NASA’s Curiosity Mars rover has identified seven organic compounds in rock near the planet’s equator, five of which have not been found before on Mars.
The researchers are publishing in the journal Nature Communications The experiment also indicated the presence of another organic compound with a structure similar to the precursor to DNA, the molecule that carries genetic information in living organisms on our planet, it said Tuesday.
However scientists also note that organic compounds – molecules composed primarily of carbon atoms attached to other elements that form the structural basis of all life on Earth – can form through non-biological processes.
Further evidence that Mars may have been a habitable planet billions of years ago
Like Earth and the other planets in the solar system, Mars is believed to have formed about 4.5 billion years ago. Early in its history it was much warmer and wetter than the cold, dry place it is today.
Both of NASA’s Mars rovers, Curiosity and Perseverance, have identified organic materials on the planet.
The Curiosity rover was exploring the giant Gale Crater, believed to have been caused by a meteorite impact and now a dry lakebed. The abundance of soil in the Glen Torridon area of the crater suggests that water was once present there. The meteorite could have brought organic matter to the planet and the water could have provided suitable conditions for it to grow.
“We can’t yet say whether Mars ever had life, but our findings support the evidence that Mars was a habitable world at the time of the origin of life on Earth,” said Amy Williams, a member of the Curiosity scientific team and an astronomer and planetary scientist at the University of Florida, and lead author of the study.
“To be clear, we haven’t found evidence of life from this study, but we are further refining the building-block molecules that exist on Mars,” Williams said.
The building blocks of life have been preserved in rocks for billions of years
The researchers estimated that the rock samples analyzed date back at least 3.5 billion years. Curiosity, which landed on Mars in 2012, took related samples in 2020.
One molecule identified, benzothiophene, has also been found in meteorites and asteroids.
“The same thing that rained down on Mars from meteorites rained down on Earth, and it probably provided the basis for life as we know it,” Williams said. “We’re seeing the building blocks for life on Mars – prebiotic chemistry – preserved in these rocks for billions of years.”
Clay may preserve such organic molecules better than other minerals, explaining why this site was chosen as the discovery point. The Curiosity rover was sent with a chemical called TMAH, which can break down organic matter and see what it is made of. Such a test had never been done before on Earth.
Williams said another nitrogen-containing molecule has been identified “that is a precursor to how DNA is ultimately formed.”
Williams said it is not possible to ultimately tell whether the organic matter “came from geologic processes, came from meteorites, or came from life”, but the findings show that “if complex organic matter from life were preserved on Mars, we should be able to detect it with current and upcoming rover instruments.”