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Investigating the site of an ancient river delta, the Perseverance rover has collected some of the most important samples to date it is mission to determine if life ever existed on Mars, say NASA scientists.
Some of the recently collected samples contain organic material, indicating that the Jezero crater, which likely once contained a lake and the delta that emptied into it potentially habitable environments 3.5 billion years ago.
“The rocks we’ve examined in the delta have the highest concentration of organic material we’ve found on the mission so far,” said Ken Farley, a scientist with the Perseverance Project at the California Institute of Technology in Pasadena.
The rover’s mission, which began 18 months ago on the red planet, includes searching for signs of ancient microbial life. endurance is collecting rock samples that could to have preserves these indicator lights biosignatures. Currently the rover contains 12 rock samples.
A series of missions invoked Return of the Mars sample will eventually bring the collection back to Earth in the 2030s.
The location of the delta makes the Jezero crater, which stretches over 45 kilometers, special high interest for NASA scientists. The fan-shaped geological feature that once existed where a river met a lake preserves layers of Martian history in sedimentary rock that formed as particles fused together in this formerly water-filled environment.
The rover examined the crater floor and found evidence of igneous or volcanic rock. During its second campaign to survey the delta in the last five months, Perseverance has found rich layers of sedimentary rock that contribute more to the history of the ancient climate and environment of Mars.
“The delta, with its diverse sedimentary rocks, contrasts nicely with the igneous rocks – formed from the crystallization of magma – that have been discovered on the crater floor,” Farley said.
“This juxtaposition provides us with a rich understanding of the post-cratering geological history and diverse sampling suite. For example, we found a sandstone bearing grains and rock fragments that originated far from the Jezero crater.”
The mission team nicknamed one of the rocks that Perseverance sampled Wildcat Ridge. The rock likely formed when mud and sand settled in a saltwater lake as it evaporated billions of years ago. The rover scraped the surface of the rock and analyzed it using an instrument known as Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC.
This rock-shattering laser acts as a fancy black light to reveal chemicals, minerals and organic matter, said Sunanda Sharma, a SHERLOC scientist at NASA’s Jet Propulsion Laboratory in Pasadena.
Analysis of the instrument revealed that the organic minerals are likely aromatics, or stable carbon and hydrogen molecules associated with sulfates. Sulfate minerals, often embedded in layers of sedimentary rock, preserve information about the aqueous environments in which they formed.
Organic molecules are interesting on Mars because they represent the building blocks of life, such as carbon, hydrogen, and oxygen, but also nitrogen, phosphorus, and sulfur. Not all organic molecules require life to form, as some can be created through chemical processes.
“While the detection of this class of organic matter alone doesn’t mean life was definitely there, these observations are starting to look like some things we’ve seen here on Earth,” Sharma said. “To put it simply, if this is a treasure hunt for potential signs of life on another planet, organic matter is a lead. And we’re getting stronger clues as we move through our Delta campaign.”
Perseverance and the Curiosity rover have already found organic matter on Mars. But this time, the discovery took place in an area where life may have once existed.
“In the distant past, the sand, mud, and salts that make up the Wildcat Ridge sample today were deposited in conditions where life could potentially have thrived,” Farley said.
“The fact that organic material was found in such sedimentary rock – known for preserving fossils of ancient life here on Earth – is important. But as powerful as our instruments aboard Perseverance are, further conclusions about what’s in the Wildcat Ridge sample will have to wait until it’s returned to Earth for in-depth study as part of the agency’s Mars Sample Return campaign becomes.
The samples collected so far represent such a wealth of diversity from key areas within the crater and delta that the Perseverance team is interested in depositing some of the collection tubes at a specific location on Mars in about two months, Farley said.
Once the rover has dropped the samples at this cache depot, it will continue exploring the delta.
Future missions can collect these samples and return them to Earth for analysis with some of the most sensitive and advanced instruments on the planet. It’s unlikely Perseverance will find unchallenged evidence of life on Mars because the burden of proof of establishing it on another planet is so heavy, Farley said.
“Having studied the habitability and geology of Mars for much of my career, I know firsthand the incredible scientific value of bringing a carefully collected set of Martian rocks back to Earth,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory, in an explanation .
“To be weeks from delivering Perseverance’s fascinating samples and only a few years from bringing them to Earth for scientists to study in minute detail is truly phenomenal. We’re going to learn so much.”
Some of the different rocks in the delta were about 20 meters apart, each telling a different story.
A piece of sandstone called Skinner Ridge is evidence of rocky material that was likely transported into the crater from hundreds of miles away and represents material that the rover cannot access during its mission. Wildcat Ridge, on the other hand, preserves evidence of clays and sulphates that have stacked and formed into rock.
Once the samples are in labs on Earth, they could provide insights into potentially habitable Martian environments, such as B. chemistry, temperature and when the material was deposited in the lake.
“I think it’s safe to say that these are two of the most important samples we’re going to collect on this mission,” said David Shuster, Perseverance Return Sample Scientist at the University of California, Berkeley.