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Georgia Tech scientists have uncovered evidence that a mountain on the rim of Jezero Crater—where NASA's Perseverance Rover is currently collecting samples for possible return to Earth—is likely a volcano. Called Jezero Mons, it is nearly half the size of the crater itself and could add critical clues to the habitability and volcanism of Mars, transforming how we understand Mars' geologic history.

The study, "Evidence for a composite volcano on the rim of Jezero crater on Mars," was this May in Communications Earth & Environment, and underscores how much we have left to learn about one of the most well-studied regions of Mars.

Lead author Sara C. Cuevas-Quiñones completed the research as an undergraduate during a summer program at Georgia Tech; she is now a graduate student at Brown University. The team also included corresponding author Professor James J. Wray (School of Earth and Atmospheric Sciences), Assistant Professor Frances Rivera-Hernández (School of Earth and Atmospheric Sciences), and Jacob Adler, then a postdoctoral fellow at Georgia Tech and now an assistant research professor at Arizona State University.

"Volcanism on Mars is intriguing for a number of reasons—from the implications it has on habitability, to better constraining the geologic history," Wray says. "Jezero Crater is one of the best studied sites on Mars. If we are just now identifying a volcano here, imagine how many more could be on Mars. Volcanoes may be even more widespread across Mars than we thought."

A mountain in the margins

Wray first noticed the mountain in 2007, while considering Jezero Crater as a graduate student.

"I was looking at low-resolution photos of the area and noticed a mountain on the crater's rim," he recalls. "To me, it looked like a volcano, but it was difficult to get additional images."

At the time, Jezero Crater was newly discovered, and imaging focused almost entirely on its intriguing water history, which is on the opposite side of the 28-mile-wide crater.

Then, Jezero Crater, due to these lake-like sedimentary deposits, was selected as the landing spot for the 2020 Perseverance Rover—an ongoing NASA mission seeking signs of ancient Martian life and collecting rock samples for possible return to Earth.

However, after landing, some of the first rocks Perseverance encountered were not the sedimentary deposits one might expect from a previously-flooded area—they were volcanic. Wray suspected he might know the origin of these rocks, but to make a case for it, he would need to show that the mountain on the edge of Jezero Crater could indeed be a volcano.

A new researcher—and old data

The opportunity presented itself several months after Perseverance landed when Cuevas-Quiñones applied to a Summer Research Experience for Undergraduates (REU) program hosted by the School of Earth and Atmospheric Sciences to work with Wray.

"A previous study led by Briony Horgan (professor of planetary science at Purdue University) had also suggested that Jezero Mons could be volcanic," Cuevas-Quiñones says. "I began wondering if there was a way to home in on these suspicions."

The team partnered with study co-author Rivera-Hernández, who specializes in characterizing the surface of planets and their habitability. They decided to use datasets gathered from spacecraft orbiting Mars to compare the properties of Jezero Mons to other, known, volcanoes.

"We can't visit Mars and definitively prove that Jezero Mons is a volcano, but we can show that it shares the same properties with existing volcanoes—both here on Earth and Mars," Wray explains.

"We used data from the Mars Odyssey Orbiter, Mars Reconnaissance Orbiter, ExoMars Trace Gas Orbiter, and Perseverance Rover, all in combination to puzzle this out," he adds. "I think this shows that these older spacecraft can be extremely valuable long after their initial missions end—these old spacecraft can still make important discoveries and help us answer tricky questions."

For Cuevas-Quiñones, it also underscores the importance of REU programs and opportunities for undergraduates. "I was an undergraduate student at the time, and this was my first time conducting research," she says. "It was fascinating to learn how different data sets could be used to decode the origin of a landscape. After Jezero Mons, it became clear to me that I would continue to study Mars and other planetary bodies."

The search for life—and determining Mars' age

The discovery makes the crater even more intriguing in the search for past life on Mars. A volcano so close to watery Jezero Crater could add a critical source of heat on an otherwise cold planet, including the potential for hydrothermal activity—energy that life could use to thrive.

This type of system also holds interest for Mars as a whole. "The coalescence of these two types of systems makes Jezero more interesting than ever," shares Wray. "We have samples of incredible sedimentary rocks that could be from a habitable region alongside igneous rocks with important scientific value."

If returned to Earth, igneous rocks can be radioisotope dated to know their age very precisely. Dating the Jezero Crater samples could be used to calibrate age estimates, providing an unprecedented window into the geologic history of the planet.

The take home message? "Mars is the best place we have to look in our solar system for signs of life, and thanks to the Perseverance Rover collecting samples in Jezero, the United States has samples from the best rocks in the best place on Mars," Wray says. "If these samples are returned to Earth, we can do incredible, groundbreaking science with them."