Scientists have detected a mysterious large mass of unknown material on the Moon’s largest crater – the South Pole-Aitken basin.
The large mass of material discovered under the largest crater in our solar system has really puzzled scientists. And they aren’t sure what it is.
According to the study, the basin may contain metal from the asteroid that hit the Moon and formed the crater.
“Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That’s roughly how much unexpected mass we detected,” lead author Dr. Peter James, assistant professor of planetary geophysics at Baylor University, said in a statement.
The Lunar South Pole-Aitken basin is as wide as 2,000 kilometers and several miles deep. It covers about one-fourth of the Moon’s surface. The Moon’s circumference is approximately 11,000 kilometers.
But despite its size, we cannot see it from Earth because it lies on the far side of the Moon.
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James and his team observed the data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission. The changes in gravity they discovered surprised them.
“When we combined that with lunar topography data from the Lunar Reconnaissance Orbiter, we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin,” James said. “One of the explanations of this extra mass is that the metal from the asteroid that formed this crater is still embedded in the Moon’s mantle.”
The anomaly – “whatever it is, wherever it came from,” James added – weighs the basin floor downward by more than half a mile. The researchers ran simulations that suggest an iron-nickel core of an asteroid scattered into the upper mantle during an impact. The upper mantle is the layer between the Moon’s crust and core.
“We did the math and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the Moon’s mantle until the present day, rather than sinking to the Moon’s core,” James said.
The team of researchers suggests one other possibility is that the large mass might be a concentration of dense oxides associated with the last stage of lunar magma ocean solidification.
However, James said the basin is “one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today.”
Researchers published their study in the journal Geophysical Research Letters.