Just now, Tianwen-1 successfully landed on Mars, leaving behind China's footprints for the first time!

At 7:18 on May 15, 2021, my country's first Mars rover "Tianwen-1" successfully landed in the pre-selected landing area in the southern Utopia Plain in the northern hemisphere of Mars. The lander carried my country's first Mars rover-"Zhu Rong" .

Source: @中国

The Tianwen-1 probe is composed of an orbiter and a landing patrol module. The landing patrol module includes the "Zhurong" rover and the entry module.

At about 1 am, the Tianwen-1 probe was de-orbited in its parked orbit and maneuvered until Mars entered orbit. At 4 o'clock, the landing patrol was separated from the orbiter. After about 3 hours of flight, it entered the Martian atmosphere. After about 9 minutes of deceleration, hovering, obstacle avoidance, and buffering, it successfully landed on the pre-selected landing zone. About 30 minutes after the two devices are separated, the orbiter will ascend and return to the parking orbit to provide relay communication for the landing patrol. In the future, the "Zhurong" rover will successively carry out global imaging of the landing site, self-check, leave the landing platform, and conduct inspections.

Landing on Mars, thrilling 9 minutes

It is understood that the entry Descent Landing EDL (Entry Descent Landing EDL) of the Zhurong lander can be roughly divided into five stages: descending, separating, decelerating, hovering, and landing, as shown in the following figure:

Source: China Aerospace News

The entire landing process took about 9 minutes, but faced many difficulties.

The first is the signal delay . Tianwen No.1 is very far away from the earth, and the one-way signal delay is more than 10 minutes. When landing, the staff on the earth cannot control the probe. Therefore, the automatic control of Mars landing is extremely important. The Mars rover must be corrected at any time according to the preset landing trajectory, and the attitude must be controlled so that the heat-resistant part faces the atmosphere. To ensure a successful landing, automatic attitude control and trajectory control are the most critical and the biggest difficulty.

In addition, the Mars rover enters the Martian atmosphere at a very high speed, which will cause violent friction. It is necessary to ensure that the components of the Mars rover work normally under high temperature conditions. Therefore, another difficulty is that the Mars rover decelerates .

China's road to Mars exploration

my country's first Mars exploration mission was formally approved in 2016. It plans to achieve orbit, land and patrol missions through a single mission, conduct global and comprehensive circumnavigation of Mars, and conduct regional patrols on the surface of Mars.

At 12:41 on July 23, 2020, the Tianwen-1 probe was launched by the Long March 5 Yaosi carrier rocket from the Wenchang Space Launch Site in Hainan, and was successfully sent into the intended orbit. The probe arrived near Mars after flying in the ground-fire transfer orbit for about 7 months, and entered the ring-fire orbit after completing Mars capture on February 10, 2021. It carried out scientific exploration and obtained a large amount of scientific data. After successfully landing on Mars, the Tianwen-1 probe will launch scientific exploration missions to Mars such as orbiting, landing, and patrolling. Its stated goal is to find evidence of current and past life and assess the planet's environment.

Reference link:

• https://zh.wikipedia.org/wiki/%E5%A4%A9%E9%97%AE%E4%B8%80%E5%8F%B7
• https://mp.weixin.qq.com/s?__biz=MjM5OTUyMzAwOQ==&mid=2654160234&idx=1&sn=164719c396a5eda2a995f718ab5222d7&chksm=bcfdc2c48b8a4bd2cb78581f81cf439aa800ffa9c9fcb618000afed0dbd2998994d25b45f9a4&mpshare=1&scene=1&srcid=0515WzOfeXtDNN7ogZPT8Xx8&sharer_sharetime=1621041162481&sharer_shareid=25f66f2583339eda80990afae77dc8d4&version=3.1.2.6203&platform=mac#rd
• https://mp.weixin.qq.com/s?__biz=MzA5NTk1MDMxMg==&mid=2652490594&idx=1&sn=4f285b5255eb143d59f66b27bf647547&chksm=8b5aefe5bc2d66f391a6e641123864937f2684e0232d2fc2af650cf7a7901c6a343e31c40eab&mpshare=1&scene=1&srcid=0515UkcWTTE51dQRtAwm6pYb&sharer_sharetime=1621041118069&sharer_shareid=25f66f2583339eda80990afae77dc8d4&version=3.1.2.6203&platform=mac#rd