Since January of this year, a small Chinese robot is going through the oldest catastrophic area of the Solar System. It is the Aitken basin, a huge crater on the hidden side of the Moon formed by the impact of a meteorite 170 kilometers in diameter about 3.9 billion years ago. It is the first time that a robotic vehicle travels this territory and, as expected, is making important discoveries.
The scientists of the Chinese mission Chang'e 4, the first to have landed successfully on the dark side of the moon, believe they have found remains of the lunar mantle, the inner layer that is hidden under the bark and from which it has not yet There was just evidence.
The Moon is a piece of Earth torn off by the impact of Theia, an asteroid the size of Mars, at the origins of the solar system, about 4.5 billion years ago. It was such a violent cataclysm that our planet disappeared for a few hours. A small part flew out and mingled with Theia's remains, turned to molten rock after the blow. For a while, the satellite was covered by an ocean of burning lava in which the heavier materials crystallized in the background and the lightest remained on the surface, from which the first astronauts collected abundant samples in the 1960s. seventy. Since then it has been a mystery what the composition of the Moon is beyond its outermost layer.
The robot Yutu-2 landed in January of this year in the crater Von Kármán, a basin about 180 kilometers in diameter which in turn is inside the Aitken crater, which with 2,500 kilometers from side to side is one of the largest known. The hidden face of the Moon is full of craters like these, many of them formed during a violent stage in the history of the solar system known as late intense bombardment. The visible face of the Moon was also devastated by this discharge, but in this case the holes were flooded with volcanic lava that when dried formed the great plains known as seas that are appreciated today.
The impact on Aitken was so violent that it penetrated beyond the lunar crust and uncovered the mantle by spreading its contents over the surface. In a study published this Wednesday in the prestigious magazine Nature, scientists from the National Academy of Sciences of China explain that the visible and infrared light spectrometer of the Yutu-2 shows that the composition of the terrain is different from that of the regolith in the seas of the satellite. The minerals have a high content of olivine and other dense compounds, of the type that could be in the deepest layers of the lava sea.
"These could be the first clear indications of the lunar mantle that surfaced after the enormous impact that formed the Aitken basin," says Bernard Foing, director of the Lunar Exploration Working Group of the European Space Agency, which has collaborated with China in the Chang'e-4 mission.
The results are "exciting", says Patrick Pinet, of the Research Institute of Astrophysics and Planetology of France, in a commentary published next to the article. The data collected by Yutu "May have important implications for determining the composition of the outer mantle", as well as revealing the "depth, cooling speed and viscosity" of the old sea of lava that covered the Moon. "The data," explains Pinet, "can also change our vision about the planetary interiors. "" It is very important to unveil the geology of the hidden face of the Moon, which will increase our knowledge about the formation of the Moon and the differences between its two faces, "explains the researcher, who nevertheless warns that the Chinese results are preliminary and should be confirmed with more analysis not only of land, but also of lunar rocks from the less explored face of the satellite.