Scientists already knew that water ice lurked below Mars' surface. But a new study published in the journal Science sheds new light on what Space.com calls "apparent glaciers," seen anew thanks to high-res imagery from the HiRISE camera on NASA's Mars Reconnaissance Orbiter. Using this data, researchers found eight spots on the Red Planet that had been eroded, with steep slopes of ice sheets, or scarps, reaching from just below the surface (meaning it won't be hard to get to if humans or robots ever get there) to more than 325 feet deep. The images, which render the ice in 3D, show discrete layers within the ice, which could offer clues on how climate change has affected Mars. The scientists believe the ice was once snow that fell when Mars' axis was tilted more prominently toward the sun; that snow has since evolved into "massive, fractured, and layered ice."
The ice sheets are located at latitudes that would be the equivalent of Scotland or the tip of South America on Earth, per NBC News. "It's like having one of those ant farms where you can see through the glass on the side to learn about what's usually hidden beneath the ground," study co-author Shane Byrne says of the detailed imagery, per Phys.org. Although scientists haven't yet figured out how these ice scarps form, they do know that once they peek out into the atmosphere, they turn from ice into water vapor, a process called sublimation, and "retreat" as they get taller and wider. The ice chunks could even prove handy as water sources if and when humans ever touch down to explore the planet, the study notes. "Astronauts could essentially just go there with a bucket and a shovel and get all the water they need," Byrne says. (What's up with those Mars "scratch marks"?)