China News Service, Beijing, February 10 (Guo Chaokai, Zheng Yingying) At 19:52 on February 10, Beijing time, the Tianwen No. 1 detector implemented near-fire capture braking, and the 3000N track-controlled engine of the orbiter ignited for about 15 minutes. The vehicle successfully entered a large elliptical orbit with an altitude of about 400 kilometers near the fire point, a period of about 10 Earth days, and an inclination of about 10o. It became China’s first man-made Mars satellite and realized the first step of "orbiting, landing, and patrol". The goal of orbiting Mars was successful.

Drawing: Li Xueyao

　　The “braking” of the Tianwen-1 probe in space not only requires “one-time success”, and the risk is very high.

If you step on early, if the speed drops too low, you will fall into the atmosphere and hit Mars; if you step on too late, you can’t be captured by Mars’ gravity and fly away from Mars.

　　The "capture window" of Mars' gravity is limited, which requires the probe to reduce its speed from 28km/s (kilometers per second) to about 1km/s within 15 minutes.

Unlike conventional satellites that can be controlled in real time by the ground, during the "braking capture" process, the Tianwen-1 probe is about 192 million kilometers away from the earth, and the one-way time delay of data communication between the earth and the probe exceeds 10.7 minutes. It is necessary to completely rely on itself to complete engine ignition and shutdown, overcome disturbances during engine ignition, and achieve precise control of ignition direction and ignition duration.

　　After China’s first Mars exploration mission entered the Mars capture phase from the ground fire transfer phase, the medium-resolution cameras, high-resolution cameras, magnetometers, mineral spectrometers, ion and neutral particle detection and detection carried by the Tianwen-1 orbiter Loads such as energy particle detectors will begin to work one after another to conduct multi-dimensional exploration of Mars.

Effect picture.

Photo courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

　　Since its successful launch on July 23, 2020, the Tianwen-1 probe has flown for 202 days, completing one deep-space maneuver and four midway corrections.

When it arrived on Mars, the Tianwen-1 probe had a flight distance of about 475 million kilometers and a distance of about 192 million kilometers from the earth. The one-way delay of the communication between the device and the ground was about 10.7 minutes, and the systems were in good condition.

　　The follow-up Tianwen-1 probe will also undergo several orbital adjustments, enter the Mars moored orbit, and carry out pre-selected landing zone exploration. It is planned to choose an opportunity to land on Mars from May to June 2021 and carry out inspections.

(Finish)