When Armstrong and Aldrin returned from the Moon, they were decontaminated and quarantined, so they would not bring infectious diseases. Very soon, however, it was confirmed that the Moon was completely hostile to life. But according to research published in the journal Astrobiology, the Moon may have been surprisingly habitable in the past for at least two periods, shortly after the formation of the Moon and when volcanic activity was at its highest point.
It is thought that the Moon had great volcanic periods 4 billion and 3.5 billion years ago. At that time there was a lot of water vapor among the gases released by these volcanoes, and this would have caused rain to create lakes and lagoons. Today, without an effective moon atmosphere, water cannot remain liquid on the surface of the Moon: it would become gas or ice almost instantaneously.
However, the presence of all these volcanic gases meant that things were different then.
According to the research, this would have created enough atmospheric pressure to keep liquids in these lakes, perhaps for millions of years.
“If liquid water and a significant atmosphere were present in the primitive Moon for long periods of time, we believe that the lunar surface would have been at least transiently habitable,” said Schulze-Makuch, an astrobiologist who led the study, in a statement.
The Moon was then much closer to Earth, had a protective magnetosphere and rotated fast enough to avoid the scorching days and stifling nights it has today.
Schulze-Makuch does not rule out the possibility that life will evolve on the Moon during this wet period, but circumstances would have been less favorable than on Earth. However, we know that Earth was still experiencing numerous impacts at the time of the great asteroids, which would have thrown rocks into space, sometimes leading to life.
“Some of the remains should have ended up on the Moon,” Schulze-Makuch told IFLScience. “A small but significant proportion”.
We know little about the lunar atmosphere at that time, but it was probably sufficiently similar to Earth’s atmosphere, which increases the possibility that life would have flourished there for a while.
Although the microbes that managed to live on the Moon during this period would already be really dead, Schulze-Makuch argues that they may have left detectable residues. To prove this, however, we are going to have to return to the Moon, at least with robots, since none of the Apollo missions collected rocks from the relevant ages.
The theory will undoubtedly face a lot of skepticism, but Schulze-Makuch is not a nutcase, being an expert in life in dry places, including the Atacama Desert.