Nine days to take the moon star river wide, sixteen spring and autumn around the fall back. On November 17, the Long March V long-range five carrier rocket and the Chang’e-5 probe, known as the Fat Five, were transferred vertically to the launch area after completing the final assembly test of the technical zone at the Wenchang Space Launch Site in China, with a launch planned for late November. For the first time, the Chang’e-5 lunar probe plans to achieve sampling and return from the moon, bringing valuable samples such as lunar soil or lunar rock back to Earth, which will hopefully bring a successful conclusion to the three-step development strategy of china’s lunar exploration project.
With an average one-way distance of about 380,000 kilometers between moons and a round trip of nearly 800,000 kilometers, what mysteries are there in the moon samples worth the effort to excavate? Looking back at history, what have mankind achieved in “digging” the moon? What are the special features of this China’s Chang’e-5 mission from sampling location to sampling weight?
Although the moon soil is soil, the value is worth ten thousand gold
“The moon is the soil of the moon, and although it is readily available on the moon, it is of great scientific value to the Earthlings.” Xiao Long, a professor at the Institute of Planetary Science at the Chinese University of Geosciences (Wuhan), said the lunar soil is a sample of the moon, formed by lunar rocks after being subjected to space weathering such as meteorite impacts, solar wind bombardments and cosmic ray radiation, including large amounts of lunar rock fragments, minerals and meteorites. By studying these moons, scientists can understand both the geological evolution of the moon and the necessary information to understand solar activity.
“There are three common ways to explore the moon.” Pang Zhihao, the country’s chief scientific communication expert for space exploration, told Science and Technology Daily that the first is orbiting exploration, mainly used for a comprehensive survey of the moon; Compared with the first two methods, sampling and return detection, the moon’s lunar soil and other key samples can be transported back to the ground laboratory for scientists to carry out accurate analysis and research, which is conducive to further understanding of the state of the moon, temperature, material content and other important information, deepen the understanding of the moon’s soil, lunar crust and moon formation and evolution.
Pang said that from a technical point of view, the three space exploration methods have a clear step-by-step relationship, each step is a further deepening of the previous step, and at the same time lay the foundation for the next step, and ultimately achieve a comprehensive and in-depth understanding of the moon. To complete the lunar sampling and return mission, we need to go through a comprehensive, detailed and in-depth scientific exploration process, which can break through a series of key technologies and provide relevant data and lay a technical foundation for future manned lunar landings and lunar base site selection.
Digging is charming, and all countries are fighting hard
“During the Cold War, the space superpowers of the time, the United States and the Soviet Union, were very keen to sample the moon.” Pang said the Soviet Moon 16 probe took a small sample of 101 grams from the moon’s rich sea. The Moon 20 and Moon 24 probes collected 55 grams and 170 grams of samples from Apollonius Heights and the Moon’s Dangerous Sea, respectively.
“The manned spacecraft returned from the moon sampling, not only a large collection, selective, but also a wide range of acquisition, because astronauts can go to extravehico-space activities, but also by lunar rover roaming to a relatively distant place to collect lunar samples. For example, the geographical distribution and geological characteristics of sampling locations for Apollo missions in the United States are very rich. Pang said.
From July 1969 to December 1972, the United States carried out seven manned missions to the moon through the Apollo 11 to Apollo 17 manned spacecraft.
According to reports, Apollo 11 landed in the moon’s equator near the tranquil sea, the reason for choosing this location is that it is relatively flat, easy to land the spacecraft and astronauts extravehloyor activities.
Both Apollo 12 and Apollo 14 landed on the moon’s equatorial plains, the former landing in the stormy sea and the latter landing at the Gopenny Crater, 177 kilometers to the right of the Apollo 12 landing site.
Apollo 15 landed at the foot of the Apinin Mountains southeast of the Archimedes Crater in the central northern hemisphere of the moon, while Apollo 16 was the first human to land near the Theo Philus Crater in the central highlands south of the moon’s equator.
Apollo 17 landed in the Dulles-Litro Valley in the northern hemisphere of the moon, where younger rock samples can be taken from the valley floor as well as older rock samples from the moon’s highlands.
“Through the analysis of lunar samples, scientists have achieved fruitful results.” Pang said researchers have found that the moon’s soil contains a large number of tiny orange-colored glass particles, typically rich in aluminum, sulfur and zinc, which form about 300 kilometers neath the moon’s surface during partial melting and spew out to the moon’s surface due to volcanic activity. Through the analysis and experiment of the samples, it is proved that the content of iron oxide in the moon soil and moon rock is very high, from which water and oxygen can be obtained, and the lunar surface material can be used in the future to support the operation of the lunar base and refuel the lunar landing vehicle. What’s more, scientists also found helium-3, the ideal raw material for nuclear fusion, in samples collected. At current levels of Earth’s energy consumption, helium-3 on the moon can meet human energy needs for about 10,000 years after nuclear fusion.
It has its own characteristics and is newly located
“China’s Chang’e-5 has a stronger sampling capacity for the moon’s soil.” Pang said that the Soviet Union’s Moon 16, Moon 20 and Moon 24 three unmanned lunar probes carried out three lunar sampling return missions, bringing back only about 330 grams of lunar soil samples, while China’s Chang’e-5 one probe alone plans to bring back 2 kg of lunar samples.
According to Pang Zhihao, the sampling weight will be so large difference, because the Soviet Union has not yet mastered the lunar orbit unmanned intersecting technology, so its three unmanned lunar sampling missions are using the moon take-off directly back to Earth program, so that its hose needs to overcome the return module and a large amount of fuel brought about by the huge load, so greatly compressed the sampling weight. The Chang’e-5 program uses the world-leading lunar orbit unmanned docking program to transfer the lunar soil, the riser does not need to carry a return module, only a small amount of fuel, so the sampling weight is geometric increase.
According to relevant reports, the sampling address of the Chang’e-5 is also very distinctive and has a high research value. Chang’e-5 will land near the Lumke Mountains in the northern part of the moon’s largest lunar storm, which has never been visited by a probe from any other country. The storm ocean is relatively young and rich in radioactive elements such as uranium, thorium and potassium, where basalt existed about 1.3 billion to 2 billion years ago, and acquiring the isotope age of these young basalts will help advance understanding of lunar volcanic activity and evolutionary history.
As the November 5 issue of Nature, the world’s leading scientific journal, says, chang’e-5 could fill an important gap in scientists’ research into lunar volcanic activity. Previous studies of the U.S. and Soviet moons showed that volcanic activity on the moon peaked 3.5 billion years ago and then weakened and stopped. But observations of the moon’s surface have found that some areas may contain volcanic lava that formed only 1 to 2 billion years ago, similar in age to the landing area of the Chang’e-5. If the samples recovered by Chang’e-5 confirm that the moon is still active during this time, it will rewrite the history of the moon.