Outpoll | Who or what dug Mars’ mysterious gullies? The answer is explosive

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Who or what dug Mars’ mysterious gullies? The answer is explosive

Who or what dug Mars’ mysterious gullies? The answer is explosive

19 hours ago7 min read4 comments

The enigmatic gullies scarring the face of Mars, long a source of planetary science debate, may finally have a culprit as dramatic as the landscape itself: explosive blocks of carbon dioxide ice. For years, scientists have puzzled over the sinuous, worm-like channels that carve through Martian dunes, features that seem to defy the simple explanations of water flow in a world now so arid.The prevailing theories often felt incomplete, like trying to explain a thunderstorm with a sprinkle. But now, a groundbreaking series of lab experiments, simulating the Red Planet's frigid temperatures and whisper-thin atmosphere, has revealed a compelling new geomorphic actor.Researchers have demonstrated that slabs of CO₂ ice, which freeze directly from the atmosphere onto the cold Martian surface during winter, can initiate these processes. As the seasons turn and the ice begins to sublimate—transforming directly from a solid into a gas in the low-pressure environment—it doesn't just vanish.The sublimation generates pockets of pressurized gas at the ice's base, effectively levitating entire blocks and sending them sliding downslope with an eerie, fluid grace. This isn't the slow creep of a glacier; it's a buoyant, almost ghostly procession.As these ice blocks skid and tumble, they act as nature's sculpting tools, plowing and scouring the soft, sandy regolith to etch the distinctive gullies we observe from orbit. This mechanism elegantly solves the puzzle of how such dynamic erosion can occur in a contemporary climate where liquid water is unstable.It paints a picture of an alien geological cycle driven not by water, but by a substance we more commonly associate with our fizzy drinks. The implications ripple outward, forcing a reinterpretation of Martian surface evolution.These CO₂-driven processes are likely responsible for a whole suite of unusual dune formations and changing features that orbiters like HiRISE have documented, suggesting that Mars is a far more active world than previously assumed, its face reshaped by the seasonal breath of its own atmosphere. This discovery deepens our fundamental understanding of landscape dynamics on other worlds, providing a new template for how planets without Earth-like hydrology can still undergo complex and rapid geomorphic change. It’s a humbling reminder that the universe operates on its own unique principles, and that the forces shaping alien worlds can be as subtle and explosive as a block of ice turning directly into a ghost of a gas.