The mystery of Mars' magnetic field may finally be solved - scientists now believe the Red Planet's ancient magnetic field only exists in its southern hemisphere. A new study suggests that this bizarre imbalance may be due to uneven core melting and internal heating, creating a strong and unbalanced magnetic field. This upends previous assumptions about Mars being Earth-like, painting Mars as a world shaped by its deep interior.
A computer simulation of a single-sided magnetic field on early Mars was performed based on data from a study led by the University of Texas Geophysical Institute. This research may explain the unusual magnetic prints now being discovered on Mars. Photo credit: Ankit Barik/Johns Hopkins University
Mars, like Earth, once had a strong magnetic field that protected its thick atmosphere from the solar wind. Today, the magnetic field has disappeared, but traces of it remain in the Martian crust. The question that has puzzled scientists for years is why these magnetic field remnants are mostly found in the Southern Hemisphere.
Now, researchers at the University of Texas Institute of Geophysics (UTIG) may have the answer. Their new research suggests that the Martian magnetic field may only exist in the southern half of the planet.
This uneven, or hemispherical, magnetic field is similar to the magnetic field pattern in the Earth's crust today, said lead author Chi Yan, a researcher at the University of Texas at Jackson's Institute of Geosciences and the School of Earth Sciences. It also means that, unlike Earth's global magnetic field, Mars' ancient magnetic field may have been unbalanced.
according toYan YanIntroduction, one explanation is that Mars had a completely liquid core at that time.
"The logic here is that since there is no solid core, it is easier to generate a hemispherical (one-sided) magnetic field," Yan said. "This could have implications for Mars' ancient dynamo and how long it was able to maintain an atmosphere."
Schematic diagram of NASA's InSight probe. The lander's instruments found that Mars may have a completely molten core. According to research from the University of Texas Geophysical Institute, this may explain the phenomenon of Mars' one-sided magnetic field. Image source: NASA/JPL-Caltech
In the study, published in Geophysical Research Letters, the researchers used computer simulations to model this scenario.
Until now, most studies of early Mars have relied on magnetic field models, which suggest that the Red Planet had an Earth-like core that was solid and surrounded by molten iron.
NASA's InSight lander found that the elements that make up Mars' core are lighter than expected, inspiring researchers to try simulating a completely liquid core. That means Mars' core melts at a different temperature than Earth's and is therefore likely in a molten state, said study co-author Sabine Stanley, the Bloomberg Distinguished Professor at Johns Hopkins University.
If Mars' core is molten now, Stanley said, it almost certainly was molten 4 billion years ago when Mars' magnetic field was active.
To test this idea, the researchers prepared a simulation model of early Mars' liquid core and ran it on a supercomputer a dozen times. After each run, the researchers set the temperature of the northern half of Mars' mantle to be slightly warmer than the southern half.
Ultimately, the temperature difference between the hotter mantle in the northern hemisphere and the cooler mantle in the southern hemisphere causes the heat escaping from the core to be released only at the southern end of the planet. In this way, the heat that escapes is enough to drive a generator, creating a strong magnetic field that is concentrated in the southern hemisphere.
A planetary dynamo is a self-sustaining mechanism that generates a magnetic field, typically through the movement of a molten metal core.
"We didn't know if it could explain the magnetic field, so we were excited to see that we could create a (single) hemispheric magnetic field with an internal structure that matched what InSight told us about the interior of Mars," Stanley said.
According to Doug Hemingway, a planetary researcher at the University of Texas Ignacy College, the discovery provides a compelling alternative to the common hypothesis that an asteroid impact would have wiped out evidence of the planet's magnetic field in Northern Hemisphere rocks.
"Mars itself is interesting because it's similar to Earth in some ways, and it's the closest planet we can imagine to Earth that we could actually build a home on," said Hemingway, who was not involved in the study. "However, there are huge differences between the northern and southern hemispheres of Mars. The terrain, topography and magnetic fields of the northern and southern hemispheres are completely different. Any clues that can explain this asymmetry are precious."
Compiled from /scitechdaily