When NASA’s Perseverance rover touched down in Jezero Crater in 2021, scientists expected to find rocks laid down by an ancient lake. What they didn’t expect was volcanic rock. And certainly not a volcano itself—towering over the landscape, hiding in plain sight.

But controversies still remained. Was Jezero Mons, a 1.5-kilometer-high mountain on the crater’s Southeastern rim, really a volcano? A team of researchers are now saying it is. And if that’s true, the rover’s samples could soon help scientists pin down the precise age of a Martian volcano for the first time.

“If we are just now identifying a volcano here, imagine how many more could be on Mars,” said James Wray, a planetary scientist at Georgia Tech and co-author of the new study published in Communications Earth & Environment. “Volcanoes may be even more widespread across Mars than we thought.”

An Ancient Mountain with a Fiery Past

Jezero Crater, once a lake bed some 3.5 billion years ago, has become the focus of NASA’s search for signs of past life. It’s where Perseverance has been drilling, scanning, and gathering samples for a future return to Earth. But Wray’s fascination with the region dates back to 2007.

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

Back then, the science community was riveted by Jezero’s watery past. Focused on deltas and clays that might preserve traces of life, researchers mostly ignored Jezero Mons. But when Perseverance landed and found volcanic rocks instead of sedimentary layers on the crater floor, Wray’s old suspicion reawakened.

He teamed up with Sara Cuevas-Quiñones, then an undergraduate researcher, to investigate. They pulled together data from an impressive lineup of Mars missions: NASA’s Mars Odyssey and Mars Reconnaissance Orbiter, Europe’s ExoMars Trace Gas Orbiter, and Perseverance itself.

What Makes a Volcano?

Cuevas-Quiñones and Wray looked at the mountain’s shape, mineral content, temperature profile, and impact history. What they found mirrored the features of explosive volcanoes—on Mars and Earth.

Jezero Mons has a conical shape and a summit crater that spans 7 kilometers. Its flanks slope at a gentle 8 degrees, comparable to well-known Martian volcanoes like Apollinaris and Zephyria Tholi, and even to Antarctica’s Mount Sidley, a terrestrial analog. The surface retains few impact craters, suggesting it’s relatively young and possibly cloaked in fine ash.

Infrared data revealed minerals consistent with volcanic rocks (pyroxenes) as well as altered minerals like smectite clays and carbonates, which may form in volcanic environments or through later chemical weathering. Some of these minerals appear in distinct, hydrated forms, which could hint at past hydrothermal activity—geological hot spots that on Earth teem with microbial life.

“The coalescence of these two types of systems makes Jezero more interesting than ever,” Wray said. “We have samples of incredible sedimentary rocks that could be from a habitable region alongside igneous rocks with important scientific value.”

Signs of Fire on a Frozen World

The researchers also considered other possibilities, but only a volcano seemed really plausible.

The mountain’s thermal inertia—how quickly it heats up or cools down— also matches that of ash-covered volcanoes. Its shape and size rule out mud volcanoes, and its summit crater doesn’t behave like an impact scar. In fact, the polygonal outline of the summit and the flanks’ flow-like textures make it more plausible that the mountain erupted rather than was struck.

Some flow features from Jezero Mons even extend toward the crater’s floor. These flows may have supplied the volcanic material Perseverance is now sampling. If so, this could mark a scientific milestone.

“If these samples are returned to Earth, we can do incredible, groundbreaking science with them,” Wray said.

That “if” looms large. The Mars Sample Return program, which would ferry Perseverance’s rock cache back to Earth, faces political headwinds from the Trump administration. Though NASA has proposed new, cheaper mission designs, a 2026 budget proposal from the administration aims to cancel the program altogether.

Why does this matter?

This matters especially because volcanic rocks can be dated precisely. Unlike sedimentary rocks, which are built slowly over time from eroded bits of other rocks, igneous rocks lock in their ages the moment they cool. That makes them geological time capsules.

Perseverance has already drilled and stored several such samples from the crater floor. If scientists can link them to Jezero Mons, they could finally assign a firm date to a volcano on another planet. That would allow researchers to calibrate Mars’s geological timeline more accurately than ever before.

“If so,” the researchers write, “then radioisotope dating of igneous rock samples cached by Perseverance could eventually make this the first volcano of precisely known age on another terrestrial planet”.

The discovery also comes with a twist: it happened in one of the most studied spots on Mars. It’s a surprise from where we least expected.

“Jezero Crater is one of the best studied sites on Mars,” Wray said. “If we are just now identifying a volcano here, imagine how many more could be on Mars.”

It’s a reminder that even after decades of missions, the Martian story is far from fully told. Jezero Mons may be just the beginning.

And the hunt for ancient Martian volcanoes—and maybe even for signs of ancient life—goes on.