The Moon is rusting — and why the Earth is responsible

Planetary scientists have discovered haematite, a type of iron oxide sometimes known as rust, on the Moon's surface, particularly near the poles. Scientists were astonished to discover that the Moon is rusting, a process that usually requires oxygen and water, both of which are sparse on the lunar surface.

Moreover, this rusting process is completely triggered by activity on Earth.

Ziliang Jin, a planetary scientist from Macau University of Science and Technology in China, told Nature that the discoveries contribute to a better understanding of Earth's fundamental connection to the Moon. Ziliang and colleagues published their findings earlier this month in Geophysical Research Letters

The scientists assume that oxygen from Earth's atmosphere is carried to the Moon. Notably, charged particles from the Sun almost always reach Earth and the Moon.

The majority of solar particles are blocked when the Earth passes between the Sun and the Moon for around five days per month. It is the time when the Moon is primarily exposed to particles that were previously part of the Earth's atmosphere, known as Earth wind.

Scientists reported in 2020 that India's Chandrayaan-1 probe discovered haematite near the Moon's poles. However, the Moon's chemical environment is not conducive to the presence of oxygen, implying that the oxygen for the haematite may have arrived from somewhere else.

As a result, Ziliang and his colleagues decided to test the discovery through a lab simulation of the Earth and the Moon. They accelerated hydrogen and oxygen ions to high energies before sending them into single crystals of iron-rich minerals found on the Moon.

When scientists exposed the crystals to high-energy oxygen, some of them transformed into haematite. Pelting the haematite with hydrogen led some of it to convert back to iron, Nature reported.

Notably, understanding rust on the moon could influence future lunar missions, resource utilisation, and equipment design.