China’s Chang’e-4 was the first mission to land on the far side of the Moon. The lunar probe collected new evidence from a crater on the Moon, which is also the largest crater in the solar system.
Li Chunlai, a professor of the National Astronomical Observatories of Chinese Academy of Sciences (NAOC), and his team landed the fourth Chang’e probe (CE-4) in the Moon’s 180km-wide impact bowl called Von Kármán crater inside the South Pole-Aitken (SPA) basin, which stretches about 2,500 kilometers and covers nearly a quarter of the Moon’s circumference
The probe collected spectral data samples from the flat stretches of the basin and as well as the deep impacts within the basin.
The findings from the CE-4 were published on May 16, 2019 in the journal Nature, clarifying how the Moon may have evolved. According to Chunlai, the evolution of the Moon may provide a window into the evolution of the Earth and other terrestrial planets, given the lunar surface is relatively untouched.
In the 1970s, it was theorised that in the Moon’s infancy, an ocean made of magma covered its surface. As the molten ocean began to calm and cool, heavier components sank, while the lighter minerals floated to the top, which crusted over in a sheet of mare basalt such as olivine and pyroxene. Asteroids crashed into the lunar surface, cracked through the crust kicking up pieces of the lunar mantle.
So, the researchers expected to find excavated mantle material on the floor of the SPA basin. Instead, the early results from the rover’s Visible and Near Infrared Spectrometer (VNIS) suggest the rocks contain minerals known as low-calcium (ortho)pyroxene and olivine, which is also the primary component of the earth’s upper mantle.
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The authors of the paper want to continue their examination of lunar rocks. The CE-4 needs to explore more to better understand the geology of its landing site on the Moon. It also needs to collect more spectral data to validate its initial findings and to fully understand the composition of the lunar mantle. The researchers have also raised the possibility of sending another mission to the moon to deliver some of these rocks to Earth for study in laboratories.