Providence RI (SPX) Jan 14, 2022 Rocks returned to Earth during NASA's Apollo program from 1968 to...
Analysis of the rocks revealed that some seemed to have formed in the presence of a strong magnetic field - one that rivaled Earth's in strength.
Now, research led by a Brown University geoscientist proposes a new explanation for the Moon's magnetic mystery.
The study, published in Nature Astronomy, shows that giant rock formations sinking through the Moon's mantle could have produced the kind of interior convection that generates strong magnetic fields.
The processes could have produced intermittently strong magnetic fields for the first billion years of the Moon's history, the researchers say.
Planetary bodies produce magnetic fields through what's known as a core dynamo.
The Moon lacks a magnetic field today, and models of its core suggest that it was probably too small and lacked the convective force to have ever produced a continuously strong magnetic field.
"You have something really cold that touches the core, and suddenly a lot of heat can flux out. That causes churning in the core to increase, which gives you these intermittently strong magnetic fields."
There could have been as many as 100 of these downwelling events over the Moon's first billion years of existence, the researchers say, and each one could have produced a strong magnetic field lasting a century or so.
Evans says the intermittent magnetic model not only accounts for the strength of the magnetic signature found in the Apollo rock samples, but also for the fact that magnetic signatures vary widely in the Apollo collection-with some having strong magnetic signatures while others don't.
The presence of those weak signatures along with the strong ones would give this new idea a big boost, which could finally put the Moon's magnetic mystery to rest.