The reaction of the scientists was the same as you probably did when they came to this conclusion. That may not be possible – after all, there is no oxygen on the moon, one of the two essential elements for rust, and the other is water.
But the evidence was there.
India’s lunar probe, Chandrayaan-1, visited the moon in 2008, collecting data that led to many discoveries over the years – including the discovery of water molecules on its surface. The probe also included a NASA-built instrument that could analyze the moon’s mineral composition.
When researchers from NASA and the Aerospace Institute of Geophysics and Planetology recently analyzed the data, they were surprised to find signs of hematite, a form of iron oxide known as forest. There are many iron-rich rocks on the moon – but rust only occurs when iron is exposed to oxygen and water.
Not only is there wind on the moon, but it is also filled with hydrogen that flows from the sun, which is driven by the solar wind. Rust occurs when oxygen removes electrons from iron; Hydrogen does the opposite by combining electrons, which means it’s hardest to rust on a hydrogen-filled moon.
After months of research, Lee and NASA scientists think they’ve cracked it – and the answer lies in our own planet.
This is their principle
One big clue was that the moon was more concentrated on the side facing the earth – suggesting that it was somehow connected to our planet.
The earth is spread out in a magnetic field, and the solar wind pulls this bubble in a stressful direction to form a long magnetic tail. The moon enters this tail three days before completion, and takes six days to cross the tail and exit the other side.
And, Lee speculates, oxygen from Earth travels to land on the moon on this magnetic tail, where it interacts with the moon’s water molecules to create rust.
The magnetic tail also blocks almost all solar winds throughout the moon – meaning the moon is temporarily protected from a hydrogen explosion, opening a window to rust.
“This discovery will reshape our knowledge of the lunar polar regions,” he added. “Earth may have played a significant role in the development of the moon’s surface.”
This theory can also explain why rust has been found on other airless bodies, such as asteroids. “It may be that the iron in these bodies is being allowed to rust under the influence of a small drop of water and dust particles,” Freeman said.
But some questions remain unanswered – for example, although most of the rust was found near the moon, some small traces were also found on its far side, where the Earth’s oxygen should not have reached. It is still unclear exactly how the moon’s water interacts with the rock.
To gather more data for these unsolved mysteries, NASA is developing a new version of the tool that collected all this existing data on the lunar mineralization. One of these features will be able to map water ice on the moon’s poles – and may also be able to reveal new details about hematite, NASA said in a statement.