On October 19th Thursday 2021, the Chinese Academy of Sciences released the latest research results of the Chang’e-5 lunar scientific research samples. A number of breakthroughs have given a new understanding of the evolution of the moon. The research results of the lunar samples of Chang’e 5 show that magma activity still existed on the moon until 2 billion years ago. The lunar mantle source area of late magma activity is not rich in radioactive heat-generating elements and is very “dry”. This series of research is led by the Institute of Geology and Geophysics of the Chinese Academy of Sciences and the National Astronomical Observatory, and jointly carried out by a number of research institutions. The related results have formed 4 papers, one published in the “National Science Review”, and published in the international academic journal “Nature” 3 articles.
The duration and geochemical characteristics of the lunar basalt magma are the “keys” for understanding the thermal-chemical evolution of the moon. Previous studies have confirmed that magma activity on the moon lasted at least approximately 2.8 to 3 billion years ago. However, there has been controversy in the scientific community about the exact time when the lunar magma activity ceased. The study found that the lunar sample of Chang’e 5 is a new type of lunar basalt, which is different from the lunar samples collected and returned by the United States and the Soviet Union. Researchers analyzed more than 50 uranium-rich minerals in the basalt cuttings of the Chang’e 5 lunar sample and determined that the basalt formation age was 20.30±0.04 billion years, indicating that there was still magma activity on the moon until 2 billion years ago, which is more than the limit of previous lunar samples. Magma activity has been extended for about 800 million years.
The cause of the most recent magmatic activity on the Moon has always been an unsolved mystery. At present, there are two possible explanations in the scientific community: the lunar mantle source is rich in radioactive elements to provide a heat source, or the lunar mantle is rich in water to lower its melting point. The latest study found that the lunar mantle source area of the basalt from the lunar sample of Chang’e 5 is not enriched in “Krip material.” Since the “Krip material” is rich in radioactive heat-generating elements, this result proves that the radioactive heat-generating elements of the lunar mantle are not the main reason for the formation of the basalt of the Chang’e-5 lunar sample. Regarding whether the magma source area is rich in water, the research team measured the water content and hydrogen isotopic composition in the basalt of the Chang’e 5 lunar sample, and found that the water content in the lunar mantle source area was only 1 to 5 micrograms/g, which means that the lunar mantle Very “dry”. This discovery also excludes the hypothesis that the lunar mantle is rich in water and has a low melting point, resulting in an abnormally prolonged duration of magma activity in this area.
According to the hypothesis of the origin of the big impact, the original Earth collided with a planetary planet the size of Mars, forming a “disk” composed of high-temperature magma and gas around the earth. When the temperature begins to cool, materials such as silicate first gather to form the moon (Figure 1), and water is a highly volatile material that escapes into space in a gaseous form and is lost. Therefore, the moon born in this way contains almost no water and is a nearly dry planet. The research results of the lunar samples of Chang’e 5 further provided supporting evidence for the origin and evolution of the moon, raised new scientific questions for the study of the lunar thermal evolution history, and proposed new directions for future lunar exploration and research.
We welcome domestic and foreign scientists to join the ranks of the research on these data and samples. At present, research on lunar samples is mainly carried out by domestic scientific research institutions, and foreign scientists have joined the Chinese team to carry out joint research. In the follow-up, we will issue relevant policies, uphold the principles of “equality and mutual benefit, peaceful use, and inclusive development”, expand international exchanges and cooperation, and provide more Chinese wisdom, Chinese solutions, and Chinese power for the peaceful use of space and the promotion of a community with a shared future for mankind.
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