NASA’s Mars Rover Perseverance Finds Surprises at Jezero Crater, Including Organics

A year and a half after it landed on Mars, NASA’s Perseverance rover is hard at work studying an ancient river delta at Jezero Crater and discovering it’s not what scientists expected. The types of rocks reveal a complex geological past and some contain organic compounds in an environment that could have been suitable for microbial life. Most scientists do not think life currently exists on Mars, but might have eons ago. They are on a “treasure hunt” to find evidence, though a definitive answer probably will have to wait until the samples Perseverance is collecting are back on Earth.

Though arid today, water flowed on the surface of Mars in the distant past. Jezero Crater is home to a delta formed about 3.5 billion years ago where a river and a lake converged. NASA chose it for Perseverance, also known as Mars 2020, precisely because of its scientific potential.

In a briefing at the Jet Propulsion Laboratory today, Perseverance project scientist Ken Farley of the California Institute of Technology explained that they anticipated finding sedimentary rocks that form when particles settle in a watery environment. But they also found igneous rocks that form deep underground from magma or from volcanoes on the surface.

“This juxtaposition provides us with a rich understanding of the geologic history after the crater formed and a diverse sample suite. For example, we found a sandstone that carries grains and rock fragments created far from Jezero Crater – and a mudstone that includes intriguing organic compounds,” Farley said.

Organics have been found before on Mars with NASA’s Curiosity rover, which landed in 2012 and is still busy studying another part of the Red Planet.

What’s different now is that this area could have been hospitable to life.

“In the distant past, the sand, mud, and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could potentially have thrived,” Farley said. But it’s too soon to make definitive conclusions on that score. “As capable as our instruments aboard Perseverance are, further conclusions regarding what is contained in the Wildcat Ridge sample will have to wait until it’s returned to Earth for in-depth study.”

Perseverance’s SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) instrument discovered organic molecules. JPL’s Sunanda Sharma said SHERLOC “found signals that we think are possibly from organic matter on every target that we’ve observed” so far. Between Curiosity’s organic discoveries and these with Perservance, it appears that “organics seem to persist in a very harsh Martian surface environment, which is very exciting for us.”

“To put it simply, this is a treasure hunt for potential signs of life on another planet, organic matter is a clue and we’re getting stronger and stronger clues as we’re moving through our delta campaign. 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. Mars 2020 is giving us a better understanding than we’ve ever had of the Martian surface to select samples to return. And then Mars Sample Return is maybe the best chance ever of answering a very profound question: are we alone in the universe?” — Sunanda Sharma

Perseverance is collecting samples in cigar-shaped tubes that will be retrieved by future spacecraft in the U.S.-European Mars Sample Return campaign.

David Shuster, a Perseverance returned sample scientist at the University of California, Berkeley, said “it’s safe to say” that the Wildcat Ridge sample and another from Skinner Ridge “are two of the most important samples that we will collect on this mission.” They record “conditions of a thermally habitable environment.”

Some of the sample tubes will be left on the ground at a “depot” in Jezero Crater, while others will remain aboard the rover. Rick Welch, JPL’s Deputy Program Manager for Perseverance, said they think they’ve identified a suitable location for the depot that is smooth and flat for the Sample Return Lander. They plan to leave 10-11 sample tubes there before the rover heads off to explore other parts of the crater and collect more samples. It has a total of 43 tubes.

NASA and ESA recently redesigned the Mars Sample Return mission. Previously, a spacecraft combining a European-built Sample Fetch Rover and a NASA rocket to boost the samples into orbit around Mars would have landed on Mars. The rover would travel across the surface to retrieve the samples, bring them back and transfer them to a capsule inside the rocket. Once in orbit, the capsule would be transfered to an ESA Earth Return Orbiter for the trip back to Earth.

The new plan omits the Sample Fetch Rover. Instead, the Sample Return Lander will land close to the depot. NASA will provide two tiny helicopters like the Ingenuity helicopter on Perseverance that can pick up the tubes one at a time and take them to the lander. NASA anticipates that Perseverance also still will be operating at that time and can rendezvous with the lander to deliver the samples it still has onboard. NASA and ESA are still designing the mission and timeline, but the current plan is for the samples to be back on Earth in 2033.

As Sharma said, all of this research is dedicated not only to understanding the history and evolution of Mars as a planet, but whether it ever hosted life.

Farley stressed any evidence of potential biosignatures does not mean life once existed there.

“I want to be very careful to define potential biosignatures. This is something we discussed a lot on the science team and I want to make sure everybody understands the concept of potential biosignatures.

Potential biosignatures is something that may have been produced by life, but also could have been produced in the absence of life. A point about a potential biosignature is it compels further investigation to draw a conclusion. This is the way science works. We don’t always know the answer. We have hypotheses. The rocks that we have been investigating on the Delta have the highest concentration of organic matter that we have yet found on the mission. You’re going to hear more about that. And of course, organic molecules are the building blocks of life.

So this is all very interesting in that we have rocks that were deposited in a habitable environment in a lake which carry organic matter. We don’t yet know the significance of these findings. These rocks are exactly the kind of rocks we came to investigate both with the rover and scientific instruments and also to bring back to Earth so that they can be studied in terrestrial laboratories. So time will tell what is in these rocks.” — Ken Farley

JPL built and manages Perseverance. JPL is a Federally Funded Research and Development Center operated for NASA by Caltech.

Perseverance launched on July 30, 2020 and landed on February 18, 2021.