On the morning of June 12, 2021, the National Space Administration held a press conference in Beijing to introduce China's first Mars exploration mission.[7]
Chinese name
Planetary exploration
Foreign name
planetary exploration
Instrument
Astronomical telescope
Interpretation
Observe the details of the planet's circular surface
In 1760, it was speculated that the distance between the planets in the solar system and the sun constituted a simple digital series.According to this seriesMarsandJupiterThere should be a gap between the two planets.At the end of the 18th century, many people began to search for this undiscovered planet.famousTitius Bode ruleFor example, European astronomers organized the world's first international scientific research projectGothaUnder the leadership of the Observatory, the whole day is divided into 24 regionsastronomerWe systematically searched for this planet called "ghost" in these 24 regions, but this project did not produce any results
On the evening of January 1, 1801,Giuseppe Piazzi staysicilyupperPalermoWithin the observatoryTaurusPiazzi himself did not participate in the project to find the "ghost", but he heard about the project. He suspected that he had found the "ghost", so he continued to observe the star in the next few days.He reported his findings to GothaobservatoryBut at first he said he found onecomet。Since then Piazzi became ill and could not continue his observation.His discovery report took a long time to reach Gotha. At that time, the star had moved towards the sun and could not be found again.
GaussianAt this time, a method was invented to calculate the orbit of planets and comets. With this method, only a few position points can be used to calculate the orbit of a celestial body. Gauss read Piazzi's discovery and then calculated the position of this celestial body and sent it to Gotha.AubersThe star was rediscovered on the night of December 31, 1801, and later acquiredCeresThis name.In 1802, Obos discovered another celestial body, which he namedZhishen Star。1803Nuptial god star1807Vestacome to light.Until1845The fifth asteroidYishen StarIt was discovered, but since then many asteroids have been discovered quickly.By 1890, there were about 300 known asteroids,
1890Photographyget intoastronomy, which has greatly promoted the development of astronomy.Before discovering an asteroid, astronomers had to record the position of each suspicious star for a long time, and compare the changes between their positions and those of the surrounding stars.But on the photographic negative, one is relative tofixed starThe moving asteroid can be easily identified by pulling a line on the negative.And with the increase of the sensitivity of the film, they will soon be more sensitive than the human eye, even the darker asteroids can be found.The introduction of photography has led to a huge increase in the number of asteroids discovered.1990CCDPhotography technology was introduced andcomputerThe improvement of analytical electronic photography technology has made more asteroids discovered in a short time.The number of asteroids known today is about 700000
After the orbit of an asteroid is determined, astronomers canAlbedoTo estimate its size.In order to analyze the albedo of an asteroid, astronomers usually usevisible lightAlso usedinfraredMeasurement of.However, this method is not reliable because the surface structure and composition of each asteroid may be different, so the analysis of albedo is often wrong,
More accurate data can be usedradarObservation.Astronomers useradio telescopeAs a high-power generator, it can project strong power to asteroidsradio wavesThe distance of the asteroid can be calculated by measuring the velocity of the reflected wave.The shape and size of the asteroid can be deduced from the analysis of other data (diffraction data).In addition, observing asteroidsOccultationWe can also calculate the size of asteroids more accurately,
The human desire for knowledge is endless. When we have a deeper understanding of the earth, we naturally turn our eyes to the broader universe.Because the vast universe has more than 100 billionGalaxy，GalaxyBut one of them is that there are billions of stars in each galaxy, and billions of star systems are formed with each star as the center,solar systemIt is just one of them, which shows how small the earth on which human beings live and multiply is relative to the universe.However, with human capabilities, what we can detect is this small solar system, because modern rockets reach the nearest star at the speed of 20 kilometers per second“Adjacent star”It will take about 65000 years toSiriusIt will take about 130000 years for meaningful exploration outside the solar system to be possible only at a speed close to the speed of light[2]
Main methods
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For many years, human beings have been observing planets far away from the atmosphere, and cannot conduct in-depth research on planets.planetary and interplanetary probe (SeeSpace probe）It opens a new prospect for planetary research.Planetary exploration began in the late 1950s, and in the late 1980s and early 1990s, various countries launched various planets in successiondetector。Detection methods include:
Fly near the planet to take photos
Measure its radiation and magnetic field, such asMariner 4 FilmedMarsThe first batch of photos.
Hard landing on the planet surface
Direct detectionPlanetary atmosphereTemperature, air pressure and other data, such asVenusDetector 4.
Detailed analysis and detection of the planet surface, such as Viking 1 and 2Mars probeVenus 7~16 detectors.These observations have deepened the understanding of the planetgeology、landforms、magnetic field、radiation zone、Atmospheric compositionIt is confirmed that there is no life form on Earth on Mars and Venus.
Activities of major U.S. and Russian planetary probes
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Moon
On January 2, 1959, the Soviet Union launched the first human space probe, "Luna 1".
It mainly measures the magnetic field of the moon and the earthcosmic raysStrength and change of;The solar particle radiation, interstellar gas composition and meteor particles are studied;Made artificial sodium cloud（Artificial comet）And took photos.On September 26 of the same year, it entered heliocentric orbit and became the first man-made planet.On September 13, 1959, the Soviet Union launched "Luna 2", which successfully achieved a hard landing on the moon, becoming the first man-made object to land on the moon.
It was not until 1961 that the United States began to launch a lunar probe, the rover. On August 27, 1962, American scientists successfully launched the first lunar probeVenus probe——Mariner 2 This is also the earliest planetary probe, which flew 34838 kilometers away from Venus,[3]It was not until 1964 that the rover 7 successfully landed on the moon and sent back photos.
Venus
Human exploration of other planets began with Venus, the nearest neighbor of the Earth.The United States first launched the planetary probe Pioneer 5 to Venus on March 11, 1960, but the radio communication was interrupted due to battery failure, which ended in failure.As a result, the Soviet "Venus 3" arrived at Venus for the first time. It made a hard landing in Venus on March 1, 1966, becoming the first probe to reach the planet in the world's space history.
Mars
For a long time, people have high hopes for the possible existence of life on Mars, hoping to investigate it near.On November 1, 1962, the Soviet Union took the lead in launching the world's firstMars probe- "Mars 1" has taken the first step in exploring Mars.However, on the way to Mars, we lost contact with the Earth more than 100 million kilometers away due to communication failure.This time, the Americans took the lead. On November 28, 1964, the United States sent the Mariner 4 probe from Cape Calaveral into the orbit to Mars.On July 15, 1965, it flew 10000 kilometers from the surface of Mars and traveled more than 500 million kilometers, becoming the first man-made planet to bypass Mars.Mariner 4 It is the first time to send a detailed survey image of Mars back to the Earth from near Mars with a TV camera.On May 28, 1971, the Soviet Union sent the "Mars 3" to the sky from Baikonur. On December 2, the same year, it entered the orbit of Mars. The orbital module successfully landed on the surface of Mars, becoming the first human "messenger" to reach Mars in the space world.
Mercury
Mercury is the planet closest to the sun in the solar system. So far, mankind has only sent a probe "Mariner 10" to it.Mariner 10 It is a double star probe. On February 5, 1974, it flew 5300 kilometers away from VenusVenusThe gravitational field flies to Mercury.Its orbital period around the sun is Mercury around the sunOrbital periodIt approaches Mercury twice every six months until the gas controlling the attitude is exhausted.It is equipped with two high-performance cameras, particle detectors, infrared radiometers, ultraviolet photometers, etc. It has detected that Mercury has a spherical magnetic field, the intensity of which is 1% of the earth's magnetic field;Trace helium, argon and neon gases are detected in the extremely thin atmosphere of Mercury;The measured surface temperature of Mercury is - 210-510 ℃, and the diameter of Mercury is 1600 km;Mercury's craters and iron cores similar to the Earth's core were also found.
outer planet
Exoplanets of the solar system——Jupiter, Saturn, Uranus, NeptunePlutoIt is very far from the earth, which is strange and strange to human beings.However, the amazing rings of Saturn and the puzzling red spots of Jupiter are deeply attracting people to explore.Since the early 1970s, the United States has sent two "expeditions", namely, Pioneer and Voyager, to explore the outer space of the solar system.Pioneer 10 flew close to Jupiter in December 1973, covering a journey of 1 billion kilometers, sent back 300 pictures of Jupiter and Ganymede, accelerated to Saturn using Jupiter's gravitational field, and then accelerated with Saturn's gravitational field. In October 1986, it crossed the average orbit of Pluto, becoming the first to fly out of the solar systemspacecraft。
asteroid
Asteroids are similar planets in the solar system that move around the sun, but are much smaller in volume and mass than planets.For a long time, the unmanned exploration of asteroids is mostly to observe or sample the physical and geological characteristics (such as shape, size, mass distribution, etc.) on the surface of asteroids. Because astronauts have subjective initiative, they can conduct on-site investigation, scientific instrument layout, sample collection, sample collection, etc[4]
Exploration in the New Period
In the late 1980s, the United States launched the Magellan Venus probe and Galileo Jupiter probe with more advanced scientific instruments;In the 1990s, lunar explorers, Mars explorersMars Global Surveyor, StardustComet detectorwait.
It can be predicted that with the rapid development of space science and technology, as countries around the world attach importance to the exploration of the mysteries of the universe and the development and utilization of space resources, human interplanetary exploration activities will become more and more active, the purpose and content of exploration will become more in-depth and clear, the means will be more complete and advanced, and space exploration will enter a new stage of development.
Significance of Mars exploration
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Understand the origin and explore life
Lunar and planetary exploration can first help us understand the origin and evolution of the solar system.Scientists hope to understand the solar nebula'sfractionation、condensationAnd formation process;To study the characteristics, origin and evolution of the atmosphere, ionosphere and magnetic field of planets and satellites;The characteristics and evolution history of the topography, geological structure, internal structure of planets and satellites are compared;Grasp the resources and energy of planets and satellites as well as the utilization prospect of special environment;Time series of solar system evolution (element age, formation interval agecelestial bodiesTo retrieve the origin and evolution of the solar system.[5]
The exploration of extraterrestrial life and the origin of life.The premise of exploring extraterrestrial life is the discovery of water.He also pointed out that whether sedimentary rocks can be found in the relevant human exploration of Mars will be the key to the problem.
Develop energy
The enthusiasm of all countries for lunar and planetary exploration is also due to the demand of human society for energy resources and environmental utilization.Taking the solar energy of the moon as an example, it is pointed out that the solar radiation energy reaching the moon every year is about 12 trillion kilowatts.On the moon, the energy density of solar energy is 1.353 kW/m2.If humans build three global parallel solar power plants on the surface of the moon, they can obtain extremely abundant and stable solar energy.The system can be composed of three basic parts, namely solar power generation device on the moon, space microwave or laser conversion and transmission device, and ground receiving and energy conversion device on the earth.
Humans also have high hopes for the development and utilization of the special environment of the moon.Because of the moon's ultrahigh vacuum, no magnetic field, stable geological structure, weak gravity, and high cleanliness, humans can establish astronomical observation stations and research bases on the moon with high precision, low cost, and low operation and maintenance costs;Earth observation stations with environmental monitoring and military strategic significance, laboratories for developing special biological products and new materials, and outposts and transfer stations for deep space exploration can also be established.
In addition, the lunar soil is rich in gases formed by the accumulation of solar wind particles, such as hydrogenhelium、neon、argon、nitrogenIn particular, helium 3, the fusion fuel, is abundant on the moon.Exploring the reserves and distribution of helium 3 on the moon is of great significance to China's future energy strategy.
Prevent asteroid impact
Since the Cenozoic, there have been six major impact events on the earth, each of which has had a significant impact on life on the earth, and will induce climate and environmental disasters andExtinction；Therefore, research on asteroids and comets, especiallyNear Earth AsteroidsTo find the technology and method to prevent it from hitting the earth has become the focus of attention.In addition, asteroids and comets are the original materials left after the formation of the solar system. They preserve a lot of precious information during the formation of the solar system and are "archaeological samples" for studying the formation and evolution of the solar system.Asteroids and comets may also be the cradle of the origin of life on the earth, and there are many types of asteroids with different compositions, which may have resources available to human beings.
Disaster Weather Research
Lunar and planetary exploration can also promote the study of solar activity and space weather environment.Space disaster weather can affect the normal operation and reliability of space-based and ground-based technology systems, and even endanger human activities, health and life. It has attracted more and more attention from all countries.[6]
The success of the Tianwen 1 mission is a landmark achievement of independent innovation and leapfrog development of China's space industry.In the history of China's space development, the Tianwen 1 mission has achieved six firsts. First, the launch of the Earth fire transfer orbit detector was achieved for the first time;Second, the first interplanetary flight;Third, the first soft landing of an extraterrestrial planet;Fourth, it is the first time to realize the inspection and detection of the surface of extraterrestrial planets;Fifth, it is the first time to realize the measurement and control communication with a distance of 400 million kilometers;Sixth, it is the first time to obtain first-hand scientific data of Mars.In the world's space history, Tianwen 1 not only left the mark of Chinese people on Mars for the first time, but also successfully achieved the three goals of circling, landing and patrolling Mars through one mission for the first time, fully demonstrating the wisdom of Chinese spacemen, marking that China has entered the world's advanced ranks in the field of planetary exploration.[7]
Mars exploration process
Space launch on July 23, 2020;
"Space Brake" on February 10, 2021;
Landing on Mars on May 15, 2021;
On May 22, 2021, "Zhurong" will be launched.[7]
Exploration technology innovation
The press conference focused on two aspects: one is to study the influence of aerodynamics. First, through a new experimental method of aerodynamics and heat, the algorithm and experimental means for aerodynamics and heat under Martian atmospheric conditions were determined.The second is the parachute. Aiming at such a supersonic, low dynamic pressure, low density situation, a new parachute type is designed, and the simulation analysis method is improved and the ground experiment scheme is constructed.[7]
