Minerals found in craters on the Moon may be remnants of asteroids that slammed into it and not, as long believed, the satellite’s innards exposed by such impacts, a study said Sunday.
The findings, published in the journal Nature Geoscience, cast doubt on the little we knew of what the Moon is actually composed of.
It had long been thought that meteoroids vaporise on impact with large celestial bodies.
Unusual minerals like spinel and olivine found in many lunar craters, but rarely on the Moon’s surface, were therefore attributed to the excavation of sub-surface lunar layers by asteroid hits.
Olivine and spinel are common components of asteroids and meteorites, and have been found on the floors and around the central peaks of lunar craters like Copernicus, Theophilus and Tycho that are around 100 kilometres (63 miles) in diameter.
A team from China and the United States simulated the formation of Moon craters and found that at impact velocities fewer than 12 kilometres per second a projectile may survive the impact, though fragmented and deformed.
“We conclude that some unusual minerals observed in the central peaks of many lunar impact craters could be exogenic (external) in origin and may not be indigenous to the Moon,” they wrote.
Unlike the Earth’s crust, which is repeatedly recycled through the process of plate tectonics, the Moon’s hard crust dates back billions of years, offering clues to the formation of the solar system, including Earth.
