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Organic matter in a crater sparks new questions about life on Mars

In this vast universe, our toughest detective isn’t a human but a robot. This unsung hero is NASA’s Curiosity rover which roves the Mars surface, and has been solving scientific mysteries for nearly 12 years. Currently, it’s busy digging up samples in a Martian crater and making innovative discoveries related to life on Mars and beyond.

Busting myths and creating questions

Recently, the rover discovered organic matter, containing carbon isotopes that puzzled the brightest minds.

On Earth, such materials indicate the presence of life. Yet, on Mars, could these be signs of life or merely chemicals reacting? The answer was blurry and left us with more questions than answers.

“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,” said Professor Matthew Johnson from Department of Chemistry at University of Copenhagen.

Organic samples and life on Mars

A collaborative study by experts at the University of Copenhagen and Tokyo Institute of Technology had a different take on the discovery. The Martian samples were the missing pieces of a puzzle that they had started a decade ago.

These samples confirmed their theory of atmospheric photolysis on Mars – a game-changer in understanding organic molecules formation.

“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,” said Professor Johnson.

Sun’s rays and life on Mars

According to the detailed study, the sun’s rays broke down CO2 in Mars’ atmosphere billions of years ago. This process, known as photodissociation, caused the carbon dioxide molecules to split into carbon monoxide and oxygen.

The resulting carbon monoxide then fused with other chemicals present in the atmosphere, such as hydrogen and nitrogen.

Over time, this complex chemical interaction eventually led to the formation of organic materials, which are the building blocks of life. This discovery sheds light on the ancient atmospheric conditions of Mars and provides valuable insights into the planet’s potential for supporting life in the distant past.

A piece of Mars on Earth

A decade ago, Johnson and his team used advanced simulations to predict the outcome of photolysis in a CO2-rich atmosphere.

The Martian samples bore evidence of these predictions, echoing the chemical makeup of a Martian meteorite found on Earth. Two samples, separated by 50 million kilometers, completed a puzzle that had emerged years ago.

“We actually have a piece of Mars here on Earth, which was knocked off that planet by a meteorite, and then became one itself, when it landed here on Earth. This meteorite, called Allan Hills 84001 for the place in Antarctica where it was found, contains carbonate minerals that form from CO2 in the atmosphere,” said Johnson.

“The smoking gun here is that the ratio of carbon isotopes in it exactly matches our predictions in the quantum chemical simulations, but there was a missing piece in the puzzle. We were missing the other product of this chemical process to confirm the theory, and that’s what we’ve now obtained.”

Looking for similar signs on Earth

The Earth and Mars once had strikingly similar CO2-rich atmospheres. However, Earth’s dynamic geology makes it challenging to find equivalent evidence.

“It is reasonable to assume that the photolysis of CO2 was also a prerequisite for the emergence of life here on Earth, in all its complexity. But we have not yet found this “smoking gun” material here on Earth to prove that the process took place,” said Johnson.

“Perhaps because Earth’s surface is much more alive, geologically and literally, and therefore constantly changing. But it is a big step that we have now found it on Mars, from a time when the two planets were very similar.”

While the Curiosity Rover continues its detective work on the Red Planet, scientists on Earth will keep dissecting its findings. They’ll link together more pieces of the puzzle, each piece bringing us closer to understanding the enigma of life’s inception not just on Mars, but in the entire universe.

Broader implications of the study

The implications of these discoveries extend far beyond the confines of Martian soil, resonating deeply within the field of astrobiology. The detection of organic molecules on Mars elevates the discourse about life’s potential on other planets and moons.

Titan, Europa, and Enceladus – all celestial bodies with icy exteriors and speculated subsurface oceans – are now viewed through a more optimistic lens. The Martian revelations highlight that organic chemistry is a common cosmic phenomenon, boosting our hopes of finding life or the precursors of life elsewhere.

Thus, the work of Curiosity not only unravels the mysteries of our cosmic neighbor but also paves the way for future exploratory missions aimed at uncovering the secrets of life across the universe.


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