Perseverance Peers Back 4 Billion Years to Reveal a Chaotic Era on Mars

When Perseverance rolled up onto the rim of Jezero Crater in early 2025, the team at JPL could barely contain their excitement. Not only was the rover taking in fresh panoramas, it was also about to stumble on a geological time capsule that dates back to the Solar System’s most violent teenage years.

The feature – affectionately dubbed the “Broom Point member” by the science crew – is a massive, 75‑metre (about 245 feet) thick pile of layered rock. Each layer is a story, a slice of history that records a series of asteroid and comet impacts that rained down on early Mars roughly 3.9 billion years ago. That puts it right in the heart of the Late Heavy Bombardment, a period when inner planets were pelted by far more space debris than today.

“We’re looking at a record that predates the Jezero Crater itself,” said Ken Farley, Perseverance’s deputy project scientist at Caltech. “On Earth, tectonic plates would have shredded or recycled this kind of ancient crust, but Mars keeps it pristine. It’s like finding a page ripped from a book that’s been lost for eons.”

Backed by instruments that can sniff, see, and even listen to the rocks, Perseverance identified six distinct rock types within the stack. Some are gritty breccias, jam‑packed with angular fragments, while others are fine‑grained dust that settled like ash after a massive blast. Tiny gas bubbles frozen in the breccias hint the rocks were once molten, and dark glass beads – the tell‑tale fingerprints of high‑energy impacts or volcanic fire – sparkle throughout the layers.

One especially intriguing find are glass beads that are almost identical in size to those produced by the Chicxulub impact that wiped out the dinosaurs on Earth. “It’s a reminder that the same violent processes that shaped our own planet were at work on Mars billions of years earlier,” noted Alex Jones, a Ph.D. student at Imperial College London and lead author of the new paper in Journal of Geophysical Research: Planets.

The layers aren’t lying flat either. Some tilt at near‑vertical angles—over 80 degrees—far steeper than anything the Jezero impact could have caused. This suggests a sequence of impacts of varying size and distance, each hurling debris that settled and then got buried by the next event. Think of it as a cosmic pastry, layered by successive impacts over millions of years.

There’s also a hint of water or ice in the story. On Earth, when molten rock slams into ice, the sudden flash‑vaporisation can trigger rapid debris flows that create bizarre, chaotic deposits. The team believes a similar dance between fire, ice, and impact may have helped shape the Broom Point formation.

Putting the puzzle together, scientists propose a two‑step scenario: first, a gargantuan impact formed the massive Isidis Basin (about 1,900 km across). Later, a second blow carved out Jezero Crater, shattering and uplifting the already‑tilted strata that Perseverance now studies. Together, these events give us a clearer timeline of how the inner Solar System evolved during its early, tumultuous epoch.

Every rock that Perseverance drags its arm over is a message from a time when the sky was a chaotic hailstorm of space rocks. Thanks to the rover’s patient work, we’re finally learning to read those messages – and they’re louder and more dramatic than anyone imagined.