2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
In the history of the Moon, there were two periods of time when life could theoretically exist on its surface, - American and British astronomers write about this in an article for the Astrobiology magazine, which caused a lot of noise in the press. N + 1 asked the experts how convincing their colleagues' reasoning seemed to them.
“Putting our moon and livability next to it seems outrageous, and just a decade ago it was. But the results of recent space missions and analysis of lunar rock samples show that the Moon is not as dry as it was thought … The presence of water sources on the Moon hints that it was not always as dead and dry as it is now, "write Dirk Schulze-Makuch (Dirk Schulze-Makuch and Ian Crawford.
According to the authors of the article, if the presence of liquid water can be considered a criterion for the existence of life, then the Moon could be inhabited by living things soon after it was formed (about four billion years ago) and during the subsequent peak of volcanic activity (about 3.5 billion years ago). The oldest evidence of life on Earth is traces of cyanobacteria 3, 5-3, 8 billion years old.
At the time, as Schulze-Makuch and Crawford write, the Moon was actively throwing out strongly heated gases and water vapor, which could theoretically form lakes of liquid water on it (and, in a highly optimistic scenario, an ocean up to one kilometer deep) and a fairly dense atmosphere to keep this water liquid for millions of years. According to one estimate, the pressure of this atmosphere could be 10 millibars, which is one and a half times more than the pressure of the modern atmosphere of Mars, and such an atmosphere could exist for up to 70 million years. In addition, the young Moon, most likely, had a magnetic field capable of protecting potential life on its surface from cosmic radiation, and meteorites could bring the necessary organic matter to its surface.
“[That the moon could have a temporal atmosphere] is a reasonable statement, I've seen articles that simulate such processes. They say that a temporary atmosphere could indeed form on the Moon, perhaps not the same as on Earth - only a fraction of the Earth's. And, in principle, water vapor could be thrown into this atmosphere from the depths,”says Maxim Litvak, head of the neutron and gamma spectroscopy laboratory of the nuclear planetology department of the Institute of Space Research (IKI), Russian Academy of Sciences. According to him, it is difficult to say how long the temporary atmosphere on the moon could last, but "the fact is that it could exist."
“It can be confirmed with confidence that water is present on the Moon now and, probably, was present in much greater quantities in the early epochs of the evolution of this celestial body,” adds Igor Mitrofanov, head of the Department of Nuclear Planetology of the IKI RAS. He recalls that on the modern Moon, water is in the vicinity of the poles in the form of "icy permafrost" - the regions of its occurrence were studied in detail by the Russian LEND neutron telescope on board the American LRO probe.
“Also, relatively recently, on modern research equipment, a re-analysis of samples of lunar soil, delivered to Earth in the 70s of the last century by American and Soviet lunar spacecraft, was carried out. Water molecules were found in the composition of the substance of these samples, which confirms the presence of water on the Moon in the early epoch of its existence,”the scientist adds.
Suitability for life is one thing, proper habitability is another. The authors themselves refrain from drawing conclusions on this score, calling the issue "extremely controversial", but note that, theoretically, with the help of meteorites, newly emerged life from Earth could get to the Moon at a time when conditions were favorable for it. Lindy Elkins-Tanton of Arizona State University, who was not involved in the original study, notes that she agrees with the authors about two “windows of opportunity” for life. “The important thing we don’t know is how long it takes for life to appear when there are good conditions for it. Therefore, it is impossible to assess the likelihood that this life was on the Moon,”says Elkins-Tanton.
“From the fact that life on the early Earth arose due to the presence of oceans and a thick atmosphere on our planet, it does not follow that a similar process of the origin of life took place in the hypothetical ocean on the young moon. No wonder the article is placed under the heading "Forum", that is, the editorial board of the journal "Astrobiology" suggests a discussion of the stated hypothesis, "Mitrofanov notes. In his opinion, this hypothesis "quite deserves" discussion.
To find out whether the Moon was habitable or just habitable, an "aggressive program of lunar exploration" is needed, says Schulze-Makuch: in particular, future space missions could obtain samples of lunar soil from sediments belonging to the period of volcanic activity in order to understand whether it contains evidence of water or other markers of life.
Igor Mitrofanov agrees: “Only a detailed study of the lunar polar matter and the water and volatile compounds present in it will allow us to get a reliable answer about the lunar paleo-life and its possible connection with life on Earth … If there was life on the Moon, then signs of its existence will be discovered in the next 5-10 years,”says the Russian scientist.
