Rust discovered on the moon - and Earth could be responsible

<p>The finding comes after analysis of data from the Indian Space Research Organisation's Chandrayaan-1 orbiter.</p><p>Light reflecting off surfaces at both poles was found to have the spectral signature for the mineral hematite - more commonly known as rust.</p><p>Hematite, a type of iron oxide, is formed when iron is exposed to oxygen and water.</p><p>The study's lead author, Shuai Li from the University of Hawaii, called it "very puzzling" as "the moon is a terrible environment for hematite to form in" because it is airless with no oxygen or liquid water.</p><p>He contacted scientists at <strong><a href="https://news.sky.com/topic/nasa-5932" target="_blank">NASA's</a></strong> Jet Propulsion Laboratory (JPL) - the department that built Chandrayaan-1's Moon Mineralogy Mapper instrument.</p><p>Abigail Fraeman, a JPL scientist, said: "At first, I totally didn't believe it. It shouldn't exist based on the conditions present on the moon.</p><p>"But since we discovered water on the moon, people have been speculating that there could be a greater variety of minerals than we realise if that water had reacted with rocks."</p><p>Three explanations have been explored.</p><p>Firstly, that despite the moon not having an atmosphere, it does contain trace amounts of oxygen - which travels 239,000 miles from Earth's magnetic field.</p><p>This explains why more hematite is found on the side of the moon facing Earth and suggests our planet may be the driving force for the rust.</p><p>It is also possible the oxygen travelled from Earth to the moon when the two were closer, as they have been moving apart for billions of years.</p><p>The second reason could be the level of hydrogen present - this is delivered to the moon and Earth via solar winds from the sun.</p><p>Hydrogen is a reducer, meaning it helps prevent oxidation and rusting.</p> <p>The Earth's magnetic field protects the planet from solar winds, it also blocks over 99% of this activity during periods of the moon's orbit - particularly when the moon is full.</p><p>This means there is an opportunity during the lunar cycle where rust has the ability to form.</p><p>The third explanation suggests that water molecules - found within the moon's surface - are released when dust particles hit the moon, mixing them with iron.</p><p>Heat from this impact may then increase the rate of oxidisation.</p><p>They also suggest the dust particles themselves may contain water molecules which then mix with iron.</p><p>At specific times, the moon is shielded from solar winds that carry hydrogen, this paired with the presence of oxygen could cause a rust-inducing chemical reaction.</p><p>Dr Fraeman suggested these reasons could also explain why rust is found on other airless bodies, such as asteroids.</p><p>JPL scientist Vivian Sun added: "I think these results indicate that there are more complex chemical processes happening in our solar system than have been previously recognised.</p><p>"We can understand them better by sending future missions to the Moon to test these hypotheses."</p><p>This research has been published in Science Advances.</p>