Tianwen No.1: Come once on the fire detection road
Intern reporter Yu Ziyue
In July of this year, Mars exploration ushered in the launch of the "window period", once missed, it will have to wait for nearly 26 months. As this critical node approaches, China ’s first Mars exploration project, which has been planning for many years, finally has its own name-"Tianwen 1", and the Chinese planetary exploration mission is named "Tianwen" series".
China ’s first Mars exploration mission is scheduled to be carried out at the Wenchang space launch site in China in July. Jia Yang, deputy chief designer of the Mars Probe of the China Academy of Aerospace Science and Technology, said previously that the goal of this exploration mission is to achieve Mars orbit, landing, and patrol detection targets through a single launch, and to conduct global and comprehensive exploration of Mars, and Carry out detailed inspections and surveys of key areas on the surface of Mars.
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Throughout the history of human spaceflight, people seem to have a soft spot for Mars. So far, there have been more than 40 Mars exploration activities in the world. Why?
Zhang Wei, a researcher at the Space Application Engineering and Technology Center of the Chinese Academy of Sciences, gave the answer in an interview with the Science and Technology Daily: "Mars is the planet in the solar system that has the closest characteristics to the earth, and it is the first choice for human migration in the future."
Needless to say, the temptation of human "second home" is too great. "Mars may have had environmental conditions suitable for life on Earth in the past." Zhang Wei said that studying the long-term evolution of Martian geology, surface composition, and the interaction of rocks with air and water will help us understand the possible existence of Martian life. And the reasons for disappearance, and then analyze and predict the future of the earth.
Zhang Wei introduced that human detection of Mars usually includes orbiting, landing, patrolling, sampling and returning, and manned landing detection. This year, "Tianwen No. 1" launches three kinds of detection targets at the same time, including rounding, landing, and patrol, which is really "less money, more work."
Behind the multi-task, complex technology and high risks are rare, and there are few international precedents. The US Pirate 1 and Pirate 2 Mars probes have achieved two types of detection targets: rounding and landing in one launch; Europe has also made similar attempts, but it has not succeeded, and only achieved "one action, one benefit".
According to Ye Peijian, the chief scientist of deep space exploration and space science at the fifth academy of China Aerospace Science and Technology Corporation and an academician of the Chinese Academy of Sciences, China's first Mars exploration mission is actually a "curvy overtaking." In an interview with the media, he said that if we want to surpass, we need to use existing technology to achieve "two steps and go one step". In fact, China has carried out relevant research very early. If China's Mars exploration orbiting, landing, and inspection plans can be completed in one step, this leap-forward plan will be the first in the world.
Join forces
Prepare for the "test"
As Academician Ye Peijian said, China's Mars exploration plan has been planned for a long time.
"In August 2010, eight academicians jointly proposed to the state to carry out a comprehensive demonstration of deep space exploration beyond the moon. The National Defense Science and Technology Industry Bureau immediately organized experts to carry out development planning and implementation program demonstration." Geng Yan, director of the General Department of Deep Space Exploration of the Aerospace Engineering Center, wrote that the first Mars exploration is the starting point and focus of deep space exploration. After three iterations and deepening of the implementation plan, it was officially launched in January 2016.
Since then, a deep space exploration drama aimed at Mars has officially begun.
The first Mars exploration mission consisted of the project as a whole and five major systems: a probe, a launch vehicle, a launch site, measurement and control, and ground applications. Among them, the detector and launch vehicle were developed by China Aerospace Science and Technology Corporation.
In September 2017, the 3rd Beijing International Forum on Lunar and Deep Space Exploration came to hear that the relevant payloads of China ’s Mars exploration mission have been basically determined, involving space environment exploration, Mars surface exploration, Mars surface structure exploration and other fields.
The Long March 5 Yao-4 rocket used in this mission is also fully prepared. In January 2020, the Long March No. 5 Yao 4 rocket thrust hydrogen-oxygen engine successfully completed the final verification before the final assembly of the assembly, marking that the performance of this engine reached the predetermined requirements and was about to enter the stage of rocket assembly.
The measurement and control system for the Mars probe is based on the existing aerospace measurement and control network and deep space measurement and control network, including the Beijing Aerospace Flight Control Center and the Jiamusi 66-meter antenna measurement and control station. , Flight control, on-orbit management and emergency response systems. In March 2020, the Beijing Aerospace Flight Control Center completed the wireless joint test of the Mars exploration mission, fully verified the matching and consistency of the interface between the detector and the ground system, and conducted a comprehensive test of various schemes, technical status, software and hardware systems, It laid a solid foundation for the smooth development of the task.
China's Wenchang Space Launch Site is also actively preparing for war. On May 5, 2020, Zhang Xueyu, commander of the command site of the first flight mission of the Long March 5B carrier rocket, said that China ’s Wenchang space launch site already has high-density launch combat capabilities, high-medium and low-orbit space delivery capabilities and mission parallelism. Test launch capability. At present, the launch site system will continue to organize and implement major space launch missions such as Mars exploration, Chang'e V and subsequent space station construction phase flight missions, and resolutely win "double victory" in epidemic prevention and control and space launch missions.
The whole hoisting of the ground application system was completed, which attracted much attention. On April 25, 2020, the ground application system of the first Mars exploration project undertaken by the National Astronomical Observatory of the Chinese Academy of Sciences successfully completed the overall lifting of the 70-meter antenna reflector in Tianjin. China ’s first Mars exploration project deputy chief designer and chief of the ground application system Commander Li Chunlai said that the 70-meter antenna will be fully equipped with data reception capabilities for Mars exploration this October.
At present, the detection mission plan is proceeding in an orderly manner, and the relevant staff are working overtime to prepare for the upcoming "big test".
Difficulties
Challenges and opportunities coexist
According to the movement relationship between Mars and the Earth, combined with reality, considering the capabilities of the current launch vehicle, it will be found that there is only a favorable launch opportunity for the Mars probe every 26 months.
This year is the outbreak of global Mars exploration. It is understood that the United States and the UAE are also planning to launch probes this year, and the European-Russian joint Mars exploration mission, which also had this plan before, was postponed to 2022 due to outbreaks and other reasons.
According to statistics, so far the global Mars exploration success rate is about 40%, due to the many difficulties in the Mars exploration project.
Zhang Wei said that the biggest difficulty of Mars exploration lies in "terror 7 minutes"-during the process of entering, descending and landing, the probe's speed must be reduced from 20,000 kilometers to zero within 7 minutes. This requires a combination of various deceleration methods, including aerodynamic shape, parachute and reverse thrust, and also requires autonomous navigation control technology to ensure.
"Furthermore, it takes more than 200 days for the probe to fly from the earth to Mars, and a long road requires reliable communication." Zhang Wei told the Science and Technology Daily reporter. In addition, under the premise of certain volume and weight constraints, the Mars probe It is also necessary to fully improve the utilization of energy, including high-efficiency multi-junction solar cell technology, high-efficiency battery technology, and nuclear power supplies with high energy density and long life.
From this point of view, it is self-evidently difficult to carry out "round", "fall" and "cruise" detection targets at the same time in China. This fearlessness and courage to challenge stems from the rapid development of China's deep space exploration technology and the unremitting efforts of countless aerospace science and technology workers!