New images from NASA’s Curiosity rover are offering the first close-up look at a part of Mars that scientists had only observed from orbit—until now. These detailed views are already raising new questions about how the Martian surface changed over billions of years. Mars once had flowing rivers, lakes, and possibly even an ocean. But for reasons still unclear, that water eventually disappeared, transforming the planet into the cold, dry desert we see today.
By the time the layer Curiosity is now exploring was formed, the long-lived lakes in Gale Crater—its landing site—had already vanished. But groundwater was still present beneath the surface. Curiosity found dramatic evidence of this underground water in the form of low ridges, just a few inches tall, that crisscross the terrain in a pattern geologists call “boxwork.” These boxy structures likely formed when mineral-rich groundwater seeped through cracks in the bedrock, depositing materials that hardened over time. While the softer surrounding rock eroded from wind and dust over eons, the hardened mineral ridges remained, revealing a hidden framework etched into the landscape.
The ridges themselves resemble a crumbling curb and stretch for miles across a specific layer of Mount Sharp, a 3-mile-high mountain whose foothills Curiosity has been climbing since 2014. Interestingly, boxwork patterns like these haven’t been seen anywhere else on the mountain, not by Curiosity or by orbiting spacecraft.
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