NASA’s Perseverance rover is finding ingredients for life strewn all across Mars, sometimes in harsh environments, bolstering the evidence that the red planet might have hosted life billions of years ago, according to a press briefing held by the agency on Thursday.
Perseverance has found an abundance of organic molecules, which can be left behind by living things or by abiotic chemical processes, in Jezero Crater, the ancient lakebed where the rover landed in February 2021 along with the mission’s helicopter, Ingenuity. In fact, according to NASA, every single target that it’s scanned for their presence so far has been found to contain signs of them.
Though previous missions have detected organic molecules on Mars, including NASA’s Curiosity rover, Perseverance is revealing unprecedented details about these molecules with the new instrument, which is called Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC).
SHERLOC recently identified aromatics, ring-shaped organic molecules, in a core Perseverance collected from a rock called Wildcat Ridge, which contains a rich sedimentary record of minerals, including salts called sulfates, that were buried in the lake when water existed on Mars more than three billion years ago.
"While the detection of this class of organics alone does not mean life was definitely there, this set of observations does start to look like some things that we’ve see here on Earth,” said Sunanda Sharma, a SHERLOC scientist at NASA’s Jet Propulsion Laboratory, in the briefing.
"On Earth sulfate deposits are known to preserve organics and can harbor signs of life which are called biosignatures,” she continued. “This makes these samples, and this set of observations, the most intriguing that we've done so far in the mission.”
Perseverance is tasked with drilling out sample cores of diverse areas as it traverses Jezero Crater, a formation that includes a river delta system with conditions that might have been conducive for life.
While the rover itself has not been able to spot any clear biosignatures, the samples it collected will eventually be picked up by a future mission that will bring them back to Earth, if all goes to plan. Scientists might be able to identify fossilized Martian microbes in these rocks using sophisticated laboratory instruments that cannot be operated from the Martian surface.
Perseverance has so far collected 12 samples, and studied countless formations, on Mars, opening a tantalizing window into the nutrient-rich environments of the red planet’s early years, when it was wetter and warmer.
“It's clear that we are uncovering a bigger story that's happening in Jezero Crater,” Sharma said. “We’ve found signals that we think are possibly from organic matter on every target that we've observed with SHERLOC to date. This isn't really unexpected. It aligns with what we’ve learned from studies on Earth of Martian meteorites and from Mars research from our sibling rover, Curiosity.”
“However, it does say that organics seem to persist in very harsh Martian surface environments, which is very exciting for us,” Sharma said.
In other words, Perseverance has not only confirmed that Mars is liberally doused in the building blocks of life, it has shown that these organic molecules are resilient. The rover’s discovery of organics in sulfate deposits also hints that fossilized microbes, if they do exist, may be exquisitely preserved in the cores Perseverance is selecting for a future trip to Earth.
“This is a treasure hunt for potential signs of life on another planet,” Sharma said. “Organic matter is a clue, and we're getting stronger and stronger clues.”
“I personally find these results so moving because it feels like we’re in the right place with the right tools at a very pivotal moment,” Sharma said. Perseverance “is giving us a better understanding than we’ve ever had of the Martian surface, to select samples for return. And Mars sample-return stands to be our best chance ever of answering a very profound question: Are we alone in the universe?”