No water? Martian gullies shaped by ice, sand: Study
Turns out those strange gullies on Mars weren't primarily made by flowing water after all—they're shaped mainly by sand and seasonal carbon dioxide (CO2) ice.
New research has flipped the old theory, showing that these icy processes—not liquid water—are behind many of these gullies.
This could totally change how scientists explore and study Mars in the future.
How CO2 ice carves out gullies
Scientists first spotted these gullies in the 1990s, sparking hopes of finding water on Mars.
But newer observations found no signs of hydrated minerals in most of the gullies examined.
The latest studies reveal that when Martian spring arrives, CO2 ice turns directly into gas (a process called sublimation), pushing sand downhill and carving out those gullies.
Lab experiments even recreated this effect with sliding blocks of dry ice, proving you don't need water to shape parts of Mars's landscape.