A few of the recently collected samples include organic material, indicating that Jezero Crater, which likely once housed a lake and the delta that drained into it, had potentially habitable environments 3.5 billion years ago.
“The rocks we studied in the delta have the highest concentration of organic matter we’ve ever found on the mission,” said Ken Farley, Perseverance project scientist at the California Institute of Technology in Pasadena.
The rover’s mission, which began on the Red Planet 18 months ago, includes searching for signs of ancient microbial life. perseverance is collect rock samples that could have kept these telltales biosignatures. Currently, the rover contains 12 rock samples.
Digging in the delta
The delta site makes Jezero Crater, which spans 28 miles (45 kilometers), a great interest to NASA scientists. The fan-shaped geological feature, once present where a river converged with a lake, preserves layers of Martian history in sedimentary rock, which formed when particles coalesced in this once water-filled environment .
The rover investigated the crater floor and found evidence of igneous or volcanic rock. During its second survey of the delta in the past five months, Perseverance has discovered rich layers of sedimentary rock that add more to the story of Mars’ ancient climate and environment.
“The delta, with its various sedimentary rocks, contrasts beautifully with the igneous rocks – formed by the crystallization of magma – discovered at the bottom of the crater,” Farley said.
“This juxtaposition provides us with a rich understanding of the geologic history after the crater was formed and a range of varied samples. For example, we found sandstone that carries grains and rock fragments created far from the Jezero crater. ”
The mission team dubbed one of the rocks sampled by Perseverance Wildcat Ridge. The rock was likely formed when mud and sand were deposited in a saltwater lake as it evaporated billions of years ago. The rover scraped the surface of the rock and analyzed it with an instrument known as Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC.
This zapping laser works like a sophisticated black light to discover chemicals, minerals and organic matter, said Sunanda Sharma, SHERLOC scientist at NASA’s Jet Propulsion Laboratory in Pasadena.
Analysis of the instrument revealed that the organic minerals are likely aromatics, or stable molecules of carbon and hydrogen, which are bonded to sulfates. Sulfate minerals, often found sandwiched in layers of sedimentary rocks, retain information about the aquatic 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, as well as nitrogen, phosphorus, and sulfur. Not all organic molecules need life to form, as some can be created through chemical processes.
“While the detection of this class of organic material alone does not mean that life was definitely there, this set of observations is starting to look like some things we have seen here on Earth,” Sharma said. “To put it simply, if this is a scavenger hunt for potential signs of life on another planet, organic matter is a clue. And we get stronger and stronger clues as we go. as we go through our delta campaign.”
Perseverance and the Curiosity rover have already found organic matter on Mars. But this time, the detection happened in an area where life may have once existed.
“In the distant past, the sand, mud and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could have thrived,” Farley said.
“The fact that organic matter was found in such sedimentary rock – known to preserve fossils of ancient life here on Earth – is significant. However, as capable as our instruments aboard Perseverance are, other conclusions regarding what is contained in the Wildcat Ridge sample will have to wait to be returned to Earth for further study as part of the agency’s Mars Sample Return campaign.”
Returning samples to Earth
The samples collected so far represent such a wealth of diversity in key crater and delta areas that the Perseverance team wants to deposit some of the collection tubes at a designated site on Mars in about two months, Farley said.
Once the rover deposits the samples in this cache deposit, it will continue to explore the delta.
Future missions can collect these samples and send them back to Earth for analysis using some of the most sensitive and advanced instruments on the planet. Perseverance is unlikely to find undisputed evidence of life on Mars because the burden of proof to establish it on another planet is so high, Farley said.
“I have studied Martian habitability and geology for much of my career and know firsthand the incredible scientific value of returning a carefully collected set of Martian rocks to Earth,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory, in a statement. .
“The fact that we are weeks away from deploying the fascinating Perseverance samples and only a few years away from arriving on Earth so that scientists can study them in exquisite detail is truly phenomenal. We will learn so much.”
Some of the various rocks in the delta were about 20 meters (65.6 ft) apart and each tells different stories.
A piece of sandstone, called Skinner Ridge, is evidence of rock material that was likely transported into the crater from hundreds of miles away, representing material that the rover will not be able to navigate during its mission. Wildcat Ridge, on the other hand, retains evidence of clays and sulfates that layered and formed in the rock.
Once the samples are in labs on Earth, they could reveal information about potentially habitable Martian environments, such as 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’ll collect on this mission,” said David Shuster, Perseverance’s return sample scientist at the University of California, Berkeley.