Earth's Fate like Mars? Investigating the Lost Magnetic Field!

Key Takeaways:

Mars’ Mysterious Transformation: Once a warm, wet, and potentially habitable planet, Mars transformed into a barren wasteland due to the loss of its magnetic field.
Critical Role of Magnetic Fields: Earth’s magnetic field shields it from the Sun’s harmful solar wind, preserving its atmosphere and habitability.

New Insights from Research: A recent study titled “Stratification in planetary cores by liquid immiscibility in Fe-S-H” sheds light on the demise of Mars’ magnetic shield.
Hydrogen’s Hidden Role: Evidence from NASA’s InSIGHT probe suggests the presence of hydrogen in Mars’ core, which may have played a crucial role in its magnetic field collapse.
Experimental Revelation: Researchers used a diamond anvil to simulate Mars’ core conditions and discovered the immiscibility of iron, sulfur, and hydrogen, offering an explanation for the loss of the planet’s magnetic field.

Mars, a planet known for its parched landscapes and ferocious dust storms, was once a vastly different world. In its distant past, it boasted a welcoming environment with liquid water flowing across its surface, carving channels, and forming lakes.

This schematic illustrates the relationship between the motion of conducting fluid, organized into rolls by the Coriolis force, and the magnetic field the motion generates. Image Credit: By Andrew Z. Colvin - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=98901558 — This schematic illustrates the relationship between the motion of conducting fluid, organized into rolls by the Coriolis force, and the magnetic field the movement generates. Image Credit: By Andrew Z. Colvin – Own work, CC BY-SA 4.0,

However, this idyllic setting drastically changed as Mars lost its magnetic field, resulting in the stripping away of its atmosphere and the subsequent disappearance of its water. Today, Mars stands as a harsh and inhospitable place, only explored by robotic rovers. The question of how Mars lost its magnetic shield has perplexed scientists for years.

The magnetic field is a vital protector of a planet’s atmosphere and habitability. It prevents the Sun’s solar wind from eroding the atmosphere, preserving the conditions conducive to life. Earth owes its lush biosphere to its robust magnetic field. Mars, on the other hand, possesses a feeble remnant of a magnetic field originating from its crust, providing minimal protection.

Earth’s magnetosphere isn’t a sphere at all. The solar wind deforms it into an asymmetrical shape. Image Credit: NASA

The loss of its magnetic shield had catastrophic consequences for Mars, leaving researchers eager to uncover the exact cause. A recent study published in Nature Communications titled “Stratification in planetary cores by liquid immiscibility in Fe-S-H” delves into this enigma. The study’s lead authors, Professor Kei Hirose from the University of Tokyo’s Department of Earth and Planetary Science and Ph.D. student Shunpei Yokoo, are at the forefront of this quest for answers.

Earth’s magnetic field is generated by the convection currents of molten metals in its core. This inner core, composed of solid iron, and an outer liquid core generate heat flow, resulting in convective currents within the liquid core. These currents, influenced by the planet’s rotation and the Coriolis effect, create Earth’s magnetosphere, a protective shield against the solar wind.

This image is a scientific visualization of the electromagnetic currents around Mars. These are remnant currents from the magnetism leftover in Mars' crust. They're far too weak to protect Mars from the solar wind. Credit: NASA/Goddard/MAVEN/CU Boulder/SVS/Cindy Starr — This image is a scientific visualization of the electromagnetic currents around Mars. These are remnant currents from the magnetism leftover in Mars’ crust. They’re far too weak to protect Mars from the solar wind. Credit: NASA/Goddard/MAVEN/CU Boulder/SVS/Cindy Starr

This magnetosphere envelops Earth, diverting the Sun’s solar wind around the planet and preventing it from reaching the atmosphere and surface. It’s this shield that keeps Earth’s atmosphere intact and conducive to life. Without it, Earth would resemble the barren and desolate Mars we know today.

So, what transpired on Mars? Professor Hirose explains, “Earth’s magnetic field is driven by inconceivably huge convection currents of molten metals in its core. Magnetic fields on other planets are thought to work the same way.” Recent evidence, including data from NASA’s InSIGHT probe and meteorite analysis, suggests that Mars’ core contains lighter elements like hydrogen, in addition to molten iron enriched with sulfur.

To investigate this further, researchers conducted experiments using a material sample mimicking Mars’ core composition: iron, sulfur, and hydrogen (Fe-S-H). They subjected this sample to extreme pressures and temperatures, simulating conditions within Mars’ core, using a diamond anvil cell. This device, capable of exerting immense pressure on microscopic samples, revealed unexpected findings. The Fe-S-H sample not only melted but also separated into two distinct liquids, one rich in sulfur and the other in hydrogen.

This immiscibility of Fe-S-H at high pressures and temperatures holds the key to understanding Mars’ magnetic field collapse. The research suggests that initially, two immiscible liquids formed within Mars’ core. Denser liquids remained at the deepest part, while lighter liquids migrated upwards and mixed with the bulk liquid core, driving Martian core convection. However, in the region where the two liquids separated, a gravitationally stable stratification developed, causing the cessation of convection.

This figure from the paper shows how Mars' core and Earth's core started out similarly, then changed over time. The Martian core became immiscible from the center out, leading to stratification and cessation of convection. Without convection, there's no magnetic shield. Earth's core is different, and our planet still has a magnetic shield. Image Credit: Yokoo et al. 2022. — This figure from the paper shows how Mars’ core and Earth’s core started similarly, then changed over time. Light- and dark-blue represent buoyant and dense liquids, respectively. The Martian core became immiscible from the center out, leading to stratification and cessation of convection. Without convection, there’s no magnetic shield. Earth’s core is different than Mars’. The liquid core’s immiscibility created stratification on the outer layers, while the inner layers remained liquid. The result is that our planet still has a magnetic shield. Image Credit: Yokoo et al. 2022.

This crucial discovery offers an explanation for the loss of Mars’ magnetic field, which occurred around 4 billion years ago. Once the two liquids separated, Mars was doomed. Convection ceased, leading to the disappearance of the magnetic shield, the atmosphere, and ultimately, the water.

However, this study represents just one piece of the puzzle. Further seismic studies of Mars are needed to confirm the predicted distinct layers within its core. If validated, this research could provide invaluable insights into the formation and composition of rocky planets, including Earth.

While Earth’s magnetic field ensures its habitability for the foreseeable future, it’s a reminder that no planet remains habitable indefinitely. In about 5 billion years, Earth will face its own existential threat when the Sun enters its red giant phase. Nonetheless, for now, Earth’s protective magnetic field remains intact, safeguarding the planet’s rich tapestry of life. So, as we ponder the mysteries of Mars, we also celebrate our billion-year head start in ensuring our planet’s continued habitability.