Chang'e 5 will be launched within the year. Why do we go to the moon to "dig earth"?
In order to commemorate the first successful landing of humans on the moon, July 20th is designated as Human Lunar Day every year. And half a century later, China will also collect lunar soil--
Our reporter Fu Yifei
Recently, with the approach of the Mars exploration window, fire detection projects in various countries have been gaining momentum. In fact, mankind’s enthusiasm for deep space exploration has never weakened, whether it is for Mars or the closest celestial body to us-the moon.
At 20:17:43 on July 20, 1969, the Apollo 11 spacecraft landed in the lunar calm sea area. American astronaut Armstrong stamped a deep mark on the surface of the moon. This is the first time that humans have successfully landed on the moon. To commemorate this exciting moment, July 20th is designated as Human Lunar Day every year.
However, the biggest contribution of the Apollo project in the field of science is not the footprint of Armstrong, but the return of rocks from the moon. From 1969 to 1972, the United States completed 6 manned moon landings, brought back about 382 kilograms of lunar samples, and obtained a lot of scientific results.
After a lapse of half a century, China will finally collect lunar soil. According to the plan, my country will launch the Chang'e-5 probe at the end of October 2020 to collect lunar samples and bring them back to Earth through two methods: scooping and drilling.
Why do we have to go to the moon to "dig earth"? What role can these samples play? Today, we will explore together.
Not only bring new understanding of the moon
Decades ago, as the United States and the Soviet Union successively obtained samples from the moon, the moon, which people could only look up and guess for thousands of years, was pulled under the microscope of scientists, and its mystery was uncovered layer by layer.
In addition to understanding the moon, the study of these samples has also helped scientists establish modern planetary science, providing a reference for understanding the geological evolution of various planets.
Eric Jarvin, a geologist at the Smithsonian's National Museum of Natural History in the United States, once wrote that the rocks from the moon have completely changed our understanding of the three major issues of the lunar surface properties, the origin of the moon, and the evolution of the solar system.
For example, planetary chemists analyzed the isotopic composition of lunar samples and found that most of these rocks are older than earth rocks, and are between 3 billion and 4.5 billion years old. Then they built a model to estimate the age of any location on the moon.
Zheng Yongchun, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, believes that the lunar soil is a transition zone from the lunar solid lithosphere to the space of the solar system and contains a lot of information about the relevant area. The study of the lunar soil not only involves the moon itself, but also contains important information about the space matter and energy of the solar system. These include the historical records of the early evolution of the solar system, the history of cosmic ray exposure and irradiation of lunar rocks and lunar soil, the history of degassing of volatiles in the moon, the composition of the solar wind, the compositional characteristics of the solar surface layer, the impact of small objects and micrometeorites on the moon History etc.
Ryan Ziegler, the sample leader of the National Aeronautics and Space Administration (NASA) Apollo program, once revealed that in decades, NASA has received more than 3,000 applications for studying special lunar samples, and more than 500 scientists from more than ten countries An application was made. NASA has distributed more than 50,000 lunar samples to scientists in astronomy, biology, chemistry, engineering, materials science, medicine, geology and other fields for research.
In 1978, when the then US National Security Advisor Brzezinski visited China, he presented China with a 1 gram sample of the moon. This stone, which can only be seen clearly with a magnifying glass, is divided into two halves. One half is stored in the Beijing Planetarium, and the other half is researched by a team led by Ouyang Ziyuan, chief scientist of the Chinese Lunar Exploration Project. "We figured out what it is, what its age is, what it contains, all clear." Ouyang Ziyuan said, researchers not only judged that the sample was collected in the Apollo 17 mission, and confirmed the collection The location, even analyzed whether the area where the stone is exposed to sunlight. Based on their research on this stone, they have published 40 articles.
In addition to scientific achievements, studying lunar rocks is also of great significance to the development of lunar resources. Pang Zhihao, the chief science communication expert of national space exploration technology, introduced that one of the important results of studying lunar samples is the discovery that they contain helium-3, which makes scientists extremely excited.
Helium-3 is recognized worldwide as an efficient, clean and safe fuel for nuclear fusion power generation. According to calculations, the energy that 100 tons of helium-3 can create is equivalent to the total energy consumed in the world in one year. The amount of helium-3 on the earth is extremely small, and only 500 kilograms are known and easily accessible in the world. Early detection results show that the amount of helium-3 in the shallow layer of the moon is as high as millions of tons, which is enough to solve the problem of humans. Energy worries. In fact, with the deepening of human understanding of the moon, scientists have discovered that the total reserves of lunar helium-3 are likely to be more.
Chinese lunar sampling does not "burn money"
Although lunar samples have brought important scientific achievements to mankind, in the Apollo project, the cost to obtain samples is also staggering. Someone calculated that the cost of the 382 kilograms of samples the United States took back from the moon was equivalent to more than 30 times the cost of diamonds of the same weight.
This is not surprising, because the Apollo project was originally a very expensive project. "There was a saying at the time: every launch of a Saturn V heavy rocket used for landing on the moon is equivalent to burning an aircraft carrier." said Yang Yuguang, a researcher at the Second Research Institute of China Aerospace Science and Industry Corporation.
According to Pang Zhihao, a Saturn V heavy rocket costs up to 500 million US dollars, and an Apollo moon landing spacecraft is more than ten times more expensive than equivalent heavy gold. The Apollo program lasted 11 years and cost US$25.5 billion. To implement the program, NASA’s annual budget accounts for about 4.5% of the US government’s total budget.
Moreover, the main purpose of the Apollo program is to send astronauts to the moon, and collecting samples is only one of the astronauts' "jobs." Pang Zhihao believes that astronauts carrying out sampling tasks have greater flexibility and can be targeted. At the same time, the astronauts can carry out mobile detection, especially the lunar rover that has been carried since the Apollo 15 mission. Its speed can reach about 10 kilometers per hour, which can greatly increase the range of astronauts' activities. However, manned missions are not only costly, but also technically complex. Although the Americans were able to send astronauts to the moon half a century ago, it is admirable, but Yang Yuguang believes that the Apollo engineering technology approach is relatively aggressive, some equipment redundancy is done very little, and it is very risky from a safety perspective.
The Chang'e-5 mission to be implemented in my country is an unmanned exploration mission built around the main target of moon sampling and return. Pang Zhihao said that China's lunar exploration project has been gradual, and the development from unmanned to manned is more scientific and the cost is much lower. However, the Chang'e-5 probe can only operate in situ after landing.
According to Liu Jizhong, director of the National Space Administration's Lunar Exploration and Space Engineering Center, the landing site of the Chang'e-5 probe is the Lumke Mountains in the northwest of the front of the moon. Ouyang Ziyuan once said that the landing site chosen by our country is thousands of kilometers away from the landing site of the Apollo program, and new phenomena and discoveries will be ushered in.
Will be a "post" for mankind in space
Since the Soviet Union launched the "Lunar One" in 1959 and opened the prelude to human lunar exploration, humans have launched more than 130 lunar probes to explore the moon by means of circumnavigation, landing patrols, and even collisions.
In the mid-1970s, the cold war situation between the United States and the Soviet Union gradually eased. The Soviet Union withdrew from the competition for manned moon landings, and the United States also cooled from its frenzy and stopped expensive moon landings. In the following 20 years, the whole world has entered a stage of calm thinking of in-depth study of the meaning of lunar exploration.
During this period, countries generally recognized that the lunar exploration activities have political, social, technological, scientific and economic significance. Therefore, the direction of human lunar exploration activities since then has changed from serving political purposes at all costs to combining scientific exploration with economic benefits, with the ultimate goal of rationally developing lunar resources.
On January 25, 1994, the United States launched the Clementine probe, obtained the most detailed image of the lunar surface at the time, and discovered that there may be a large amount of water ice in the south pole of the moon. This mission also announced the arrival of the second lunar exploration boom in the world.
In the future, the moon may become a "post" for mankind in space. Pang Zhihao said that after landing on the moon, "station to the moon" will become the next stage of mankind's goal. Water resources mined from the moon can be used for the lives of astronauts, and can also be decomposed into hydrogen and oxygen to make hydrogen and oxygen fuel for spacecraft. Solar power stations can be built to provide resources in the permanent illumination areas of the moon's poles. A scientific research station can be built on the back of the moon to avoid radio interference from the earth and look into the starry sky. The helium-3 mentioned above may be difficult to transport back to the earth conveniently and cheaply for a period of time, but it can be used directly by building a nuclear fusion power station on the moon to send the generated electricity back to the ground by wireless transmission.
By then, the lunar base will not only provide humans with resources and obtain scientific results, but will also become a transit point for humans to travel to far and deep space.