Rover Curiosity on Mars discovered previously unseen molecules: What does this mean in the search for life?

It all started back in 2020 when Curiosity drilled a sample from a clay-rich rock called “Mary Anning 3”, located in Gale Crater. The area, known as Glen Torridon, was the bottom of a lake in the distant past, making it an ideal place to preserve traces of ancient chemistry. For years, scientists have analyzed the collected dust with the help of the SAM (Sample Analysis at Mars) miniature laboratory located in the “belly” of the rover. For the first time on Mars, a special method of “wet chemistry” was used. The sample was immersed in a strong solution (TMAH) that managed to break down the larger, more complex molecules into smaller parts that could be more easily identified by the instruments. It was this process that unlocked a treasure trove of new information.

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The results, published in the journal Nature Communications, revealed the presence of 21 organic compounds containing carbon. Seven of them have never been detected on Mars before. Nitrogen heterocycles stand out among them, ring molecules that contain nitrogen and which on Earth are considered key precursors for the formation of RNA and DNA, carriers of genetic information.

​- This detection is quite profound because these structures can be chemical precursors to more complex molecules that contain nitrogen – said the leader of the research Amy Williams from the University of Florida.

In addition to them, methyl benzoate was also found, a complex molecule that confirms that Mars is capable of preserving “mature” organic compounds. Benzothiophene, a sulfur compound that is abundant in meteorites, was also discovered. Scientists believe that the sulfur in such molecules can act as a shield, protecting organic matter from the harsh radiation on the surface of Mars.

What will this discovery mean for the search for life?

It should be emphasized: this is not proof of the existence of extraterrestrial life. Organic molecules can also be created through geological processes or arrive on the planet via meteorites, without any participation of living organisms. However, this is the strongest evidence so far that Mars in its past had all the necessary chemical ingredients for life as we know it. The key conclusion is that the Martian soil, despite billions of years of exposure to radiation, capable of preserving complex organic molecules. This raises the hope that future missions, such as those that will return samples to Earth, could find even more convincing bio-signatures, such as amino acids.

​- This collection of organic molecules once again raises the possibility that Mars offered a home for life in the ancient past, said mission scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory.