Author: Guo Chaokai
July-August 2020 is an important "window period" for Mars exploration, and the world ushered in the "fire season". Following the successful launch of the UAE "Hope" probe on July 20, China's first Mars exploration mission, Tianwen-1, will be implemented at the right time from late July to early August, taking the first step in China's planetary exploration.
Why did China, the United States, and the UAE “get together” to explore Mars recently? What is the difference between detectors in different countries? The reporter interviewed relevant experts to find out.
The Long March 5 rocket was vertically transported to the launch area. Recently, the opportunity was selected to implement China's first Mars exploration (planetary exploration project "Tianwen 1" mission). Photo by Zhang Gaoxiang
Why detect fire?
Why is Mars exploration so attractive, attracting countries around the world to carry out exploration missions one after another?
The picture shows the panoramic photos taken by the "Phoenix" Mars rover on Mars released on July 31, 2008. Image source: Visual China
This starts with the relationship between Mars and the earth. Mars is the planet most similar to the earth in the solar system. Exploring Mars and understanding Mars will help humans further understand the formation and evolution of the earth and the solar system, and predict the future trend of the earth. In addition, detecting the origin and evolution of life on Mars can promote research on the origin and evolution of life on Earth and even the solar system, and help human beings understand their own status and ultimate destiny in the universe.
"A large number of indications indicate that Mars was likely to be the same as the present Earth before, but only after billions of years of evolution did it become the current thinner atmosphere and lower temperature." Pang Zhihao, a researcher at the Chinese Academy of Space Technology, told a reporter from China News Agency. , The detection of Mars has a promoting effect on studying the evolution of the earth and preventing the earth from evolving into a second Mars that is difficult for humans to survive.
On September 28, 2015, in Washington, the capital of the United States, this picture jointly released by NASA and the University of Arizona shows that the "seasonal slope patterns" on the Martian hills are strong evidence of liquid water on the surface of Mars.
Pang Zhihao said that in the long run, the earth may one day become unfit for survival due to impacts from extraterrestrial planets and other reasons. Some scientists believe that because Mars is most similar to the Earth, Mars can be transformed into a second home suitable for human habitation, and then immigrate to Mars. "For this reason, we must now have a comprehensive and in-depth understanding of Mars, and lay the foundation for manned to board the fire, transform Mars, and build a Mars base." This is also an important reason why countries around the world are "not tired" of Mars exploration.
The success rate is about 50%
Throughout the world's space history, humans seem to have a "soft spot" for Mars. The exploration activities of Mars in countries around the world date back to the 1960s.
According to Geng Yan, director of the Deep Space Exploration Department of the China National Space Administration's Lunar Exploration and Space Engineering Center, the history of human fire detection can be roughly divided into three stages of development. 1960-1970 was the first stage. At that time, international deep-space exploration was still in the early stage of research. The countries concerned mainly focused on Martian flyover exploration, transmission of Martian pictures and atmospheric parameters, but the success rate of exploration missions was not high. 1970-1990 was the second stage, when the United States and the Soviet Union resumed Mars exploration activities, focusing on orbiting and landing exploration. The 1990s to the present is the third stage, and Mars exploration has once again become a hot spot for deep space exploration. Many countries and regions led by the United States have carried out exploration activities on Mars. The main detection method is landing exploration, and the main goal is to find evidence of the existence of Martian water and signs of life.
American researchers released Mars vibration data, claiming that the "Insight" lander has detected hundreds of Mars vibrations, and believes that the red planet is very "active" and is a "living" star.
In October 1960, the Soviet Union launched two probes "Mars 1A" and "Mars 1B" to Mars, but they all ended in failure. It was not until October 1964 that the U.S. "Sailor 4" probe sent back to Earth the first close-up image of the surface of Mars in human history, opening a new chapter in Mars exploration.
As of June this year, countries around the world have implemented more than 40 fire detection activities. Among them, there are only 24 successful and partially successful missions, with a success rate of about 50%; the ones that can land on Mars and successfully carry out exploration missions are only in the single digits.
Although humans have longed for Mars for a long time, Mars exploration is not easy. Mars is known as the "cemetery" for human probes. So far, 8 probes have successfully landed on Mars: Pirate One, Pirate Two, Pathfinder, Opportunity, Valor, Phoenix, Curiosity, and Insight, all developed by the United States.
In 2003, the European Space Agency (ESA) launched the "Mars Express" satellite and the "Beagle 2" lander, which was the first Mars probe launched by the agency.
Up to now, there are 6 Mars exploration orbiters and 2 landing patrols still in operation. Among them, the orbiters include the United States "Mars Odyssey", "Mars Survey Orbiter", "Mars Atmosphere and Volatile Evolution", Europe's "Mars Express" and "Trace Gas Orbiter" and India's "Mangalian". The only landing patrols that are still working are the American "Curiosity" rover and "Insight" Mars lander.
Three Kingdoms
Combining the revolution cycles of the Earth and Mars, there will be a window period of "Mars opposing the sun" approximately every 26 months. The window period from July to August this year is a favorable time for launching Mars probes. Implementing Mars probes during this time period can save probe fuel, time and effort.
Once the window period is missed, the next good time for Mars exploration can only wait until 2022. Europe originally planned to join the Mars exploration queue this year, but due to the epidemic and other technical factors, the Mars rover developed by ESA and the Russian Space Agency had to be postponed until two years later. Therefore, only China, the United States and the UAE are left for Mars exploration this year.
According to the technological development process and the requirements of mission objectives, humans’ current missions to detect Mars are mainly divided into four types: flyby missions with only a glimpse, surround missions with a comprehensive survey, landing missions with detailed area surveys, and freely movable patrols. task. In the future, human beings will implement the fifth task: sampling and returning.
The three countries implementing fire detection this year have different Mars exploration missions. Among them, the UAE's "Hope" Mars rover only implements orbiting missions, the US "Perseverance" Mars rover plans to complete landing and inspection missions, while China's Tianwen-1 mission will complete orbiting, landing, and inspection at one time. Three goals.
The picture shows the rendering of the "Perseverance" Mars rover.
On July 20, the UAE's "Nozomi" Mars probe was launched at the Tanegashima Space Center in Japan. If the mission is successfully implemented, Nozomi will become the world's first Martian meteorological satellite, which can be used to comprehensively explore the Martian atmosphere, study Martian climate changes, low-altitude weather changes, sand and dust storm forecasts, etc.
The American "Perseverance" rover will replace the aging "Curiosity" rover and continue to explore the environment and signs of life on Mars. Pang Zhihao said that the biggest highlight of the "Perseverance" rover is that the rover will collect 30 samples of the rocks and soil inside Mars and place them on the surface of Mars. In the future, a probe will be launched to bring the samples back to Earth.
The United States currently plans to cooperate with the European Union on a launch mission in 2026 and bring rock samples back to Earth in 2031, but this concept has not yet been formally advanced. If it goes well, these rocks are expected to be the first samples that humans can obtain from Mars, and scientists can use them to analyze whether there is (ex) life on Mars. Previously, the "Curiosity" rover had found traces of water that are vital to life.
Photograph by Zhang Gaoxiang Photo courtesy of the China National Space Administration Press and Propaganda Center
China's first Mars exploration mission, Tianwen-1, which has attracted much attention from the Chinese people, is planned to be implemented in late July to early August. The Tianwen-1 mission will achieve the three missions of Mars orbit, landing and patrol through a single launch. It can not only use the orbiter to carry out global and comprehensive circumnavigation of Mars, but also use the patrol device for local areas of scientific research value. Carry out high-precision, high-resolution detailed surveys.
Tianwen No.1 will open
Compared with the United States, Russia and other countries, China is still a "novice" in Mars exploration. In the process of human fire detection, only the US "Pirate 1" and "Pirate 2" have achieved two missions, namely Mars orbiting and landing through a single launch. Earlier, Europe had twice attempted to achieve two missions to orbit and land on Mars with one launch, but both landings ended in failure and only completed orbit detection.
Photograph by Zhang Gaoxiang Photo courtesy of the China National Space Administration Press and Propaganda Center
Pang Zhihao believes that China’s “Tianwen No. 1” mission adopts the “three kills with one stone” method of fire detection, which has a high starting point and high efficiency, but it has great challenges. If successful, it will enable China's deep space exploration capabilities and levels to achieve leapfrog development.
Geng Yan said that the Chinese Mars Rover carries 13 kinds of payloads, including 7 on the orbiter and 6 on the landing patrol. Five scientific goals were set for the first Mars exploration mission, which mainly involved research on the space environment, morphological features, and surface structure.
"Scientifically speaking, this is a comprehensive mission to study Mars morphology, geology, mineralogy, space environment, soil and water ice distribution, etc., to deepen the Chinese scientific understanding of Mars and the solar system, and to advance comparative planetary science, etc. Research on major issues." Pang Zhihao said.
Soon, China will use the Long March 5 Yaosi rocket at the Wenchang Space Launch Site to send the Tianwen-1 probe into space, and the "planet exploration era" belonging to the Chinese is coming.