China News Service, October 22 (Zheng Yingying, Ma Shuaisha, Guo Chaokai) According to the news released by China National Space Administration on the 22nd, "Tianwen-1" has passed the first solar transit safely a few days ago, and the measurement and control communication between the probe and the earth Back to normal.

　　Why did "Tianwen No. 1" "lost contact" for a month?

Chu Yingzhi, deputy commander of the Mars Orbiter, Tianwen-1, the Eighth Academy of China Aerospace Science and Technology Corporation, explained the details as follows:

"Tianwen No. 1" Riling renderings courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

What is Riling?

　　China launched its first autonomous Mars exploration mission on July 23, 2020, launching the Tianwen-1 Mars probe, which consists of a Mars orbiter and a landing patrol.

　　According to the laws of movement of celestial bodies, Mars and the earth will be arranged on both sides of the sun every 26 months, and the three celestial bodies are approximately connected in a line.

Mid-September to late October 2021 is such a period. During this period, all Mars probes working on Mars, including the United States, Europe, and India, lost contact with the ground. China’s "Tianwen No. 1" is no exception. .

　　Chu Yingzhi explained that Ri Ling in the traditional sense was proposed for communication satellites.

When detecting Mars, the rover orbits Mars. From a macro point of view, the space position of the rover coincides with Mars.

Then, when Mars is blocked by the sun, or completely submerged by sunlight, the probe will naturally be blocked by the sun.

　　From late September to mid-October 2021, Mars and the earth travel to both sides of the sun, and the three are almost in a straight line, and solar transit occurs. Due to the influence of solar electromagnetic radiation interference, the communication between the device and the earth is interrupted. The orbiter and the Mars rover turned into safe mode and stopped the detection work.

What did "Tianwen No.1" do during the "lost connection" period?

　　"Tianwen No. 1" is currently about 400 million kilometers away from the earth. Even if it flies at the speed of light, it will take us more than 20 minutes to reach the position of the probe.

"Tianwen No.1" is so far away from the earth, we can only know its status through radio signals.

Once the radio signal is interrupted, the ground will not be able to talk to the "Tianwen-1", and will not be able to direct the "Zhurong" rover to conduct scientific research.

In short, it's on holiday!

　　Although there are holidays, "Tianwen No.1" still has "homework".

　　Chu Yingzhi introduced that during the Japanese Ling, the face had no knowledge of the status of "Tianwen No. 1", which put forward higher requirements for the "Tianwen No. 1"'s autonomous control capabilities.

First of all, because ground control personnel have accumulated data and experience on the detector's on-orbit status, the external environmental conditions experienced by the detector during the "lost connection" period are predictable.

Secondly, the detector can take evasive measures against possible risks, and according to the estimated environmental conditions, set the state of the detector's related system before entering the solar transit, and adjust the entire detector state to a relatively simple and reliable " Safe Mode".

Third, the detector has the ability to manage independently. During the solar transit period, the on-board system will be checked regularly. If an abnormal situation is found, it will be handled independently according to the pre-planned plan to ensure that the probe will normally establish communication with the ground after the solar transit. link.

　　After the end of the "cosmic holiday" that people on the earth could not find, the measurement and control communication between the "Tianwen-1" and the earth returned to normal. The Tianwen-1 orbiter will enter the remote sensing mission orbit in early November to carry out global remote sensing exploration of Mars. , Obtain scientific data such as Mars morphology and geological structure, surface material composition and soil type distribution, atmospheric ionosphere, Martian space environment and other scientific data, while taking into account the relay communication during the mission expansion stage of the rover.

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