Author: Guo Chaokai

  On May 15, Beijing time, the Tianwen-1 Landing Patrol steadily landed on the pre-selected landing zone-the Utopia Plain in the northern hemisphere of Mars. China's first Mars exploration mission to Mars was successfully landed.

  The Tianwen-1 probe was launched on July 23, 2020, reached Mars in February this year and was successfully captured by Mars.

After three months of rejuvenation, Tianwen No. 1 has recently dropped its orbit and completed the separation of its landing patrol device and orbiter.

After a successful soft landing on the surface of Mars, China's first Mars rover "Zhu Rong" will also leave the landing platform to carry out inspections and other tasks.

  What are the difficulties of the Tianwen-1 landing on Mars this time?

In what way will the "Zhurong" rover explore Mars?

What's the story behind it?

Landing on Mars experienced "Black Nine Minutes"

  After being successfully captured by Mars, Tianwen-1 finally launched the second phase of its mission-"Landing" after several months of adequate preparation.

Mars has many plains in the northern hemisphere, and many mountains in the southern hemisphere. Therefore, the site of the soft landing of the Tianwen-1 Landing Patrol on Mars was chosen to be in the southern Utopia Plain in the northern hemisphere of Mars.

  The entire landing process 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.

In general, the entire process of Tianwen No. 1 will be reduced from a speed of about 20,000 kilometers/hour to 0 meters/hour in 9 minutes.

  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 surface of the earth), and the environment of Mars is more complicated than that of the moon; 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.

 13 payloads help Tianwen-1 explore Mars

  After the successful landing, Tianwen-1's series mission of "circumnavigation", "patrol" and "patrol" finally reached the final step.

After landing, the Tianwen-1 entry module forwarded the landing information to the ground through the orbiter.

The entry module and the "Zhu Rong" rover have completed the ramp and the solar wing antenna deployment. The "Zhu Rong" rover will send the news of the successful deployment back to the ground as soon as possible.

After everything is ready, the rover will leave the entry capsule autonomously, reach the surface of the fire, and start a new journey.

  Exploring Mars is not only a breakthrough in engineering missions, but also a breakthrough in the field of planetary science.

In addition to conventional communications, energy (solar panels), support structures, power systems, etc., Tianwen-1 carries 13 scientific payloads as a whole, of which 7 are on the orbiter above Mars and 6 are distributed on Mars. In the car.

  According to reports, the seven scientific payloads carried by the Tianwen-1 orbiter are medium-resolution cameras, high-resolution cameras, subsurface detection radar, Martian mineral spectrometer, Martian magnetometer, Martian ion and neutral particle analysis. Instrument, Mars energy particle analyzer.

The six scientific payloads distributed on the Mars rover are multispectral cameras, subsurface detection radars, Mars surface composition detectors, Mars surface magnetic field detectors, Mars weather measuring instruments, and terrain cameras.

  According to experts, these scientific payloads have five major missions, which mainly involve research on the Martian space environment, surface morphology, and soil surface structure. They 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, such as what kind of climate Mars is.

 How does "Zhurong" "survive in the wilderness"?

  Previously, Zhang Rongqiao, chief designer of China's first Mars exploration mission, announced the configuration details of the "Zhu Rong" rover: The rover weighs about 240 kilograms, is independently driven by 6 wheels, carries 6 loads, and its solar wing is in the shape of a butterfly wing.

Therefore, some people vividly compare the "Zhurong" rover to the "Martian butterfly."

  The Martian environment is notoriously bad. To complete its mission, the "Zhurong" rover must be strong enough to "survive".

China has visited the moon several times and has accumulated valuable experience.

But the biggest difference between the moon and Mars is that the surface of the moon is almost vacuum, while Mars has an atmosphere, which greatly increases the difficulty of exploring Mars.

  Judging from the pictures taken by the Mars rover in the past, the topography of Mars seems to be no different from the desert Gobi on Earth.

But in fact, the wind speed on Mars can reach 180 meters per second, which is almost three times the wind speed of a super typhoon on Earth.

This violent gale like a beast will set off a large amount of dust and rocks, forming a huge sandstorm.

Let the "eyes" of the "Zhurong" rover be covered with dust, and the "wings" are no longer flexible.

Faced with this situation, the designer used a new type of material, which is not easy to get dust, and even if it gets wet, it can be shaken off by vibration.

  The surface of Mars is also densely covered with obstacles such as stones, which makes the rover need to be more "careful" in order to avoid being stuck by obstacles and causing delays in operation.

So how can the rover take every step more safely?

The designers also came up with a countermeasure.

In the laboratory of the Fifth Academy of China Aerospace Science and Technology Corporation, there is a Mars rover exactly the same as the "Zhurong".

When the "Zhurong" encounters complicated road conditions on Mars, the Mars rover on Earth will simulate the road conditions on Mars and issue instructions after confirming that it is correct.

  According to the plan, after 90 days of intense work on Mars, the "Zhurong" rover will end its patrol and exploration work, and the Tianwen-1 orbiter will also adjust its orbit to carry out scientific exploration.

  "A butterfly in the tropical rainforest of the Amazon River Basin in South America, occasionally flapping its wings, can cause a tornado in Texas in two weeks." Some scholars have used the above language to describe the "butterfly effect."

Now that the "Zhu Rong", the world-renowned "Martian Butterfly" has successfully landed on Mars, what surprises it will bring to us in the future, let us wait and see.

  The source of the pictures in the article are: The Fifth Academy of China Aerospace Science and Technology Corporation