Chang & e-4 Lander and his rover revealed new mysteries on the far side of the moon. The mantle of the moon blown on the surface?

On January 3, 2019, the Chinese National Space Administration (CNSA) successfully disembarked Chang & # 39; E-4 mission from the other side of the moon. This mission represents a major milestone for China, being the fourth Lander-Rover mission to be sent to the moon and the first mission of history to land on the "dark side of the moon". And what he manages to discover The is sure to excite and inspire scientists for many years.

For example, the Mission's Yutu-2 (Jade Rabbit-2) rover made an impressive discovery that could confirm a theory of lunar impacts. After collecting spectral data from the largest crater of the moon (the South Pole-Aitken Basin), the Chang & # 39; E-4 The mission team of the Chinese Academy of Sciences (CAS) concluded that the impact that created the basin had lifted the matter from the bottom of the moon. This discovery could offer a new insight into how the Moon has evolved over billions of years.

An article describing the findings of the team was recently published in the scientific journal Nature. The team was led by Li Chunlai, a professor at the National Observatory of Astronomical Astronomers of the Chinese Academy of Sciences (NAOC), and included many members of the major lunar and deep exploration laboratories and technology. active optoelectronics of the CAS.

For about 60 years, robots and even a handful of crewed missions have explored the lunar surface. On the basis of the data collected, a theory emerged in the 1970s that, at the beginning of its history, the surface of the Moon was covered with an ocean of magma. As the surface began to cool and solidify, lighter minerals (such as basalt) floated upward, while heavier elements (olivine and pyroxene) sank deeper into the core.

According to this theory, the scientists also hypothesized that the impacts caused by asteroids, meteors and space debris would crack the crust and project heavier materials from the mantle. As Li explained in a recent press release from the CAS:

"Understanding the composition of the lunar mantle is essential to verify if an ocean of magma has ever existed, as postulated. It also helps us to better understand the thermal and magmatic evolution of the Moon. "

Located at the South Pole of the Moon, the SPA basin is the largest, oldest and deepest crater known to the Moon. Measuring approximately 2500 km (930 mi) in diameter and 13 km (8.1 mi) deep, it is thought to have formed as a result of a massive impact that is occurring. is produced 3.9 billion years ago. This corresponds to the heavy bombardment late period, when the planets of the inner solar system were hit by a disproportionate number of asteroids.

To test this theory, the mission team collected spectral data samples from the flat expanses of the SPA basin, as well as smaller and deeper impact craters. What they were expecting to find was a wealth of mantle material on the flat expanses, but were rather surprised to find simple traces of olivine. On Earth, this rock-forming mineral is a major component of the upper mantle.

In itself, this conclusion could be taken as an indication that predictions about the composition of the lunar mantle are false. However, samples taken during deeper impacts revealed higher concentrations of olivine, which posed a real problem. One possible explanation, according to Li, is that the mantle is made up of equal parts of olivine and pyroxene, rather than being dominated by one alone.

In order to confirm these conclusions, the Chang & # 39; E-4 will have to explore the area around its landing site and gather more spectral data to better understand its geology. What it reveals may force scientists to re-evaluate their theories about the composition of the lunar mantle, not to mention the geological history of the moon.

In addition, a better understanding of the evolution of the Moon could also give an idea of ​​the evolution of the Earth and other terrestrial planets. Not only is the Moon's surface very well preserved in relation to the Earth (due to lack of atmosphere, weather, or geological activity), but the prevailing theory is that the Earth and Moon are formed from the same basic materials.

These theories, as well as others about the birth of our solar system and celestial bodies, will be tested by Chang'e-4 and his brave Yutu-2 rover. Among them, terrestrial life forms may or may not live on the moon for long periods of time! Stay tuned …

For more information: Chinese Academy of Sciences, Nature