Tianwen-1 successfully landed on Mars: what happened to the “nine minutes of horror” of the landing?

On July 23, 2020, the Long March 5 rocket was ignited and launched into the sky with much anticipation, and successfully sent the “Tianwen-1” probe into the ground fire transfer orbit, announcing that China’s fire exploration officially started.

On May 15, the Tianwen-1 Mars probe, developed by the General Manager of the Fifth Academy of Aerospace Science and Technology Group, successfully landed on the Utopia Plain in the northern hemisphere of Mars.

In the follow-up, the “Zhurong” rover, named after the god of fire in Chinese mythology, will carry out global imaging of the landing site, self-check and leave the landing platform, and carry out inspection and detection.

So how did Tianwen-1 achieve China’s first exoplanet landing?

It is reported that at about 1 am today, the Tianwen-1 probe was de-orbited in the parking orbit and maneuvered to Mars to enter the orbit.

At about 4 o’clock, the landing rover was separated from the orbiter, and after about 3 hours of flight, it entered the Martian atmosphere. Subsequently, Tianwen-1 experienced the most thrilling “nine minutes of horror” during the entire landing process.

Tianwen-1 successfully landed on Mars: what happened to the “nine minutes of horror” of the landing?

According to media reports, the first fright in “Nine Minutes of Fright” comes from the distance. Due to the long distance between the Earth and Mars, the communication delay reaches about 18 minutes, while the entire landing process is only nine minutes.

Huang Xiangyu, deputy chief designer of the Mars Probe Entry Cabin Guidance and Navigation Control Subsystem of the Fifth Academy of Aerospace Science and Technology Group, said that the whole process is irreversible, and the ground cannot intervene, and the whole process must be decided by the probe itself.

In addition, another scary point is the deceleration stage. Tianwen-1 needs to go through three stages of aerodynamic deceleration, parachute deceleration and dynamic deceleration.

Li Qi, chief designer of the aerodynamics of the Mars Probe of the Fifth Academy of Aerospace Science and Technology Group, said that the shape of the windward outsole entering the cabin this time is a tangential combination of spherical cones.

The advantage of this shape is that it can provide a greater deceleration effect and at the same time provide a greater resistance.

Through friction with the Martian atmosphere, the speed of entering the capsule was reduced from 4.8 kilometers per second to about 460 meters per second.

Although the aerodynamic deceleration has reduced most of the speed, the entry cabin is still in a supersonic state at this time, so the parachute opening process is particularly important to maintain the stability of the attitude.

Finally, after slowing down by the parachute, the Landing Rover will hover in the air and look for a safe landing spot.

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