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 solved a long-standing puzzle surrounding the Moon's magnetic field, a debate ignited by rock samples returned by the Apollo missions. For decades, evidence from these lunar samples suggested the Moon possessed a robust magnetic field for extended periods, at times even surpassing Earth's own magnetic strength. This finding posed a significant scientific quandary, particularly when considering the Moon's relatively small core – roughly one-seventh of its radius – which conventional models suggested was insufficient to generate such a powerful, sustained field.

However, new research spearheaded by Associate Professor Claire Nichols and her team at Oxford's Department of Earth Sciences offers a compelling, albeit surprising, resolution. Their analysis focused on a specific type of lunar rock known as Mare basalts. Through meticulous examination, they uncovered a novel correlation: the magnetism preserved within these rocks is directly linked to their titanium content. The study revealed that lunar samples exhibiting strong magnetic signatures were consistently rich in titanium, whereas those with less than 6 percent titanium were associated with significantly weaker magnetic fields.

The Oxford team's hypothesis posits that the simultaneous occurrence of high-titanium rocks and a strong lunar magnetic field was not coincidental but rather a direct consequence of geological processes. They propose that the melting of titanium-rich material deep within the Moon, specifically at the core-mantle boundary, was the catalyst for generating a powerful magnetic field. Crucially, this process is believed to have been geologically brief, lasting for approximately 5,000 years – a mere 'blip' in the Moon's extensive history.

"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 revised understanding also sheds light on why the Mare basalt plains were favored landing sites for the Apollo missions. Their relatively flat terrain made them ideal for astronaut operations. However, the proximity of these basaltic plains to the landing zones meant that astronauts collected a disproportionately high number of titanium-rich samples compared to a truly representative sample of the Moon's surface. This geological sampling bias, the researchers argue, led to a misinterpretation of the duration of the Moon's strong magnetic field.

The implications of this research extend to future lunar exploration. Co-author Dr. Simon Stephenson noted the practical applications: "We are now able to predict which types of samples will preserve which magnetic field strengths on the Moon. The upcoming Artemis missions offer us an opportunity to test this hypothesis and delve further into the history of the lunar magnetic field." Understanding the transient nature and drivers of the Moon's magnetic field not only refines lunar geology but could also provide insights into the magnetic field evolution of other terrestrial planets, including Earth.

Ekhbary News Agency