At least since the first manned missions to the Moon in the 1960s and early 1970s, the general belief was that Earth’s orbiting partner was dry. Then, about two years ago, several lunar missions showed that this is not entirely true. Some lunar soil contains minute amounts of water molecules. But where did the water on the moon come from? Answering this question can help us understand the history and evolution of the moon, but also allow future engineers to potentially tap into this resource when building a sustainable moon base. Chinese scientists discovered that minerals in lunar soil may have this life-critical substance from the solar wind that bombards the moon’s surface with hydrogen ions, according to a study published in the journal Nature Communication on Saturday. In a previous study, published in June, Chinese scientists concluded that most of the water found on the moon may have come from its interior. That study, like the new one, was conducted on lunar samples from China’s 2020 Chang’e-5 mission from the moon’s Oceanus Procellarum basin. The study in June found that the lunar soil had about 30 parts per million of water content in the form of hydroxyl, a close chemical relative of water made up of one oxygen atom and one hydrogen atom. However, lunar minerals can contain up to 179 ppm water. One ppm of water would yield about 1 gram of water per metric ton of soil. The latest study essentially confirms estimates from previous research, and these lunar minerals could contain even more water. In addition, the new study identified the solar wind as a key mechanism for the existence of water on the Moon’s surface. The study found that the solar wind resulted in at least 170 ppm of water content in lunar samples collected by the Chang’e-5 mission. Minerals such as pyroxene, plagioclase and olivine are probably the main reservoirs of water derived from the solar wind. “This study has important implications for understanding the evolution of water on the lunar surface and assessing the contribution of solar wind protons to lunar surface water reservoirs,” the researchers said. Scientists still debate exactly how much water there is on the moon. They suggest three sources for this: that it was created inside the moon when it was full of volcanic activity; that it came from the solar wind and that it came from comets and meteoroids falling on the lunar surface. Lunar samples collected during the Chang’e-5 mission may hold the keys to answering these questions, as they are much younger than those collected by US and Soviet moon missions, according to the Institute of Geology and Geophysics of the Chinese Academy of Sciences. . Because of this, the water content in the Chinese samples had less time to be affected by other factors, making these samples ideal for studying lunar water.
