The Temptation Of Mars: China'S "Tianwen" Expedition, Exploring Over 400 Million Kilometers

After the long space mission of "Hainan Long March" of more than four and a half hours, Hainan's long space exploration mission was launched for the first time in more than four and a half hours.

The successful launch of tianwen-1 has opened a new chapter in China's space industry. In fact, "tianwen-1" is not China's first Mars probe. As early as November 9, 2011, China's "Yinghuo-1" Mars probe carried Russian rockets to Mars, but unfortunately, the mission ended in failure.

Subsequently, China's Mars exploration remained silent for many years. Until January 2016, China's first Mars exploration mission was approved by the state. In April this year, the National Space Administration announced that China's Mars exploration mission was named "Tianwen", which led to today's "tianwen-1" flight. Compared with Yinghuo-1, tianwen-1 will be more significant because it is the first Mars probe launched by China.

According to the plan, tianwen-1 will orbit, land and inspect Mars in one launch mission. If successful, China will become the second country after the United States to independently master the Mars landing inspection and exploration technology.

Human exploration of Mars started in the 1960s. Up to now, 44 activities have been carried out (the United Arab Emirates hope Mars probe launched on July 20, 2020 is on the way), including 21 in the United States, 19 in the Soviet Union / Russia, 1 in Japan, 2 in the European Space Agency and 1 in India. Of all the missions, only 23 were completely or partially successful, and the success rate was just over half. Therefore, Mars is also known as "the graveyard of explorers".

But even so, human exploration of Mars has never stopped. This is because in the solar system, Mars is close to the earth and the natural environment is most similar to the earth, so it has become the first choice for human beings to go out of the Earth Moon system to carry out deep space exploration.

In addition, a series of major discoveries made on Mars in recent years have also strengthened the belief of human beings to go to Mars. The discovery of liquid and ancient lakes on Mars. In 2018, the European Space Agency's Mars Express discovered a suspected groundwater lake on Mars, which greatly increased the possibility of more water and even life on Mars.

In the face of such a wonderful Mars, China's Aerospace will not be absent. The name of "Tianwen" comes from Qu Yuan's long poem Tianwen, which expresses Qu Yuan's spirit of seeking truth, which coincides with the spirit of China's deep space exploration series.

However, there are still many successful missions to Mars before the successful launch of Mars.

The temptation of Mars

Compared with the moon, Mars is too far away from the earth. The distance between the moon and the earth is about 360000-400000 km, while that of Mars is between 56 million and 400 million km. The longest distance of the earth fire is about 1000 times that of the Earth Moon.

An aerospace expert told the 21st century economic reporter that the long distance has brought many new challenges to Mars exploration. First of all, in terms of launch window, lunar exploration theoretically has a launch opportunity every month, while Mars exploration only has one launch opportunity every 26 months.

Secondly, the longest time delay of radio signal transmission between the earth and Mars can reach 23 minutes, while the delay between the earth and the moon is only a few seconds. This difference puts forward higher requirements for the communication ability of the earth and the earth and the autonomous operation ability of the probe. In addition, because Mars is farther away from the sun than the earth and the moon, Mars probes have to consider energy acquisition and thermal control issues.

Obviously, Mars exploration is several orders of magnitude more difficult than lunar exploration. For China, "tianwen-1" needs to realize three major tasks of "circling, descending and patrolling". Before this, no country has achieved this feat, so the task of "tianwen-1" is even more difficult.

It can be divided into four stages: exploration, landing, landing and landing. Among them, entering the descent and landing phase is the most risky link.

Pang Zhihao, an aerospace expert, once told reporters of the 21st century economic report that the difficulty of the probe into Mars orbit is like playing a golf ball from Paris and falling into a hole in Tokyo.

Especially in the near fire acquisition, separation of the two spacecraft orbit control, these operations will determine the success or failure of the mission, and only one chance. But at this time, the distance between the detector and the earth is about 300 million kilometers, and the signal delay is more than 15 minutes. Therefore, it is not realistic to rely on the ground for control. Therefore, all data must be injected in advance to allow the detector to complete independently.

"This is a great test for the autonomous management and control ability of the detector." A person familiar with the space field told reporters that there should be no deviation at this time. If the entry point of the probe is too far from Mars, it can not be captured by Mars' gravity and pass over Mars. If the entry point is too close to Mars, it may crash into the atmosphere of Mars.

After entering Mars orbit, the descent and landing phases will be more difficult. Under normal circumstances, it only takes about 7 minutes for the probe to enter the Martian atmosphere and finally land, which is also known as "7 minutes of terror".

It's terrifying because there are thousands of complex operations involved in this process, and like the near fire capture, these operations can only be done by pre-set and then autonomous by the lander. Moreover, it is more difficult to decelerate the surface of Mars by 1% compared with the atmosphere of Mars, which is more difficult to slow down the atmosphere of Mars and the atmosphere.

In order to overcome these challenges, China Aerospace has made numerous efforts in the past few years. Among them, the successful combination of "Queqiao + chang'e-4 + yutu-2" has also laid a solid technical foundation for Mars exploration.

On November 14, 2019, China's first hovering obstacle avoidance test of the lander for Mars exploration mission was completed in Huailai, Hebei Province. The test successfully simulated the hovering, obstacle avoidance and slow descent process of the lander in the Martian environment. In March this year, the wireless joint test of the Mars exploration mission was also successfully completed. So far, tianwen-1 is ready to go.

The journey of "Heaven asked"

It is reported that the "launch vehicle" is mainly composed of a launch vehicle and a ground launch vehicle. Among them. The total mass of the lander is about 5 tons.

There are 7 Mars medium resolution and high resolution magnetic instruments, including medium resolution and high resolution Mars magnetic instruments.

The landing rover is composed of an entry module and a Mars rover. According to the plan, the entry module will complete the Mars entry, descent and landing missions, and the Mars rover will carry out patrol exploration in the landing area. The rover will be equipped with six scientific payloads, including multispectral camera, subsurface detection radar, Mars surface composition detector, Mars surface magnetic field detector, Mars meteorological instrument and Terrain Camera.

According to the plan, the Long March 5 carrier rocket will fly with "Tianwen 1" for about seven months and arrive at the earth fire transfer orbit. In the middle and late February 2021, the probe and the carrier rocket will be separated, and then after halfway correction, the near fire point will be braked to realize Mars capture.

Next, "tianwen-1" will enter an elliptical orbit around the fire with a period of about 10 Martian days, then select an aircraft to carry out orbital maneuver, and then enter an elliptical parking orbit with a cycle of about 2 Mars days, which will take about 2 months.

Next, it is expected that on April 23, 2021, "tianwen-1" will select an aircraft to release the landing Rover after completing the pre exploration of the landing area and the adjustment of the landing site. The orbiter will immediately adjust its orbit and enter the relay communication orbit to provide relay communication links for the Mars rover and carry out scientific exploration.

After the lander is separated from the orbiter, it enters the Martian atmosphere and realizes soft landing by multi-stage deceleration such as aerodynamic shape, parachute, reverse thruster and landing leg buffer. The rover will then separate from the carrier platform and conduct scientific exploration on the surface of Mars.

"The mariner" has found the most successful lakes in the earth's bottom of the earth, such as the Martian Mars lander and the mariner's discovery of the largest lakes in the earth's bottom, such as the Martian lander's discovery of the largest lakes in the earth's bottom, such as the Martian lander's discovery of the largest lakes in the earth's bottom of the earth, such as the Martian lander's discovery of the largest lakes in the earth's oceans, such as the Martian Mars lander and the mariner's discovery of the largest lakes in Direct evidence of the existence of methane organic compounds was found.

The "tianwen-1" mission to Mars also has five scientific objectives: one is to study the morphology and geological structure of Mars. To explore the geological features and geomorphology of Mars with high precision, and to obtain the data of global topography and geomorphology.

The second is to study the soil characteristics and water ice distribution on the surface of Mars. To explore the types of Martian soil, weathering sedimentary characteristics and global distribution, search for water ice information, and carry out the research on the layered structure of Martian soil profile.

The third is to study the material composition of Mars surface. To identify the types of Martian surface rocks, to explore secondary minerals on the surface of Mars, and to carry out surface mineral composition analysis.

The fourth is to study the atmospheric ionosphere, surface climate and environmental characteristics of Mars. To explore the space environment of Mars and the temperature, pressure and wind fields on the surface of Mars, and to carry out the research on the structure of Mars ionosphere and the seasonal variation of surface weather.

The physical properties of Mars and the physical structure of Mars are studied. Research on the early geological evolution history of Mars and the mass distribution and gravity field in Mars.

Some aerospace practitioners told reporters that if China's first Mars exploration mission is successfully completed, it will undoubtedly be a milestone in China's aerospace industry. However, it should not be overstated because it does not represent that China's space technology has achieved overtaking in a curve. This actually fills up the gap in China over the past decades.

However, the success of tianwen-1 will represent that China has the basic ability to further carry out deep space exploration. Standing on the shoulder of Mars, China can also start planning further space travel. For Mars, the next goal is to break through the more difficult sample return before 2030.

Now, we need to give Tianwen 1 some time to wait for its good news next year.

On July 23, 2020, Hainan Wenchang Satellite Launch Center launched the tianwen-1 Mars probe using the Long March 5 spacecraft. People were watching the rocket launch on the beach. People's vision

Voice over

In the midsummer of Hainan, the heat wave is striking. However, on the beach of qishuiwan, not far from Wenchang rocket launching site, there are still many spectators waiting to watch the launch of tianwen-1 in the scorching sun.

Among these audiences, there are tourists who come to visit, astronomical enthusiasts who come specially, and student teams organized by schools. A tourist from Guangzhou told reporters that he had come to Hainan for a tour, and later learned that there was a rocket launch, so he took a day to watch. Before that, the tourist had only seen the rocket launch on television.

It's 12 o'clock in the morning, but it's not expected that the rocket will be launched at 9 o'clock. He told reporters that there were many people on the beach who came earlier than him.

A teacher from Sanya Branch of the high school affiliated to the National People's Congress came to watch with dozens of students. He told reporters that for this kind of space launch, as long as the audience is allowed to watch, their school will organize students to come over. Last year, he brought another student team here.

The teacher said that taking students to watch the rocket launch on the spot has a great effect on cultivating students' curiosity and interest, because the feeling on the spot must be more profound than that in books or in front of TV.

An astronomy enthusiast who had come to watch the launch many times told the reporter that every time he watched the rocket launch, he was very excited, especially at the moment of ignition and launching, there would always be a burst of tears in his eyes.

The astronomy enthusiast also said that affected by the epidemic situation, the number of people on the scene today was significantly less than that when "fat 5" went around last year. "At that time, there were orchestras playing spontaneously on the beach, and the scene was very lively.".

In addition, the 21st century economic reporter also noticed that the launch of "tianwen-1" has also led to a lot of commercial activities. For example, on the spot, brand companies in watch, automobile, real estate, games and other industries have set up exhibition booths.

In fact, as a national project, the content related to the general public is very limited. However, just as the audience is needed in the competition field, people's attention and enthusiasm for the space industry can also inspire the astronauts.

In order to increase the public's sense of participation in the space industry, many space projects will carry out name calling activities. For example, the name "Tianwen" of China's Mars exploration mission is collected from the world. According to the reporter's understanding, next, the center for lunar exploration and space engineering of the National Space Administration will jointly launch a global naming campaign for China's first Mars rover. What is the name of China's first Mars Rover? Let's wait and see.

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