Martian Gullies Carved by Exploding Dry Ice,new Research Reveals
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A groundbreaking study suggests that mysterious gullies on Martian sand dunes are not the result of flowing water,but rather the dramatic action of sliding,sublimating blocks of carbon dioxide ice.
For decades, planetary scientists have been puzzled by the sinuous channels etched into the Martian landscape. Now, research led by Dr. Lonneke Roelofs of Utrecht University proposes a novel explanation: sublimation, the process where a solid transitions directly into a gas. This process, driven by the unique Martian surroundings, appears to be a key sculptor of the Red PlanetS surface.
Simulating Martian Landscapes on Earth
Roelofs and her team replicated Martian conditions in a specialized “Mars chamber” at The Open University in Milton Keynes. this controlled environment mimics the Red Planet’s frigid temperatures and low atmospheric pressure. Within the chamber, blocks of CO2 ice were observed sliding down simulated dunes, carving channels remarkably similar to those seen in images captured by orbiting spacecraft. “It felt like I was watching the sandworms in the film Dune,” Roelofs remarked, referencing the colossal creatures that traverse desert landscapes.
The Explosive Power of Sublimation
The process begins during the Martian winter, when temperatures plummet to as low as minus 120 degrees Celsius, allowing CO2 ice to accumulate on dunes. As spring arrives and sunlight warms the surface,blocks of CO2 ice – sometimes reaching up to a meter in length – break away. The warmer sand beneath these blocks triggers rapid sublimation on the ice’s lower surface.
This sublimation isn’t a gentle melting; it’s an explosive vaporization. “In our simulation, I saw how this high gas pressure blasts away the sand around the block in all directions,” Roelofs explained. The escaping gas acts as a propellant, forcing the ice block downward and forward, creating a trough surrounded by small ridges of displaced sand. This cycle continues as the ice block continues to sublimate, pushing it downhill and forming the characteristic long gullies with rippled ridges.
Distinct Morphology and Previous Research
Roelofs had previously investigated how CO2 sublimation contributes to debris flows on Martian crater walls. Though, the newly observed dune gullies exhibited a different morphology, prompting a dedicated investigation into their formation.By varying the steepness of simulated slopes within the Mars chamber, roelofs and her student, Simone Visschers, discovered the conditions under which the ice blocks began to self-propel and burrow downward, resembling the movement of a mole or, again, the sandworms of Dune.
The research indicates that these blocks form when a considerable layer – up to 70 centimeters thick – of CO2 frost accumulates across southern Martian dune fields each winter. The upper layers vaporize first with the return of sunlight, leaving behind isolated slabs that eventually fracture and tumble downslope. The sublimation process continues untill the ice entirely evaporates, leaving behind the distinctive hollowed-out troughs and gullies.
Implications for Understanding Planetary Evolution
“Mars is our nearest neighbor and the only rocky planet close to the green zone where liquid water might exist,” Roelofs stated. “By studying how its landscapes form,we can think differently about similar processes on Earth and perhaps gain new insights into our own planet’s evolution.” This research demonstrates that significant geological processes can occur on Mars without the presence of liquid water, expanding our understanding of planetary habitability and surface modification.
the findings are detailed in a research report titled “Sliding and burrowing blocks of CO2 create sinuous ‘linear dune gullies’ on Martian dunes by explosive sublimation-induced particle transport.”
Related details can be found at Utrecht University and MarsDaily.com.
