As you know, the Moon does not have a global magnetic field. But it was not always so. Measurements of the lunar crust and lunar rocks using special equipment show that some samples contain remnants of magnetization. They may have formed about 4 billion years ago. The scientists believe that earlier the Moon's magnetic field was created by constant shaking of the molten metal core of the Moon.
But it could not generate enough energy to support the magnetic field. The researchers at the University of Massachusetts decided to test the assumption, which has existed since the 80s of the last century. It can induce residual magnetization in the lunar crust.
This is a kind of temporary plasma formed as a result of impacts of meteorites. In science, there are two explanations for the ancient magnetic field of the Moon. The first is that the Moon created a kind of dynamo machine, but the main problem was that there was not enough energy to create a high-intensity surface magnetic layer. In fact, it was present, and this was determined using bark samples obtained during the Apollo mission.
An alternative theory is that the source of the Moon's magnetic field was not its inner surfaces, but the impact of meteorites on the outer part. Impact plasma in such cases expanded and absorbed the Moon, forming a magnetic curtain.
In doing so, the plasma amplified and compressed the interplanetary magnetic field known as the solar wind. Induction then took place in the lunar crust and the amplified field signal became visible on another part of the planet. This assumption partly explains the magnetic field and is supported by observations of four young lunar craters.
They all have large and strong magnetic signals on the opposite side of the Moon. The scientists recognize that the evolution of a magnetized plasma is a complex process during which the plasma flow and electromagnetic fields can change in response to each other.
But only by simultaneously simulating the plasma and the magnetic field, the researchers believe, make it possible to get a realistic idea of the process.