The South Pole-Aitken Basin on the Moon was formed about 4.3 billion years ago. The impact may have changed the look of the moon, and explain why the side we see from Earth is different.
The lead author of a new study said that big impacts like the one that formed the South Pole-Aitken would create a lot of heat. We show that at the time that SPA formed, it ends up concentrating the heat-produced elements on the nearside. We expect that mantle melting contributed to the lava flows we see on the surface.
The side of the Moon that always faces towards Earth is different from the side that is hidden. The lunar mare dominates the nearside with the large, dark-colored lava flows on the mantle. The far side is scarred with craters and has no large-scale mare features. One of the Moon's most enduring mysteries is why the two sides are different.
The impact that formed the giant South Pole and the Aitken basin was confirmed in this new research.
The largest impact basin on the Moon is the South Pole-Aitken basin. It is roughly 2,500 km in diameter. The basin stretches across nearly a quarter of the moon because it is under 11,000 km.
The impact would have created a huge amount of heat in the lunar interior. The researchers argue that the Moon would have been home to a suite of rare-Earth and heat- producing elements. The volcanism that created the nearside volcanic plains was caused by the concentration of elements.
There is a region called the Procellarum KREEP Terrane. There is a lot of specific elements in that region. KREEP stands for K, REE, and P, the atomic symbols for potassium, REE, and P. The KREEP terrane has elements that decay radioactively and produce heat.
After the rest of the Moon cooled, this heat would have allowed that part of the Moon to remain volcanic.
The researchers used computer simulations to figure out how heat generated by a giant impact would affect the Moon's interior. The last part of the mantle to solidify after the Moon's formation is thought to be called KREEP.
The heat from the SPA impact would have disrupted the distribution of the lunar crust, according to Jones and his team.
The team said that the material was eventually delivered because of the wave of heat coming from the impact zone. The simulations show that the South Pole-Aitken impact provided the best location and pattern of creating KREEP concentrations on the nearside.
The South Pole impact is one of the most significant events in lunar history. I think our results are really exciting, because this work brings those two things together.
The study was a collaboration between Jones and his advisor Alexander Evans, an assistant professor at Brown.
The Brown University press release was about the paper "A South Pole impact origin of the lunar compositional asymmetry".
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