Diverse organic molecules on Mars revealed by the first SAM TMAH experiment

NASA's Curiosity rover has discovered a diverse array of organic molecules on Mars, marking the first time a chemical experiment using TMAH (tetramethylammonium hydroxide) has been conducted on another planet. The findings, published in Nature Communications, reveal over 20 organic compounds preserved in rock samples from Gale Crater's Glen Torridon region, an ancient lake bed rich in clay minerals that can protect organic material for billions of years. Among the detected molecules was a nitrogen-bearing compound structurally similar to chemicals involved in DNA formation, a first for Mars exploration.

Led by University of Florida professor Amy Williams, the team used the Sample Analysis at Mars (SAM) instrument to break apart larger organic molecules for analysis. The experiment, conducted in 2020, demonstrated that Mars can preserve complex organic matter for up to 3.5 billion years. While the compounds themselves could originate from non-biological processes or meteorite impacts—benzothiophene, for instance, is commonly associated with space-delivered material—the discovery supports the idea that ancient Mars had habitable conditions. These results could guide future missions searching for biosignatures on Mars and Saturn's moon Titan.