According to a new study, major changes deep in Mars' core may have resulted in the planet's magnetic field being lost early in its history.
Despite the fact that Mars has a thin atmosphere and is unable to support significant amounts of running water on its surface, scientists have discovered evidence of ancient lakes, streams, and maybe seas, indicating that things were different back then. In order to inform estimates of the likelihood of life on Mars, scientists are keen to learn about the existence (or absence) of water on the Red Planet in its early past.
Researchers are particularly interested in figuring out what caused the planet's protective atmosphere to shrink substantially. A new study looks at changes in the planet's core that may have caused Mars' magnetic field to diminish over time, exposing the planet's atmosphere to erosion.
"The behavior of the molten metal thought to be present likely gave rise to a brief magnetic field that was destined to fade away," representatives of the University of Tokyo, where researchers were stationed, wrote in a statement based on the work of the study team.
Using a sample of material believed to be found in the early Martian core, such as iron, sulfur, and hydrogen, the researchers reproduced the conditions of the early Martian core. To try to reproduce the tremendous pressures and heat found within the core, this sample was squeezed and heated between two diamonds.
The scientists observed the changes in the sample as it was pressured and compressed using X-ray and electron beam measurements. The scientists observed that the Martian substance, which was initially homogeneous, had split into two liquids.
In the same statement, co-author Kei Hirose, a professor at the University of Tokyo's Department of Earth and Planetary Science, said, "One of the iron liquids was rich in sulfur, the other rich in hydrogen, and this is key to explaining the birth and eventually death of the magnetic field around Mars."
The less dense hydrogen liquid also outperformed the considerably denser sulfur-rich liquid in the experiment. Mars experienced brief convection currents comparable to those that currently exist on Earth as a result of this liquid migration. Our magnetic field, according to scientists, is created by these currents.
The magnetic field on Mars, on the other hand, was only there for a short time. The currents stopped after the liquids separated, according to the study, because there was no longer any activity to generate the currents.
Due to erosion from the solar wind, or the continual stream of charged particles emerging from our sun, light hydrogen in the atmosphere flew into space about the same time. As a result of the lower atmospheric pressure, water vapor eventually broke down (as water includes hydrogen). Liquid water stopped flowing on the surface when the atmosphere thinned.
Missions like NASA's InSight lander, which is monitoring seismic activity on Mars, could reveal further information about the composition of the planet's core, according to the experts.
"With our results in mind, further seismic study of Mars will hopefully verify the core is indeed in distinct layers as we predict," Hirose said. "If that is the case, it would help us complete the story of how the rocky planets, including Earth, formed — and explain their composition."
On February 3, Nature Communications released a study based on the findings. Shunpei Yokoo, a Ph.D. student who works in Hirose's lab, was in charge of the project.