Scientists Link Moon’s Swirls to Underground Magma Activity

Scientists Link Moon’s Swirls to Underground Magma Activity

Key Takeaway

Planetary scientists propose that the mysterious lunar swirls are linked to underground magma activity. This new theory suggests that cooling subsurface lavas, reacting in the Moon’s magnetic field, may be responsible for these enigmatic features. The study provides a fresh perspective on lunar geology and highlights the potential for future missions to unravel these mysteries further.

Summary

• Lunar swirls are sinuous, light-colored features on the Moon’s surface.
• These swirls extend for hundreds of kilometers and their origin is not fully understood.
• Previous theories include meteorite impacts and surface lava flows.
• New research suggests that underground magma cooling in a magnetic field could be causing the swirls.
• Experiments by Michael J. Krawczynski and Yuanyuan Liang at Washington University tested this theory using the mineral ilmenite.
• Ilmenite reacts to form magnetizable iron metal particles under lunar conditions.
• These findings align with observations from lunar meteorites and Apollo mission samples.
• The study emphasizes the need for future lunar missions to collect subsurface samples.
• The upcoming Lunar Vertex mission will further investigate these swirls, particularly at Reiner Gamma.

The Mystery of the Lunar Swirls

In the latest chapter of “The Mystery of the Lunar Swirls,” planetary scientists have a new theory to explain these odd markings on the Moon’s surface. It invokes underground magmas and strange magnetic anomalies.

Lunar swirls are sinuous features that appear much lighter than the surrounding landscape. They extend for hundreds of kilometers and nobody’s quite sure why they exist. No astronaut has visited one of these weird regions, but that hasn’t stopped scientists from speculating based on images and magnetic field measurements. “Impacts could cause these types of magnetic anomalies,” said Michael J. Krawczynski, an associate professor of earth, environmental, and planetary sciences in Arts & Sciences at Washington University in St. Louis. Krawczynski points out that meteorites supply iron-rich material to areas on the Moon’s surface. However, these swirls exist in regions that aren’t necessarily disturbed by meteorites. So, what else could explain the swirls?

“Another theory is that you have lavas underground, cooling slowly in a magnetic field and creating the magnetic anomaly,” said Krawczynski, who, along with post-doctoral student Yuanyuan Liang, designed experiments to test this explanation. They measured the effects of different atmospheric chemistries and magmatic cooling rates on a mineral called ilmenite and found that under certain conditions, cooling subsurface lavas could be causing the ghostly lunar swirls.

Using Earth-Based Geological Principles to Understand Lunar Swirls

Despite the fact that more than a dozen people have walked on the Moon, nobody visited a lunar swirl or picked up samples of their dust. That left Earth-bound planetary scientists to use Earth analogs for Moon rocks to understand lunar magnetism. “Earth rocks are very easily magnetized because they often have tiny bits of magnetite in them, which is a magnetic mineral,” Krawczynski said. “A lot of the terrestrial studies that have focused on things with magnetite are not applicable to the Moon, where you don’t have this hyper-magnetic mineral.”

So, the research team turned to ilmenite as their test material. It’s a titanium-oxide mineral with a weak magnetic signal. Ilmenite exists all over the Moon. It readily reacts to form magnetizable iron metal particles. “The smaller grains that we were working with seemed to create stronger magnetic fields because the surface area to volume ratio is larger for the smaller grains compared to the larger grains,” Liang said. “With more exposed surface area, it is easier for the smaller grains to undergo the reduction reaction.”

Interestingly, planetary scientists have seen a similar reaction creating iron metal in lunar meteorites in samples from the Apollo missions. The difference, however, is that those samples came from surface lava flows. Krawczynski and Liang’s study focused on the types of magma that cooled underground.

The Experiment: Testing the Magma Theory

“Our analog experiments showed that at lunar conditions, we could create the magnetizable material that we needed. So, it’s plausible that these swirls are caused by subsurface magma,” said Krawczynski. “If you’re going to make magnetic anomalies by the methods we studied, then the underground magma needs to have high titanium.”

To test their theory, Krawczynski and Liang conducted a series of experiments. They recreated lunar conditions in the lab to observe how ilmenite behaves under different atmospheric chemistries and cooling rates. These experiments revealed that smaller grains of ilmenite, due to their larger surface area to volume ratio, are more reactive and more likely to form strong magnetic fields.

Table 1: Experimental Conditions and Results

Why Study Swirls on the Moon?

Those mysterious dust patterns aren’t just there by accident. They contain clues to the processes that shaped the lunar surface. In addition, if magnetism is involved in their formation, that says something about magnetism on the Moon as a whole.

Until astronauts can get to the Moon to study these swirls for themselves, the ilmenite experiment offers a good way to test the underground magma idea from afar, according to Krawczynski. Of course, it would be nice to get actual samples of underground rocks on the Moon, but that’s going to have to wait. “If we could just drill down, we could see if this reaction was happening,” he said. “That would be great, but it’s not possible yet. Right now, we’re stuck with the surface.”

Future Missions and Lunar Exploration

Studies like Krawczynski and Liang’s will be quite useful when NASA sends future lunar missions to the surface. There’s a whole rover project, part of a mission called Lunar Vertex, planned to study Reiner Gamma. That’s one of the Moon’s better-known swirls. Vertex should launch this year and is a predecessor to the larger return to the Moon NASA plans for later this decade. That mission could confirm whether or not swirls are magnetic field-related. If not, then there’s something else going on at Reiner Gamma and other swirl sites.

Table 2: Upcoming Lunar Missions

Implications for Lunar Geology

The study of lunar swirls is more than an academic exercise; it has real implications for our understanding of the Moon’s geological history. The presence of magnetic anomalies suggests that the Moon once had a magnetic field, which has since faded. Understanding how these anomalies formed can provide insights into the Moon’s past magnetic activity and its cooling history.

Conclusion

The mystery of the lunar swirls is far from solved, but the work of scientists like Krawczynski and Liang brings us one step closer. Their experiments with ilmenite provide a plausible explanation for the magnetic anomalies observed in these swirls. As future missions like Lunar Vertex and Artemis prepare to explore the Moon, we can look forward to more answers and perhaps even more questions about these fascinating features.

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