There could be water, atmosphere and life on the early moon
Today our moon is uninhabited and absolutely lifeless. It has practically no atmosphere, no liquid water, no magnetosphere to protect the surface from the solar wind and cosmic radiation. To assume the existence of life on the moon, even in the distant past, seems very daring. At least it was only ten years ago. But now such an assumption no longer seems nonsense. A discussion article on this was published in the scientific journal Astrobiology, in the Forum section (doi: 10.1089 / ast.2018.1844).
Its authors are Dirk Schulze-Makuch (Dirk Schulze-Makuch) from the Center for Astronomy and Astrophysics, Berlin Technical University, and Ian A. Crawford, professor of planetology and astrobiology from the Department of Natural and Planetary Sciences, Birkurk College, University of London. Scientists say that the results of recent space missions, as well as analyzes of lunar rock and soil samples, show that the Moon is not as waterless as previously thought. In addition to the likely appearance of ice in polar craters with a constant shade, spectroscopic studies indicate the presence of hydrated surface materials at high, but not always shaded latitudes. In addition, recent studies of lunar volcanism products suggest that the lunar interior also contains more water than previously thought.
The presence of water sources means that the moon was not always dead and dry, like today. Scientists theoretically determine two possible windows for the existence of life on the moon. It could exist immediately after the formation of the
moon and several hundred million years after this point, after the release of gases into the atmosphere due to lunar volcanic activity.
According to scientific consensus, the moon broke away from the earth 4.5 billion years ago as a result of a giant collision. Part of the matter of the earth's mantle was thrown into Earth orbit. From these debris gathered proto-Luna. Previous scientific studies have shown that after this, a certain amount of water remained in the formed Moon. The presence of water molecules at a concentration of several hundred parts per million in the mantle regions of the sources of lunar basalts indicates either that the volatile substances actually survived during the formation of the moon, or they appeared shortly thereafter due to the effects of asteroids.
After the formation in orbit, the Moon existed mainly in molten form, with silicate components in the form of the lunar ocean of magma.. Such magma oceans are known for gas evolution, which leads to the formation of a significant transitional atmosphere, although here different scientists put forward different versions. But in any case, it seems that a considerable amount of water was present at the last stages of the evolution of the lunar ocean of magma. Allocation of water vapor at a concentration of even 500 ppm during the lunar phase of the magma ocean could already lead to the formation of a 1 km deep surface ocean (!), The authors of the scientific paper write. They stipulate that a stable depth of the ocean is possible only when protected by a sufficiently dense atmosphere. Plus losses due to erosion. But this calculation shows the approximate amount of water that could be on the moon.
The second window for potential aquatic life on the Moon is 3.5 billion years ago, during the stage of gas evolution into the atmosphere and the associated peak of lunar atmospheric pressure. According to calculations, gases from the effusions of lava could create an atmosphere with a pressure of about 10 mbar, which is higher than the triple point of water and about 1.5 times greater than the current atmospheric pressure on Mars (and taking into account the difference in gravity, the lunar atmosphere was three times as massive as the Martian). The release of water vapor weighing 10 14 kg corresponds to the formation of a continuous water layer with a depth of about 3 millimeters.
In addition to water, there appeared to be a magnetic field on the young Moon, which protected life forms on the surface from the deadly solar wind and cosmic radiation.
Thus, life on the moon could originate at about the same time as on earth. The earliest evidence of earthly life is fossilized cyanobacteria from 3.5 to 3.8 billion years old. Perhaps the same cyanobacteria were brought to the satellite from the Earth itself.