The investigations conducted by scientists on samples from the Apollo missions to the moon – during the sixties and seventies of the last century – still cast a shadow over today's discoveries. The results announced by a team of researchers in research paper Published in the journal Science Advances, it reveals the intriguing causes of the Moon's thin atmosphere.
Space flights over the past decades have shown that the moon has a thin atmosphere, which is technically called “Exosphere(Exosphere) It consists primarily of the elements helium, argon, sodium and potassium. Also, when darkness falls, this atmosphere falls on the surface of the moon, and is not suitable for breathing.
Researchers from the Massachusetts Institute of Technology have found that meteorites exploding on the moon's surface are the main driver of the formation of the thin atmosphere. The strong impact generates heat ranging between 2,000 and 6,000 degrees Celsius, which is enough to melt rocks and cause them to evaporate, similar to the evaporation of water when exposed to heat, which results in many atoms rising and escaping from the moon's gravity.
The moon's atmosphere is so thin and fragile that it is almost imperceptible, because the atoms are scattered in a vacuum and are not homogeneous, unlike the Earth, which has a thick and stable atmosphere.
Space flights to study the moon's atmosphere up close
Although the Apollo missions of the last century were the first to raise this hidden astronomical feature of the moon, the space flightLIDAANASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), launched in 2013, is the most specialized spacecraft for studying the atmosphere. The satellite orbited the moon and collected a lot of data about the composition and fluctuations of the lunar atmosphere.
One of the primary mission goals was to identify the sources of lunar dust and understand how this dust interacts with the lunar atmosphere. The satellite carried scientific instruments to achieve the mission goals that provided comprehensive measurements, helping scientists better understand the dynamics and composition of the atmosphere.
The space mission lasted about 6 months before the satellite was deliberately crashed into the surface of the moon, revealing the two types of “space weathering” it is exposed to: the first type is the frequent collision of meteorites, and the other is the “solar wind spray.”
Space weathering is an astronomical term that refers to the harsh conditions experienced by celestial bodies that do not have a thick atmosphere capable of providing protection from various foreign external objects.
The solar wind, carrying high-energy charged particles such as protons, affects the lunar soil, transferring energy to it, causing the soil, which has become charged, to scatter and rise scattered from the surface of the moon.
Moon's atmosphere
Although the LIDAA space mission has reached unprecedented results regarding the lunar atmosphere, it has not determined the contribution rates of each of the two factors mentioned, which is what was shown by the recent study, which said that the lunar atmosphere is formed by meteor impacts by 70%, while solar winds contribute about 30%.
As the moon appears in its current form with its large craters spread throughout its regions, it has been exposed to different sizes of meteorites throughout history during the stages of its formation. Despite the decrease in the frequency of large meteorites falling on it, smaller meteorites continue to fall continuously until today, causing the formation of the moon’s thin atmosphere.
This atmosphere extends from the surface of the moon to an altitude of about 100 kilometers, while the Earth's atmosphere extends to about 10 kilometers. In their study, the researchers relied on studying the samples brought back by astronauts within the Apollo program instead of studying the actual atmosphere of the moon.
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This is because the lunar soil is constantly interacting with the atmosphere, and this interaction leaves distinctive fingerprints about the composition of isotopes that can be compared. Isotopes are atoms of the same chemical element with slightly different masses due to different numbers of subatomic particles known as neutrons.
Scientists used advanced mass spectrometry equipment to examine the ratio of different isotopes of elements such as potassium and rubidium in lunar soil, which led to the current results.
