Space exploration refers to the exploration of the earth's upper atmosphere and outer space.space scienceA branch of.Soundingrocket、Artificial earth satellite、Artificial planetandspacecraftetc.AerocraftMainly, it forms a complete space exploration system in combination with the ground observation station network and balloons.[1]
Chinese name
Space exploration
Foreign name
space exploration
Detection equipment
Rocket, satellite
Time of origin
1783
Definition
Exploration of the Earth's upper atmosphere and outer space
Although mankind has always yearned for the vast space, the truly meaningful action began with the first launch balloon in 1783. Due to the technical conditions at that time, it is impossible to rise very high, and the detection has great limitations.The V-2 sounding rocket launched after the Second World War only reached an altitude of about 160 kilometers.In the 1950s, a global collaborative observation system was composed of a large number of ground stations, balloons and rockets, but no breakthrough was achieved.The first one on October 4, 1957Artificial earth satelliteThe launch was successful. Since then, human beings have stepped into the gate of space and started a new era of space exploration.In the following 30 yearsInterplanetary spaceEffective detection has been carried out, and the detection field has been expanding.
Space probeIt is a planetary detector that can fly to other celestial bodies in the solar system. The scope of space exploration focuses on the earth environment, space environment, astrophysics, material science and life science.Since the first man-made satellite was launched on October 4, 1957, more than 100 satellites have been launched in the world by 2000Space probe。 Since 1958, humans have used artificial satellites, spaceships, space stations and space shuttles as detection means to detect the near Earth space environment.After 1959, human beings have crossed the near earth space to the moon and even to the deep space beyond the moon for exploration activities.Among them, the lunar exploration is the most detailed.The space environment exploration in China has also developed with the development of space industry.Since "Shijian No.1" in 1971, China has had a history of satellite space environment exploration for more than 30 years.
Many aerospace models under development, such as manned spaceflight, lunar exploration, meteorological satellite, resource satellite, etc., have arranged space environment exploration. Professional exploration satellites, such as the Kuafu Program, are being demonstrated. Many countries or organizations, including the Soviet Union, the United States, Japan, the European Space Agency, have launched space probes in succession, obtaining a large number of unprecedentedAbundant exploration data of the sun, earth, moon and planets provide scientific basis for human understanding, development and utilization of the universe.Nowadays, space-based space environment detection in China has developed into an important discipline field.The space environment detector has become one of the loads widely used in spacecraft.With the development of human society and the continuous improvement of space technology, the breadth and depth of space exploration are also expanding.
Main purpose
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Understand the origin, evolution and current situation of the solar system;Through the comparative study of the main planets in the solar system, we can further understand the formation and evolution of the Earth's environment;Understand the change history of the solar system;Explore the origin and evolution of life.
The space probe has realized the close observation and direct sampling detection of the moon and planets, which has created a new stage for human beings to explore the celestial bodies in the solar system.[1]
Exploring Objects
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Neutral particle
The earth, some planets and a few satellites have an atmosphere, which is mainly composed of neutral atoms and molecules. There are also a few neutral particles in interplanetary space.The detection is mainly conducted by directly sampling and analyzing the composition and density of neutral particles by mass spectrometer.
Most matter in space exists in the form of plasma, the ionospheresolar windThey are composed of plasma, and there are several plasma dense areas in the magnetosphere. The detection instruments mainly includeFaraday cylinderDeceleration potential analyzer, ion trap and probe.
Micrometeoroid
In the solar system, in addition to a large number of larger stars, there are also a large number of granular small materials, whose mass is generally below 10-3 mg.But their speed is generally very high, the maximum speed can reach 70km/s, and they have great penetration ability.Therefore, its measurement has practical significance.
The unstable process of space plasma and the change of electromagnetic field will excite electromagnetic waves and plasma waves of various frequencies.They are not only the products of space physical processes, but also the means to detect the state of space environment.For fluctuations with a change frequency of less than a few hertz, the magnetometer is generally used for measurement. For fluctuations with a higher frequency, the magnetometer is used for measurementReceiver measurement。
magnetic field
Is an important physical field.The magnetic field intensity in various regions of space varies greatly. For example, the magnetic field intensity on the Earth's surface is several orders of magnitude stronger than that in interplanetary space.Instruments for detecting magnetic field mainly include coil magnetometer, fluxgate magnetometer, proton precession magnetometer and optical pump magnetometer.
electric field
Electric field can be generated by the accumulation of electric charge and the change of magnetic field.However, due to the high conductivity of space plasma, the space electric field is generally small.
Characteristic function
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Space exploration
China Academy of Space TechnologyInternational SpaceAssociate EditorPang ZhihaoThe characteristics of global space exploration activities in 2004 are reviewed and the future development trend is analyzed.The world's space exploration in 2004 presented a promising prospect of prosperity. All kinds of new achievements, whether for the progress of aerospace technology or other scientific research,human societyDevelopment has a positive role in promoting.Space exploration has entered a new era of comprehensive development, and has some remarkable characteristics different from the past.First of all, space exploration has become diversified, rather than one or two such as the United States and the Soviet UnioncountryDominate the space exploration field.EuropeIt is rising rapidly, not only has it been launched successfullyMars probe, lunar probe andComet detectorAnd will launch Venus and Mercury probes, and announced its huge "Dawn" space exploration plan at the beginning of 2004, namelyU.S.A"Challenge" to send people to Mars around 2030.China andIndiaIt will also play a role in space exploration.In early 2004, China officially launched the "Chang moth" lunar exploration project, and launched the first satellite in 2006-2007Lunar satellite。In 2004, India decided to advance the original plan of launching the "initial lunar voyage" probe in 2008 to 2007 or earlier.
The second characteristic is that the level of detection technology has been greatly improved.For example, the performance of "Courage" and "Opportunity" is far higher than that of the "Traveler" rover, which was first driven on Mars in 1997. It has realized a large-scale mobile investigation on Mars, representing an important stage of Mars exploration.After 13 months of flight, the European "Wisdom" 1 moondetectorIt entered the orbit around the moon on November 15, 2004, which shows that the first space probe in the world to jointly use solar electric propulsion system and lunar gravity has achieved the expected results, which will play an important role in the development of future aerospace technology.After an interstellar journey of about 7 years and 3.5 billion kilometers, the world's first Saturn dedicated probe "Cassini" finally entered the orbit of Saturn on July 1, 2004. It has sent back many valuable images and will release "Huygens" to the surface of Titan on December 25, 2004Lander。
Space exploration
The third feature is that comet detection has become a "new favorite".In January 2004, the long flying US "Stardust" comet probe andWilderComet 2 rendezvous, and used silica aerosol with very low density to obtain the comet nucleus material for the first time at a very close distance from the comet nucleus. Now it is flying back to the Earth.This will be the first time for humans to send samples to the earth other than the moon, the satellite of the earth, and also the first sample return mission after the Apollo program.These samples can be used for the formation of the universe and the EarthFrom lifeThe source study provides important clues.European Space AgencyOn March 2, 2004, it launched its first comet detector, Rosetta.It will enter the orbit of "Chuliumov Graximenk" comet after 10 years' long journey, and land on the comet landerAerospace historyIt is also unprecedented.The space exploration acquired in 2004 can make people further understandsolar systemAnd the origin of the universe (including life)evolutionTo prepare for the development and utilization of space resources and the expansion of human living space.For example, scientists believe thatcometIn fact, it is the primitive material left over during the generation of the universe. Therefore, the detection of comets will help mankind to understand the origin of life on the earth.The discovery of water on the surface of Mars by the ESA Mars Express probe is also of great significance to mankind, because water can not only be used for human survival on Mars in the future, opening up a second home, but also the hydrogen element in water can be used as fuel for future human interstellar travel.
In general, space exploration will lay a technical foundation for human large-scale development of space resources and solve the problems existing on the earthenergyIssues, population issues andEnvironmental ScienceProblems, etc.For example, the population that the earth can accommodate is limited, about 8-11 billion, so some people have begun to study the scheme of emigration to the outer space;The energy on the earth is also increasingly tense, and the development of space mineral resources is also a major goal of space exploration.
When looking forward to the development trend of space exploration in the future, Pang Zhihao believed that after the end of the Cold War, the scientific significance of space exploration andeconomic performanceAre recognized by more and more countries.Therefore, as countriesEconomicsWith the rapid progress of technology, the number of countries participating in space exploration is gradually increasing, and the depth and breadth of space exploration are also expanding.The plan of space exploration is becoming more and more long-term, and the investment is becoming increasingly huge.On January 14, 2004, President Bush of the United States announced at the headquarters of NASA a new space program aimed at exploring space and extending human footprint to the entire solar system, that is, the United States will create a new generationspacecraftSo that American astronauts could return to the moon to establish a base as early as 2015, and use this as a springboard to send humans to Mars and even more distant space after 2030.The "Dawn" plan introduced by Europe in 2004 is similar to that of the United States, and it is also an unprecedented "package" plan.
Due to the large investment in space exploration, international cooperation will be one of the characteristics of future space exploration.For its part, India has received applications from 20 countries to participate in its lunar exploration program.USAIsrael、Canada、GermanyBoth the European Space Agency (ESA) and the European Space Agency (ESA) have submitted applications for cooperation. They hope to place scientific instruments on the Indian lunar probe, which is scheduled to launch in 2007.USARussiaAnd Europe are also actively exploring ways of international cooperation on manned Mars exploration.In the foreseeable future, the focus of space exploration will still be the moon and Mars, based on the comprehensive consideration of human scientific knowledge, technical level and economic conditions.The strategic goal of lunar exploration is to build a lunar base, develop and utilize the resources, energy and special environment of the moon, and serve the sustainable development of human society.
Europe's "wisdom" No.1 plan, China'sChanghe No.1Both the plan and India's lunar exploration plan aim at lunar resource exploration.The first 20 years of this century will set off a new upsurge of human exploration of Mars.It is a key step for human to carry out deep space exploration.Humans are expected to obtain Mars return samples on the earth in 2011, and finally achieve manned landing on Mars.
Detection mode
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Interplanetary space
Space exploration
Mainly to explore the magnetic field, electric field, charged particles andInterplanetary mediumThe distribution of and changes with time.The detection confirmed the existence of the solar wind and found thatInterplanetary magnetic fieldThe sector structure of the.The spacecraft for exploring interplanetary space can have four types of orbits: one is geocentric orbit. Satellites orbiting the earth can enter the interplanetary space for exploration as long as their apogee exceeds the magnetosphere.The second is heliocentric orbit. It is ideal to explore interplanetary space using aircraft orbiting the sun, and it is often combined with planetary exploration.The third is to fly away from the orbit of the solar system. When the aircraft reaches the third cosmic speed, it can overcome the gravitational effect of the sun, fly to the interstellar space along the parabolic orbit, and can directly detect the part of the solar system outside the Earth orbit.The fourth is the equilibrium point orbit. There is an equilibrium point on the connection line between the sun and the earth, where the gravity of the sun and the earth is exactly equal. The spacecraft can move along an elliptical orbit on a plane perpendicular to the sun earth connection line through this point.It is ideal for fixed-point monitoring of interplanetary physical state.
Exploration of the Moon and Planets
The moon is the nearest to the earthcelestial bodiesPeople explored the moon early and in detail.Launched on July 16, 1969Apollo 11It was the first time to land a man on the moon, conduct field investigation and collect more than 400 kg of moon rock and soil samples.The interplanetary probe series has explored planets, and has developed from inner planets to outer planets.[2]
Near earth space
Space exploration
It mainly refers to the exploration of the earth's upper atmosphere, ionosphere, magnetosphere and other regions.The sounding rocket is an important means of near earth space exploration. It can take the detection instrument to tens to thousands of kilometers high for direct measurement.The successful launch of artificial earth satellites has made it possible to conduct detailed exploration of the Earth's magnetosphere,Earth radiation zoneThe discovery of is the first major discovery of artificial earth satellites and confirms the existence of the earth's magnetosphere.The artificial earth satellite operates in circular or elliptical orbit around the earth, and different orbit types can be selected according to different detection purposes: first, polar circular orbit, with an inclination of about 90 ° to the equator.This kind of orbit is often used in the measurement of the upper atmosphere, ionosphere and upper magnetic field.The second is the high flatness orbit, whose apogee height is much higher than the perigee height, and it is easy to obtain complete magnetospheric profile data.The third is the synchronous orbit. When the satellite is in a circular orbit with a height of 36000 kilometers on the equator, the time for the satellite to circle the earth is exactly the same as the time for the earth to rotate, and it is stationary relative to the earth.The measurement results of this kind of satellite can be easily combined with the ground observation results for analysis.However, in practice, the exploration of near Earth space is mostly carried out by satellite series.
Main methods of detector detection
The space probe is to carry out the space exploration task through the loaded scientific exploration instruments.Space probes are divided into lunar probesplanetary and interplanetary probe , small object detector, etc.The launched space detectors mainly adopt the following methods:
● Fly near the extraterrestrial planet or hard land on its surface to detect and photograph
● Obtain information by means of moon or planetary satellite
● The probe makes soft landing on the surface of the moon or planet and its satellites, and conducts field investigation, shooting, detection and sampling analysis in the form of fixed or rover.
● Use manned or unmanned detectors to take samples after soft landing on the lunar surface and return to the earth for laboratory analysis.
● Carry out roaming flight in deep space
● Conduct impact detection,
● Establish permanent manned base
Several spacecraft will be launched in the next five years to carry out space environment exploration.The layout of space environment detection in different space locations, the richness of detection content, and the continuous stability of detection time make it possible for space environment detection to enter the comprehensive application stage.[3]
Performer
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The space exploration system includes space detectors and deep space networks.The space detector is the space part of the system, which is loaded with scientific detection instruments to carry out space detection tasks.In order to carry out different detection tasks and detect different targets, different space detection systems can be formed.The main methods of space exploration include: ① flying near the moon or planet for close observation; ②Become a man-made satellite of the moon or planet, and carry out long-term repeated observation; ③Hard landing on the moon or planet surface, using the short time before the crash for exploration; ④Soft landing on the surface of the moon or planet for field investigation, or send the obtained samples back to the Earth for research.
In January 1959, the Soviet Union launched the first lunar probe, "Moon" 1, and then the United States launched the "Wanderer" probe“Lunar Orbiter ”, the Surveyor spacecraft and the Apollo spacecraft.In the early 1960s, the United States and the Soviet Union launched a variety of planetary and interplanetary probes, respectively detecting Venus, Mars, Mercury, Jupiter and Saturn, as well as interplanetary space and comets.Among them are Pioneer (US), Venus (USSR), Mariner (US), Mars (USSR), Helios (USSR), Pirate (US) and Voyager (US).By the end of 1984, the United States and the Soviet Union had launched 109 space probes. The Pioneer 10 planetary probe launched by the United States in March 1972 could fly over the average orbit of Pluto by about October 1986, becoming the first spacecraft to fly out of the solar system.
Flight principle When the space probe leaves the earth, it must obtain enough speed (see cosmic speed) to overcome or get rid of the gravity of the earth and realize deep space flight.When the detector runs along a heliocentric elliptical orbit (double tangent orbit) that is tangent to both the Earth orbit and the target planet orbit, it may encounter the target planet, or increase the speed to change the flight orbit, which can shorten the time to reach the target planet.For example, the speed of the US Voyager 2 probe is 0.2 km/s higher than that required by the dual tangent orbit, and the time to reach Jupiter is shortened by nearly a quarter.
In order to ensure that when the detector flies along the double tangent orbit to the tangent of the target planet orbit, the target planet will also run there, the detector must be launched when the Earth and the target planet are in a specific relative position.For example, it takes about 1000 days to fly to Jupiter. When the Jupiter probe is launched, Jupiter should be 83 ° away from the rendezvous point (equivalent to a 1000 day journey of Jupiter in orbit).According to certain relative position requirements, the corresponding date can be found in the astronomical almanac. This favorable launch date usually occurs every one or two years.When orbiting a star, the detector can use the planet gravitational field to accelerate and realize continuous orbiting of multiple planets (see the orbit of the planetary detector).
Technical characteristics Space detector is developed on the basis of artificial earth satellite technology, but compared with artificial earth satellite, space detector has some significant technical characteristics.
Control and navigation space probes fly hundreds of thousands to hundreds of millions of kilometers away from the earth. When entering orbit, there is a slight error in speed and direction, and when reaching the target planet, there will be a big deviation.For example, when the Mars probe enters orbit, the speed error is 1 m/s (about one tenth of the speed), and the distance error when reaching Mars is about 100000 km.Therefore, precise control and navigation must be carried out in the long flight.Flying to the moon is usually controlled by the cooperation of the ground TT&C network and the orbit control system of the space probe (see spacecraft orbit control).The interplanetary flight distance is far, the radio signal transmission time is long, and real-time remote control cannot be carried out on the ground, so the orbit control system of planetary and interplanetary probes should have autonomous navigation capability (see interstellar navigation and control).For example, the US "Pirate" probe flew more than 800 million kilometers in space. After 11 months, it made more than 2000 autonomous orbit adjustments, and finally achieved a soft landing on the surface of Mars, with a landing accuracy of 50 kilometers.In addition, in order to ensure the accurate working attitude of the orbital control engine, the communication antenna is always aimed at the earth, and other systems work normally, the detector also has the ability of autonomous attitude control.
In order to transmit a large amount of detection data and images to the ground, communication must solve the transmission problem of low data rate and long distance.The solution is to use data compression, anti-interference, coherent reception and other technologies on the detectorRadio transmitterThe transmission power and antenna aperture of the antenna are more than 50%, and measurement and control stations or measurement ships equipped with giant parabolic antennas are set up in many places on the earth.The space probe is also equipped with a computer to complete the storage and processing of information.
The intensity of the solar light of the power supply is inversely proportional to the square of the distance from the sun. The outer planet is far away from the sun, where the intensity of the solar light is very weak. Therefore, the outer planet detector cannot use solar cell power but space nuclear power.
Structural space detectors are subject to very severe space environment conditions, and some need special protective structures.For example, when the Helios probe runs in the heliocentric orbit with the perihelion of 0.309 astronomical units (about 46 million kilometers)Solar radiation intensityIt is one order of magnitude higher than man-made earth satellites.Some space probes land or walk on the surface of the moon or planet, and need some special structures, such as flexible wheels suitable for walking on uneven surfaces.
China
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In general, the current space environment detection technology in China started from the beginning of 1990. After more than 10 years of development, it has made considerable progress in scientific research team training, detection technology development and other aspects, and has made considerable achievements.However, due to the weak foundation, compared with foreign advanced detection technologies, there is an obvious gap in general, and many fields are still blank.Short development time, less investment, and lack of ground development, development, testing and calibration equipment have become the key bottleneck restricting the development of detection technology.The calibration test of some detectors can only be achieved through international cooperation.There is a relative shortage of talents, and it takes a process to cultivate experimental physicists who are very familiar with space physics and exploration physics.
In short, China has made remarkable achievements in exploration development, but at the same time, it has a long way to go.With the international double star program, Kuafu program, and space environment detection by meteorological satellites, the development prospect of space environment detection in China will be very broad.On September 21, 2016, China FOSN optical fiber inertial navigation assisted the launch of near space detection airship[4]
The Chinese Academy of Sciences has announced a new plan for space exploration and research of gravitational waves, the "Space Taiji Plan", and said that this plan has been in the process of pre research and is expected to be declared at the end of 2016.
Academician of CASHu Wenrui, chief scientist of the Tai Chi Program, revealed that one of the ideas of the Tai Chi Program is to launch a gravitational wave detection star group composed of three satellites around 2030, and use laser interferometry to directly detect gravitational waves in the medium and low frequency bands. The goal is to observe the gravitational wave radiation generated by the merger of two black holes and celestial bodies with a maximum mass ratio, as well as other cosmic gravitational wave radiation processes.
According to reports, the Taiji Plan is an international cooperation plan for China EU cooperation, with two plans.The first option is to participate in the European Space Agency's eLISA bilateral cooperation plan.The second plan is to launch three Chinese gravitational wave detection satellite groups, travel in space at the same time with the eLISA satellite group launched around 2035, and carry out gravitational wave detection independently. The two groups of satellites complement each other and verify the measurement results.
Why is this plan called "Tai Chi"?Hu Wenrui explained that according to China's cosmology, everything begins to be "Tai Chi", and detectionPrimary gravitational waveIt is to study the origin of the universe, and the figure of Tai Chi is very similar to the image of double black holes.
Hu Wenrui said that the "Space Taiji Program" involves a wide range of disciplines and front-end technologies, and needs to develop space ultra long distance ultra high precision laser measurement and ultra high sensitivityInertial sensor, as well as the next generation of high-end space technologies such as ultra-high precision satellite drag free control, which are of great significance for improving the technical level of space science and deep space exploration in China, and will also play an active role in inertial navigation, earth science, high-precision satellite platform construction and other application fields.
It is reported that space gravitational wave detection has been included in the space 2050 plan formulated by the Chinese Academy of Sciences.In 2008, initiated by the Chinese Academy of Sciences, with the joint participation of several research institutes of the Chinese Academy of Sciences and scientific research units of universities outside the academy, the Space Gravitational Wave Detection Demonstration Group of the Chinese Academy of Sciences was established.After several years of efforts, a working group of "Space Taiji Plan" has been formed, with Hu Wenrui and Wu Yueliang as the chief scientists, and has made many progress in the theory and detection research of gravitational wave sources and satellite technology research.[5]
