Science

Our Moon May Have Briefly Harbored Life, Say Astrobiologists

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Nearly a half-century after Apollo 11 astronaut Buzz Aldrin marveled at our Moon’s ‘magnificent desolation,’ two astrobiologists now contend that the lunar surface may have briefly had liquid water, a magnetic field and incredibly even transient life.

This composite image of the moon using Clementine data from 1994 is the view we are most likely to see when the moon is full.Credit: NASA

Although the Moon is among the most foreboding pieces of real estate in our inner solar system, in a paper just published online in the journal Astrobiology, Washington State University (WSU) astrobiologist Dirk Schulze-Makuch, and Ian Crawford, a professor of planetary science and astrobiology at the University of London, contend that that microbial life may have been there in fits and starts as late as 3.5 billion years ago. Or during two separate 70 million year early windows of habitability.

Lunar surface conditions could have supported simple lifeforms shortly after the Moon formed some 4.47 billion years ago and again during a peak in lunar volcanic activity around 3.5 billion years ago, the authors say.

Schulze-Makuch and Crawford write that this volcanic outgassing could have formed pools of liquid water on the lunar surface and an atmosphere dense enough to keep it there for millions of years. And the authors characterize this lunar epoch as potentially habitable.

During this period of the inner solar system’s late heavy bombardment, it’s completely possible that cyanobacteria or organic material could have been dislodged from Earth’s surface and sent spiraling toward the lunar surface.

“There could have actually been microbes thriving in water pools on the Moon until the surface became dry and dead,” Schulze-Makuch said in a statement.

Today, the Moon is the very definition of inhospitable. As the authors write, the Moon has “no significant atmosphere, no liquid water on its surface, no magnetosphere to protect its surface from solar wind and cosmic radiation.”

Any life would be long gone. But what regions would be best to look for microfossils?

“In the subsurface, if we find hydrated paleo-regolith layers between lava flows,” Schulze-Makuch told me.

Some researchers have posited that life may have evolved on Earth in only 10 million years. Thus, say the authors, there is a chance that life might have even evolved in these hypothetical liquid water lunar surface pools.

Such assertions are not as far-fetched as they seemed a mere decade ago. That’s because as the authors note in their paper, recent studies indicate that the lunar mantle may even be as comparably water-rich as Earth’s upper mantle.

The early Moon may have also had a significant, if not fleeting atmosphere protected from the solar wind by a magnetic field.

If so, the authors argue that the chances of microorganisms surviving “within terrestrial meteorites impacting the Moon would be increased by the presence of even a tenuous lunar atmosphere.” That’s because such an atmosphere would slow the meteorites lunar impact velocity.

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