China News Service, Beijing, February 15 (Reporter Sun Zifa) The Chang'e 5 mission, which returned China's first extraterrestrial celestial object sampling, has produced new results: Chinese scientists have studied and established new and more accurate samples based on the samples collected by Chang'e 5 from the moon. The lunar chronology model will provide a more precise time scale for lunar and planetary science research.
The Institute of Aerospace Information Innovation of the Chinese Academy of Sciences (CAS) announced on the 15th that the Planetary Remote Sensing Team of the State Key Laboratory of Remote Sensing Science of the Academy cooperated with the Institute of Geochemistry of the Chinese Academy of Sciences and the National Astronomical Observatory of the Chinese Academy of Sciences to use the Chang'e-5 lunar samples. A new and more accurate age function model is established on the basis of the current international commonly used lunar age function, which can be used for future lunar geological unit dating and deduction of new age functions of planets such as Mars and Mercury. , to improve the dating accuracy.
The Chang'e-5 sample age provides a precious "golden nail" for the improvement of the lunar age function, and is also a unique contribution of the Chang'e-5 sample to lunar scientific research.
This important achievement paper in lunar and planetary research was published in the international professional academic journal "Nature Astronomy" at 15:00 Beijing time. The reviewers of the paper said that this original work is of great significance, and the entire field of planetary science will Interested in this result.
Researcher Yue Zongyu and researcher Di Kaichang of the Planetary Remote Sensing Team of the Chinese Academy of Astronautics and Astronautics are the first and corresponding authors of the paper respectively. They said that in lunar and planetary scientific research, it is very important to determine the age of important geological units and major geological events.
In the early days, European and American scientists used the samples collected on the lunar surface by the American Apollo and Soviet Luna missions to accurately date and establish a statistical dating method for impact craters. The most famous and widely used are German scientists. The yield function and chronological function established by Gerhard Neukum have been used since 1983.
The lunar landing sampling area (left) and the Chang'e-5 landing area impact crater statistics (right).
Photo courtesy of the Chinese Academy of Sciences
However, unfortunately, the age of the samples collected by Apollo and Luna has a large blank interval between about 3 billion and 1 billion years, accounting for almost half of the lunar geological history, which also makes the reliability of its age function always questioned. .
Therefore, finding samples of geological units on the lunar surface about 2 billion years old is of great significance to verify and improve the lunar age model, which has also become one of the scientific goals of the Chang'e-5 mission.
In December 2020, Chang'e-5 landed safely near the Lumke Mountain and Sharpyue Stream in the northern part of the Ocean of Storms on the front of the moon. The isotopic measurements of the returned samples showed that its age was 2.03 billion years, which was in good agreement with expectations.
The planetary remote sensing team and collaborators of the Academy of Astronautics and Astronautics of the Chinese Academy of Sciences carried out research on the lunar samples of Chang'e 5. Based on the statistical analysis results of the impact craters and the crater yield function of the high-resolution lunar remote sensing images, they obtained the impact craters of the geological unit of the Chang'e 5 sampling point. The normalized frequency is combined with the age composition of the Chang'e-5 sample to establish a lunar chronology function model. A new set of control data is used to update the Neukum (1983) chronology function through the nonlinear least squares fitting algorithm to establish a new lunar chronology. function model, and compare the differences between the old and new functions.
The research team's analysis shows that the dating results obtained from the new chronological function are older in most cases, with the largest difference being around 200 million years.
Due to the addition of the key data points of Chang'e-5, the accuracy of the new lunar age function model is better than that of the classical Neukum (1983) model, and can be used for the future dating of lunar geological units.
Further research shows that the new age functions of other exoplanets such as Mars and Mercury can be deduced according to the new lunar age function, and the dating accuracy can be improved.
Di Kaichang said that the new lunar age function based on the study of the Chang'e-5 lunar samples is a more accurate time scale and will play an important role in lunar and planetary scientific research in the future.
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