Science / Chandrayaan-1 orbiter data shows Moon rusting at poles

Bengaluru: Another sign that the Moon’s poles are home to water has emerged from the Chandrayaan 1’s data.

The Indian Space Research Organisation’s (ISRO) maiden mission to Earth’s natural satellite has revealed that there may be rusting on the Moon — something that can only occur if iron interacts with water and oxygen.

And, even though the Moon has a lot of iron, it’s not known to be rich in oxygen and water. "The Moon is a terrible environment for hematite to form in," said Shuai Li, the lead author of the paper published in Science Advances.

Researchers with the National Aeronautics and Space Administration (NASA) believe that Earth may have had a role to play.

The Earth’s atmosphere could be protecting the Moon as well

The Moon is constantly bombarded by solar particles coming off the Sun. Without an atmosphere to protect itself, the hydrogen should make it difficult for rust to form.

Hydrogen is a reducer. It adds electrons to the material it touches.For iron to rust, it needs the opposite — an oxidiser which removes electrons instead.

Instead, Earth’s atmosphere may have had a helping hand to give. The planet’s magnetotail — the part of its magnetic atmosphere that extends away from the Sun — is capable of blocking out 99% of the solar wind aimed at the Moon when it’s in its Full Moon phase.

That part of the lunar cycle gives iron on the Moon occasional windows of opportunity for rust to form.

Building the perfect storm for the Moon to rust

Earth’s magnetotail does more than just provide the Moon with a shield. During that interaction, some of the oxygen from the planet also gets transferred over. This was confirmed by Japan’s Kaguya orbiter in 2007.

So, even though the Moon isn’t rich in oxygen, it does have access to oxygen during the same window of opportunity when it’s not being bombarded with hydrogen.