Researchers found that Japan’s SELENE lunar orbiter (aka Kaguya), detected high levels of oxygen ions – positively charged oxygen molecules – while it was orbiting the Moon between 2007 and 2009.
Analysing data from Japanese lunar orbiter Kaguya, researchers suggest that this oxygen exchange occurs when Earth’s protective magnetosphere passes over the Moon. This shielded the Moon from the blast of the Sun’s solar wind and while allowing a stream of positively charged oxygen molecules from Earth to travel to the lunar surface instead.
“Our new finding suggests that the Earth-Moon system coevolves not only physically but also chemically,” astrophysicist Kentaro Terada from Osaka University in Japan told EOS.
The Japanese spacecraft only detected the chemical during a distinct five-day period during each lunar orbit – which takes approximately 27 days.
Although the possibility of the presence of terrestrial nitrogen and noble gases in lunar soil has been
suggested, this is the first time that researchers have found oxygen is transported to the Moon after escaping the Earth’s atmosphere.
The new findings suggest the possibility that the Earth’s atmosphere of billions of years ago may be preserved on the present-day lunar surface.
In 2008, the Moon and Kaguya both lay within the Earth’s plasma sheet for tens of minutes to a few hours per month. When the Moon moved into the central magnetosphere, Kaguya’s plasma detector picked up a significant amount of high-energy oxygen ions.
The findings have been reported in Nature Astronomy.