Special Discovery at Gale Crater – Mars May Help Explain the So-Called “Chemical Reactions that Generate Life” on Earth.
More than a decade ago, the Mars rover Curiosity made headlines by discovering “building blocks of life.”
To date, a series of similar findings from this rover and other exploration missions have confirmed that the surface of the red planet is rich in organic compounds, which may have both biological and abiotic origins.
Gale Crater on Mars – (Photo: NASA).
While we often expect organic materials to have biological origins—because they serve as evidence of extraterrestrial life—a new study suggests that abiotic organic compounds are also a “treasure.” This is because they may help explain the origins of life on Mars as well as on our own Earth.
Organic compounds can be produced by the existence of organisms, but conversely, the earliest life forms on Earth would have needed to originate from abiotic organic compounds through a process that remains somewhat vague — known as “chemical reactions that generate life.”
Among these, the most widely accepted hypothesis is the process of photolysis, a chemical reaction that breaks down compounds when molecules absorb light photons.
The challenge is to prove that this process actually occurred on Mars. A group of scientists led by planetary scientist Yuichiro Ueno from the Tokyo Institute of Technology (Japan) has been searching for concrete evidence.
They believe that the source of carbon-rich materials on the Martian surface is the photolysis of CO2 in the atmosphere. However, the CO2 molecule can possess one of two isotopes: carbon-12 or the heavier carbon-13. The photolysis process occurs more rapidly with the lighter isotope.
Thus, when UV light breaks down a mixture of CO2 containing carbon-12 and carbon-13 in the atmosphere, the molecules containing carbon-12 are depleted more quickly, leaving a notable surplus of carbon-13 in the Martian atmosphere.
Meanwhile, the carbon-12-rich material that was separated falls to the ground, creating a surplus sufficient to stimulate the formation of a range of complex carbon-based organic molecules.
In the new study, the authors identified this link through data collected by Curiosity from the organic material-rich Gale Crater.
The carbonate minerals that Curiosity collected here show a depletion of carbon-13, meaning the ratio of carbon-12 to carbon-13 is unusually high due to the input from photolyzed CO2.
Billions of years ago, when the Solar System was still “youthful,” Earth, Venus, and Mars all had very similar atmospheres, suggesting that a similar process may have occurred on our home planet, creating initial organic materials without any biological processes.
It is quite possible that, fortuitously, from this abiotic organic material, a series of favorable reactions occurred, giving rise to actual life on Earth.
This could have also continued on Mars and Venus, before unfortunate planetary evolutionary processes led to the extinction of life in those places.
