New data from NASA's Curiosity rover reveals strange, rocky formations on Marsthat, from orbit, resemble giant spider webs spread across the Red Planet's surface. The close-up images captured by the rover may be a crucial piece to the puzzle of Mars' water history, providing new clues about when and for how long liquid water existed near its surface.
Boxwork: A geological footprint of groundwater
The formations are part of a boxwork-like area on the slopes of Mount Sharp, inside Gale Crater. They are networks of low ridges, 1 to 2 meters high, that intersect, creating sandy hollows between them. On September 26, 2025, Curiosity captured high-resolution panoramic images with its Mastcam camera, giving scientists an unprecedented look at this unusual terrain.
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From above, the intersecting ridges form patterns reminiscent of a spider's web. The prevailing theory is that ancient groundwater seeped through cracks in the rocks, depositing minerals that hardened specific zones. Over billions of years, wind erosion removed the softer material, leaving behind the durable network of ridges.
Mars: How long did it have liquid water?
The significance of the discovery goes beyond the aesthetic appeal of the formations. These structures may indicate that groundwater remained active at later stages of Martian history than previously thought. If confirmed, this would expand the window of potential habitability for Mars.
Until Curiosity arrived in the area, scientists relied exclusively on satellite data. However, only an on-site mission could clarify the morphology and chemical composition of the formations. Access, however, was not an easy task. Operators had to guide the rover, weighing almost a ton, over narrow ridges barely wider than itself, avoiding slipping in sandy hollows.
Trace minerals and geochemical surprises
Detailed analysis revealed small mineral nodulesembedded in both the ridges and the floors of the cavities. What was surprising was their distribution: instead of being concentrated near major faults, as predicted by models, they were found scattered throughout the area. This suggests more complex interactions between water and minerals in the Martian subsurface.
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At the same time, Curiosity used its drill to collect rock samples. The analyses identified clay minerals on the ridge tops and carbonate deposits in the depressions. Clays are often associated with the presence of water, while carbonates can form in environments with neutral to alkaline pH — conditions theoretically friendly to microbial life.
Search for organic molecules and the next step
Using wet chemistry, the scientists examined samples for carbon-based organic compounds. This process allows for the discovery of molecular “signatures” that could be linked to biological processes. While the presence of organic molecules is not proof of life, it is a crucial step in understanding the chemical evolution of the planet.
Mount Sharp, about 5 kilometers high, acts as a geological record of Mars' climate history. As Curiosity ascends, it records a clear transition from wetter to increasingly drier conditions, with intervening episodes of the reappearance of rivers and lakes. The existence of boxwork so high suggests that the water table was once significantly elevated.
See also: Mars was once blue – New evidence for a lost ocean
The rover is expected to leave the area in March, continuing its mission. Every meter it travels is not just a spatial shift, but a journey back in time, to a time when Mars might not have been the frozen desert we know today, but a worldwith water, chemical complexity and—possibly—the building blocks of life.
