A recent work by Ian Crawford of the University of London and myself, just published in the journal [Astrobiology claims that the earth's moon could have been habitable about a billion years after its creation, when dealing with pools of liquid acts water could have existed on the lunar surface. Of course, the moon has no atmosphere and no liquid water today. It is uninhabitable and certainly lifeless. But 3.5 billion years ago, a billion years after its creation, the lunar environment was very different.
During this period of extreme outgassing of lunar magma, the moon has an atmospheric pressure of 1
Combine this with recent findings that lunar rocks are more water rich than previously thought, and we can hypothesize that lakes, even an ocean, could exist stably on the moon for a considerable time. There is also evidence that the early moon had a magnetic field that could have partially protected its surface from solar and cosmic rays. This would have led to a temporary habitable world at a time when life on earth had already gained a foothold.
When meteorite impacts spread the early earthly life on the moon, it would have thrived there if the lunar surface were actually habitable. Simulations show that transferring microbes from Earth to Mars is possible – albeit only marginally – because of the distance between the two planets and meteorites called lithopanspermia. However, the Moon is much closer than Mars, so an Earth-Moon transfer would have been much easier. And the moon was even closer to Earth 3.5 billion years ago than it is today.
The image of liquid water teeming with microbes on the lunar surface shatters the Moon's current paradigm as dead rock in space. Of course, we have to be careful that we do not get carried away by the idea. Finally, we do not see any of the water-modified topographies on the moon that we see on Mars. But would we really expect that, given that the moon has been hit by solar wind, cosmic rays and micrometeorites for billions of years?
Crawford and I suggest ways to rigorously test our hypothesis. We propose to search for rich minerals in geological strata trapped between lava flows from that period. We also propose a more aggressive lunar future program, where state-of-the-art instruments are placed on the lunar surface and moon samples returned to Earth for analysis. In addition, we recommend conducting experiments in laboratories on Earth simulating the early lunar environment to observe whether microorganisms can remain viable under environmental conditions predicted 3.5 billion years ago on the Moon.
With this fascinating new idea in mind I have already expanded our lunar research group and started to plan some of the required experiments.
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