Lunar Lava May Have Preserved a Record of the Origin of Life in Our Solar System
Life began on Earth 3.8 billion years ago, back when our Moon was covered in flowing lava. But where Earth has all but destroyed its fossil record from that time period, the Moon's molten surface may have preserved the first organic chemicals. As a result, the study of lunar fossils could give us insight into the origin of life in our solar system.
Since the first organisms emerged billions of years ago, Earth's tectonic forces have essentially erased the fossil record from that time period. "Both geology and life are efficient recyclers and hinder preservation," said co-author Mark Sephton of Imperial College London. So although there are prevailing theories regarding the origins of life, scientists really have no idea how the first organic chemicals reached and/or emerged in our solar system.
One of the prevailing theories of the origin of life is panspermia, or the idea that an extraterrestrial object such as an asteroid or comet that were host to organic compounds crashed into the Earth, thereby 'seeding' life on Earth, so to speak. If this theory proves correct, then it stands to reason that the same asteroids or comets could have crash-landed on our nearby Moon, which means we may be able to find evidence of these first organic compounds in the moon's fossil record. And unlike Earth, which constantly changes and shifts from a geological perspective, the Moon has been geologically quiet for billions of years, so the lava may have "sandwiched" and preserved a record of the first organic chemicals.
From the paper: "A recently proposed model suggests the possibility that volatiles, including organic material, remain archived in buried paleoregolith deposits intercalated with lava flows on the Moon. Where asteroids and comets allow the study of processes before planet formation, the lunar record could extend that chronicle to early biological evolution on the planets."
In the new study, the researchers tested the plausibility of this theory by putting organic compounds that mimic the origin of life in simulated moon dust and heated them up to 700° C. After a series of experiments, they found that the organic materials would only need to be buried in the lava a few dozen centimeters below the surface, which is perfectly reasonable considering the potential impact of the asteroid or comet. If they were sufficiently buried, then the chemicals would have survived the initial high temperatures and would have been protected by the lava from exposure to solar winds, radiation, and meteorite impacts.
"Evidence of prebiotic evolution on asteroids and comets or the emergence of life on Earth and Mars could all be preserved," said Sephton. "It is an ironic possibility that one of the best places to look for records of early life is our dry and lifeless Moon."
Although only time and further study will tell if this method could yield information about the origins of life, the paper appears in the journal Astrobiology, which is peer-reviewed, and several experts in the field have gone on record in support of this new theory. If Sephton and his colleagues are proven correct, then we could discover the origins of life in our solar system in the very near future.