NASA's Curiosity rover has discovered a variety of organic molecules on Mars, including compounds similar to DNA building blocks. The findings, from an innovative chemical experiment, suggest the planet's surface can preserve ancient organics potentially billions of years old. Scientists emphasize that while promising, the molecules do not confirm past life.
NASA's Curiosity rover, which landed in Gale Crater in 2012, conducted a pioneering experiment in 2020 in the Glen Torridon region. Using the Sample Analysis at Mars (SAM) instrument suite, the team applied tetramethylammonium hydroxide (TMAH) to break down larger organic molecules into detectable fragments. This marked the first such chemical analysis performed on another planet, revealing over 20 different chemicals preserved in clay-rich rocks that once held water. Among them was a nitrogen-containing molecule resembling DNA components, previously undetected on Mars, and benzothiophene, a sulfur-rich compound often delivered by meteorites. Amy Williams, a geological sciences professor at the University of Florida and member of the Curiosity and Perseverance science teams, led the research. Published on April 21 in Nature Communications, the study indicates these organics may date back 3.5 billion years. Williams stated, 'We think we're looking at organic matter that's been preserved on Mars for 3.5 billion years. It's really useful to have evidence that ancient organic matter is preserved, because that is a way to assess the habitability of an environment.' Jennifer Eigenbrode, an astrobiologist at NASA's Goddard Space Flight Center, co-authored the paper and helps lead the SAM team. The discovery highlights Mars' potential to retain signs of habitability but cannot distinguish between biological origins, geological processes, or extraterrestrial delivery. Williams added, 'The same stuff that rained down on Mars from meteorites is what rained down on Earth, and it probably provided the building blocks for life as we know it on our planet.' This method will inform future missions, such as Europe's Rosalind Franklin rover on Mars and NASA's Dragonfly to Titan. Williams noted, 'We now know that there are big complex organics preserved in the shallow subsurface of Mars, and that holds a lot of promise for preserving large complex organics that might be diagnostic of life.'