Earth may be giving the Moon a case of rust: scientists
Researchers say oxygen drifting out of Earth’s atmosphere may be reaching the Moon and turning iron in its soil into hematite, a reddish mineral also known as rust
The Moon doesn't have rain, oceans or much of an atmosphere. But it does appear to have rust - and a new study suggests the culprit is Earth.
Researchers say oxygen drifting out of Earth's atmosphere may be reaching the Moon and turning iron in its soil into hematite, a reddish mineral also known as rust, says Science Alert.
"We conducted a series of oxygen and hydrogen irradiation experiments to simulate lunar surface irradiation processes," said Xiandi Zeng, a planetary scientist at Macau University of Science and Technology, who led the study. "For the first time, our experiments demonstrate both the formation and reduction of hematite minerals."
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Rust was first spotted at the lunar poles a few years ago, baffling scientists. The Moon lacks the two things that usually create rust on Earth — water and a thick oxygen-rich atmosphere. On top of that, it's constantly blasted by hydrogen from the solar wind, which tends to block oxidation.
The team found that Earth may be quietly lending the Moon the missing ingredient. When the Moon passes through Earth's magnetotail during its full phase, oxygen from our planet streams across while most of the solar wind is blocked. That gives iron on the lunar surface a chance to oxidize.
In the lab, the researchers bombarded iron-rich minerals such as metallic iron and ilmenite with oxygen ions. Hematite formed, while other minerals like pyroxene and olivine stayed unchanged, reports Science Alert.
"Our experimental results provide strong evidence that hematite can form on the lunar surface through oxygen ion irradiation," the study said.
Hydrogen fired at hematite could partially reverse the process, but only if it came in high-energy bursts, similar to conditions in Earth's magnetotail. The weaker solar wind hydrogen didn't undo the rusting.
That helps explain why the rust seems clustered near the poles, where Earth's oxygen gets funneled and hydrogen is deflected.
The findings, published in Geophysical Research Letters, suggest the Moon's rusty patches may even hold clues about Earth's atmospheric history stretching back billions of years.
"The formation of hematite (and potentially magnetite) via Earth wind irradiation underscores the material exchange between Earth and the Moon," the researchers wrote.
