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

NASA’s Curiosity rover has found a new set of organic molecules on Mars, including compounds scientists say are linked to the building blocks of life. The discovery comes from a chemical experiment carried out for the first time on another planet and suggests Mars can preserve complex organic material for billions of years.

Scientists say the rover identified more than 20 organic compounds in rock samples collected from Gale Crater, a former lake bed where water once existed. Among them was a nitrogen-bearing molecule with a structure similar to chemicals that help form DNA, something never before detected on Mars. The findings, published Tuesday in the journal Nature Communications, show Mars can preserve organic material, supporting the idea that the planet may once have had conditions suitable for life.

However, the compounds alone are not proof that life ever existed there. “We think we’re looking at organic matter that’s been preserved on Mars for 3.5 billion years,” said Amy Williams, a professor of geological sciences at the University of Florida who led the study. “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.”

Organic molecules are considered key ingredients for life, but they can also form through non-biological processes or arrive on planets via meteorites. One of the compounds identified, benzothiophene, is commonly associated with material delivered from space. Curiosity landed on Mars in 2012 to investigate whether the planet once had environments capable of supporting life.

The rover conducted this latest experiment in 2020 in the Glen Torridon region of Gale Crater, an area rich in clay minerals. To analyze the samples, scientists used an instrument called Sample Analysis at Mars (SAM), relying on a chemical known as TMAH to break apart larger organic molecules. The results suggest the technique can reveal complex organic chemistry that might otherwise remain hidden, potentially shaping future missions to Mars and Saturn’s moon Titan.