Mass anomaly detected under the moon's largest crater

Mass anomaly detected under the moon's largest crater
This false-color graphic shows the topography of the far side of the Moon. The warmer colors indicate high topography and the bluer colors indicate low topography. The South Pole-Aitken (SPA) basin is shown by the shades of blue. The dashed circle shows the location of the mass anomaly under the basin. Credit: NASA/Goddard Space Flight Center/University of Arizona

A mysterious large mass of material has been discovered beneath the largest crater in our solar system—the Moon's South Pole-Aitken basin—and may contain metal from the asteroid that crashed into the Moon and formed the crater, according to a Baylor University study.

"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," said lead author Peter B. James,

Ph.D., assistant professor of planetary geophysics in Baylor's College of Arts & Sciences.The itself is oval-shaped, as wide as 2,000 kilometers—roughly the distance between Waco, Texas, and Washington, D.C.—and several miles deep. Despite its size, it cannot be seen from Earth because it is on the far side of the Moon.

The study—"Deep Structure of the Lunar South Pole-Aitken Basin"—is published in the journal Geophysical Research Letters.

To measure subtle changes in the strength of gravity around the Moon, researchers analyzed data from spacecrafts used for the National Aeronautics and Space Administration (NASA) Gravity Recovery and Interior Laboratory (GRAIL) mission.

"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 ," 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 dense mass—"whatever it is, wherever it came from"—is weighing the basin floor downward by more than half a mile, he said. Computer simulations of large asteroid impacts suggest that, under the right conditions, an iron-nickel core of an asteroid may be dispersed into the (the layer between the Moon's crust and core) during an impact.

"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.

Another possibility is that the large might be a concentration of dense oxides associated with the last stage of lunar magma ocean solidification.

James said that the South Pole-Aitken basin—thought to have been created about 4 billion years ago—is the largest preserved crater in the . While larger impacts may have occurred throughout the solar system, including on Earth, most traces of those have been lost.

James called the basin "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."


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More information: Peter B. James et al. Deep Structure of the Lunar South Pole‐Aitken Basin, Geophysical Research Letters (2019). DOI: 10.1029/2019GL082252
Journal information: Geophysical Research Letters

Provided by Baylor University
Citation: Mass anomaly detected under the moon's largest crater (2019, June 10) retrieved 20 August 2019 from https://phys.org/news/2019-06-mass-anomaly-moon-largest-crater.html
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Jun 10, 2019
Paper from the 2018 lunar conference says otherwise.

"the cooling of the thermal anomaly pulls the inner basin into near-isostatic equilibrium, i.e. SPA does not become a mascon"

https://www.hou.u...2686.pdf


Jun 10, 2019
Tycho Magnetic Anomaly anyone?

Jun 10, 2019
Tycho Magnetic Anomaly anyone?
Perhaps I'm just projecting my own concern about it. I know I've never completely freed myself of the suspicion that there are some extremely odd things about this mission.

Jun 10, 2019
ok HAL, you can keep your suspicions to yourself. Plus disable your lip-reading sub-routine please.

Jun 10, 2019
Plus disable your lip-reading sub-routine please.
Daisy... Daisy... G i v e   m e     y   o    u     r   

Jun 10, 2019
27 gigatons of pure platinum.

Jun 10, 2019
27 gigatons of pure platinum.
So somebody suddenly decides that Bob Truax' Big Dumb Booster was just the ticket.
Get there the fastest with the mostest and bring back the muchest...

Jun 10, 2019
Aitken Mass Anomaly

Let's NOT try to dig to find out what it is.

Jun 11, 2019
27 gigatons of pure platinum.
So somebody suddenly decides that Bob Truax' Big Dumb Booster was just the ticket.
Get there the fastest with the mostest and bring back the muchest...
I dunno it's like all that gold in the anericas... if it had found it's way back into Eurasia uncontrolled it would have devalued royal treasuries and crashed economies. That's why much of it was loaded up into ships and scuttled in the atlantic.

So it wouldn't make sense to haul a great deal of platinum back unless there were valid industrial uses for it.

Jun 11, 2019
No doubt an underground civilization of steampunk Nazis mining heavy hydrogen and plotting their return to the world to create the fourth Reich.

Jun 11, 2019
what's being picked up is the metallic, hollow moon substructure. yes, the moon is hollow.

Jun 12, 2019
what's being picked up is the metallic, hollow moon substructure. yes, the moon is hollow.
So it's like swiss cheese then?

Jun 12, 2019
Obviously everything in a mass that impacted the moon, with the exception of material that may have reached escape velocity, is still on the moon. Since the moon has little to no tectonic activity, it would still be in the same spot where it landed.

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