Researchers pinpoint the origins of the moon’s tiny atmosphere

The researchers claim to have found a ‘definitive answer’ that the moon’s atmosphere was created by various asteroids crashing into it, causing particles to remain suspended around it.

A new study claims to have identified how the moon managed to develop an extremely thin atmosphere – through a combination of asteroids and solar wind.

The moon lacks breathable air, but it does have an extremely delicate atmosphere – technically known as an exosphere – that was observed by astronomers in the 1980s. It has been widely believed that this exosphere is the result of space weathering – being exposed to the harsh environment of space – but the specific causes have been a mystery.

But now, researchers from MIT and the University of Chicago say they have identified the main process that formed this tiny atmosphere and continues to sustain it. The team believes the primary cause is “impact vaporisation”.

As part of the study, the researchers analysed samples of lunar soil collected during NASA’s Apollo missions. This analysis suggests that the moon has been continuously bombarded by meteorites throughout the past 4.5bn years. These bombardments included massive meteorites and – more recently – smaller, dust-sized ‘micrometeoroids’.

The study claims these constant impacts kicked up the lunar soil and vaporised certain atoms on contact, throwing the particles into the air. This causes some of the atoms to eject into space, while others remain suspended over the moon, forming the tiny atmosphere that is constantly replenished by more impacts.

“We give a definitive answer that meteorite impact vaporisation is the dominant process that creates the lunar atmosphere,” said the study’s lead author Dr Nicole Nie. “The moon is close to 4.5bn years old, and through that time the surface has been continuously bombarded by meteorites.

“We show that eventually, a thin atmosphere reaches a steady state because it’s being continuously replenished by small impacts all over the moon.”

The researchers also believe the creation of the lunar atmosphere is boosted by a space weathering process called ‘ion sputtering’ – where solar wind carries energetic charged particles from the sun through space. The researchers believe that when these particles hit the moon’s surface, they can transfer their energy to the atoms in the soil and send those atoms flying into the air.

The researchers believe that 70pc or more of the moon’s atmosphere is the result of meteorite impacts, while the remaining 30pc is a result of ion sputtering.

The US recently received a boost to its space exploration endeavours, as one of its private lunar landers touched down on the moon’s surface for the first time in more than half a century.

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