Scientists have discovered in one of the lunar meteorites minerals that form only in the presence of liquid water, which suggests that it existed in the past on the surface of the Earth's satellite. Their findings were published in the journal Science Advances.
“For the first time, we were able to prove that real ice was once present in this lunar matter. As a rule, moganites themselves contain little water, as they form when it evaporates. Something similar happened on the surface of the moon. In its depths, on the other hand, most of the water had to remain in the form of ice crystals, protected from the light of the sun,”said Masahiro Kayama from Tohoku University (Japan).
It is believed that the Moon was formed as a result of the collision of Theia, a protoplanetary body, with the "embryo" of the Earth. The collision led to the ejection of the matter of Theia and the proto-Earth into space, from which the Moon was "molded". This cataclysm was considered the reason why its bowels and surface are practically devoid of water. This hypothesis was challenged in February 2012 when scientists discovered an unexpectedly high concentration of water in lunar igneous rocks.
There are two major controversies - where this water came from and where it is hiding. Some astronomers assume that comets were the main source of water, while others attribute this role to asteroids, and there are sets of evidence in favor of both theories.
Kayama and his colleagues may have figured out where most of the lunar water reserves are hidden by studying the structure of the meteorite NWA 2727, found in Morocco in June 2005. Scientists today believe that this small piece of the lunar crust was knocked out of its surface about 2.67 billion years ago when the moon collided with a large asteroid. All this time, it revolved around the Earth and the Moon, falling to the surface of the planet about 16 thousand years ago.
In recent years, geologists have found dozens of such "heavenly stones", which have given scientists a lot of new information about how the moon is arranged and how it looked in the distant past. However, NWA 2727 turned out to be a special meteorite due to one unique mineral that had never been found in Apollo specimens or other lunar rocks before.
In this fragment of lunar rocks, as noted by geologists, there were large inclusions of moganite - a mineral that occurs when puddles or lakes dry out, containing a large amount of alkaline compounds. In the desert where NWA 2727 was found, there were no other deposits of this mineral, which suggests that it originated on the Moon, and not on Earth.
How could this mineral appear on the "waterless" satellite of our planet? As scientists suggest, the upper layers of the Moon's rocks were formed from the debris of chondrites and other primitive asteroids that fell on its surface in the last phases of the formation of the solar system. In addition to silicate rocks and organics, they contained large amounts of water in the form of microscopic ice crystals.
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Some of them were on the surface of the moon, and the rays of the sun gradually melted this water and made it collect in films and miniature puddles hidden directly under the top layer of the soil. This water gradually evaporated, leaving the Moganites, which were subsequently thrown into space with NWA 2727 when another asteroid hit the moon.
If so, then today the upper layers of the lunar rocks, as the calculations of Kayama and his colleagues show, contain a gigantic amount of water - about 6 liters for every cubic meter of soil. Scientists hope that subsequent missions to collect soil from the moon will help verify whether this is so or not.
“This amount of water is quite enough for both future astronauts and colonists who will live on the moon in the future, to meet all their needs. We won't have to carry our drinking water and fuel production with us when we fly to Mars. The moon will provide us with everything we need,”concludes Kayama.