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An Ancient Asteroid Impact May Have Caused a Megatsunami on Mars

Maps of the Martian surface suggest something big hit the planet 3.4 billion years ago.

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A recent impact crater on Mars, seen by the MRO's HiRise camera.
A recent impact crater on Mars, seen by the MRO.
Image: NASA/JPL-Caltech/University of Arizona

The Viking 1 lander arrived on the Martian surface 46 years ago to investigate the planet. It dropped down into what was thought to be an ancient outflow channel. Now, a team of researchers believes they’ve found evidence of an ancient megatsunami that swept across the planet billions of years ago, less than 600 miles from where Viking landed.

In a new paper published today in Scientific Reports, a team identified a 68-mile-wide impact crater in Mars’ northern lowlands that they suspect is leftover from an asteroid strike in the planet’s ancient past.


“The simulation clearly shows that the megatsunami was enormous, with an initial height of approximately 250 meters, and highly turbulent,” said Alexis Rodriguez, a researcher at the Planetary Science Institute and lead author of the paper, in an email to Gizmodo. “Furthermore, our modeling shows some radically different behavior of the megatsunami to what we are accustomed to imagining.”

Rodriguez’s team studied maps of the Martian surface and found the large crater, now named Pohl. Based on Pohl’s position on previously dated rocks, the team believes the crater is about 3.4 billion years old—an extraordinarily long time ago, shortly after the first signs of life we know of appeared on Earth.


According to the research team’s models, the asteroid impact could have been so intense that material from the seafloor may have dislodged and been carried in the water’s debris flows. Based on the size of the crater, the team believes the impacting asteroid could have been 1.86 miles wide or 6 miles wide, depending on the amount of ground resistance the asteroid encountered.

The impact could have released between 500,000 megatons and 13 million megatons of TNT energy (for comparison, the Tsar Bomba nuclear test was about 57 megatons of TNT energy.)

“A clear next step is to propose a landing site to investigate these deposits in detail to understand the ocean’s evolution and potential habitability,” Rodriguez said. “First, we would need a detailed geologic mapping of the area to reconstruct the stratigraphy. Then, we need to connect the surface modification history to specific processes through numerical modeling and analog studies, including identifying possible mud volcanoes and glacier landforms.”

Both lines of investigation are noble pursuits, but it may be some time before a new Mars lander gets off the ground. NASA is always juggling missions, but its main planetary focus in the future is Venus. The DAVINCI+ and Veritas missions would see two spacecraft arrive at the second planet from the Sun at the turn of the decade.


There are no plans for a future Mars lander, besides the Mars Sample Return mission, which will retrieve the rock core samples currently being extracted by the Perseverance rover on the western edge of the planet’s Jezero Crater.

NASA is canceling and delaying missions as it deals with a budget crunch, so exactly when the agency could turn its attention to the Pohl crater is unclear. With the InSight lander on its last legs, we will soon lose one of our best interrogators of the Martian interior.


More: Stunning New View of Mars Shows Where Ancient Flowing Water Once Carved Its Surface