Question corner | Is the Moon rusting?

On September 6, Union Minister Jitendra Singh said that images sent by Chandrayaan-1 suggest that the moon may be rusting along the poles. He was referring to a recently published study that found an oxidised iron mineral called hematite (Fe₂O₃) at high latitudes on the Moon.

The researchers say that this lunar hematite is formed through oxidation of the iron on the Moon's surface by the oxygen from Earth's upper atmosphere. The team analysed the data acquired by the Moon Mineralogy Mapper onboard Chandrayaan-1.

“More hematite on the lunar nearside suggested that it may be related to Earth,” said lead author Dr. Shuai Li at the Hawaii’s Institute of Geophysics and Planetology (HIGP) in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST) in a release. Along with the oxygen, water on the lunar surface and heat from interplanetary dust also helped in the oxidation process. The paper in Science Advances notes that the hematite is not absolutely absent on the lunar farside. There, a small amount of iron oxides “might be formed under the presence of water and energies induced by interplanetary dust impacts and then be decomposed to hematite.” They write that the hematite formed at lunar craters of different ages may help understand the oxygen of Earth’s atmosphere in the past 2.4 billion years and reveal facts about the evolution of Earth’s atmosphere in the past billions of years.

The team hopes that NASA's ARTEMIS missions can bring some hematite samples, and detailed chemical studies can confirm if the lunar hematite was indeed oxidised by Earth’s oxygen.