The successful landing of tianwen-1 on Mars will help to establish a reference frame for the study of the earth and point out the direction for the future development of human beings on the earth.

On May 15, China's first Mars exploration mission, tianwen-1, landed in the pre selected landing area in the south of the Martian Utopian plain, leaving China's "footprint" on Mars for the first time. China has thus become the third country in the world to land on the surface of Mars after the United States and the Soviet Union, which is of great significance.

Planetary exploration mission is an important task in China's space exploration project. On July 23, 2020, tianwen-1 (including landing platform, orbiter and Mars Rover) was launched by long March-5 yao-4 carrier rocket at China Wenchang space launch site on the northeast coast of Hainan Island. After nearly 10 months in space, tianwen-1 finally set foot on Mars.

Successful landing on other planets, there is a very high threshold

The successful landing of tianwen-1 on Mars first means that China's extraterrestrial space technology has reached an unprecedented height in entering other planets, and this is based on the successful landing of eight planets as the test standard.

From earth to Mars, it seems simple, but without long-term flying spacecraft and successful landing technology, it is difficult for human beings to set foot on other planets. Therefore, "successful landing" is a very high threshold. Previously, only nine of the 21 Mars landing missions that have been carried out in the world have been successful.

Mars exploration has three target missions of "circling, landing and patrolling". Among them, "landing" fire is the most difficult step, and the moment known as "dark nine minutes" is the blind spot for landing on Mars. Because there is no ready-made airport on Mars, no standard runway, no tower navigation, and no actual control by astronauts on the spacecraft.

Tianwen-1 is composed of landing Rover (landing Rover) and orbiter. After the fire, the lander was divided into two parts: the lander and the rover, the latter being the "zhurong" Mars rover. The whole process of lander landing on Mars is abbreviated as EDL, which means the first step to enter, the second step to descend and the third step to land.

After tianwen-1's lander and orbiter bid farewell to each other, the EDL process started. The lander needs to enter the Martian atmosphere by ballistic method, high-speed aerodynamic deceleration, parachute deployment deceleration, backstepping dynamic deceleration and landing buffer, and finally make a soft landing on the Martian surface.

From passing through the Martian atmosphere to soft landing on the Martian surface, the speed of the rover will slow down from 4.8 km / s to nearly 0, which takes about 9 minutes. Within 9 minutes, the lander must execute nearly a thousand instructions timely and accurately. Moreover, the supersonic spacecraft will squeeze the atmosphere to produce ionization, which will lead to "black barrier" phenomenon, resulting in communication interruption, affecting the communication between the spacecraft and the ground, and Beijing's flight control center is unable to grasp its landing situation.

China's successful landing of tianwen-1 on Mars by injecting navigation information and action instructions into the spacecraft 17 hours in advance means that we have mastered the key to Mars, which is a great success in the process of space exploration.

Setting foot on Mars will help to establish a reference system for studying the earth

Leaving "footprints" on Mars and greeting Mars is only the first step. There are more and more important tasks waiting for tianwen-1.

This mission mainly landed on the Mars body of zhurong, which is also the process of testing the Mars rover and China's exploration technology. In this process, zhurong Mars rover will successively carry out global imaging of landing points, self inspection, leave the landing platform and carry out patrol exploration.

According to the plan, the Mars rover zhurong will explore Mars for 90 days. In addition to conducting exploration operations, it will also send back to earth what it saw and heard on Mars hundreds of millions of kilometers away, so as to help people know and understand Mars.

The importance of "close contact" with Mars is that Mars can be used as a reference frame for the earth. On the one hand, we can acquire the cognition of extraterrestrial space and form a new cosmology and knowledge system; On the other hand, we can get resources from Mars that are not available on earth to enrich and build the earth.

So far, human beings have carried out a lot of research on the earth's surface, deep, atmosphere and biosphere, but it is still not thorough. One important reason is the lack of reference system.

In addition to the atmosphere, temperature, water and day night conversion, there are also mountains, valleys, volcanoes, glaciers, cold and dry areas on Mars. If we study these environments on Mars, we can make the earth and Mars reference each other, find the similarities and differences between them, and point out the direction of human development in the future.