fast flight speed and high altitude.For example, TV networks can cover the whole country and the whole world through satellite;meteorological satelliteCan conduct globalweather forecast, includinglong-range weather forecast；Reconnaissance satelliteMilitary activities in various regions of the world can be found in time.Many of these cannot be achieved by conventional means.
Third, space activities are characterized by high investment, high efficiencyhigh-riskThe cause of.Despite the great risks, the development of space technology has made great contributions to mankind, so it willsustained development。
significance
Announce
edit
To sum up, there are four aspects:
EconomicallySpace activities have high economic and social benefits.Multiple application satellitesCommunication broadcasting, resource surveyEnvironmental monitoring、Meteorological forecast, navigation and positioning have made great contributions to mankind.According to the research and analysis of some countries, space technologyInvestment benefitThe ratio is more than 1:10.The more profound significance is that space activities will provide mankind with unlimited valuable resources.
MilitarilyMany military experts believe that who ownsSpatial advantages, who has the militaryStrategic advantages。these years,SuperpowerAre developingStrategic nuclear weapon, in order to select strike target, improvehit accuracy And understand the enemyMilitary deployment, competing to develop reconnaissance satellites, which areintercontinental missileAnd has become a supporting project of strategic nuclear weapons.The development of communication, navigation and other satellites has also greatly enhanced the nationalmilitary force。The continuous development of space technology will have a revolutionary impact on the military.
In science and technologySpace activities have driven and promoted the development of many disciplines.First, space activities have driven technological development, such as electronic technology, remote sensing technology, jet technology, automatic control technology, etc;Second, yesBasic SciencesThere will be great impetus, including important new discoveries in life science and the formation and development of the universe;Third, it has formed manyMarginal discipline, such as space technology, spaceMaterials Science、Space biology, satellite geodesySatellite meteorology, satellite oceanography, etc.
Politically, space technology has greatly improved thecomprehensive national strengthAnd its position in international activitiesMajor issuesBoth are related to space, and the summit talks of world powers cannot be separated from this issue.Due to the importance of space technology, more than 60 countries are participating in the development of spacetechnological achievementsOur country covers almost every corner of the world.
The history of human sounding activities has roughly experienced balloons, rocketsArtificial satelliteWait several stages.
In the 1880s, scientists used balloons to carry out scientific research.By the 1920s, various balloons (mainlyHydrogen balloonandNitrogen balloon）Already under scientific investigationTransportation, military reconnaissance, etc.However, the structure of the balloon determines that it can only rise to about 50 kilometers,Atmospheric densityThe balloon can only look "empty" at the higher space because of its lower height.To carry out scientific exploration in higher space, we must rely on another means of delivery, which is rocket.The rocket was first invented by China. It was used by China during the Yuan and Ming dynastiesRocket weaponIt is the ancestor of modern rockets.
In 1903,RussiaThe scientist Ziolkovsky published a paper entitled "Research on the Space of Space Windows with Jet Instruments", and proposed to use rockets to exploreCosmic spaceThe famousZiolkovsky formulaIn March 1926, American physicist Goddard independently studied the propulsion principle of rockets, designed, manufactured and launched the world's firstLiquid rocket。Since then, scientists in many countries, with the support of the government, have carried outRocket manufacturingAnd launch studies.In October 1942,Made in GermanyAnd successfully launched the first military liquid rocketV-2。After the war, scientists used V-2 and its improved version as a new tool to explore the space above 50 kilometers, and obtained a lot of information about high-level space.
By the late 1950s, the launch capability of rockets had reachedArtificial satelliteIn order to implement the Geophysical Year plan, the United States and the former Soviet Union actively planned to launch scientific satellites. On October 4, 1957, the former Soviet Union successfully launched the world's first satelliteArtificial earth satelliteHe marks the real beginning of the "space age".In 1958, the United States launched a man-made earth satellite.In 1970, China also launched a man-made earth satellite.Since then, various artificial satellites have been launched, with more than 4800, including more than 50 in China.
Human beings enter the space mainly byManned spacecraftandEarth orbitspace stationImplemented.On April 12, 1961, the former Soviet Union launched the first manned spacecraft, which sent Gagarin into Earth orbit and returned to the ground safely after 108 minutes of operation, opening a new era of human spaceflight and marking a new era of human space technology.On July 16, 1969, the United States successfully used“Saturn-V "carrier rocket launchApollo spacecraft, sent astronauts Armstrong and Aldrin to the moon and returned to Earth on July 25.
On May 14, 1973, the United States used the "Saturn V" rocket to transport the 82 ton“SkylabNo. 1 "sent three batches of nine astronauts into the laboratory and carried out more than 20 scientific researches with the Apollo spacecraft as the transportation vehicle. During this period, the former Soviet Union focused on the establishment of the space station to carry out a series of sounding activities. From 1971 to 1986, the first was launched."Gun salute"1 to 7 space stations," Mir "space orbital station. Launch in stages and batches"Soyuz"," Progress "," Cosmos "and other spacecraft docked with the" Salute "space station to deliver various instruments, fuel, household supplies and replace astronauts and researchers for the space station. In 1982, the former Soviet Union had two astronauts in the"Salyut 7 "It took 211 days to create space for astronautsflight timeRecords of.Except for the United States and the former Soviet UnionFederal Germany, UK, FranceBelgiumWait for 10Western EuropeNational participationEuropean Space AgencyOn November 28, 1983“Space laboratoryNo. 1 "space station.
The 47th IAF Congress was held in Beijing in October 1996. The theme of the Congress was to expand spaceScope of application。The participants recognized that the next century will be the space century,AerospaceIndustry will be the entry point of economic growth.manycountries and regions , such as the United StatesRussia, Europe, Japan, etc., all plan to invest a lot of manpower and material resources to develop space shuttles, space stations, space vehicles, etc., and further develop and utilize themSpace resources。
To make the aircraft becomeArtificial earth satelliteThe aircraft must obtain a certain speed. Its minimum speed V1=7.91 km/s is calculated by using the formula of physics.This speed is called“First cosmic velocity". Make the aircraft flyMoonorsolar systemOther planetarySpace probeThe aircraft must also obtain a certain speed, and its minimum speed V2=11.18 km/s can be calculated by using the physical formula.This speed is called“Second cosmic speed". So called"Third cosmic speed"Refers to the gravity of the aircraft beyond the solar systemScope of actionThe minimum speed required, its value V3=16.7 km/s.
2. Rocket propulsion principle
The basis for rocket flight isLaw of conservation of momentum。During rocket launch and flightpropellant(fuel and oxidizer) in a very short timeExplosiveCombustion produces a large amount of high-temperature, high-pressure gas from the tail.The gas ejected has great momentum. According to the law of conservation of momentum, the rocket must obtain momentum with equal value and opposite direction, so there is a continuousreactive movement , fast forward.As the fuel decreases, the speed of the rocket becomes faster and faster. When the fuel burns out, the rocket will continue to fly at the last speed.
famousZiolkovsky formulaTell people that they are ignoring gravity andair resistanceThe maximum speed V, the jet speed C, the mass M1 when the rocket takes off, and the mass M2 of the rocket after propellant consumption have the following relations
v=C㏑M1/M2
Where M1/M2 is called rocketmass ratioIt can be seen that to increase the speed of the rocketrocket engineThe ratio of the jet speed to the mass of the rocket is to use high-performance propellant, develop advanced engines, and minimize the structural weight of the rocket.
Important content
Announce
edit
Space technology, also known as aerospace technology, includescarrier 、spacecraftAnd ground measurement and control technology.
1. Carrier
Launch vehicles are mainly launch vehicles.The launch vehicle hasArrow body structure, propulsion system and control system.Since the propellant used isChemical propellantSingle stage rockets cannot put satellites and spacecraft into orbit.UsedMultistage rocketIt is composed of 2-4 stages. When the fuel of the previous stage rocket is used up, it will fall off automatically. At the same time, the ignition of the next stage rocket will continue to work.The spacecraft carried by the rocket is installed in the last stage of the rocket.The largest carrier rocket in the world is American“Saturn 5"Rocket. It is composed of three stages. It weighs nearly 3000 tons at takeoff and has a takeoff thrust of 35711 kilonewtons. China's carrier rocket technology is among the world's advanced and has been equipped to launchManned spacecraftIn addition to meeting the needs of domestic satellite launch, it has also entered the international commercial satellite launchservice market 。
There are many kinds of spacecraft, mainly man-made earth satellites, space stationsspacecraft, Space ShuttleSpace probeEtc.
Spacecraft is an important means of transportation between the earth and the space station.For example, AmericanApolloThe spaceship is between the earth and the space laboratory;The Soviet Union's Soyuz, Progress, Cosmos and other spacecraft are connected to the Earth andSalute Space Stationbetween.Because spaceships are not ideal enough, people have studied a more advanced tool - the space shuttle.The space shuttle combines the technologies of ordinary rockets, spaceships and aircraft, and has three functions of carrying, spaceflight and returning, which can be reused for many times.The United States first successfully trial produced the space shuttle in 1981, and officially put it into use that year. It has flown dozens of times.
In addition to the United States, the former Soviet UnionWestern Europe, Japan and France are also developing space shuttles.People have also developed another advanced means of transportation - the aerospace plane.This kind of aircraft is more similar to ordinary aircraft in some aspects, and can be executed like the space shuttleSpace missionsThe launch cost is only 10% to 20% of the cost of the space shuttle.
A space probe is a spacecraft that flies to the moon and other planets, or travels between stars, free from the constraints of the earth.The first space probe was launched in the early 1960s. It flew to Venus.In the 1960s and mid-1970s, it mainly explored Venus, Mars and Mercury;The exploration of the distant large planets Jupiter and Saturn began in the 1970s.
3. Ground measurement and control technology
groundMeasurement and control systemTracking, telemetry, remote control and communication of spacecraft on the ground.Through the ground TT&C system, people can obtain various information about the operation of the spacecraft, control the spacecraft, and adjust itsrunning state To achieve people's expectations.
Space resource development
Announce
edit
outer spaceRich resources, including location resourcesenvironmental resource andmaterial resources The development and utilization of these resources have brought many benefits to mankind, and further development in the future will enable mankind to obtain more benefits.
（1） Development of spatial location resources
The spacecraft is located at a high altitude, which can comprehensively observe the situation on and near the earth surface, and can easily complete tasks that are difficult to complete on the ground.For example, the emergence and wide application of communication satellites have brought about fundamental changes in the world's communication system.As an industry, it has achieved great economic and social benefits.The most important communication satelliteSynchronous communication satellite。The geostationary communication satellite is located 35786 kilometers above the equator. The time for it to rotate around the earth's center is the same as that for the earth to rotate.Seen from the ground, the satellite seems to be hanging in the sky and still.From a regionSatellite ground stationThe microwave signal is sent to the synchronous communication satellite, and thenTransponderholdsignal amplificationAnd send it back to the satellite ground station in another region, which constitutes the communication between the two places.As long asSynchronous orbitIn 1958, the United States launched the world's first experimental communication satellite, and in 1963, the first synchronous communication satellite.Since then, countries around the world have rapidly established a complete internationalcommunication system 。There are many kinds of communication satellites, including fixed communication satellitesMobile communication satellite、TV direct broadcast satellite、Tracking and Data Relay Satellite, and proposed spaceinformation superhighway。The orbit of communication satellites has also expanded from a single geostationary orbit to a medium low orbit.IntelsatThe international communication satellite has developed to the eighth generation, with a total capacity of 22500 analog channels, 112500 digital channels and 3television channel。It undertakes more than 85% of global commercial communication business.Used in China“Dongfanghong No.3"Synchronous communication satellite, with 24 transponders, can transmit 8100 calls and 6 calls at the same timeColor TVIt basically meets the needs of domestic TV, radio and communication.
Another example is civil remote sensing satellites (including meteorological satellites andEarth resource satellite）It has played an important role in meteorology, resources, surveying and mapping and other fields.The emergence of meteorological satellites has brought about significant changes in meteorological observation.It can use all kinds of weatherDetecting instrument, take global cloud pictures, accurately measure the temperature and precipitation around the world, and monitor typhoons, torrential rains, etcDisastrous weatherTo improveMeteorological forecastOfaccuracy, decreasenatural disasterLoss to people.The earth resource satellite is equipped with high-resolutionTV camera、Multispectral scanner、Microwave radiometerAnd othersRemote sensing instrumentCan be used to complete a variety of tasks, such as surveying the forest, water and marine resources on the earth's surface, investigating underground mineral deposits andGroundwater sourceObserve the growth of crops, estimate the yield of crops, monitor the diseases and pests of crops and environmental pollution, and conduct geographical surveys.
Space has weightlessnesshigh vacuum, strong radiationUltralow temperatureEtc.Although the environment with these special conditions is not suitable for human life, it can bring some rare opportunities.For example, outer space does notatmosphere, high vacuum, astronomicalObservation stationSet up in this space, you can get clear images of celestial bodies, which is conducive to revealing the true face of celestial bodies.Hubble that has been in orbit for many yearsSpace telescope, with extremely highResolutionAnd sensitivity, can observe objects 14 billion light years awayObserve objectsOf the resulting imagedefinitionIt is 10 times higher than the best telescope on the ground.For another example, the conditions of high vacuum and high cleanliness in outer space can be used to manufacture new materials andSpace medicineIt can not only ensure the high quality of products, but also ensure the safety and convenience of production.
（3） Development of space material resources
The material resources in the space are mainlySolar energy resources、Lunar resourcesAnd other planetary resources.Inside the SunWith intenseFusion reaction, release a lot of energy.Set in outer spaceSolar power station, can fully absorb solar energy and effectively use solar energy.Its main advantages are: power stations set in geosynchronous orbit,Sunshine timeUp to 99.98%, which can generate electricity continuously;Without atmospheric interference, the utilization rate of solar energy is more than 10 times higher than that on the ground;There is no need to worry about the attack of wind and rain and the shelter of clouds and mist. Power can be generated every day throughout the year.People's assumption is: useSolar panelConvert solar energy into electric energy, and then convert electric energy into microwave energy and send it toGround receiving stationThe ground receiving station converts microwave energy into electric energy for users.IfSolar satellitePower stations can be built and put into use, and human beings will get clean, safe and extremely rich power resources.Although there is no life on the moon, it contains a lot of metal and other raw materials.Iron, nickel, aluminum, manganese, cobalt, uranium, thorium and other important metal raw materials are all available, and helium-3 reserves are quite abundant.According to the exploration, if only theresource development It can be used for more than 1000 years.The development of the moon can not only become a new production base for mankind, but also becomeSpace navigationThe relay station of.Some countries have planned to establish it on the moon in a few yearsSpace base。
（1）Satellite altitude(h) (Satellite to Earth surfaceVertical distance。It is generally calculated in kilometers.The altitude in orbit from the Earth's Recently position, calledPerigee altitude。The height of the farthest position from the earth, calledApogee altitude。）
(2) Operation period (T) (The time required for a satellite to fly around the earth in orbit is generally calculated in minutes. The operation period of the satellite should be ≥ 84 minutes.)
（3）Rail inclination(i) (SatelliteTrack planeAnd the EarthEquatorial planeThe included angle between.The larger the dip angle, the larger the satellite coverage area;On the contrary, the coverage area is smaller.)According to the inclination, satellite orbits can be divided into three types:Equatorial orbit、Polar orbit, inclined track.
The geosynchronous orbit, namely, the operation period andearth rotationSame cycle (23 hours, 56 minutes and 4 seconds)Artificial earth satellite orbit。In this orbit, satellites pass over the same place at the same time almost every day. Some people also call the satellite orbit whose operation period is an integral multiple of the Earth's rotation period geosynchronous orbit.
Geostationary orbitIt refers to a circular geosynchronous orbit with an operating period equal to the Earth's rotation period and an inclination of 0 ° (in this orbit, the satellite is 35786 kilometers above the ground,running speed Is 3.07 km/s.Because it windsthe earth 's axisOfangular velocityAndEarth rotation angular velocityThe size is the same, the direction is the same, and the satellite is stationary relative to the ground.One satellite in this orbit can cover 40% of the earth's surface, and three satellites are equally spaced over the equatorGeostationary satelliteIt can cover the whole world except the two polesradio and televisionAnd the ideal orbit of early warning satellites).
The sun synchronous orbit refers to the rotation direction and period of the satellite's orbital plane around the earth axis, andDirection of revolutionSame as the period (this orbit is a kind of retrograde inclined orbit, with an inclination between 90 ° and 100 °,Track heightBetween 500 and 1000 kilometers.It is characterized by that the track plane andsunlightThe included angle of remains unchanged.When the satellite runs along this orbit, it will keep the same space every time it passes over the ground target at the same latitudeLocal time, the same running direction, the same lighting conditions),Master the goalThe dynamic change of, reasonable deployment and utilization of satelliteSolar cellHave incomparable advantages.The United States' near Earth reconnaissance satellitesResource satelliteandMilitary meteorological satelliteMost adopt this track.
(3) Polar orbit
Polar orbit is an orbit with an inclination of 90 °, passing through the south of the eartharcticA kind of track of.It is characterized by satelliteSubsatellite point trackIt can cover the whole world.It is the most suitable orbit for observing the whole earth, and is the common orbit for navigation, meteorology, resources and reconnaissance satellites.
The more mature launch vehicles developed by countries around the world mainly include: the "Proton" large launch vehicle of Russia (the former Soviet Union), the "Thor" of the United States"Hercules" series carrier rocket, Chinese“long march”Series launch vehicles, EU's Ariana liquid rocket, etc.
（2） Spacecraft technology
SpacecraftSpacecraftIt is the general name or space system of various aircrafts that operate in space according to the laws of celestial mechanics and complete certain missions.
Manned spacecraft refers to the space shuttle between the earth's surface and space, which can transport people andPayloadSpacecraft providing living and working environment for astronauts.Manned spacecraft can be divided into manned spacecraft, space station and space shuttle according to different functions.
(1) Manned spacecraft
Manned spacecraft is a spacecraft that can carry people to the sky and return to the ground at one time.There are two kinds of manned spacecraft: satellite manned spacecraft and moon landing manned spacecraft.ChinaShenzhouThe test spacecraft was successfully launched using the Long March 2F carrier rocket on November 20, 1999.
(2) Space station
The space station is a large spacecraft that can accommodate astronauts to seek, work and live for a long time.The space station is located hundreds of kilometers from the groundLow Earth orbitRun on.It hasDocking compartment, used to dock manned spacecraft or space shuttles, and can also be connected with multiple space stations to form a space complex (Space City).On April 9, 1971, the Soviet Union launched the firstSpace Station"Salute" - 1. On February 20, 1986, the Soviet Union launched a new generation of space station "Peace".16 countries in March 2002Co investmentDevelopedInternational Space StationIt has officially operated in space.
(3) Space Shuttle
The space shuttle is a reusable spacecraft that shuttles between the Earth's surface and low Earth orbit to transport payloads and personnel.Generally, solid rockets are used to boost the vehicle into orbit, and the vehicle operates like a spaceship in orbit to complete a variety of tasksSpace missions，atmospheric reentry Glide and land like an airplane.April 1981, USASpace Shuttle ColumbiaThe test flight was successful.ChallengerAnd“Discoverer”The space shuttles have also been put into practical flight.
3. Composition of spacecraft
Spacecraft is composed of several systems and subsystems with different functions, generally consisting ofDedicated systemAnd support system.
(1) Dedicated system
This is a system used to directly perform specific tasks, which is set according to the tasks performed by spacecraft.
Space TT&C technology is a technology for telemetry, remote control, tracking and communication between ground and spacecraft to ensure the normal operation of spacecraft in orbit.Space TT&C consists of TT&C subsystem carried by spacecraft and ground TT&C system.
Key achievements
Announce
edit
Because of the importance of space technology, it has developed very rapidly.Since 1957Soviet UnionAfter launching the first satellite, the United States launched its first satellite in 1958, France in 1965, and Japan and China in 1970Artificial satellite, causing a world sensation.The former Soviet Union and the United States have the largest space investment in the world.Of the more than 4000 spacecraft launched, the former Soviet Union and the United States accounted for the vast majority.In addition, the European Union, China, Japan, IndiaCanadaThey also have a certain scale.Relying on self-reliance, China has successfully developed and launched about 40 different domestic man-made satellites, built a satellite land sea TT&C network and a large number ofEarth stationAnd made important contributions to national construction and social progress.Here is a brief introductionWorld AerospaceThe main achievements of.
（1） Space technology
space flightMeans of deliveryIts development is one of the most important achievements in 40 years.AsSpacecraftOfMeans of transportMainly disposableCarrier rocketThe most developed countries in this regard are the former Soviet Union and the United States, as well as France, China, Japan and India.Typical large rockets in the world are those of the former Soviet UnionProton numberThe Hercules of the United States, the Arianna of France, the Long March of China and the HZ rocket of Japan can send heavy satellites 36000 kilometers awayGeosynchronous transfer orbit。China has developedLong March Series Launch VehicleAnd three launch bases have been built, which not only launch domestic satellites, but also provide international launch services.Another vehicle isspace shuttleThe space shuttle can be used for many times, but it is expensive and risky.The United States was the first to develop the space shuttle, with a carrying capacity of 20 tons, carrying 3 to 7 astronauts, a flight orbit height of 200 to 400 kilometers, and an inclination of about 28 degrees.
Artificial earth satellites are of great value to military and economic construction, so satellite technology has developed rapidly.In addition to the United States and the former Soviet Union, the European Union, China, Japan and India all have the ability to develop satellites and launched a variety ofApplication satellite。Communication satelliteWith high economy andsocial results。China launched in the 1980sDongfanghong No.2The geostationary communication satellite was launched again in the 1990sCommunication capability10 times larger than the formerDongfanghong 3 communication satellite。IntelsatIt has developed to the eighth generation, and the communication capacity of a satellite can reach tens of thousandsSpeech path, can forward dozens of TV programs at the same time.Satellite launchPower increase andSpot beamTechnological progress has madeground stationMiniaturization becomes a reality.The rapid progress of satellite technology has made the satellite's in orbit life up to 12 to 15 years.The typical representative of resource satellite is the United StatesLandsatAnd FranceSport satelliteThey have high resolution and multi spectral remote sensing capabilitiesResource surveyIt is of great value.Meteorological satellites have polar orbits andGeostationary orbitTwo.Polar orbiting meteorological satellites can fly through all regions of the earth, providinglong-range weather forecastAccording to the data, only the United States, the former Soviet Union and China have developed and launched such meteorological satellites in the world.Geostationary meteorological satelliteRelative to the fixed earth surface, it can continuously observe the distribution and change of clouds in the region in real time.China successfully launched theFY-2 satelliteIt is a geostationary meteorological satellite.The representative of navigation and positioning is the United StatesGPSSatellite, which is composed of 18 satellites, can be used for global navigation and positioning with an accuracy of meters.canRecoverable satelliteIt has important economic, military andScientific valueIn the world, only the former Soviet Union, the United States and China have the ability to recover satellites.China's recoverable satellites have a very high success rate, and their level is internationally recognized.
Manned spaceflight is an important part of aerospace achievements in the past 40 years.The Soviet Union and the United States launched their first man-made satellite firstManned spacecraft, mainly to compete for the first place in the world.The former Soviet Union was the first country in the world to land astronauts in space, while the United States was the first to land on the moon.Manned spaceflighteconomic performanceIt has been argued all the time, but it has great political influence.More than 400 people have entered space, with the former Soviet Union slightly aheadresidence timeBoth exceed the United States.The development path of the United States and the Soviet Union is slightly different, and the development order of the former Soviet Union is spacecraft orbital station——space station；The United States is a spaceship - the space shuttle - the space station.Manned spaceflighttechnical progressFaster, astronauts can not only move out of the cabin, but also repair failed large spacecraft, and operate spacecraft docking.
In the past 40 years, space technology has developed rapidly.To sum up, the capacity of launch vehicles to transport spacecraft has increased from dozens of kilograms to 100 tons;Satellite acquisition and transmissionInformation capabilityThe number of telephones for one communication satellite has increased from dozens to tens of thousands;Satellite lifetimeFrom several decades to more than ten years;People's stay in space has increased from several hours to more than one year.In short, the main indicators have been improved by 2-3Order of magnitude, while the price dropped significantly.
The achievements of space technology in the past 40 years have been enormous.It has been rapidly and widely used in many fields.Contemporaryspace technologyIts application is not only in military and economic construction, but also in every family and personal life.
1．satellite communication, Radio.The progress of communication satellite technology has made it widely used in the field of communication and broadcasting. Almost all trans ocean communications in the world have been replaced by communication satellites.A lot of traffic is inconvenient, communication trunk lines are not accessible, and communication satellites at sea, in the air, and in disaster areas show more advantages.Satellite communications can provide information aboutinformation transferMore than 100 businesses.Take Intelsat as an example, the benefits of its operational activities reach US $10 billion annually.
satelliteTelevision broadcastingIts application has been well known, which not only enriches people's newscultural life, and foreducationHas made important contributionseducation by satellite televisionChannel, for example, has more than 5000 satellite television education reception stations, with more than 20 million people receiving various kinds of education, and the effect is very good.
2. Satellite navigation and positioning.satellite navigationpositioning systemDue to its wide range, good timeliness and high precision, it has been widely used in navigation of ships, aircraft, land vehicles, and variousengineering constructionAnd positioning in business activities.U.S.AGPS systemOfpositioning accuracy It can reach meter level.High precision satellite navigation and positioning can improve various transportation industriesTransport efficiencyAnd security.
3. Resource survey and mapping.utilizeSatellite photographInvestigate land andocean resourcesIt has been widely used and proved to be an effective method, which not only saves manpower and material resources, but also has a fast time.China has used domestic and foreign satellites toeconomic regionResources and environment.At the same time, we also used satellite photos to mapTopographic mapAnd various professional maps.
4. Meteorology andDisaster forecast。Meteorological satellites not only improve the weather forecastAccuracyAt the same time, the forecast of typhoon, storm, etcSea surface temperatureMonitoring andmarine fisheryThe development of has played an extremely effective role.Since the advent of meteorological satellites, the typhoon weather forecast has been almost accurate.China uses meteorological satellite data toforest fire, flood and other disasters have played an active role in monitoring.
5. Military applications.In application satelliteMilitary satelliteOccupy an important position, includingmilitary reconnaissance, missile early warning, military communication command, navigation andMeteorological supportEtc.Reconnaissance satellites can not only monitor the enemy'smilitary actionAnd can be importantmilitary objectiveConduct a detailed survey.Various military satellites not only provide various needs of troops in peacetime, but also play an important role in wartime.Typical application is 1991Persian Gulf WarCentral AmericaThe use of a variety of military satellites to participate in operations has played an extremely important role.
In the next 30 years, the world's aerospace technology will continue to develop rapidly. The investment of major aerospace countries will mainly focus on the following aspects, with the focus of investment having obvious economic benefitsSpace transportation systemAnd various application satellites.
（1） Space transportation system
Reducing the launch price of spacecraft is the main direction of efforts.ExistingLow orbitTransportation priceIt is about 10000 to 20000 dollars per kilogram, far from the goal of 1000 dollars per kilogram.Therefore, major aerospace countries are studying and developing new worldsTransport system。A variety of new aerospaceTransport scheme。The main point is to develop reusable transportation tools.According to their takeoff and landing modes, they can be roughly divided into three categories:
1. Vertical takeoff and landing.McDonnell Douglas ResearchJib sailIt is a typical representative.It isSingle stage rocket, 8 sets in totalMain engineWhen taking off, all 8 sets will work, and when returning to land, 4 of them will work to slow down and be recycled for reuse.Takeoff weight463 tons, load weight 4.5 tons,Arrow bodyThe total height is 38.7m.
2. Vertical takeoff and horizontal landing.The typical representative is the existing space shuttle of the United States.However, due to the high maintenance and other costs of the space shuttle, the transportation cost per kilogram is still $10000, much more than the designed $350.In order to reduce the freight rate, Martin is studying the new "Adventure Star" program, code named X-33. Its takeoff weight is 1000 tons, and its load weight is 20 tons. Its transportation price is expected to be significantly reduced.
3. Horizontal takeoff and landing.Typical representatives are being studied abroadAerospace aircraft。The air breathing engine is adopted, and the oxygen in the atmosphere and the self-containedliquid hydrogenAs propellant.It can be divided into single stage (US NASP program) and two stages (German Sanger program).The space plane can be used for many times. After sending the satellite into space, it will return to the ground like an airplane for reuse.Due to the technical difficulty and the need for more investment, it is still in the research stage.
Although a variety of reusable transport systems are under research, space launch is still inseparable from one-time launch vehicles for a long time, so the development of new, pollution-free, high thrust, low-cost launch vehicles is still the direction of efforts of space powers.In China's 863 High Technology PlanRound trip transportation systemAnd a new generation of large launch vehicles, have arranged tracking research, concept research andkey technology Pre research.
（2） Artificial satellite
Application satellites will be more commercialized due to their high economic benefits.It is estimated that 1700 satellites will be launched in the next 10 years, worth 120 billion US dollars, of which 70% will beCommercial satelliteAnd great benefits.Therefore, countries and companies that develop space technology first concentrate their funds on developing various artificial satellites.Various application satellites will continue to improve their level, reduce their cost and expand their application scope.In terms of remote sensing, in addition to developing land and marine resource satellites, we will strengthen the monitoring of the Earth's environment and disaster reduction activities.The Earth Mission Plan of the United States and the Earth Environment Monitoring Plan envisaged by Japan and Europe aim toenvironmental change Monitor and make prediction for possible disasters.In terms of satellite communications, in addition to the continuous development of large capacity, multi band, high-power, long-life staticOrbital communication satelliteIn addition, individuals who develop and launch medium and low orbit networks by small satellitesMobile communication systemIt is an important direction today.For example, the United StatesMotorolaSmall satellite group communication system to be built by the company.It is a global network composed of 66 satellites, which can carry out direct personal mobile phone communication worldwide.
It is a trend worth noting that in order to obtain a variety of remote sensing information and navigation positioning at any place in the world in real timeHigh speed transmission, space powers are studying to establishSpace-basedIntegrated Information Network.Its emergence will certainly have a significant impact on economic construction and military applications.UN-SPIDERIt will become an important part of the information highway.someFuturistIt is predicted that by 2010, satellite feed information will become the most commontransmission mode。Its cost is low,developing countryNo needConstruction costExpensiveHardware foundationFacilities.
Various technologies in artificial satellites will continue to innovate. In addition to developing comprehensive large application satellites,MicrosatelliteThe development ofDevelopment trend。Its characteristics of small quality, low cost and fast development have attracted the attention of relevant units.
In the next 15 years, China's application satellites will reach a big stage.The large communication satellites under development not only have large capacity and long service life, but also have multiple frequency bands to adapt to different uses.The different remote sensing satellites in the plan include multiple uses of resources, meteorology, oceans, environment and disasters. They will not only provide domestic services, but also contribute to the world.With regard to the use of satellites for microgravity scientific research, China has become one of the world's advanced countries, making full use of the favorable conditions on the ground and in space, and with the joint support of relevant parties, it has an excellent development prospect, which is likely to be used in microbial, plant breedingsemiconductor material And other aspects.
（3） Large space station
Manned spaceflightIt is an inevitable development for human beings to develop the universe.Unlike the 1960s, the core of today's manned space program is to build a long-life large space station in orbit close to the Earth.The main functions of the space station are as follows: (1) scientific research on remote sensing and microgravity;(2) Stop, repair and refuel the satellite;(3) Assembly of parts or complete machine in the space station;(4) Supplies, astronauts andSpacecraft transferBase.
In the 1980s, the United States decided to develop the Liberty, which weighs about 200 tonsPermanentSpace station.The space station carries 6-8 astronauts.Europe, Canada and Japan participated in the program.The former Soviet Union built Heping 1 Space Station in the late 1980s, and decided to build Heping 2 Space Station in the 1990s, which weighs 115 tons and has six astronauts.However, both the United States and the Soviet Union have made slow progress due to too much investment, and have repeatedly revised and reduced the original scale.The disintegration of the Soviet UnionLater, the Cold War ended.The two countries discuss plans for cooperation and joint construction of large space stations（The International Space Station）To save money.A total of 16 countries, including Europe, Japan and Canada, participated.The International Space Station weighs 423 tons,electric power110 kW,Frame structure, 108m x 88m in length and width, 6 experimental chambers,Sealed cabinThe volume is 1202 cubic meters.Six astronauts.The height of the running track is about 400km, and the inclination of the track is 5l. 6..
On orbit service life is 10-15 years.It was originally planned to be completed in 2002, but due to financial and technical difficulties, it is expected that the completion plan will be delayed for 2-3 years.In addition, the operating costs and benefits of the space station are still a major problem.
In order to adapt to the development of China's space industry in the 21st century,National 863 ProgramIn addition to the concept study of the space station, it also supports the pre research of the key technologies of the space station system and the application of the space station.
It should be mentioned that space robots andVirtual Reality Technology。In this way, scientists and engineers can work on the ground to complete some people's actions in the sky. This is an extremely important field, and many countries in the world are carrying out research.
（4） Deep space exploration
In the past 40 yearsdeep spaceAlthough great achievements have been made in detection, it is still preliminary.In the future, the United States, Russia, Europe and Japan will continue to conduct in-depth exploration of deep space.There are mainly two aspects. One isSolar system planetsThe second is astronomical observation.The exploration in the solar system includes the solar and solar terrestrial space environment, as well as theVenus、Jupiter, MarsMercuryAnd its surrounding environment.The primary survey in the 21st century focuses on the moon and Mars.In addition to launching orbiting spacecraft to take photos of the planet's surface, there will also beLander, walking robots, and plans to build manned bases on the moon and Mars.The United States will launch Mars Global Surveyor several times before 2005.As for astronomical observation, it is expected that there will be severalOrbital observatoryWorking in space.The future plans of American and European Hubble telescopes are promisingGalaxysecret, will make astronomical observation enter anew era。And the ones that will be launchedInfrared observatory, UniverseBackground radiationDetectors and other projects are of great significance at the end of this century.
In the next 30 years, the world will form more complex international space relations, and the era of space monopoly by superpowers will become a multipolar group competitive development.After the United States and the Soviet Union, Europe will gradually form a larger space system;Secondly, Japan has accelerated its pace of becoming a world space power, and its space investment has increased significantly every year;Many other developing countries will also actively participate in space activities.Future InternationalSpace relations can be summarized in six words: cooperation, competition and confrontation.Countries all over the world should be encouragedJoint developmentSpace, but in the real world, cooperation is limited. Projects with common interests in some aspects, such as deep space exploration, Earth environment monitoring, and the construction of the International Space Station, may facilitate cooperation.But there will be no comprehensive cooperation in the space field.There will be fierce competition for launch services of launch vehicles and projects with commercial interests of various application satellites, and the competition will not be fairCommercial competition, inevitablePolitical intervention。However, due to the existence of space military needs, major countries are competing to develop space military systems, so there is a potential confrontation between countries.
Because the development of space technology is of great significance in economy, military, science and technology, and in politics, space technology has greatly improved the country's comprehensive national strength and its position in international activitiesdeveloped countryAll put space on their owndevelopment strategy Is important.Since the development of space technology involves global interests, many major issues discussed internationally are related to it, and various official and non-governmental organizations have been established,the United NationsAlso establishedCommittee on Outer SpaceTo coordinate space activities among countries and formulate variousinternational treaty, laws and regulations.
China's space industry will continue to develop.China is a developing country with limited financial resources. Compared with the world's major aerospace countries, China is a country with low investment in aerospace.Therefore, China can only make contributions in some aerospace fields.In order to make China have a commensurate position in the world aerospace field, we should increase investment.At the same time, China advocates that all countries should work together to develop and utilize space peacefully, with equality and mutual benefit, and jointly contribute to the interests of all mankind.
