China's lunar rover Yutu ends 60-year riddle of moon's mantle with discovery of mineral olivine

By Stephen Chen / | May 16, 2019 12:25 PM SGT
China's lunar rover, Yutu, has made a groundbreaking discovery that proves what scientists have been thinking for decades: that the moon has a mantle.
Scientists have long suspected that the moon has a mantle under its crust, just like the Earth, but for the past 60 years lunar explorations, including the US Apollo missions, have failed to provide proof. While there were clues, there was no direct evidence.
"Now we have it," said Professor Li Chunlai, deputy director of the National Astronomical Observatory of China and a lead scientist on the Chang'e-4 mission that put Yutu, or Jade Rabbit as it is known in English, on the moon.
The findings, published in the latest issue of journal Nature on Thursday, answer some fundamental questions about the moon, such as its internal structure and history of its formation.
The rover discovered olivine in surface samples collected near its landing site. Photo: Xinhua
During its first mission on January 3, Yutu discovered olivine, a green, crystallised mineral usually found deep underground " like the upper mantle of the Earth " in surface samples collected near its landing site.
Further analysis showed that the olivine was not local, but had originated from a 72km diameter (45-mile) crater nearby.
The far side of the moon has more craters than the near side, which faces the Earth, and a meteor strike probably penetrated to the mantle and brought up materials to the surface.
Yutu's landing site used to be littered by rocks, but cosmic rays and solar wind weathered them to dust, Li said.
"What we found is the first direct evidence of materials from deep below the lunar crust," though how deep is still unknown, he said.
It is generally believed that the moon was once covered by oceans of molten rock. Lighter substances rose to the surface and formed a crust while heavier ones sank to form...