“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,” Peter James, assistant professor of planetary geophysics at Baylor University, said in a statement on Phys.org
The mysterious mass of material is found buried under South Pole-Aitken basin, the moon’s largest crater, and may contain substances from an asteroid that crashed into the Moon and created the crater, the statement quotes the Baylor University Study.
— CyberHUMINT (@Cyber_HUMINT) June 10, 2019
This crater cannot be seen from earth because it’s on the far side of the moon.
“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 in the statement. “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 Baylor University Study, “Deep Structure of the Lunar South Pole-Aitken Basin,” is published in the journal “Geophysical Research Letters.”
Researchers studied data obtained from the spacecrafts used for NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission.
According to James, the dense substance “whatever it is, wherever it came from” is weighing down the crater floor by half a mile.
“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.
According to their statement, there’s another possibility that the large mass might be a concentration of dense oxides associated with the last stage of lunar magma ocean solidification.
The lunar magma ocean solidification is a hypothesis that explains the early evolution of terrestrial planets, according to Science.gov The hypothesis that explains how the terrestrial planets reach their long-term solid-state planet dynamics is however poorly understood, according to the portal.
South Pole-Aitken Basin
The South Pole-Aitken basin is the largest and the oldest impact basin on the moon, according to NASA.
An impact basin is an impact crater with a rim diameter of more than 186 miles and there are 40 such impact basins on the moon, explains Lunar Science and Exploration. These impact basins are said to control the moon’s geology.
NASA explains that the South Pole-Aitken basin is roughly 1,550 miles in diameter. This means it extends across almost the quarter of the moon’s surface.
“Stratigraphic relationships show that SPA is the oldest impact basin on the moon, but scientists are intensely interested in just how old it is. Lunar samples suggest that most of the major basins on the moon formed around 3.9 billion years ago in a period called the late heavy bombardment,” according to NASA.