Planetary scientists analyzing data from NASA’s Perseverance rover have found signs of organic molecules on Mars, implying that the planet has a more complex geochemical cycle than previously thought. If true, it indicates that the building blocks of life have existed on the Red Planet for nearly billions of years.

These new findings published Naturederived from studies at the base of Jezero Crater, a 45 kilometers (28 mi) wide impact basin north of the Martian equator. NASA chose it as Perseverance’s landing site because of geological evidence that an ancient river flowed into the crater about 2.5 billion years ago.

Now, a team led by Sunanda Sharma (California Institute of Technology) has analyzed data from the Perseverance Scanner of Residential Environments Using Raman and Luminescence (SHERLOC) for Organics and Chemicals. It’s the first instrument we’ve brought to Mars that can map organic molecules, which are compounds containing carbon-hydrogen or carbon-carbon bonds. Mounted on the tip of the rover’s robotic arm, SHERLOC shines an ultraviolet laser on rock samples and studies how vibrating molecular bonds scatter light.

Sharma and his team focused on several targets in two geological formations at the crater floor, named Máaz and Séítah. They found signals consistent with organic molecules in all 10 targets they examined; these molecules were retained in the sulfate crystals and were more concentrated in Máaz than in Séítah.

“It was surprising and exciting to see that possible organic signals differ in the number of detections and their distribution between the two crater floor units,” says Sharma. “This opens up the possibility of different mechanisms of formation, protection or transport across the crater and more broadly across the Martian surface.”

So where did organic molecules come from? It’s possible that they were once left by microbes that cling to these ancient rocks, but Sharma isn’t coming to that conclusion yet. “To claim that life is the source of organic matter . . . – the hypothesis of last resort,” says Sharma. “We need to rule out any non-biological source of origin.”

Organic molecules may have fallen from interstellar dust or from an impact, but Sharma points a finger elsewhere. “It looks like a collection of organic matter associated with rocks interacting with water,” he says. This would fit the Lake’s watery past. Water interactions may also explain how molecules survive the extreme conditions on the planet’s surface.

This isn’t the first time organic molecules have been found in sulfate crystals on Mars. Planetary scientists have also spotted them in Gale Crater, where the Curiosity rover landed. But now there are measurements from several craters. “Predicting a single crater for the entire planet Mars is like visiting New York and trying to understand the whole Earth,” says Sharma. “Each mission at the surface adds more points of comparison so that we can move from a regional understanding to a global one.”

“This is a really interesting discovery,” says astrobiologist Lewis Dartnell (University of Westminster, UK), who was not involved in the study. Several processes may be involved to explain the variation, as the researchers found several different organic matter pools in Jezero. “This suggests that ancient Mars may have had a longer carbon cycle than previously thought.” https://mars.nasa.gov/maps/location/?mission=M20&site=NOW

To see if these molecules are directly related to life, the sample would require much more extensive study than the rover could provide. “[Нам] It will have to wait for the Mars Sample Return mission to bring them back to Earth for full analysis,” says Dartnell.

There is an ambitious multi-agency plan to launch a massive heavy lander by 2028. According to the plan, it will land in the Lake and send a rover (or possibly helicopters) to collect key samples identified by Perservance, then send them back home, waiting for the scientists until 2033. But once we have these samples, we will have a clearer understanding of what these organic molecules really are and how important they are to the possible history of life on Mars. Source