Moon's Mighty Magnetic Field Was a 5,000-Year Titanium Blip, New Study Suggests

United Kingdom - Ekhbary News Agency

Moon's Mighty Magnetic Field Was a 5,000-Year Titanium Blip, New Study Suggests

Scientists at the University of Oxford have potentially resolved a long-standing enigma surrounding the Moon's magnetic field, a debate ignited decades ago by the rock samples brought back from the Apollo missions. For years, evidence from these missions indicated that the Moon possessed a robust magnetic field for extended periods, sometimes even exceeding the strength of Earth's current field. This presented a significant puzzle for planetary scientists, especially given the Moon's relatively small core – approximately one-seventh of its radius – which was widely believed to be incapable of generating such a powerful and enduring magnetic dynamo.

However, new research led by Associate Professor Claire Nichols from Oxford's Department of Earth Sciences offers a compelling, albeit surprising, resolution. The team meticulously analyzed the composition of a specific type of lunar rock known as Mare basalts. Their findings revealed a crucial correlation: the magnetism preserved within these rocks is directly linked to their titanium content. Specifically, samples exhibiting strong magnetic signatures consistently contained substantial amounts of titanium, while those with less than 6 percent titanium were associated with significantly weaker magnetic fields.

The study posits that the formation of these high-titanium Mare basalts and the generation of a strong lunar magnetic field were not separate phenomena but rather interconnected consequences of a specific geological process. It suggests that the melting of titanium-rich material deep within the Moon, likely at the core-mantle boundary, not only produced these distinctive rocks but also fueled a powerful magnetic dynamo. Critically, this dynamo appears to have been active for a surprisingly short duration – estimated at around 5,000 years.

"Our new study suggests that the Apollo samples are biased to extremely rare events that lasted a few thousand years – but up to now, these have been interpreted as representing 0.5 billion years of lunar history," stated Professor Nichols. "It now seems that a sampling bias prevented us from realizing how short and rare these strong magnetism events were." She further elaborated, "We now believe that for the vast majority of the Moon's history, its magnetic field has been weak, which is consistent with our understanding of dynamo theory. But that for very short periods of time – possibly as short as a few decades – melting of titanium-rich rocks at the Moon's core-mantle boundary resulted in the generation of a very strong field."

This revelation also sheds light on the landing site selections for the Apollo missions. The Mare basalt plains were favored for their relatively flat terrain, making them ideal landing zones. Consequently, the rock samples collected were predominantly from these easily accessible, titanium-rich basaltic regions. This geographical bias in sampling inadvertently created an impression of a long-lived, strong magnetic field, as the collected samples disproportionately represented these brief, high-titanium, high-magnetism events.

Co-author Dr. Simon Stephenson highlighted the practical implications of this research: "We are now able to predict which types of samples will preserve which magnetic field strengths on the Moon." He added, "The upcoming Artemis missions offer us an opportunity to test this hypothesis and delve further into the history of the lunar magnetic field." This research not only reframes our understanding of lunar evolution but also provides a critical framework for future lunar exploration, guiding the selection of sampling sites and the interpretation of data gathered by missions like Artemis, aiming for a more comprehensive picture of the Moon's dynamic past.

Ekhbary News Agency