On the far side of the moon, Chang’e 4 has discovered mantle rocks

The Yutu-2 rover of the Chang’e mission 4, which landed on the hidden side of the Moon on January 3, discovered minerals interpreted by researchers as originating from the lunar mantle. A first in 60 years of exploration of our natural satellite.

On January 3, 2019, the Chang’e 4 Lander and the accompanying Yutu-2 astromobile became the first gears made on Earth to land on the far side of the Moon. The site chosen by the teams of the Chinese mission is Von Kármán (180 kilometers in diameter), one of the many impact craters that line the floor of the huge basin of the South Pole-Aitken.

The latter, with an approximate diameter of 2,500 kilometers and a depth of 13 kilometers, was created by a giant impact in the youth of our satellite, some 3.9 billion years ago. And during this shock, as suggested by simulations and also observations of the surface by the Grail orbiter, rocks of the lunar mantle were probably ejected. But as the volcanic activity during this period covered everything, the excavated materials no longer really cling to the surface, unless meteorites later dig the soil again.

A glimpse of the lunar mantle

In the South Pole-Aitken Basin region, these suspected pieces of the lunar mantle were able to resurface after the more recent formation of the Finsen crater (about 72 kilometers in diameter), a neighbor of Von Kármán. And luckily, some are lying on the path of the rover Yutu-2, which has not failed to analyze the light they reflect through its VNIS instrument (Visible and Near Infrared Spectrometer). The verdict is that their composition is different from anything his predecessor Yutu-1 had studied on the other side of the moon, in the Sea of ​​Rains. This time, the minerals contain olivine and pyroxene with a low content of calcium. In the article just published in the journal Nature, researchers argue that they could come from the lunar mantle.

This is good news, because if these first results are confirmed, this will provide researchers with an unprecedented overview of the mantle of our natural satellite and therefore its history. “This initial reconnaissance will be deepened and validated by ongoing exploration at the surface of Chang’e-4,” said James W. Head, Professor of Geoscience at Brown University, “and we look forward to these additional results.”

It is, of course, no coincidence that Chang’e 4 has come here. On the one hand, the relatively flat terrain is suitable for the rover and the lander, and on the other hand, traces of the mantle are suspected to be there. Not to mention that this is a historical first to explore the hidden face of the Moon. The gathering is starting well and is paving the way for a future return of samples to Earth.

Janice Clark

I'm a student at the University of Waterloo and am one of the main editors for 3LM News. I have many years of experience as a freelance writer and editor and, like Fred, have maintained an interest in astronomy from an early age.

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Janice Clark

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