Rover Curiosity found new signs of life on Mars

These are organic molecules with nitrogen and sulfur, associated with the “building blocks of life”. And, little by little, Curiosity’s objective begins to answer another question: what is the origin of these compounds?

NASA’s Curiosity rover has identified a diverse mix of organic molecules on Mars, including compounds that, on Earth, are seen as essential building blocks for the origin of life.

The discovery, made in Gale crateralso represents the first time that a new type of chemical experiment of this type has been carried out on another planet, according to .

Curiosity’s mission has been ongoing since August 6, 2012, the day the rover landed on the red planet. Since then, the “curious” has been exploring Gale Crater and Mount Sharp, two regions considered particularly relevant to understanding whether Mars had, in other times, conditions favorable to habitability.

More recently, the robot has been operating in the Glen Torridonan area rich in clays where scientists believe there may have been, in the past, environments conducive to the preservation of organic compounds. That’s precisely where Curiosity turned to its onboard laboratory, the Sample Analysis at Mars (SAM) instrument, designed to search for carbon compounds associated with life and study the processes that form or destroy them in the Martian environment.

In this new experiment, the instrument used a chemical reagent called tetramethylammonium hydroxide (TMAH)which allowed him to detect organic molecules that were previously difficult to identify.

Among the compounds found are molecules that contain nitrogen and sulfurimportant elements in the chemistry of life as it is known on Earth. Still, the researchers emphasize that the discovery does not prove the existence of past life on Mars, nor does it allow us to determine whether these substances are the result of ancient biological processes or whether they were produced by geological rather than biological mechanisms.

The study was led by Amy Williamsassociate professor in the Department of Geological Sciences at the University of Florida, and this Tuesday at Nature Communications.

The analysis focused on clayey sandstones from the section Knockfarrill Hillin Glen Torridon, around 3.5 billion years old. Curiosity identified more than 20 organic molecules in these materials. According to the researchers, the variety observed suggests that a A significant part of the original chemical diversity may have been preserved in ancient Martian sedimentsdespite billions of years of geological transformation and radiation exposure.

The study authors argue that this set of compounds could correspond to degradation products of ancient macromolecular organic material, preserved in the sedimentary rocks of Gale Crater. In other words, the molecules now detected could be fragments of more complex organic structures that have remained hidden in the Martian subsoil throughout geological eras.

To confirm the results, the team used support equipment and backup versions of the SAM instruments, to confirm that the detected molecules do, in fact, derive from more complex macromolecular carbon preserved on Mars.

The discovery is seen as another step in the evolution of robotic exploration of the planet. If, at an early stage, the goal was just to check whether there were organic molecules on Mars, research is now moving towards a new question: What is the origin of these compounds?

Scientists admit two major scenarios. One of them points to external sources, such as meteorites, comets or interplanetary dust particles. The other refers to origins internal to the planet, either through abiotic processes or, in a more daring hypothesis, through ancient biological activity.

The work also gains importance because it can pave the way for the future identification of ancient biosignals preserved in complex moleculesif they exist. According to the study, future more optimized experiments with TMAH could release and reveal even more informative chemical signatures about the eventual biological history of Mars.

Curiosity’s results are consistent with observations from NASA’s other active rover on the planet — the Perseverance. Although it uses different instruments, Perseverance also found evidence of cyclic organic compounds and macromolecular carbon. For researchers, the fact that signals of this type appear in different locations and with different technologies reinforces the idea that organic carbon is better preserved on Mars than previously thought, despite the hostile environment and intense radiation on the surface.

This finding could have direct implications for future planetary exploration missions. Versions of this TMAH experiment are already included in the Mars Organic Molecule Analyzer instrument on the European Rosalind Franklin mission, destined for Mars, and in the mass spectrometer on the Dragonfly mission, which will explore Titanthe moon of Saturn.

The central question remains open: are the molecules now identified just the result of ancient geological chemistry or could they be traces of something more? For now, scientists don’t have an answer to the big question.