The Chang'e-4 Chinese lunar lander has confirmed a long-standing theory about its landing site at the far side of the moon.
What The Chang'e-4 Found On The Far-Side Of The Moon
The 180 kilometer-wide Von Kármán, where the lunar lander touched down earlier this year, is an impact bowl. It lies within the larger South Pole Aitken Basin, which measures at about 2,300 kilometers wide and nearly covers a quarter of the circumference of the Moon.
Scientists do not know exactly how old the South Pole Aitken Basin is, but they believe it is about 3.9 billion years old. It was created when a 170 kilometer-wide asteroid slammed on the lunar surface a long time ago, punching through the crust, and into the mantle.
Now, mission scientists from the National Astronomical Observatories of Chinese Academy of Sciences reported in a study published in Nature that they have identified mantle rocks on the lunar surface.
The Yutu-2 rover, which was deployed to explore the South Pole Aitken Basin, spotted rocks that have different chemical makeup than those around it. Upon closer analysis, the rover's Visible and Near Infrared Spectrometer revealed that the rocks contained low-calcium pyroxene and olivine, elements that the scientists expect to find much deeper beneath the lunar surface.
This confirmed that the impact that created the South Pole Aitken Basin billions of years ago drove straight through the Moon's crust and into the mantle, spraying rocks that otherwise would be buried beneath the lunar surface.
Uncovering The History Of The Moon
The core theory posits that the moon, in its earlier years, was a molten marble with oceans of magma. As time went on, the oceans cooled.
The heavier elements, like the olivine and low-calcium pyroxene, sank to the bottom and formed the lunar mantle. The less dense mineral, meanwhile, floated to the top.
The Yutu-2 rover will have to explore the impact basin and collect more data in order to better understand the geology and history of the Moon.
"Understanding the composition of the lunar mantel is critical for testing whether a magma ocean ever existed, as postulated," stated Li Chunlai, one of the authors of the study. "It also helps advance our understanding of the thermal and magmatic evolution of the moon."
Scientists believe that studying the evolution of the Moon could also lead to new clues about the evolution of Earth and other terrestrial planets in the universe.