(ORDO NEWS) — There are water molecules and ice on the Moon, but how did they get there? It’s likely that some of the water came from asteroid-comet collisions, but a new study suggests a different source of lunar water – Earth’s atmosphere.
Hydrogen and oxygen ions escaping from our planet’s upper atmosphere and then fusing on the Moon could create up to 3,500 cubic kilometers (840 cubic miles) of surface permafrost, or subsurface liquid water, scientists say.
According to scientists, hydrogen and oxygen ions hit the lunar surface when the moon passes through the Earth’s magnetotail (a teardrop-shaped bubble around the Earth that is affected by its magnetic field). This happens five days in every lunar month.
Due to the fact that the solar wind of the Sun presses on this bubble, some of the lines of the Earth’s magnetic field are broken: they are tied to the planet at only one end.
When the Moon interferes with the Earth’s magnetotail, some of these broken bonds are restored, causing hydrogen and oxygen ions that previously escaped the Earth’s atmosphere to suddenly rush back towards it.
“It’s like the moon is in a shower – a shower of water ions returning to Earth falls on the surface of the moon,” says geophysicist Günter Kletechka of the University of Alaska Fairbanks.
The moon does not have a magnetosphere, so when ions crash into the lunar surface, permafrost forms, the researchers suggest. Part of this permafrost, as a result of various geological processes, can be driven under the surface and turned into liquid water.
The researchers suggest that there was a slow accumulation of these ions over billions of years after the Late Heavy Bombardment, a period when the early Earth and Moon were subjected to heavy impacts from other celestial bodies rushing through space.
Gravity data from NASA’s Lunar Reconnaissance Orbiter has been used to closely study the Moon’s polar regions and several large craters. The team found anomalies that could indicate rock faults capable of holding permafrost.
“Crater impacts that form structural expansions and faults allow the creation of suitable pore space networks to accommodate large subsurface liquid water reservoirs,” the researchers wrote in the published paper.
“Inverse estimation calculations show that over the past 3.5 billion years, several thousand cubic kilometers of the water phase have accumulated in the interior of the Moon in this way.”
Although scientists believe the water on the Moon most likely comes from several sources – including reactions of hydrogen and oxygen driven by the solar winds – most of it could very well have been produced this way.
The projected amount of water would be enough to fill Lake Huron in North America. The coating created by the craters and cracks in the rocks will provide the necessary protection to keep the water from evaporating back into space.
NASA aims to ensure a long-term human presence on the Moon, and for this it is necessary to create a suitable lunar station with a nearby source of water. This latest study could help experts decide where to place such a station.
“Because the NASA Artemis team plans to build a base camp at the south pole of the moon, water ions originating many eons ago on Earth could be used in the astronauts’ life support system,” says Kletechka.
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