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Advanced analysis of Apollo samples reveals lunar evolution

Image of slide 46 of 76535 taken with a polarizing microscope. Credit: Nelson et al. , 2021

Advanced analysis of rock samples taken from the Moon during the Apollo 17 mission reveals new information about the complex cooling and evolutionary history of the Moon. The results of a survey by researchers at the University of Hawaii at Manoa are available today. Nature Communications..


Astronaut Apollo 17 rock sample Out of the surface of the Moon in 1972, Troctrite 76535 continues to be one of the most scientifically valuable samples of the Moon due to its pristine nature. In addition, rock types are widely distributed in the Moon and may contain important clues to understanding the formation of the Moon.

William Nelson and co-author, the lead author of the study and a graduate student of Earth Sciences at the University of Hawaii at Manoa, Graduate School of Earth Sciences (SOEST), and co-authors used a special electronic microprobe to perform high-resolution analysis of the Troctrite 76535. Was executed.

“Previous reports suggest that the minerals in the Apollo 17 sample are chemically homogeneous,” Nelson said. “Surprisingly, there were chemical changes in the olivine crystals. Plagioclase.. These non-uniformities allow numerical models to be used to constrain the earliest hot cooling history of these minerals. “

SOEST researchers used Mana, a UH high-performance computing facility, to study the effects of various computer-simulated cooling paths. This is a chemical diffusion model that far exceeds 5 million.

Advanced analysis of Apollo samples reveals lunar evolution

Earth moon. Credit: NASA

“Simulations have shown that these non-uniformities can survive at high temperatures for a relatively short period of time,” Nelson said.

The diffusion pattern preserved in the mineral particles and observed with the microprobe was consistent with the rapid cooling history within 20 million years at high temperatures. This finding challenges previous estimates of the 100 million year cooling period and supports the early rapid cooling of magma within the lunar crust.

“This is changing our view of how an important suite of moon rocks was formed,” Nelson said.

To adjust the high temperature cooling Based on the generally accepted view of how these rocks are formed, the researchers probably have this type of rock in which the melt interacts with the rock and changes its chemical and physical composition. We proposed that it be formed by a process called sexual penetration.

Advanced analysis of Apollo samples reveals lunar evolution

Olivine Phosphorus Intensity Map — Shows both sharp phosphorus heterogeneity and truncation, suggesting dissolution events. Credit: Nelson et al. , 2021

This study also shows the value of reviewing previously analyzed samples using the latest technology and how new data can quickly reshape an understanding of planetary evolution.

To better understand the observed chemical heterogeneity, the research team is currently investigating how fast phosphorus can diffuse. Olivine crystal. In addition, they are looking for similar heterogeneity in other Apollo samples.


The moon rocks recovered by astronauts probably come from Earth


For more information:
William S. Nelson et al, Chemical Heterogeneity Reveals Premature Rapid Cooling of Apollo Troctolite 76535. Nature Communications (2021). DOI: 10.1038 / s41467-021-26841-4

Quote: The evolution of the moon taken on December 14, 2021 from https: //phys.org/news/2021-12-advanced-analysis-apollo-sample-illuminates.html by advanced analysis of Apollo samples (2021) December 14, 2014) will be revealed.

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