Chinanews.com, Beijing, May 15th, title: Demystifying the journey of "Tianwen No.1" falling into flames: Where did it fall?

How to fall?

What to explore?

  Author Guo Chaokai

  After nearly 10 months of "space journey", the Tianwen-1 Landing Patrol successfully landed on the 15th in the pre-selected landing area in the southern part of the Martian Utopia Plain. China's first Mars exploration mission to Mars was a complete success.

The rendering of Tianwen 1 landing on Mars.

Photo courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

  Why did Tianwen No. 1 choose the Utopia Plain as its landing site?

How to safely land on the surface of Mars?

What detection tasks will be carried out in the future?

The reporter interviewed space experts and answered questions.

Where it falls: Utopia Plain

  In the history of human exploration of the solar system, Mars has always given people unlimited expectations and reveries.

Up to now, more than 40 Mars explorations have been carried out globally, but the success rate is only about 50%.

Choosing a suitable landing site is crucial to the successful soft landing of Tianwen-1.

  Mars is so big, and the climatic conditions, topography, and atmospheric conditions are extremely complicated. Where is the ideal landing zone for Tianwen-1?

Zhao Xiaojin, secretary of the Party Committee of the Fifth Academy of China Aerospace Science and Technology Corporation, said in an interview with a reporter from China News Agency that aerospace experts have selected the landing area based on the principle of low project realization risk and high scientific exploration value through full demonstration of science and engineering. In the largest plain on Mars-Utopia Plain.

  According to reports, the preferred landing site for the Tianwen-1 probe is located in the southern Utopia Plain, and the alternative location is located in the magma flow zone of the Elsion Volcano in the southeast of the Utopia Plain.

  Why did the landing zone choose the Utopia Plain?

Experts explained that the Utopia Plain is located in the northern hemisphere of Mars.

The topography, geological structure, surface and subsurface rocks and minerals of the southern and northern hemispheres of Mars are very different.

The southern part of Mars is highlands, and 60% of these highlands are covered with "scarred" craters.

The northern part of Mars is a low plain filled with volcanic lava. The terrain is flat, with fewer craters, a younger geological age, and a thinner crust. Therefore, the Utopia Plain in the Northern Hemisphere is of course chosen as the landing zone.

The rendering of Tianwen 1 landing on Mars.

Photo courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

How to fall: "Nine Minutes in Black"

  After selecting the landing site, how to successfully land on Mars is a big problem.

Experts said that the Tianwen No. 1 landing patrol must reduce the speed from about 20,000 kilometers per hour to zero and achieve a soft landing in about 9 minutes. This process can be called "black nine minutes."

  The entire landing process of Tianwen No. 1 is roughly divided into three steps: entry-deceleration-soft landing, referred to as EDL (Entry, Descent, Landing).

According to Wang Chuang, the chief designer of the Mars Probe, the General Design Department of the Fifth Academy of China Aerospace Science and Technology Corporation, after entering the Martian atmosphere, Tianwen-1 first uses the Martian atmosphere to aerodynamically decelerate. This process overcomes the high temperature and attitude deviation.

After the pneumatic deceleration was completed, the descent speed of Tianwen No. 1 was also reduced by about 90%.

  "Then Tianwen No.1 opened the parachute to decelerate the parachute. When the speed dropped to 100m/s, Tianwen No.1 decelerated by the reverse thrust engine, and entered the dynamic deceleration stage from the atmospheric deceleration stage." Wang Chuang introduced, in the distance At 100 meters from the surface of Mars, Tianwen-1 entered the hovering phase. After completing obstacle avoidance and slow descent, the landing patrol reached the surface of Mars under the protection of the buffer mechanism.

  It is worth mentioning that although China has had lunar surface landing experience before, the soft landing mission of Tianwen-1 to Mars is even more difficult.

On the one hand, there is an atmosphere on the surface of Mars (the density of the atmosphere on the surface of Mars is about 1% of the density of the atmosphere on the earth's surface), and the Martian environment is more complicated than that of the moon; on the other hand, Mars is farther away from the earth, and the communication delay is about 20 minutes. During the entire landing process, the distant geoscientists had no time to do anything, so they could only rely on Tianwen-1 to complete the "black nine minutes" on their own.

The rendering of Tianwen 1 landing on Mars.

Photo courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

What to explore: 13 loads continue to exert force

  After successfully landing on Mars, what scientific research will Tianwen-1 carry out on Mars?

Aerospace experts said that the Tianwen-1 probe carried 13 scientific payloads, of which 7 were on the orbiter above Mars and 6 were on the "Zhurong" rover.

  These scientific payloads have five major missions, which mainly involve research on the Martian space environment, surface morphology and soil surface structure, etc., and will bring China first-hand information on Mars.

Among them, meteorological-related research projects will collect atmospheric data about temperature, pressure, wind speed and wind direction, and study the magnetic and gravitational fields of Mars, which will also answer the public's curiosity about Mars.

  For a long time, people are most concerned about whether there is life on Mars, which has become a hot issue in Mars exploration.

According to expert analysis, the Utopia Plain is likely to be the location of the ancient ocean on Mars, and the landing site of Tianwen-1 is located at the junction of the ancient ocean and the ancient land.

In September 1976, the US "Pirate II" Mars rover also landed here and sent back photos of frost.

  The latest scientific exploration found that there is a large amount of groundwater ice under the shallow bottom of the Martian Utopia Plain 1 to 10 meters above the ground, and the water storage is equivalent to the largest freshwater lake on the earth-Lake Superior. There is water in the ground on Mars. Does it mean that Mars has existed or that life has existed? Does it mean that Mars is the future of humans on Earth? These questions have to be further answered by Tianwen No.1 in this magical place of Utopia Plain. (Finish)

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