"Tianwen 1" flying over 465 million kilometers is expected to be "captured" around New Year's Eve
Journey around Mars is about to start
Around the Lunar New Year's Eve, the "Tianwen-1" probe, which performed my country's first Mars exploration mission, will perform near-fire braking, and will be "captured" by Mars after "braking".
This means that after a long flight of more than 200 days, "Tianwen-1" will finally arrive in orbit around Mars, and officially start the Mars exploration journey.
"Brake" to slow down and enter the ring fire track after being "captured"
There is gravitational attraction between all things, and the super gravitational force of the "big object" drags the small object past. This process can be simply understood as the "Tianwen-1" probe being "captured" by the gravity of Mars.
The "brake" action is extremely critical.
After the rover reaches within the gravitational range of Mars, it needs to brake by "stepping on the brakes" to slow down the rover and prevent it from flying out or hitting Mars.
After being accurately "captured" by Mars, the probe becomes a Martian satellite and enters the phase of orbiting the fire.
Not long ago, the Chang'e-5 probe performed a "brake" after reaching the moon, and completed the near-moon braking; compared to the lunar exploration mission, the near-fire braking of the "Tianwen-1" is much more difficult.
There is still only one chance, but because the ground fire is too far away and the communication delay exceeds 10 minutes, the ground cannot do any real-time control and intervention.
"We use the engine start command as a program control, and it has been solidified in the program. It depends on the program to carry out independently." said Li Zhencai, deputy commander of the "Tianwen No. 1" probe of the Fifth Academy of China Aerospace Science and Technology Corporation. The control team issued an instruction to "start the engine", and this time, the detector will judge by itself and automatically execute the start. The ground team can only learn the final completion of the "brake" based on the telemetry data nearly an hour later.
As of February 9, "Tianwen No. 1" has been in orbit for about 201 days. The detector systems are currently in good condition, with a flight mileage of more than 465 million kilometers.
Four midway corrections have been completed, and it will take about 3 months for the fire to fall
At 12:41 on July 23, 2020, my country's first Mars exploration mission "Tianwen-1" probe took off. After more than 2,000 seconds of flight, the probe successfully entered the scheduled orbit and started the journey of rushing into fire.
The distance between Mars and the Earth varies periodically during the earth-fire journey. The distance between Mars and the earth is about 50 million kilometers at the latest and more than 400 million kilometers at the farthest.
Since the Earth and Mars are also moving around the sun, the probe's mileage is farther than the distance between it and the Earth.
It is understood that when the "Tianwen-1" probe arrives near Mars, it will be about 190 million kilometers away from Earth, and its total flight mileage will reach 470 million kilometers.
At this time, more than half a year has passed since launch.
During this period, “Tianwen-1” chased Mars all the way along the “arc” orbit. So far, it has successfully completed the earth-moon photo, the probe “self-portrait”, four midway corrections, deep-space maneuvering, payload self-check, etc. .
On the evening of February 5th, in order to ensure the implementation of Mars "capture" as planned, the "Tianwen-1" probe engine ignited and successfully completed the fourth midway correction of the ground fire transfer section.
At the same time, a "beautiful photo" was refreshed.
The first image of Mars sent back by "Tianwen-1" was announced. This is the first image of Mars taken by a Chinese probe. It was taken by "Tianwen-1" at a distance of about 2.2 million kilometers from Mars.
In the picture, iconic landforms such as the Plains of Asidalia on Mars, the Plains of Kruse, and Vale of Sailors are clearly visible.
The landing site of "Tianwen-1" is the Utopian Plain in the northern hemisphere of Mars.
However, after the near-fire braking, it will have to orbit Mars for a scientific expedition for about three months to conduct a preliminary exploration of the landing area, and then it can land when the weather conditions are good.
Zhang Rongqiao, chief designer of China’s first Mars exploration mission, said that the biggest feature of the Mars exploration project is its long distance and new environment. “The logic of spacecraft design is to first understand the environment to be visited, and use various technologies, methods, and measures to protect the spacecraft. Adapt to this environment, but the characteristic of deep space exploration is to go to an environment that is not yet known."
"At present, our understanding of Mars is still very limited. During the period from ring fire to falling fire, the probe will make a pre-detection of the landing area, so that we can land more safely and more controllable." China Aerospace Science and Technology Wang Chuang, the overall chief designer of the Mars Rover of the Group's Fifth Academy, told reporters.
A mission to achieve circumnavigation, landing, patrol and detection, landing will be another critical moment
"Tianwen-1" is my country's first Mars exploration mission. It is planned to achieve the three major objectives of "orbiting, landing, and patrolling" through a single launch, which is the first time in the world's space history.
The landing about 3 months later is another critical moment.
Mars has a thin atmosphere and high uncertainty.
When descending, the lander enters the Martian atmosphere at a speed of up to 18,000 kilometers per hour, and super-high-speed friction will generate super-high temperatures. After experiencing thousands of degrees of high temperature, it will slow down with the help of parachutes.
Afterwards, it will turn on the fully automatic driving mode, autonomously complete deceleration and hover, avoid the complicated terrain on the surface of Mars, and then slowly fall to the surface of Mars.
The entire process can only be executed autonomously by the GNC (Navigation, Guidance, Control) system on the probe.
This process is described as "black 7 minutes", thrilling and extremely difficult.
"The core and most difficult part of our Mars exploration mission is the aerodynamic shape and the parachute deceleration process after the probe enters the Martian atmosphere. There is only one chance." said Sun Zezhou, chief designer of the Mars probe of the Fifth Academy of China Aerospace Science and Technology Corporation. The research and development team has made full preparations and specially designed a new aerodynamic shape and a new type of parachute.
The "Tianwen-1" probe also carried my country's first Mars rover.
After the soft landing, the rover will "drive" to the surface of Mars for exploration.
Currently, the Mars rover is currently being called for, and there are ten shortlisted names, namely Hongyi, Qilin, Nezha, Chitu, Zhurong, Seeking, Hot Wheels, Chasing Dreams, Tianxing and Xinghuo.
It is reported that the finalized name of China's first Mars rover will be announced on the occasion of the "Tianwen-1" rover landing on Mars.
"Who can make the most of it?" About 2,300 years ago, the poet Qu Yuan used the long poem "Heaven Questions" to ask questions about the cosmos and the natural world; as my country's first interplanetary exploration mission, "Heaven Question No. 1" carried Our curiosity and yearning rush to Mars to explore the many mysteries of this planet.
(Our reporter Chai Yaxin)