Billions of years ago, something slammed into the dark side of the moon and a very, very big hole dug. Width of 1,550 miles and depth of 8 km South Pole Aitken Basin, as the huge hole known to Earthlings is, is the oldest and deepest crater on the Moon and one of the largest craters in the entire Solar System.
For decades, researchers have suspected that the gargantuan watershed was created by a head-on collision with a very large, very fast meteor. Such an impact would spoil the crust of the moon and scattered pieces of lunar mantle across the surface of the crater, providing a rare glimpse of what the moon really is made of (Spoiler: It's not cheeseThat theory gained credibility earlier this year when the Chinese rover Hutu-2, which sits at the bottom of the ship's crater landlord Changi 4 in January, traces of minerals that appeared to come from the moon's clothing were discovered.
But now, a study published August 19 in the journal Geophysical Research Letters questions these results – and the story of the crater's origin. After analyzing the minerals in six plots of soil at the bottom of the South Pole-Aitken watershed, a team of researchers argues that the composition of the crater is entire crust and no mantle, suggesting that whatever impact the crater opened billions of years ago did not hit. strong enough to spray the Moon's surface meters.
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"We do not see the mantle material at the landing site as expected," said study co-author Yao Angang, a planetary scientist at the Chinese University of Geological Sciences. it said in a statement. These findings, in addition, exclude direct collision with a high-speed meteorite and raise the question: What, if not a meteorite, created the largest crater on the moon?
Lighting on the dark side
In their new study, the researchers used a technique called reflection spectroscopy to identify specific minerals in the lunar soil based on how individual grains reflect visible and near infrared light.
Using equipment above the Hutu-2 Rover, the team conducted reflection tests on six patches of soil in the first two days after landing on Yangtze 4, covering about 175 meters (54 meters) from the ground. Using a database that identifies lunar minerals based on a variety of factors, including size, reflection and degradation due to solar wind, the team estimated the concentration of minerals in each of the plots.
Crystalline rock called plagiarism was by far the most abundant mineral in any sample, accounting for 56% to 72% of the crater composition, the researchers write. Formed as primeval oceans with cold lava, plagiarism is extremely common in earth's crust and the Moon the same, but less abundant in the clothing of any body. Although the team discovered other minerals in the crust that are more common in lunar clothing, such as olivine, these rocks made up a small fraction of soil samples to indicate that part of the mantle had penetrated the crust.
This mineral make-up complicates the theory that the enormous high-speed meteorite created the South Pole watershed Aitken a few billion years ago, because such an impact would almost certainly scatter mantle pieces over the lunar surface.
So what, then, created the crater? The researchers do not speculate in the new study – however, previous research has suggested that the renegade space rock is still the culprit, but the hit may not have been so direct. A study published in 2012 in the journal Science claimed that a slightly slower meteor could hit the back of the moon at an angle of about 30 degrees and resulted in an appropriately large crater that never disrupted the moon's coat – yet those researchers only had simulations to go on.
If anything, the new research suggests there is still a lot of research to be done in the South Pole ititken watershed before the answer becomes obvious. See you on the dark side of the moon.
Originally posted on Live Science.