Two billion smaller craters scattered across a thousand miles
Some 2.3 million years ago, a mountain-sized asteroid struck the Martian equator, leaving behind not one wound but two billion — a vast field of secondary craters scattered across a thousand miles of the Red Planet's surface. Scientists studying the Corinto crater through NASA orbital imagery have reconstructed the geometry of this ancient violence, finding in its asymmetry and composition clues about the angle of impact, the nature of the ground it struck, and the hidden ice that once lay beneath. Such events, rare by human reckoning but inevitable across geological time, remind us that the surfaces of worlds are not fixed canvases but living records of catastrophe and change.
- Two billion secondary craters — some nearly a mile wide — were blasted across Mars in a single moment 2.3 million years ago, making Corinto one of the most destructive recent impact events in the planet's visible history.
- The ejecta field stretches 1,150 miles from the main crater, nearly four times the length of the Grand Canyon, and its lopsided shape reveals the asteroid struck at a shallow angle from the north or northeast rather than straight down.
- Machine learning algorithms trained on NASA Mars Reconnaissance Orbiter imagery allowed scientists to isolate and count Corinto's secondary craters from the planet's vast background noise of ancient impact scars.
- Pits on the crater floor suggest the asteroid punched into ice-rich or water-bearing material underground, releasing trapped volatiles in the chaotic seconds after impact.
- Impacts of this magnitude strike Mars only once every three million years, placing Corinto at the edge of what planetary scientists consider geologically recent — a fresh scar on an ancient face.
Two point three million years ago, an asteroid the size of a small mountain struck the Martian equator and carved a crater nearly nine miles wide and half a mile deep. That wound, named Corinto, sits in Elysium Planitia — and planetary scientists still consider it young. But the crater itself was only the beginning.
The real scale of the event lies in what the impact scattered outward: two billion secondary craters, ranging from 656 feet to nearly a mile across, spread across a thousand miles of Martian surface. They form a ray system extending southward and southwestward in a nearly 180-degree arc, with some debris traveling as far as 1,150 miles from the point of impact.
A research team used thermal and visible imaging from NASA's Mars Reconnaissance Orbiter, feeding high-resolution data into a machine learning program to separate Corinto's secondary craters from the planet's countless older scars. The varying shapes of those craters — round, elliptical, flattened — encode information about fragment size, velocity, and the nature of the terrain they struck.
The distribution of ejecta told the scientists something else: almost nothing landed to the north of Corinto, indicating the asteroid came in at a 30-to-45-degree angle from that direction — a glancing blow rather than a vertical strike. Analysis of the ejected material showed mostly basalt consistent with the volcanic terrain near Elysium Mons, but pits on the crater floor suggest the asteroid also hit subsurface ice or water-rich material, releasing trapped volatiles in the moments after impact.
Events of this magnitude strike Mars roughly once every three million years. Presented at the 55th Lunar and Planetary Science Conference in Texas, the findings add another layer to our understanding of how planetary surfaces are shaped — not gradually, but sometimes in a single, world-altering instant.
Two point three million years ago, an asteroid the size of a small mountain punched through the Martian atmosphere and struck the equator. The impact created a crater nearly nine miles across—a scar so fresh that planetary scientists still call it young. But the real violence lay in what came after: two billion smaller craters, scattered across a thousand miles of the Red Planet's surface like shrapnel from a detonation.
The main crater, named Corinto, sits in a region called Elysium Planitia. It measures 8.6 miles wide and drops more than half a mile deep into the Martian crust. The secondary craters—the fragments thrown outward by the initial blast—range from 656 feet to nearly a mile in diameter. They form what researchers call a "ray system," a pattern of ejected material that extends southward and southwestward from the impact zone, covering an arc of nearly 180 degrees across the planet. Some of that debris traveled as far as 1,150 miles away, roughly four times the length of the Grand Canyon.
A team of scientists used thermal and visible imaging data from NASA's Mars Reconnaissance Orbiter to map this devastation. The spacecraft's high-resolution cameras captured the crater and its surrounding field of secondary impacts with enough detail that researchers could feed the images into a machine learning program. The algorithm separated craters formed by this particular impact from the countless other impact scars that dot Mars, allowing the team to count and classify what they found. The secondary craters vary not just in size and distance from the main impact, but in shape—some are round or semi-circular, others flattened or elliptical. These morphological differences tell a story about how fast the fragments were traveling when they struck, how large they were, and what kind of ground they hit.
The asymmetry of the impact field revealed something crucial about the asteroid's trajectory. There is almost no ejecta blanket to the north of Corinto, suggesting the space rock came in at an angle of 30 to 45 degrees from the north or northeast. It was not a straight-down collision but a glancing blow, one that still had enough force to reshape the landscape for hundreds of miles in every direction.
Analysis of the ejected material itself provides further clues. Most of the fragments appear to be basalt—volcanic rock formed from rapidly cooled lava rich in magnesium and iron. This makes sense: the asteroid struck near Elysium Mons, an extinct Martian volcano, and much of the surrounding terrain is ancient lava flows. But the researchers also found evidence that the asteroid hit something else beneath the surface: water or ice. Pits scattered across the crater's floor suggest that the impact released water or gas trapped in ice-rich materials deep underground, material that vaporized or drained away in the moments after the collision.
Impacts of this scale are rare. Asteroids large enough to create such widespread secondary cratering strike Mars roughly once every three million years. The Corinto impact, at 2.3 million years old, ranks among the most extensive impact events visible on the Red Planet in recent geological history. The research was presented at the 55th annual Lunar and Planetary Science Conference in Texas in March, adding another piece to the ongoing effort to understand how planetary surfaces evolve and what hazards—past and future—shape the worlds around us.
Citações Notáveis
Corinto crater is a fresh impact crater in Elysium Planitia that produced one of the most extensive systems of thermal rays and secondary craters on Mars, extending around 1,243 miles to the south and covering a nearly 180° arc.— Research team
The large number of secondary craters formed by Corinto are consistent with most of the ejected material being strong, competent basalt.— Research team
A Conversa do Hearth Outra perspectiva sobre a história
Why does the shape of these secondary craters matter so much? They're all just holes in the ground.
The shape tells you about the physics of the impact. A semi-circular crater means the fragment hit at a certain speed and angle. An elliptical one means something different—maybe it was traveling faster, or the ground was softer. By reading the shapes, you're reading the energy of the collision itself.
And the fact that there's almost no debris to the north—that's how you figured out the angle of approach?
Exactly. If the asteroid had come straight down, you'd see ejecta spread evenly in all directions. But it didn't. The asymmetry is like a fingerprint. It tells you the asteroid came in from the northeast at a shallow angle, maybe 30 to 45 degrees from vertical.
What does it mean that they found water or ice beneath the surface?
It means the impact didn't just carve rock. It hit something volatile. The heat and pressure released water that had been locked in the subsurface for millions of years. Those pits in the crater floor—they're evidence of that release. Water or gas drained away after the impact.
How do scientists know all this happened 2.3 million years ago and not, say, 5 million?
Machine learning. They used imaging data to identify which craters were formed by this specific impact, then counted how many secondary craters there are. The number and distribution of secondaries correlates with age. Older impacts have fewer visible secondaries because erosion and dust cover them up over time.
So this is recent, geologically speaking.
Very recent. On Mars, 2.3 million years is practically yesterday. The crater is still sharp, the ejecta still visible. In another hundred million years, wind and dust will have softened those edges considerably.