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New experiments reveal Mars' striking gullies are carved by rapidly sublimating CO₂ ice blocks, not liquid water, solving a major planetary science puzzle and shifting the search for Martian habitability.
October 16, 2025
Source:
http://Phys.org
Martian Gullies: An Explosive Discovery
Laboratory experiments have settled a long-standing Martian mystery: the gullies etched across the planet’s dunes owe their existence to explosive movements of dry ice, not flowing water. The results, published in Phys.org, overturn previous assumptions about the Red Planet’s surface and its habitability.
CO₂ Ice in Martian Winters
Blocks of carbon dioxide ice, known as dry ice, form during Mars’ harsh winters as temperatures plunge to -120°C.
As sunlight returns, meter-long slabs of CO₂ ice break from dune crests.
The Sublimation Process
Martian sunlight heats the sand, causing the bottom of the ice to sublimate rapidly—directly transitioning from solid to gas.
This creates a pressurized gas cushion, "burrowing" and sliding the ice block downhill, carving deep, sinuous gullies.
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Source:
http://Phys.org
Proof From the Lab and Orbit
Experimental Evidence
Researchers at the Open University used a Mars simulation chamber to recreate the atmospheric and temperature conditions found on Mars (ScienceDaily).
CO₂ ice blocks rapidly dug worm-like channels in sand, exactly mirroring those seen in Mars orbiter images.
Visual Confirmation
Images from experiments closely match satellite pictures of Martian gullies, as seen in reporting from Utrecht University.
These processes are unique to Mars, as similar ice-sand interactions do not occur on Earth.
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Source:
http://Phys.org
Implications for Mars Exploration
New Perspective on Martian Geology
The findings challenge long-held theories that water sculpted the gullies and reduce the likelihood of near-surface water-driven habitability in these regions (AGU Publications).
Future rover missions will shift their search away from these gullied areas, focusing on other potential habitats for signs of life.
Adapting Planetary Science
Mars’ unique climate and atmospheric pressure create geological processes unseen anywhere else.
Researchers stress the importance of context-specific analysis when interpreting extraterrestrial landscapes (Sci.News).
How does the sublimation process of CO₂ ice blocks differ from other geological processes on Mars?
CO₂ ice blocks sublimate directly into gas, creating a gas cushion that blasts sand aside and carves gullies, unlike slower processes involving wind, dust, or potential water flow.
What are the implications of these findings for future Mars missions?
How do these gullies compare to those formed by liquid water on Earth?
What other unique geological features might be explained by similar processes on Mars?
How does the Martian atmosphere contribute to the formation of these gullies?
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