Regular meteoric strikes raise withthe surface of the moon is a particle of water, which may indicate that the satellite of our planet still has some reserves of a precious resource under the surface, according to a new study based on data from analysis of several recent space research missions using automated interplanetary stations. The findings of these studies were published Monday in the journal Nature Geoscience.
Once the mission "Apollo" aerospaceNASA agencies brought samples of lunar soil to Earth; scientists could not find evidence of water availability on the satellite. However, over the past decades, data collected by various spacecraft, including NASA’s Cassini missions, Deep Impact and Lunar Prospector, as well as Chandrayaan-1 Indian, have found traces of water on the lunar surface. In addition, it was found that water is located on the entire surface of the satellite, and not only at its poles, as previously assumed.
However, scientists still havequestions about the source of all this water, as well as its quantitative reserves on the moon. A group of researchers led by Mehdi Benna from the NASA Goddard Space Center decided to answer these questions by analyzing the information collected by the LADEE lunar orbital probe (Lunar Atmosphere and Dust Environment Explorer). During the eight-month mission, this device investigated the composition of the lunar exosphere using an NMS spectrometer and was able to collect data on the amount of key volatile substances, including methane, helium, neon, argon, and others. In addition, during the mission, the probe made 743 measurements of the number of water molecules.
The median value was 22.8 molecules percubic centimeter, but scientists found 214 cases of a sharp excess of water concentration over the “background” - more than 10 times. Moreover, these bursts occurred mainly in the period from mid-November 2013 to mid-January 2014, which accounts for the period of maximum activity of 29 meteor showers, including such well-known Leonids, Geminids and Quadrantides.
"The bulk of geological processes, withwhich we encounter when studying planets and satellites proceed very slowly. We have never seen dynamic changes occur so quickly, literally on the scale of some hours, ”Mehdi Benn comments.
The researchers found that both the moon and the earth inThis period of time bombards the flow of meteoroids, including fairly large bodies of tens of meters in size. Benn and his colleagues found that in most cases a sharp increase in the concentration of water coincided with the maximum activity of the meteor showers. Calculations show that the main part of the water rises into the exosphere of the Moon when meteoroids strike a mass of from a few grams to tens of kilograms, which could penetrate deep enough into the depths of the lunar soil. After analyzing the data on the size of the streams, as well as on the volumes that were found in the atmosphere of the satellite, the scientists came to the conclusion that at a depth of less than 8 centimeters in the lunar soil the water concentration by weight can be 220–520 ppm.
According to the authors of the study, from the lunarsoil for the year in the interplanetary space due to meteorite impacts hits about 200 tons of lunar water. If the calculations of entrained water into space are correct, then it turns out that the water should have been on the satellite about 4.5 billion years ago. Perhaps it was brought there as a result of bombardment by meteorites and asteroids, which had a high concentration in their depths.
As for the lunar soil samples,collected in the framework of the Apollo missions, the lack of water in these samples can be explained by the fact that there was no this element directly inside the collected stones, since they were collected from the surface, and not deeper layers. There is a possibility that some certain amount of water particles could be on top of the stones, but the astronauts manipulated the samples during their collection, as well as transportation to Earth, most likely led to the fact that she could not hold onto them, suggests Benn.
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