New Delhi: Analysis of a rock sample collected by NASA’s Curiosity rover has revealed the most diverse collection of organic molecules yet found on Mars. Extracted from a region on Mount Sharp, the sample, known as Mary Anning 3 contains 21 carbon-containing molecules, seven of which have never before been detected on Mars. The sample site was chosen for its high concentration of clay minerals, which formed in the presence of liquid water on the surface billions of years ago, when the region was an oasis of lakes and streams. Clay is particularly effective at preserving organic compounds for extended periods, insulating the compounds from harsh radiation.

Nitrogen heterocycle, a ring-shaped molecular structure is among the new discoveries. This discovery is significant as such structures serve as chemical precursors to complex, nitrogen-bearing molecules, including the nucleic acids RNA and DNA, that are carriers of genetic information. The rover also identified benzothiophene, a molecule containing carbon and sulphur, often found in meteorites. The presence of these compounds suggest that prebiotic chemistry may have been seeded in thee Early Solar System. It remains unclear if these molecules originated from geological or biological processes. Their variety confirms that ancient Mars had the chemical inventory necessary to support advance life forms.

The SAM instrument

These discoveries were made using the Sample Analysis at Mars (SAM) instrument which is a compact laboratory within the rover. SAM used a wet chemistry technique, dropping pulverised rock into a solvent called tetramethylammonium hydroxide (TMAH) that breaks down larger, complex molecules into identifiable fragments. The researchers tested the TMAH process on Earth using the Murchison meteorite, which produced similar molecular breakdowns. The research suggests that MArtian molecules may be the remnants of larger, life-relevant molecules. The success of the experiment provides a framework for future missions, including the Rosling Frankkin Rover and the Dragon flu mission to Titan, which will use similar instruments.