filling the historical gap in lunar farside research: the composition of chang'e-6 lunar samples revealed
2024-09-21
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xinhua news agency, beijing, september 18title: filling the historical gap in lunar farside research: the composition of chang'e-6 lunar samples revealed
xinhua news agency reporters zhang quan and song chen
the first research results of chang'e-6 lunar samples are released!
on the 18th, the reporter learned from the national astronomical observatory of the chinese academy of sciences that chinese scientists have revealed the physical, mineralogical and geochemical characteristics of the chang'e-6 lunar samples, and analyzed the information related to the early evolution of the moon and volcanic activity on the far side of the moon, filling the gap in the history of human research on the far side of the moon.
the research was completed by a joint research team led by li chunlai, a researcher at the national astronomical observatory of the chinese academy of sciences, hu hao, chief designer of the chang'e-6 mission, and yang mengfei, an academician of the 5th academy of the china aerospace science and technology corporation.
what is the unique value of the chang’e-6 lunar samples?
the moon is the closest celestial body to us. for thousands of years, humans have never stopped exploring the moon. the chang'e-6 mission completed the feat of collecting samples from the back of the moon for the first time, bringing back 1,935.3 grams of precious samples. before this, all the lunar samples obtained by humans came from the front of the moon.
schematic diagram of the landing points of chang'e 6 and chang'e 5, the us apollo program and the soviet luna program. (photo courtesy of the national astronomical observatory of the chinese academy of sciences)
the chang'e-6 sampling point is located at the edge of the apollo crater inside the south pole-aitken basin on the far side of the moon. the lunar crust in this area is extremely thin, and it is expected to reveal the original material of the early impact basin on the far side of the moon.
li chunlai introduced that the chang'e-6 lunar samples not only include basalts that record the volcanic activity history of the sampling points, but also contain non-basaltic materials from other areas. these samples are like "messengers" from the ancient moon, providing important first-hand information for our study of the early impact history of the moon, volcanic activity on the far side of the moon, and the composition of the moon's internal materials.
what is the composition of the chang'e-6 lunar samples?
in this study, the team found that the density of the chang'e-6 lunar samples was low, indicating that their structure was relatively loose and their porosity was high. the particle size of the samples showed a bimodal distribution, suggesting that the samples may have experienced a mixture of different sources. compared with the chang'e-5 lunar samples, the plagioclase content in the chang'e-6 lunar samples increased significantly, while the olivine content decreased significantly, indicating that the lunar soil in this area was obviously affected by non-basaltic materials.
the study found that the rock debris collected by chang'e 6 is mainly composed of basalt, breccia, cementite, light-colored rocks and glassy materials. among them, basalt fragments account for 30% to 40% of the total, and breccia and cementite are composed of basalt fragments, glass beads, glass fragments and a small amount of light-colored rock fragments such as plagioclase and syenite, further revealing the complexity of the source of the samples.
mineralogical analysis shows that the main phases of the chang'e-6 lunar samples are plagioclase (32.6%), pyroxene (33.3%) and glass (29.4%). in addition, a small amount of orthopyroxene was detected in the samples, suggesting the presence of non-basaltic materials.
further analysis shows that the chang'e-6 lunar samples have high aluminum oxide and calcium oxide content, while the iron oxide content is relatively low, which is consistent with the characteristics of a mixture of lunar mare basalt and anorthite. in addition, the content of trace elements such as thorium, uranium and potassium in the samples is significantly lower than that of kreep basalt, showing a huge difference from the lunar samples obtained by the apollo mission and the chang'e-5 mission.
a typical image of the chang'e-6 lunar sample. (photo courtesy of the national astronomical observatories of the chinese academy of sciences)
the above research results have been published in the academic journal national science review a few days ago.
"these discoveries not only fill the historical gap in the study of the far side of the moon, provide direct evidence for our study of the early evolution of the moon, volcanic activity and impact history on the far side of the moon, but also open up new perspectives for understanding the geological differences between the far side and the front side of the moon," said li chun.
china's lunar exploration project has gone through a 20-year journey, from chang'e-1 taking full-moon images, to chang'e-4 achieving the first soft landing on the far side of the moon, from chang'e-5 returning with lunar soil, to chang'e-6 achieving the world's first sample return from the far side of the moon, step by step, constantly pioneering and moving forward. with the continuous deepening of the research on the lunar samples of chang'e-6, more and more traditional cognitions will be refreshed, and humans will know a "new" moon.
