Further research can reveal whether or not organic material on Mars led to the emergence of life on the Red Planet.
NASA’s Curiosity rover found organic material near Mount Sharp on Mars, which occupies the heart of the Gale Crater. (Image Credit: NASA/JPL-Caltech/MSSS).
New Delhi: Carbon has two stable isotopes carbon-12 and carbon-13. Carbon-12 has six neutrons and six protons, while carbon-13 has six neutrons and seven protons. Carbon-13 is heavier. About 99 per cent of the natural carbon is made up of Carbon-12. About 12 years ago, NASA’s Curiosity rover discovered organic material in sedimentary deposits, suspended particles that were deposited in layers by flowing water on an ancient mars. The ratio of carbon isotopes in the organic material surprised researchers, because it could be a consequence of metabolism of life forms, or natural geochemical processes as well.
12 years ago, researchers used simulations based on quantum mechanics to investigate what happens when an atmosphere rich in carbon dioxide is exposed to harsh ultraviolet light from the Sun. Because of a process called photolysis, about 20 per cent of the carbon dioxide is split into oxygen and carbon monoxide. The process works faster on the lighter carbon-12, which is the same reason it is used more by lifeforms on Earth. The carbon monoxide produced by photolysis has less carbon-13, while the leftover carbon dioxide has more carbon-13 than the expected natural ratio.
Two samples, 50 million kilometres apart
The researchers were able to derive two different expected fingerprints in Martian samples, one of which was identified last year in a different Martian sample. The sample, from a rare Martian meteorite, was enriched in carbon-13. The new study based on a sample collected on Mars by Curiosity, mirrors the enrichment of carbon-13 in the Martian meteorite sample, with a depletion of carbon-13 in a Martian sample.
Sure, but is there life on Mars?
A paper describing the findings has been published in Nature Geoscience. One of the authors of the study, Matthew Johnson says, “Such carbon-based complex molecules are the prerequisite of life, the building blocks of life one might say. So, this it is a bit like the old debate about which came first, the chicken or the egg. We show that the organic material found on Mars has been formed through atmospheric photochemical reactions – without life that is. This is the ‘egg’, a prerequisite of life. It still remains to be shown whether or not this organic material resulted in life on the Red Planet. Additionally because Earth, Mars and Venus had very similar CO2 rich atmospheres long ago when this photolysis took place, it can also prove important for our understanding of how life began on Earth.”
Shambhu Kumar is a science communicator, making complex scientific topics accessible to all. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
