Scientist on Mars Find: 'Is It Life? We Can't Tell'

NASA says its Curiosity rover has turned up its richest haul of organic molecules yet, sharpening, though not settling, the question of whether the planet once hosted life. In a study published Tuesday in Nature Communications, researchers say a drilled sample dubbed "Mary Anning 3" from a single rock on Mars' Mount Sharp contained 21 organic molecules, seven of which had never before been seen on the planet.

• The rock Curiosity drilled and analyzed in 2020 came from an ancient lakebed rich in clay, which is known to lock in organic compounds for billions of years despite harsh radiation. Scientists stress they still can't tell if the molecules were forged by biology or by non-living geological processes, but the chemistry again points to an early Mars that could have been habitable.

Among the most notable finds: a nitrogen-containing ring structure known as a nitrogen heterocycle, considered a potential chemical stepping stone toward RNA and DNA. "That detection is pretty profound," lead author Amy Williams says, noting such molecules hadn't been previously confirmed on the Martian surface or in Martian meteorites. "We think we're looking at organic matter that's been preserved on Mars for 3.5 billion years," says Williams, an astrogeologist and Curiosity mission scientist, per the Guardian. "Is it life? We can't tell, based on this information."

• "There are several steps between what we found and DNA," Williams explains. "It is definitely a building block to how DNA is made now. But it is truly just the bricks, not the house. You can generate these molecules geologically. 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."

"Within 10 years, we have advanced from the search for organic molecules to identifying indigenous Martian organics," researchers wrote. The discoveries came from Curiosity's onboard lab, Sample Analysis at Mars, which heated rock powder and also ran a rare "wet chemistry" test using a powerful solvent, TMAH, to break apart large molecules. To confirm what they were seeing, scientists ran the same technique on a piece of the famous Murchison meteorite on Earth and produced some of the same molecules found in the Martian rock, suggesting they may be fragments of even more complex compounds.