Experiments reveal how dry ice shapes Martian dunes every spring

Dry Ice Burrows Beneath Mars Dunes (Image: NASA/JPL)

Scientists have cracked a long-standing Martian mystery. Those seasonal gullies on sand dunes that everyone thought were made by water. Turns out, carbon dioxide (CO₂) ice, or dry ice, is the culprit. Experiments under simulated Martian conditions confirm this surprising process.

When Did Scientists Begin Investigating?

The phenomenon was first noticed in 2013, prompting alternative explanations. Because Mars is so cold, liquid water is not responsible for those winding gullies. Instead, scientists thought that maybe sliding dry ice that turns into gas was creating them. Scientists proposed that sublimating dry ice sliding down the slopes might create these features instead.

Where Were the Experiments Conducted?

Dr. Lonneke Roelofs and her Utrecht University group, along with the Open University's Mars chamber, rebuilt Martian sand dunes right here on Earth. The chamber copied the low pressure, super cold and dry conditions of Mars.

What did the experiments show?

The team put CO₂ ice blocks on sand slopes with different angles and grain sizes. High-speed cameras captured their movement. On gentler slopes below 22.5 degrees, the ice partially burrowed into the sand. As it sublimated, it explosively ejected sand, creating sinuous tracks, raised levees and terminal pockets resembling Martian gullies.

Why Is This Important?

The study demonstrates that water is not required to form these dune gullies. Instead, dry ice burrowing and blasting sand shapes the Martian landscape each spring. This improves our understanding of active surface processes on Mars and reshapes assumptions about potential liquid water activity.

How Does This Change Mars Research?

By verifying that CO₂ ice changes from solid to gas, researchers can now read Martian surface features better. This idea explains this strange textures, curves and pockets that were once hard to understand. It gives us a full idea of how gullies form on sand dunes all over Mars.