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Original title: The “braking” of the Tianwen-1 probe entering the orbit of Mars is very important
Representations of the “Tianwen-1” landing pad and the Mars roverAt 7:52 p.m. on February 10, the first probe of my country’s Mars exploration mission “Tianwen-1” implemented the Mars capture brake. After the engine ran for about 15 minutes, the probe smoothly entered the near-fire altitude of about 400 kilometers with a period of about The large elliptical orbit with 10 Earth days and an inclination of about 10o has become the My country’s first man-made satellite of Mars. It is the first step to achieve the mission objective of “orbit, orbit and patrol”, successfully opening the way to orbit Mars.
Chengdu Commercial Daily-Red Star News learned from the China Sixth Academy Aerospace Science and Technology Group that the “Tianwen-1” propulsion system developed by the Academy was working perfectly. The 3000N main engine implemented ignition and braking for more than 800 seconds, assisting my country’s first Mars exploration The vehicle goes into orbit around Mars.
Salim Marie, Assistant Director-General for Science and Technology Affairs, Mohamed Bin Rashid Space Center, United Arab Emirates:
We successfully put the “Hope” probe into orbit around Mars, and China’s “Tianwen-1” was also successfully put into orbit. These explorations will benefit the entire world.
Professor Gao Yang, Director of the “Space Technology Laboratory for Autonomous and Robotic Systems”, Surrey Space Center, UK:
This marks another solid step forward in China’s aerospace industry towards deep space exploration.
Vladimir Sulkin, Principal Investigator at the Russian State Institute of Astronomy Stenberg:
In recent years, China’s aerospace science and technology has developed rapidly, and the lunar exploration project has been a great success. On the contrary, the mission of the expedition to Mars is more complicated. I hope that “Tianwen-1” will successfully reach Mars and the rover it is carrying will successfully land on the surface of Mars.
“Brakes”
Missing the exit detection trip can die
Since its successful launch on July 23, 2020, the “Tianwen-1” probe has been flying for 202 days, with a flight mileage of about 475 million kilometers when it reaches Mars, and a distance of about 192 million kilometers. from the earth. After approximately 10.7 minutes, all systems are in good condition.
The reporter learned from the China Sixth Academy Aerospace Science and Technology Corporation that on the Mars Rover “Tianwen-1”, the Sixth Academy developed and delivered the orbiter and landing patrol propulsion subsystem, with a total of 48 large and small engines. . The task of these engines is to provide reliable power for the process of hovering, obstacle avoidance and slow descent of the landing patrol during landing, and to provide orbital transfer, brake capture, orbit adjustment and attitude control for the orbiter with the precise power required. for the control.
The Earth’s fire transfer orbit is understood to be like a high-speed closed-loop elliptical centered on the Sun. Mars is just one exit at this high speed. Once the propulsion system does not turn on and brake in time, it will help the probe to get off the high speed of the Mars exit. Then you can only lose the exit, and next time it will take several years to pass it. Once such a situation occurs, it is very likely that the “Tianwen No. 1” Mars exploration voyage will face the danger of a half death.
To avoid this phenomenon, at this extremely critical braking stage, the research team from the Sixth Academy of Aerospace Engineering devised a precise braking plan.
“A good start”
High lane-entry precision after near-fire braking
Li Hejun, director of the Deep Space Exploration Systems Department of the Sixth Academy of the Sixth Academy of the Mars Rover Propulsion System Development Unit “Tianwen No. 1″, introduced that the orbiter propulsion system engine ” Tianwen No. 1 “implements ignition and brakes and decelerates through engine thrust. Control to slow down the probe so that it can be captured by the gravity of Mars. This action is vividly called “pressing the brake.”
Since the probe was put into orbit, the orbiter’s propulsion subsystem has successfully completed 4 intermediate fixes and 1 deep space maneuvering orbit change mission. More than 20 subsystem orbit attitude control motors have passed the in-orbit ignition test. The thrust parameters are accurate and normal, and the subsystem parameters are stable and normal.
Lan Xiaohui, 6th Aerospace Academy chief engine model engineer and technical leader of the Institute 11’s 3000N fire detection main engine, said this 3000N engine work is the longest work time of this type of engine. The working conditions are very perfect. After near-fire braking The high precision of the orbit has gained a “good start” for the smooth development of the next ring flight. After braking, “Tianwen No.1” changed from a large elliptical orbit around the sun to a Martian orbit, which will be the most critical step for the subsequent exploration of the orbit of Mars, the soft landing on the surface of Mars and the patrol exploration.
The “Tianwen-1” tracking will also undergo various orbital adjustments, enter the mooring orbit of Mars and carry out the exploration of the preselected landing zone. It is planned to choose an opportunity to land on Mars from May to June 2021 and carry out inspections.
Ren Jiangbo, Chengdu Commercial Daily-Red Star News reporter
Two difficulties landing on Mars
After successfully landing on Mars, how many obstacles will “Tianwen 1” pass? Liu Tongjie, deputy director of the National Space Administration’s Lunar Space Exploration and Engineering Center and spokesperson for China’s first Mars exploration mission, presented in a media interview:
The first difficulty is finding a very good little window after orbiting Mars for 2 to 3 months to allow it to enter the Martian atmosphere and complete the landing. Mars has an atmosphere and the density of its atmosphere is about 1% of the Earth’s atmosphere. In the process of deceleration, it has atmospheric deceleration, pneumatic deceleration, parachute deceleration and reverse thrust motor deceleration, and finally lands on the surface of Mars by landing legs to absorb the impact energy. This process is very difficult. Due to the considerable distance, there is also a long delay from Mars back to the ground control ground station, and real-time control is impossible. Therefore, the process of entry, deceleration and soft landing is based on the “Tianwen No. 1” to complete a series of actions autonomously, not by ground control.
The second difficulty is that after the soft landing on the surface of Mars, the work is not yet complete, and the rover must be released on the surface of Mars, let it go and explore. It is also very difficult for the six science instruments on the Mars rover to work, because we still have very little knowledge of the environment on the surface of Mars. If the soft landing on the surface of Mars is not flat enough or the posture is not correct enough, how can the rover lower? You can descend from the front of the court or from behind, depending on the position and terrain of the fall.
Three “stars” shine in February
From February 9 to 18, the UAE’s “Hope” probe, China’s “Tianwen-1” probe and the US’s “Perseverance” rover will successively fly to Mars. Why are you exploring Mars right now? The experts explained that this coincides with the window period for the spacecraft to fly to Mars and the plans of the three countries to explore Mars.
Alexander Zheleznyakov, a well-known Russian aerospace historian, told reporters that as a near-Earth planet, Mars has always attracted humans. In addition to observing with astronomical telescopes, the probe is the main tool for studying Mars. “The relative position of Mars and Earth makes the timing of the Mars probe launch very important. Sending a probe to Mars when the distance between the two is relatively close can reduce the probe’s power consumption and shorten the time it takes to reach Mars. The launch window of the Mars rover is July 2020. Therefore, the UAE, China and the US rover left the same month and arrived at Mars in a while Similary “.
Pang Zhihao, the leading science communication expert of the national space exploration technology, told reporters that the three countries that sent spacecraft to Mars this time have different plans for space exploration, but the timing of the launch of this mission coincides. The window period for launching spacecraft to explore Mars is every 26 months. The United States has space launches related to Mars research almost every 26 months. Sending the “Perseverance” rover to Mars is an established mission and its departure time only in the most recent launch window, at the end of July 2020. According to the Xinhua News Agency
